Cleanups
kdb: Remove unused command flags, repeat flags and KDB_REPEAT_NONE
Fixes
kgdb/kdb: Allow access on a single core, if a CPU round up is deemed
impossible, which will allow inspection of the now "trashed" kernel
kdb: Add enable mask for the command groups
kdb: access controls to restrict sensitive commands
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Merge tag 'for_linus-3.19-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/jwessel/kgdb
Pull kgdb/kdb fixes from Jason Wessel:
"These have been around since 3.17 and in kgdb-next for the last 9
weeks and some will go back to -stable.
Summary of changes:
Cleanups
- kdb: Remove unused command flags, repeat flags and KDB_REPEAT_NONE
Fixes
- kgdb/kdb: Allow access on a single core, if a CPU round up is
deemed impossible, which will allow inspection of the now "trashed"
kernel
- kdb: Add enable mask for the command groups
- kdb: access controls to restrict sensitive commands"
* tag 'for_linus-3.19-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/jwessel/kgdb:
kernel/debug/debug_core.c: Logging clean-up
kgdb: timeout if secondary CPUs ignore the roundup
kdb: Allow access to sensitive commands to be restricted by default
kdb: Add enable mask for groups of commands
kdb: Categorize kdb commands (similar to SysRq categorization)
kdb: Remove KDB_REPEAT_NONE flag
kdb: Use KDB_REPEAT_* values as flags
kdb: Rename kdb_register_repeat() to kdb_register_flags()
kdb: Rename kdb_repeat_t to kdb_cmdflags_t, cmd_repeat to cmd_flags
kdb: Remove currently unused kdbtab_t->cmd_flags
Taking the global mutex "trace_types_lock" in the trace_pipe files
causes a bottle neck as most the pipe files can be read per cpu
and there's no reason to serialize them.
The current_trace variable was given a ref count and it can not
change when the ref count is not zero. Opening the trace_pipe
files will up the ref count (and decremented on close), so that
the lock no longer needs to be taken when accessing the
current_trace variable.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
When one of the trace pipe files are being read (by either the trace_pipe
or trace_pipe_raw), do not allow the current_trace to change. By adding
a ref count that is incremented when the pipe files are opened, will
prevent the current_trace from being changed.
This will allow for the removal of the global trace_types_lock from
reading the pipe buffers (which is currently a bottle neck).
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
- Fix a regression in leds-gpio introduced by a recent commit that
inadvertently changed the name of one of the properties used by
the driver (Fabio Estevam).
- Fix a regression in the ACPI backlight driver introduced by a
recent fix that missed one special case that had to be taken
into account (Aaron Lu).
- Drop the level of some new kernel messages from the ACPI core
introduced by a recent commit to KERN_DEBUG which they should
have used from the start and drop some other unuseful KERN_ERR
messages printed by ACPI (Rafael J Wysocki).
- Revert an incorrect commit modifying the cpupower tool
(Prarit Bhargava).
- Fix two regressions introduced by recent commits in the OPP
library and clean up some existing minor issues in that code
(Viresh Kumar).
- Continue to replace CONFIG_PM_RUNTIME with CONFIG_PM throughout
the tree (or drop it where that can be done) in order to make
it possible to eliminate CONFIG_PM_RUNTIME (Rafael J Wysocki,
Ulf Hansson, Ludovic Desroches). There will be one more
"CONFIG_PM_RUNTIME removal" batch after this one, because some
new uses of it have been introduced during the current merge
window, but that should be sufficient to finally get rid of it.
- Make the ACPI EC driver more robust against race conditions
related to GPE handler installation failures (Lv Zheng).
- Prevent the ACPI device PM core code from attempting to
disable GPEs that it has not enabled which confuses ACPICA
and makes it report errors unnecessarily (Rafael J Wysocki).
- Add a "force" command line switch to the intel_pstate driver
to make it possible to override the blacklisting of some
systems in that driver if needed (Ethan Zhao).
- Improve intel_pstate code documentation and add a MAINTAINERS
entry for it (Kristen Carlson Accardi).
- Make the ACPI fan driver create cooling device interfaces
witn names that reflect the IDs of the ACPI device objects
they are associated with, except for "generic" ACPI fans
(PNP ID "PNP0C0B"). That's necessary for user space thermal
management tools to be able to connect the fans with the
parts of the system they are supposed to be cooling properly.
From Srinivas Pandruvada.
/
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Merge tag 'pm+acpi-3.19-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
Pull more ACPI and power management updates from Rafael Wysocki:
"These are regression fixes (leds-gpio, ACPI backlight driver,
operating performance points library, ACPI device enumeration
messages, cpupower tool), other bug fixes (ACPI EC driver, ACPI device
PM), some cleanups in the operating performance points (OPP)
framework, continuation of CONFIG_PM_RUNTIME elimination, a couple of
minor intel_pstate driver changes, a new MAINTAINERS entry for it and
an ACPI fan driver change needed for better support of thermal
management in user space.
Specifics:
- Fix a regression in leds-gpio introduced by a recent commit that
inadvertently changed the name of one of the properties used by the
driver (Fabio Estevam).
- Fix a regression in the ACPI backlight driver introduced by a
recent fix that missed one special case that had to be taken into
account (Aaron Lu).
- Drop the level of some new kernel messages from the ACPI core
introduced by a recent commit to KERN_DEBUG which they should have
used from the start and drop some other unuseful KERN_ERR messages
printed by ACPI (Rafael J Wysocki).
- Revert an incorrect commit modifying the cpupower tool (Prarit
Bhargava).
- Fix two regressions introduced by recent commits in the OPP library
and clean up some existing minor issues in that code (Viresh
Kumar).
- Continue to replace CONFIG_PM_RUNTIME with CONFIG_PM throughout the
tree (or drop it where that can be done) in order to make it
possible to eliminate CONFIG_PM_RUNTIME (Rafael J Wysocki, Ulf
Hansson, Ludovic Desroches).
There will be one more "CONFIG_PM_RUNTIME removal" batch after this
one, because some new uses of it have been introduced during the
current merge window, but that should be sufficient to finally get
rid of it.
- Make the ACPI EC driver more robust against race conditions related
to GPE handler installation failures (Lv Zheng).
- Prevent the ACPI device PM core code from attempting to disable
GPEs that it has not enabled which confuses ACPICA and makes it
report errors unnecessarily (Rafael J Wysocki).
- Add a "force" command line switch to the intel_pstate driver to
make it possible to override the blacklisting of some systems in
that driver if needed (Ethan Zhao).
- Improve intel_pstate code documentation and add a MAINTAINERS entry
for it (Kristen Carlson Accardi).
- Make the ACPI fan driver create cooling device interfaces witn
names that reflect the IDs of the ACPI device objects they are
associated with, except for "generic" ACPI fans (PNP ID "PNP0C0B").
That's necessary for user space thermal management tools to be able
to connect the fans with the parts of the system they are supposed
to be cooling properly. From Srinivas Pandruvada"
* tag 'pm+acpi-3.19-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (32 commits)
MAINTAINERS: add entry for intel_pstate
ACPI / video: update the skip case for acpi_video_device_in_dod()
power / PM: Eliminate CONFIG_PM_RUNTIME
NFC / PM: Replace CONFIG_PM_RUNTIME with CONFIG_PM
SCSI / PM: Replace CONFIG_PM_RUNTIME with CONFIG_PM
ACPI / EC: Fix unexpected ec_remove_handlers() invocations
Revert "tools: cpupower: fix return checks for sysfs_get_idlestate_count()"
tracing / PM: Replace CONFIG_PM_RUNTIME with CONFIG_PM
x86 / PM: Replace CONFIG_PM_RUNTIME in io_apic.c
PM: Remove the SET_PM_RUNTIME_PM_OPS() macro
mmc: atmel-mci: use SET_RUNTIME_PM_OPS() macro
PM / Kconfig: Replace PM_RUNTIME with PM in dependencies
ARM / PM: Replace CONFIG_PM_RUNTIME with CONFIG_PM
sound / PM: Replace CONFIG_PM_RUNTIME with CONFIG_PM
phy / PM: Replace CONFIG_PM_RUNTIME with CONFIG_PM
video / PM: Replace CONFIG_PM_RUNTIME with CONFIG_PM
tty / PM: Replace CONFIG_PM_RUNTIME with CONFIG_PM
spi: Replace CONFIG_PM_RUNTIME with CONFIG_PM
ACPI / PM: Do not disable wakeup GPEs that have not been enabled
ACPI / utils: Drop error messages from acpi_evaluate_reference()
...
as I thought it might be. I'm pushing this in now.
This will allow Thomas to debug his irq work for 3.20.
This adds two new features:
1) Allow traceopoints to be enabled right after mm_init(). By passing
in the trace_event= kernel command line parameter, tracepoints can be
enabled at boot up. For debugging things like the initialization of
interrupts, it is needed to have tracepoints enabled very early. People
have asked about this before and this has been on my todo list. As it
can be helpful for Thomas to debug his upcoming 3.20 IRQ work, I'm
pushing this now. This way he can add tracepoints into the IRQ set up
and have users enable them when things go wrong.
2) Have the tracepoints printed via printk() (the console) when they
are triggered. If the irq code locks up or reboots the box, having the
tracepoint output go into the kernel ring buffer is useless for
debugging. But being able to add the tp_printk kernel command line
option along with the trace_event= option will have these tracepoints
printed as they occur, and that can be really useful for debugging
early lock up or reboot problems.
This code is not that intrusive and it passed all my tests. Thomas tried
them out too and it works for his needs.
Link: http://lkml.kernel.org/r/20141214201609.126831471@goodmis.org
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Merge tag 'trace-3.19-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull tracing updates from Steven Rostedt:
"As the merge window is still open, and this code was not as complex as
I thought it might be. I'm pushing this in now.
This will allow Thomas to debug his irq work for 3.20.
This adds two new features:
1) Allow traceopoints to be enabled right after mm_init().
By passing in the trace_event= kernel command line parameter,
tracepoints can be enabled at boot up. For debugging things like
the initialization of interrupts, it is needed to have tracepoints
enabled very early. People have asked about this before and this
has been on my todo list. As it can be helpful for Thomas to debug
his upcoming 3.20 IRQ work, I'm pushing this now. This way he can
add tracepoints into the IRQ set up and have users enable them when
things go wrong.
2) Have the tracepoints printed via printk() (the console) when they
are triggered.
If the irq code locks up or reboots the box, having the tracepoint
output go into the kernel ring buffer is useless for debugging.
But being able to add the tp_printk kernel command line option
along with the trace_event= option will have these tracepoints
printed as they occur, and that can be really useful for debugging
early lock up or reboot problems.
This code is not that intrusive and it passed all my tests. Thomas
tried them out too and it works for his needs.
Link: http://lkml.kernel.org/r/20141214201609.126831471@goodmis.org"
* tag 'trace-3.19-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
tracing: Add tp_printk cmdline to have tracepoints go to printk()
tracing: Move enabling tracepoints to just after rcu_init()
Add the kernel command line tp_printk option that will have tracepoints
that are active sent to printk() as well as to the trace buffer.
Passing "tp_printk" will activate this. To turn it off, the sysctl
/proc/sys/kernel/tracepoint_printk can have '0' echoed into it. Note,
this only works if the cmdline option is used. Echoing 1 into the sysctl
file without the cmdline option will have no affect.
Note, this is a dangerous option. Having high frequency tracepoints send
their data to printk() can possibly cause a live lock. This is another
reason why this is only active if the command line option is used.
Link: http://lkml.kernel.org/r/alpine.DEB.2.11.1412121539300.16494@nanos
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Enabling tracepoints at boot up can be very useful. The tracepoint
can be initialized right after RCU has been. There's no need to
wait for the early_initcall() to be called. That's too late for some
things that can use tracepoints for debugging. Move the logic to
enable tracepoints out of the initcalls and into init/main.c to
right after rcu_init().
This also allows trace_printk() to be used early too.
Link: http://lkml.kernel.org/r/alpine.DEB.2.11.1412121539300.16494@nanos
Link: http://lkml.kernel.org/r/20141214164104.307127356@goodmis.org
Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Pull block driver core update from Jens Axboe:
"This is the pull request for the core block IO changes for 3.19. Not
a huge round this time, mostly lots of little good fixes:
- Fix a bug in sysfs blktrace interface causing a NULL pointer
dereference, when enabled/disabled through that API. From Arianna
Avanzini.
- Various updates/fixes/improvements for blk-mq:
- A set of updates from Bart, mostly fixing buts in the tag
handling.
- Cleanup/code consolidation from Christoph.
- Extend queue_rq API to be able to handle batching issues of IO
requests. NVMe will utilize this shortly. From me.
- A few tag and request handling updates from me.
- Cleanup of the preempt handling for running queues from Paolo.
- Prevent running of unmapped hardware queues from Ming Lei.
- Move the kdump memory limiting check to be in the correct
location, from Shaohua.
- Initialize all software queues at init time from Takashi. This
prevents a kobject warning when CPUs are brought online that
weren't online when a queue was registered.
- Single writeback fix for I_DIRTY clearing from Tejun. Queued with
the core IO changes, since it's just a single fix.
- Version X of the __bio_add_page() segment addition retry from
Maurizio. Hope the Xth time is the charm.
- Documentation fixup for IO scheduler merging from Jan.
- Introduce (and use) generic IO stat accounting helpers for non-rq
drivers, from Gu Zheng.
- Kill off artificial limiting of max sectors in a request from
Christoph"
* 'for-3.19/core' of git://git.kernel.dk/linux-block: (26 commits)
bio: modify __bio_add_page() to accept pages that don't start a new segment
blk-mq: Fix uninitialized kobject at CPU hotplugging
blktrace: don't let the sysfs interface remove trace from running list
blk-mq: Use all available hardware queues
blk-mq: Micro-optimize bt_get()
blk-mq: Fix a race between bt_clear_tag() and bt_get()
blk-mq: Avoid that __bt_get_word() wraps multiple times
blk-mq: Fix a use-after-free
blk-mq: prevent unmapped hw queue from being scheduled
blk-mq: re-check for available tags after running the hardware queue
blk-mq: fix hang in bt_get()
blk-mq: move the kdump check to blk_mq_alloc_tag_set
blk-mq: cleanup tag free handling
blk-mq: use 'nr_cpu_ids' as highest CPU ID count for hwq <-> cpu map
blk: introduce generic io stat accounting help function
blk-mq: handle the single queue case in blk_mq_hctx_next_cpu
genhd: check for int overflow in disk_expand_part_tbl()
blk-mq: add blk_mq_free_hctx_request()
blk-mq: export blk_mq_free_request()
blk-mq: use get_cpu/put_cpu instead of preempt_disable/preempt_enable
...
After commit b2b49ccbdd (PM: Kconfig: Set PM_RUNTIME if PM_SLEEP is
selected) PM_RUNTIME is always set if PM is set, so files that are
build conditionally if CONFIG_PM_RUNTIME is set may now be build
if CONFIG_PM is set.
Replace CONFIG_PM_RUNTIME with CONFIG_PM in kernel/trace/Makefile
for this reason.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org.
clean ups from that branch.
This code solves the issue of performing stack dumps from NMI context.
The issue is that printk() is not safe from NMI context as if the NMI
were to trigger when a printk() was being performed, the NMI could
deadlock from the printk() internal locks. This has been seen in practice.
With lots of review from Petr Mladek, this code went through several
iterations, and we feel that it is now at a point of quality to be
accepted into mainline.
Here's what is contained in this patch set:
o Creates a "seq_buf" generic buffer utility that allows a descriptor
to be passed around where functions can write their own "printk()"
formatted strings into it. The generic version was pulled out of
the trace_seq() code that was made specifically for tracing.
o The seq_buf code was change to model the seq_file code. I have
a patch (not included for 3.19) that converts the seq_file.c code
over to use seq_buf.c like the trace_seq.c code does. This was done
to make sure that seq_buf.c is compatible with seq_file.c. I may
try to get that patch in for 3.20.
o The seq_buf.c file was moved to lib/ to remove it from being dependent
on CONFIG_TRACING.
o The printk() was updated to allow for a per_cpu "override" of
the internal calls. That is, instead of writing to the console, a call
to printk() may do something else. This made it easier to allow the
NMI to change what printk() does in order to call dump_stack() without
needing to update that code as well.
o Finally, the dump_stack from all CPUs via NMI code was converted to
use the seq_buf code. The caller to trigger the NMI code would wait
till all the NMIs finished, and then it would print the seq_buf
data to the console safely from a non NMI context.
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Merge tag 'trace-seq-buf-3.19' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull nmi-safe seq_buf printk update from Steven Rostedt:
"This code is a fork from the trace-3.19 pull as it needed the
trace_seq clean ups from that branch.
This code solves the issue of performing stack dumps from NMI context.
The issue is that printk() is not safe from NMI context as if the NMI
were to trigger when a printk() was being performed, the NMI could
deadlock from the printk() internal locks. This has been seen in
practice.
With lots of review from Petr Mladek, this code went through several
iterations, and we feel that it is now at a point of quality to be
accepted into mainline.
Here's what is contained in this patch set:
- Creates a "seq_buf" generic buffer utility that allows a descriptor
to be passed around where functions can write their own "printk()"
formatted strings into it. The generic version was pulled out of
the trace_seq() code that was made specifically for tracing.
- The seq_buf code was change to model the seq_file code. I have a
patch (not included for 3.19) that converts the seq_file.c code
over to use seq_buf.c like the trace_seq.c code does. This was
done to make sure that seq_buf.c is compatible with seq_file.c. I
may try to get that patch in for 3.20.
- The seq_buf.c file was moved to lib/ to remove it from being
dependent on CONFIG_TRACING.
- The printk() was updated to allow for a per_cpu "override" of the
internal calls. That is, instead of writing to the console, a call
to printk() may do something else. This made it easier to allow
the NMI to change what printk() does in order to call dump_stack()
without needing to update that code as well.
- Finally, the dump_stack from all CPUs via NMI code was converted to
use the seq_buf code. The caller to trigger the NMI code would
wait till all the NMIs finished, and then it would print the
seq_buf data to the console safely from a non NMI context
One added bonus is that this code also makes the NMI dump stack work
on PREEMPT_RT kernels. As printk() includes sleeping locks on
PREEMPT_RT, printk() only writes to console if the console does not
use any rt_mutex converted spin locks. Which a lot do"
* tag 'trace-seq-buf-3.19' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
x86/nmi: Fix use of unallocated cpumask_var_t
printk/percpu: Define printk_func when printk is not defined
x86/nmi: Perform a safe NMI stack trace on all CPUs
printk: Add per_cpu printk func to allow printk to be diverted
seq_buf: Move the seq_buf code to lib/
seq-buf: Make seq_buf_bprintf() conditional on CONFIG_BINARY_PRINTF
tracing: Add seq_buf_get_buf() and seq_buf_commit() helper functions
tracing: Have seq_buf use full buffer
seq_buf: Add seq_buf_can_fit() helper function
tracing: Add paranoid size check in trace_printk_seq()
tracing: Use trace_seq_used() and seq_buf_used() instead of len
tracing: Clean up tracing_fill_pipe_page()
seq_buf: Create seq_buf_used() to find out how much was written
tracing: Add a seq_buf_clear() helper and clear len and readpos in init
tracing: Convert seq_buf fields to be like seq_file fields
tracing: Convert seq_buf_path() to be like seq_path()
tracing: Create seq_buf layer in trace_seq
to the trace_seq code. It also removed the return values to the
trace_seq_*() functions and use trace_seq_has_overflowed() to see if
the buffer filled up or not. This is similar to work being done to the
seq_file code as well in another tree.
Some of the other goodies include:
o Added some "!" (NOT) logic to the tracing filter.
o Fixed the frame pointer logic to the x86_64 mcount trampolines
o Added the logic for dynamic trampolines on !CONFIG_PREEMPT systems.
That is, the ftrace trampoline can be dynamically allocated
and be called directly by functions that only have a single hook
to them.
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Merge tag 'trace-3.19' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull tracing updates from Steven Rostedt:
"There was a lot of clean ups and minor fixes. One of those clean ups
was to the trace_seq code. It also removed the return values to the
trace_seq_*() functions and use trace_seq_has_overflowed() to see if
the buffer filled up or not. This is similar to work being done to
the seq_file code as well in another tree.
Some of the other goodies include:
- Added some "!" (NOT) logic to the tracing filter.
- Fixed the frame pointer logic to the x86_64 mcount trampolines
- Added the logic for dynamic trampolines on !CONFIG_PREEMPT systems.
That is, the ftrace trampoline can be dynamically allocated and be
called directly by functions that only have a single hook to them"
* tag 'trace-3.19' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (55 commits)
tracing: Truncated output is better than nothing
tracing: Add additional marks to signal very large time deltas
Documentation: describe trace_buf_size parameter more accurately
tracing: Allow NOT to filter AND and OR clauses
tracing: Add NOT to filtering logic
ftrace/fgraph/x86: Have prepare_ftrace_return() take ip as first parameter
ftrace/x86: Get rid of ftrace_caller_setup
ftrace/x86: Have save_mcount_regs macro also save stack frames if needed
ftrace/x86: Add macro MCOUNT_REG_SIZE for amount of stack used to save mcount regs
ftrace/x86: Simplify save_mcount_regs on getting RIP
ftrace/x86: Have save_mcount_regs store RIP in %rdi for first parameter
ftrace/x86: Rename MCOUNT_SAVE_FRAME and add more detailed comments
ftrace/x86: Move MCOUNT_SAVE_FRAME out of header file
ftrace/x86: Have static tracing also use ftrace_caller_setup
ftrace/x86: Have static function tracing always test for function graph
kprobes: Add IPMODIFY flag to kprobe_ftrace_ops
ftrace, kprobes: Support IPMODIFY flag to find IP modify conflict
kprobes/ftrace: Recover original IP if pre_handler doesn't change it
tracing/trivial: Fix typos and make an int into a bool
tracing: Deletion of an unnecessary check before iput()
...
Currently, blktrace can be started/stopped via its ioctl-based interface
(used by the userspace blktrace tool) or via its ftrace interface. The
function blk_trace_remove_queue(), called each time an "enable" tunable
of the ftrace interface transitions to zero, removes the trace from the
running list, even if no function from the sysfs interface adds it to
such a list. This leads to a null pointer dereference. This commit
changes the blk_trace_remove_queue() function so that it does not remove
the blk_trace from the running list.
v2:
- Now the patch removes the invocation of list_del() instead of
adding an useless if branch, as suggested by Namhyung Kim.
Signed-off-by: Arianna Avanzini <avanzini.arianna@gmail.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
The initial reason for this patch is that I noticed that:
if (len > TRACE_BUF_SIZE)
is off by one. In this code, if len == TRACE_BUF_SIZE, then it means we
have truncated the last character off the output string. If we truncate
two or more characters then we exit without printing.
After some discussion, we decided that printing truncated data is better
than not printing at all so we should just use vscnprintf() and remove
the test entirely. Also I have updated memcpy() to copy the NUL char
instead of setting the NUL in a separate step.
Link: http://lkml.kernel.org/r/20141127155752.GA21914@mwanda
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Currently, function graph tracer prints "!" or "+" just before
function execution time to signal a function overhead, depending
on the time. And some tracers tracing latency also print "!" or
"+" just after time to signal overhead, depending on the interval
between events. Even it is usually enough to do that, we sometimes
need to signal for bigger execution time than 100 micro seconds.
For example, I used function graph tracer to detect if there is
any case that exit_mm() takes too much time. I did following steps
in /sys/kernel/debug/tracing. It was easier to detect very large
excution time with patched kernel than with original kernel.
$ echo exit_mm > set_graph_function
$ echo function_graph > current_tracer
$ echo > trace
$ cat trace_pipe > $LOGFILE
... (do something and terminate logging)
$ grep "\\$" $LOGFILE
3) $ 22082032 us | } /* kernel_map_pages */
3) $ 22082040 us | } /* free_pages_prepare */
3) $ 22082113 us | } /* free_hot_cold_page */
3) $ 22083455 us | } /* free_hot_cold_page_list */
3) $ 22083895 us | } /* release_pages */
3) $ 22177873 us | } /* free_pages_and_swap_cache */
3) $ 22178929 us | } /* unmap_single_vma */
3) $ 22198885 us | } /* unmap_vmas */
3) $ 22206949 us | } /* exit_mmap */
3) $ 22207659 us | } /* mmput */
3) $ 22207793 us | } /* exit_mm */
And then, it was easy to find out that a schedule-out occured by
sub_preempt_count() within kernel_map_pages().
To detect very large function exection time caused by either problematic
function implementation or scheduling issues, this patch can be useful.
Link: http://lkml.kernel.org/r/1416789259-24038-1-git-send-email-byungchul.park@lge.com
Signed-off-by: Byungchul Park <byungchul.park@lge.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Add support to allow not "!" for and (&&) and (||). That is:
!(field1 == X && field2 == Y)
Where the value of the full clause will be notted.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Ted noticed that he could not filter on an event for a bit being cleared.
That's because the filtering logic only tests event fields with a limited
number of comparisons which, for bit logic, only include "&", which can
test if a bit is set, but there's no good way to see if a bit is clear.
This adds a way to do: !(field & 2048)
Which returns true if the bit is not set, and false otherwise.
Note, currently !(field1 == 10 && field2 == 15) is not supported.
That is, the 'not' only works for direct comparisons, not for the
AND and OR logic.
Link: http://lkml.kernel.org/r/20141202021912.GA29096@thunk.org
Link: http://lkml.kernel.org/r/20141202120430.71979060@gandalf.local.home
Acked-by: Alexei Starovoitov <ast@plumgrid.com>
Suggested-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Introduce FTRACE_OPS_FL_IPMODIFY to avoid conflict among
ftrace users who may modify regs->ip to change the execution
path. If two or more users modify the regs->ip on the same
function entry, one of them will be broken. So they must add
IPMODIFY flag and make sure that ftrace_set_filter_ip() succeeds.
Note that ftrace doesn't allow ftrace_ops which has IPMODIFY
flag to have notrace hash, and the ftrace_ops must have a
filter hash (so that the ftrace_ops can hook only specific
entries), because it strongly depends on the address and
must be allowed for only few selected functions.
Link: http://lkml.kernel.org/r/20141121102516.11844.27829.stgit@localhost.localdomain
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Seth Jennings <sjenning@redhat.com>
Cc: Petr Mladek <pmladek@suse.cz>
Cc: Vojtech Pavlik <vojtech@suse.cz>
Cc: Miroslav Benes <mbenes@suse.cz>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
[ fixed up some of the comments ]
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Fix up a few typos in comments and convert an int into a bool in
update_traceon_count().
Link: http://lkml.kernel.org/r/546DD445.5080108@hitachi.com
Suggested-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The seq_buf functions are rather useful outside of tracing. Instead
of having it be dependent on CONFIG_TRACING, move the code into lib/
and allow other users to have access to it even when tracing is not
configured.
The seq_buf utility is similar to the seq_file utility, but instead of
writing sending data back up to userland, it writes it into a buffer
defined at seq_buf_init(). This allows us to send a descriptor around
that writes printf() formatted strings into it that can be retrieved
later.
It is currently used by the tracing facility for such things like trace
events to convert its binary saved data in the ring buffer into an
ASCII human readable context to be displayed in /sys/kernel/debug/trace.
It can also be used for doing NMI prints safely from NMI context into
the seq_buf and retrieved later and dumped to printk() safely. Doing
printk() from an NMI context is dangerous because an NMI can preempt
a current printk() and deadlock on it.
Link: http://lkml.kernel.org/p/20140619213952.058255809@goodmis.org
Tested-by: Jiri Kosina <jkosina@suse.cz>
Acked-by: Jiri Kosina <jkosina@suse.cz>
Reviewed-by: Petr Mladek <pmladek@suse.cz>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The function bstr_printf() from lib/vsprnintf.c is only available if
CONFIG_BINARY_PRINTF is defined. This is due to the only user currently
being the tracing infrastructure, which needs to select this config
when tracing is configured. Until there is another user of the binary
printf formats, this will continue to be the case.
Since seq_buf.c is now lives in lib/ and is compiled even without
tracing, it must encompass its use of bstr_printf() which is used
by seq_buf_printf(). This too is only used by the tracing infrastructure
and is still encapsulated by the CONFIG_BINARY_PRINTF.
Link: http://lkml.kernel.org/r/20141104160222.969013383@goodmis.org
Tested-by: Jiri Kosina <jkosina@suse.cz>
Acked-by: Jiri Kosina <jkosina@suse.cz>
Reviewed-by: Petr Mladek <pmladek@suse.cz>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Add two helper functions; seq_buf_get_buf() and seq_buf_commit() that
are used by seq_buf_path(). This makes the code similar to the
seq_file: seq_path() function, and will help to be able to consolidate
the functions between seq_file and trace_seq.
Link: http://lkml.kernel.org/r/20141104160222.644881406@goodmis.org
Link: http://lkml.kernel.org/r/20141114011412.977571447@goodmis.org
Tested-by: Jiri Kosina <jkosina@suse.cz>
Acked-by: Jiri Kosina <jkosina@suse.cz>
Reviewed-by: Petr Mladek <pmladek@suse.cz>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Currently seq_buf is full when all but one byte of the buffer is
filled. Change it so that the seq_buf is full when all of the
buffer is filled.
Some of the functions would fill the buffer completely and report
everything was fine. This was inconsistent with the max of size - 1.
Changing this to be max of size makes all functions consistent.
Link: http://lkml.kernel.org/r/20141104160222.502133196@goodmis.org
Link: http://lkml.kernel.org/r/20141114011412.811957882@goodmis.org
Tested-by: Jiri Kosina <jkosina@suse.cz>
Acked-by: Jiri Kosina <jkosina@suse.cz>
Reviewed-by: Petr Mladek <pmladek@suse.cz>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Add a seq_buf_can_fit() helper function that removes the possible mistakes
of comparing the seq_buf length plus added data compared to the size of
the buffer.
Link: http://lkml.kernel.org/r/20141118164025.GL23958@pathway.suse.cz
Reviewed-by: Petr Mladek <pmladek@suse.cz>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
To be really paranoid about writing out of bound data in
trace_printk_seq(), add another check of len compared to size.
Link: http://lkml.kernel.org/r/20141119144004.GB2332@dhcp128.suse.cz
Suggested-by: Petr Mladek <pmladek@suse.cz>
Reviewed-by: Petr Mladek <pmladek@suse.cz>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
As the seq_buf->len will soon be +1 size when there's an overflow, we
must use trace_seq_used() or seq_buf_used() methods to get the real
length. This will prevent buffer overflow issues if just the len
of the seq_buf descriptor is used to copy memory.
Link: http://lkml.kernel.org/r/20141114121911.09ba3d38@gandalf.local.home
Reported-by: Petr Mladek <pmladek@suse.cz>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The function tracing_fill_pipe_page() logic is a little confusing with the
use of count saving the seq.len and reusing it.
Instead of subtracting a number that is calculated from the saved
value of the seq.len from seq.len, just save the seq.len at the start
and if we need to reset it, just assign it again.
When the seq_buf overflow is len == size + 1, the current logic will
break. Changing it to use a saved length for resetting back to the
original value is more robust and will work when we change the way
seq_buf sets the overflow.
Link: http://lkml.kernel.org/r/20141118161546.GJ23958@pathway.suse.cz
Reviewed-by: Petr Mladek <pmladek@suse.cz>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Rewrite seq_buf_path() like it is done in seq_path() and allow
it to accept any escape character instead of just "\n".
Making seq_buf_path() like seq_path() will help prevent problems
when converting seq_file to use the seq_buf logic.
Link: http://lkml.kernel.org/r/20141104160222.048795666@goodmis.org
Link: http://lkml.kernel.org/r/20141114011412.338523371@goodmis.org
Tested-by: Jiri Kosina <jkosina@suse.cz>
Acked-by: Jiri Kosina <jkosina@suse.cz>
Reviewed-by: Petr Mladek <pmladek@suse.cz>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Create a seq_buf layer that trace_seq sits on. The seq_buf will not
be limited to page size. This will allow other usages of seq_buf
instead of a hard set PAGE_SIZE one that trace_seq has.
Link: http://lkml.kernel.org/r/20141104160221.864997179@goodmis.org
Link: http://lkml.kernel.org/r/20141114011412.170377300@goodmis.org
Tested-by: Jiri Kosina <jkosina@suse.cz>
Acked-by: Jiri Kosina <jkosina@suse.cz>
Reviewed-by: Petr Mladek <pmladek@suse.cz>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The iput() function tests whether its argument is NULL and then
returns immediately. Thus the test around the call is not needed.
This issue was detected by using the Coccinelle software.
Link: http://lkml.kernel.org/r/5468F875.7080907@users.sourceforge.net
Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
If the trace_seq of ftrace_raw_output_prep() is full this function
returns TRACE_TYPE_PARTIAL_LINE, otherwise it returns zero.
The problem is that TRACE_TYPE_PARTIAL_LINE happens to be zero!
The thing is, the caller of ftrace_raw_output_prep() expects a
success to be zero. Change that to expect it to be
TRACE_TYPE_HANDLED.
Link: http://lkml.kernel.org/r/20141114112522.GA2988@dhcp128.suse.cz
Reminded-by: Petr Mladek <pmladek@suse.cz>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The trace_seq_printf() and friends are used to store strings into a buffer
that can be passed around from function to function. If the trace_seq buffer
fills up, it will not print any more. The return values were somewhat
inconsistant and using trace_seq_has_overflowed() was a better way to know
if the write to the trace_seq buffer succeeded or not.
Now that all users have removed reading the return value of the printf()
type functions, they can safely return void and keep future users of them
from reading the inconsistent values as well.
Link: http://lkml.kernel.org/r/20141114011411.992510720@goodmis.org
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The functions trace_seq_printf() and friends will not be returning values
soon and will be void functions. To know if they succeeded or not, the
functions trace_seq_has_overflowed() and trace_handle_return() should be
used instead.
Reviewed-by: Petr Mladek <pmladek@suse.cz>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The functions trace_seq_printf() and friends will soon no longer have
return values. Using trace_seq_has_overflowed() and trace_handle_return()
should be used instead.
Link: http://lkml.kernel.org/r/20141114011411.693008134@goodmis.org
Link: http://lkml.kernel.org/r/20141115050602.333705855@goodmis.org
Reviewed-by: Masami Hiramatsu <masami.hiramatu.pt@hitachi.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The functions trace_seq_printf() and friends will soon not have a return
value and will only be a void function. Use trace_seq_has_overflowed()
instead to know if the trace_seq operations succeeded or not.
Link: http://lkml.kernel.org/r/20141114011411.530216306@goodmis.org
Reviewed-by: Petr Mladek <pmladek@suse.cz>
Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The return values for trace_seq_printf() and friends are going to be
removed and they will become void functions. The mmio tracer checked
their return and even did so incorrectly.
Some of the funtions which returned the values were never checked
themselves. Removing all the checks simplifies the code.
Use trace_seq_has_overflowed() and trace_handle_return() where
necessary instead.
Reviewed-by: Petr Mladek <pmladek@suse.cz>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Instead of checking the return value of trace_seq_printf() and friends
for overflowing of the buffer, use the trace_seq_has_overflowed() helper
function.
This cleans up the code quite a bit and also takes us a step closer to
changing the return values of trace_seq_printf() and friends to void.
Link: http://lkml.kernel.org/r/20141114011411.181812785@goodmis.org
Reviewed-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Reviewed-by: Petr Mladek <pmladek@suse.cz>
Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Instead of doing individual checks all over the place that makes the code
very messy. Just check trace_seq_has_overflowed() at the end or in
strategic places.
This makes the code much cleaner and also helps with getting closer
to removing the return values of trace_seq_printf() and friends.
Link: http://lkml.kernel.org/r/20141114011410.987913836@goodmis.org
Reviewed-by: Petr Mladek <pmladek@suse.cz>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The branch tracer should not be checking the trace_seq_printf() return value
as that will soon be void. There's a new trace_handle_return() helper function
that will return TRACE_TYPE_PARTIAL_LINE if the trace_seq overflowed
and TRACE_TYPE_HANDLED otherwise.
Reviewed-by: Petr Mladek <pmladek@suse.cz>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Remove checking the return value of all trace_seq_puts(). It was wrong
anyway as only the last return value mattered. But as the trace_seq_puts()
is going to be a void function in the future, we should not be checking
the return value of it anyway.
Just return !trace_seq_has_overflowed() instead.
Reviewed-by: Petr Mladek <pmladek@suse.cz>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Checking the return code of every trace_seq_printf() operation and having
to return early if it overflowed makes the code messy.
Using the new trace_seq_has_overflowed() and trace_handle_return() functions
allows us to clean up the code.
In the future, trace_seq_printf() and friends will be turning into void
functions and not returning a value. The trace_seq_has_overflowed() is to
be used instead. This cleanup allows that change to take place.
Cc: Jens Axboe <axboe@fb.com>
Reviewed-by: Petr Mladek <pmladek@suse.cz>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Adding a trace_seq_has_overflowed() which returns true if the trace_seq
had too much written into it allows us to simplify the code.
Instead of checking the return value of every call to trace_seq_printf()
and friends, they can all be called normally, and at the end we can
return !trace_seq_has_overflowed() instead.
Several functions also return TRACE_TYPE_PARTIAL_LINE when the trace_seq
overflowed and TRACE_TYPE_HANDLED otherwise. Another helper function
was created called trace_handle_return() which takes a trace_seq and
returns these enums. Using this helper function also simplifies the
code.
This change also makes it possible to remove the return values of
trace_seq_printf() and friends. They should instead just be
void functions.
Link: http://lkml.kernel.org/r/20141114011410.365183157@goodmis.org
Reviewed-by: Petr Mladek <pmladek@suse.cz>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
In trace_seq_bitmask() it calls bitmap_scnprintf() not from the current
position of the trace_seq buffer (s->buffer + s->len), but instead from
the beginning of the buffer (s->buffer).
Luckily, the only user of this "ipi_raise tracepoint" uses it as the
first parameter, and as such, the start of the temp buffer in
include/trace/ftrace.h (see __get_bitmask()).
Reported-by: Petr Mladek <pmladek@suse.cz>
Reviewed-by: Petr Mladek <pmladek@suse.cz>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Stack traces that happen from function tracing check if the address
on the stack is a __kernel_text_address(). That is, is the address
kernel code. This calls core_kernel_text() which returns true
if the address is part of the builtin kernel code. It also calls
is_module_text_address() which returns true if the address belongs
to module code.
But what is missing is ftrace dynamically allocated trampolines.
These trampolines are allocated for individual ftrace_ops that
call the ftrace_ops callback functions directly. But if they do a
stack trace, the code checking the stack wont detect them as they
are neither core kernel code nor module address space.
Adding another field to ftrace_ops that also stores the size of
the trampoline assigned to it we can create a new function called
is_ftrace_trampoline() that returns true if the address is a
dynamically allocate ftrace trampoline. Note, it ignores trampolines
that are not dynamically allocated as they will return true with
the core_kernel_text() function.
Link: http://lkml.kernel.org/r/20141119034829.497125839@goodmis.org
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The function probe counting for traceon and traceoff suffered a race
condition where if the probe was executing on two or more CPUs at the
same time, it could decrement the counter by more than one when
disabling (or enabling) the tracer only once.
The way the traceon and traceoff probes are suppose to work is that
they disable (or enable) tracing once per count. If a user were to
echo 'schedule:traceoff:3' into set_ftrace_filter, then when the
schedule function was called, it would disable tracing. But the count
should only be decremented once (to 2). Then if the user enabled tracing
again (via tracing_on file), the next call to schedule would disable
tracing again and the count would be decremented to 1.
But if multiple CPUS called schedule at the same time, it is possible
that the count would be decremented more than once because of the
simple "count--" used.
By reading the count into a local variable and using memory barriers
we can guarantee that the count would only be decremented once per
disable (or enable).
The stack trace probe had a similar race, but here the stack trace will
decrement for each time it is called. But this had the read-modify-
write race, where it could stack trace more than the number of times
that was specified. This case we use a cmpxchg to stack trace only the
number of times specified.
The dump probes can still use the old "update_count()" function as
they only run once, and that is controlled by the dump logic
itself.
Link: http://lkml.kernel.org/r/20141118134643.4b550ee4@gandalf.local.home
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Usually, "msecs" notation means milli-seconds, and "usecs" notation
means micro-seconds. Since the unit used in the code is micro-seconds,
the notation should be replaced from msecs to usecs.
Link: http://lkml.kernel.org/r/1415171926-9782-2-git-send-email-byungchul.park@lge.com
Signed-off-by: Byungchul Park <byungchul.park@lge.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
On the function_graph tracer, the print_graph_irq() function prints a
trace line with the flag ==========> on an irq handler entry, and the
flag <========== on an irq handler return.
But when the latency-format is enable, it is not printing the
latency-format flags, causing the following error in the trace output:
0) ==========> |
0) d... | smp_apic_timer_interrupt() {
This patch fixes this issue by printing the latency-format flags when
it is enable.
Link: http://lkml.kernel.org/r/7c2e226dac20c940b6242178fab7f0e3c9b5ce58.1415233316.git.bristot@redhat.com
Reviewed-by: Luis Claudio R. Goncalves <lgoncalv@redhat.com>
Signed-off-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Printing a single character to a seqfile might as well be done with
seq_putc instead of seq_puts; this avoids a strlen() call and a memory
access. It also shaves another few bytes off the generated code.
Link: http://lkml.kernel.org/r/1415479332-25944-4-git-send-email-linux@rasmusvillemoes.dk
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Consecutive seq_puts calls with literal strings can be merged to a
single call. This reduces the size of the generated code, and can also
lead to slight .rodata reduction (because of fewer nul and padding
bytes). It should also shave a off a few clock cycles.
Link: http://lkml.kernel.org/r/1415479332-25944-3-git-send-email-linux@rasmusvillemoes.dk
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Using seq_printf to print a simple string or a single character is a
lot more expensive than it needs to be, since seq_puts and seq_putc
exist.
These patches do
seq_printf(m, s) -> seq_puts(m, s)
seq_printf(m, "%s", s) -> seq_puts(m, s)
seq_printf(m, "%c", c) -> seq_putc(m, c)
Subsequent patches will simplify further.
Link: http://lkml.kernel.org/r/1415479332-25944-2-git-send-email-linux@rasmusvillemoes.dk
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Currently kdb's ftdump command will livelock by constantly printk'ing
the empty string at KERN_EMERG level if it run when the ftrace system is
not in use. This occurs because trace_empty() never returns false when
the ring buffers are left at the start of a non-consuming read [launched
by ring_buffer_read_start()].
This patch changes the loop exit condition to use the result of
trace_find_next_entry_inc(). Effectively this switches the non-consuming
kdb dumper to follow the approach of the non-consuming userspace
interface [s_next()] rather than the consuming ftrace_dump().
Link: http://lkml.kernel.org/r/1415277716-19419-3-git-send-email-daniel.thompson@linaro.org
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Currently kdb's ftdump command unconditionally crashes due to a null
pointer de-reference whenever the command is run. This in turn causes
the kernel to panic.
The abridged stacktrace (gathered with ARCH=arm) is:
--- cut here ---
[<c09535ac>] (panic) from [<c02132dc>] (die+0x264/0x440)
[<c02132dc>] (die) from [<c0952eb8>]
(__do_kernel_fault.part.11+0x74/0x84)
[<c0952eb8>] (__do_kernel_fault.part.11) from [<c021f954>]
(do_page_fault+0x1d0/0x3c4)
[<c021f954>] (do_page_fault) from [<c020846c>] (do_DataAbort+0x48/0xac)
[<c020846c>] (do_DataAbort) from [<c0213c58>] (__dabt_svc+0x38/0x60)
Exception stack(0xc0deba88 to 0xc0debad0)
ba80: e8c29180 00000001 e9854304 e9854300 c0f567d8
c0df2580
baa0: 00000000 00000000 00000000 c0f117b8 c0e3a3c0 c0debb0c 00000000
c0debad0
bac0: 0000672e c02f4d60 60000193 ffffffff
[<c0213c58>] (__dabt_svc) from [<c02f4d60>] (kdb_ftdump+0x1e4/0x3d8)
[<c02f4d60>] (kdb_ftdump) from [<c02ce328>] (kdb_parse+0x2b8/0x698)
[<c02ce328>] (kdb_parse) from [<c02ceef0>] (kdb_main_loop+0x52c/0x784)
[<c02ceef0>] (kdb_main_loop) from [<c02d1b0c>] (kdb_stub+0x238/0x490)
--- cut here ---
The NULL deref occurs due to the initialized use of struct trace_iter's
buffer_iter member.
This is a regression, albeit a fairly elderly one. It was introduced
by commit 6d158a813e ("tracing: Remove NR_CPUS array from
trace_iterator").
This patch solves this by providing a collection of ring_buffer_iter(s)
and using this to initialize buffer_iter. Note that static allocation
is used solely because the trace_iter itself is also static allocated.
Static allocation also means that we have to NULL-ify the pointer during
cleanup to avoid use-after-free problems.
Link: http://lkml.kernel.org/r/1415277716-19419-2-git-send-email-daniel.thompson@linaro.org
Cc: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
According to the documentation, adding "traceoff_on_warning" to the boot
command line should be enough to enable the feature. But right now it is
necessary to specify "traceoff_on_warning=". Along with fixing that, also
verify if the value passed, if any, is either "0" or "off".
Link: http://lkml.kernel.org/r/20141112231400.GL12281@uudg.org
Signed-off-by: Luis Claudio R. Goncalves <lgoncalv@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
With the new logic, if only a single user of ftrace function hooks is
used, it will get its own trampoline assigned to it.
The problem is that the control_ops is an indirect ops that perf ops
uses. What that means is that when perf registers its ops with
register_ftrace_function(), it has the CONTROL flag set and gets added
to the control list instead of the global ftrace list. The control_ops
gets added to that instead and the mcount trampoline calls the control_ops
function. The control_ops function will iterate the control list and
call the ops functions that are attached to it.
But currently the trampoline is added to the perf ops and not the
control ops, and when ftrace tries to find a trampoline hook for it,
it fails to find one and gives the following splat:
------------[ cut here ]------------
WARNING: CPU: 0 PID: 10133 at kernel/trace/ftrace.c:2033 ftrace_get_addr_new+0x6f/0xc0()
Modules linked in: [...]
CPU: 0 PID: 10133 Comm: perf Tainted: P 3.18.0-rc1-test+ #388
Hardware name: Hewlett-Packard HP Compaq Pro 6300 SFF/339A, BIOS K01 v02.05 05/07/2012
00000000000007f1 ffff8800c2643bc8 ffffffff814fca6e ffff88011ea0ed01
0000000000000000 ffff8800c2643c08 ffffffff81041ffd 0000000000000000
ffffffff810c388c ffffffff81a5a350 ffff880119b00000 ffffffff810001c8
Call Trace:
[<ffffffff814fca6e>] dump_stack+0x46/0x58
[<ffffffff81041ffd>] warn_slowpath_common+0x81/0x9b
[<ffffffff810c388c>] ? ftrace_get_addr_new+0x6f/0xc0
[<ffffffff810001c8>] ? 0xffffffff810001c8
[<ffffffff81042031>] warn_slowpath_null+0x1a/0x1c
[<ffffffff810c388c>] ftrace_get_addr_new+0x6f/0xc0
[<ffffffff8102e938>] ftrace_replace_code+0xd6/0x334
[<ffffffff810c4116>] ftrace_modify_all_code+0x41/0xc5
[<ffffffff8102eba6>] arch_ftrace_update_code+0x10/0x19
[<ffffffff810c293c>] ftrace_run_update_code+0x21/0x42
[<ffffffff810c298f>] ftrace_startup_enable+0x32/0x34
[<ffffffff810c3049>] ftrace_startup+0x14e/0x15a
[<ffffffff810c307c>] register_ftrace_function+0x27/0x40
[<ffffffff810dc118>] perf_ftrace_event_register+0x3e/0xee
[<ffffffff810dbfbe>] perf_trace_init+0x29d/0x2a9
[<ffffffff810eb422>] perf_tp_event_init+0x27/0x3a
[<ffffffff810f18bc>] perf_init_event+0x9e/0xed
[<ffffffff810f1ba4>] perf_event_alloc+0x299/0x330
[<ffffffff810f236b>] SYSC_perf_event_open+0x3ee/0x816
[<ffffffff8115a066>] ? mntput+0x2d/0x2f
[<ffffffff81142b00>] ? __fput+0xa7/0x1b2
[<ffffffff81091300>] ? do_gettimeofday+0x22/0x3a
[<ffffffff810f279c>] SyS_perf_event_open+0x9/0xb
[<ffffffff81502a92>] system_call_fastpath+0x12/0x17
---[ end trace 81a53565150e4982 ]---
Bad trampoline accounting at: ffffffff810001c8 (run_init_process+0x0/0x2d) (10000001)
Update the control_ops trampoline instead of the perf ops one.
Reported-by: lkp@01.org
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The only code that references tracing_sched_switch_trace() and
tracing_sched_wakeup_trace() is the wakeup latency tracer. Those
two functions use to belong to the sched_switch tracer which has
long been removed. These functions were left behind because the
wakeup latency tracer used them. But since the wakeup latency tracer
is the only one to use them, they should be static functions inside
that code.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
After the previous patch it is clear that "tracer_enabled" can never be
true, we can remove the "if (tracer_enabled)" code in probe_sched_switch()
and probe_sched_wakeup(). Plus we can obviously remove tracer_enabled,
ctx_trace, and sched_stopped as well.
Link: http://lkml.kernel.org/p/20140723193503.GA30217@redhat.com
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
tracing_{start,stop}_sched_switch_record() have no callers since
87d80de280 "tracing: Remove obsolete sched_switch tracer".
The last caller of tracing_sched_switch_assign_trace() was removed
by 30dbb20e68 "tracing: Remove boot tracer".
Link: http://lkml.kernel.org/p/20140723193501.GA30214@redhat.com
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
With the introduction of the dynamic trampolines, it is useful that if
things go wrong that ftrace_bug() produces more information about what
the current state is. This can help debug issues that may arise.
Ftrace has lots of checks to make sure that the state of the system it
touchs is exactly what it expects it to be. When it detects an abnormality
it calls ftrace_bug() and disables itself to prevent any further damage.
It is crucial that ftrace_bug() produces sufficient information that
can be used to debug the situation.
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Acked-by: Borislav Petkov <bp@suse.de>
Tested-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Tested-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
When the static ftrace_ops (like function tracer) enables tracing, and it
is the only callback that is referencing a function, a trampoline is
dynamically allocated to the function that calls the callback directly
instead of calling a loop function that iterates over all the registered
ftrace ops (if more than one ops is registered).
But when it comes to dynamically allocated ftrace_ops, where they may be
freed, on a CONFIG_PREEMPT kernel there's no way to know when it is safe
to free the trampoline. If a task was preempted while executing on the
trampoline, there's currently no way to know when it will be off that
trampoline.
But this is not true when it comes to !CONFIG_PREEMPT. The current method
of calling schedule_on_each_cpu() will force tasks off the trampoline,
becaues they can not schedule while on it (kernel preemption is not
configured). That means it is safe to free a dynamically allocated
ftrace ops trampoline when CONFIG_PREEMPT is not configured.
Cc: H. Peter Anvin <hpa@linux.intel.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Borislav Petkov <bp@suse.de>
Tested-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Tested-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
This patch introduces several new flags to collect kdb commands into
groups (later allowing them to be optionally disabled).
This follows similar prior art to enable/disable magic sysrq
commands.
The commands have been categorized as follows:
Always on: go (w/o args), env, set, help, ?, cpu (w/o args), sr,
dmesg, disable_nmi, defcmd, summary, grephelp
Mem read: md, mdr, mdp, mds, ef, bt (with args), per_cpu
Mem write: mm
Reg read: rd
Reg write: go (with args), rm
Inspect: bt (w/o args), btp, bta, btc, btt, ps, pid, lsmod
Flow ctrl: bp, bl, bph, bc, be, bd, ss
Signal: kill
Reboot: reboot
All: cpu, kgdb, (and all of the above), nmi_console
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Cc: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Since we now treat KDB_REPEAT_* as flags, there is no need to
pass KDB_REPEAT_NONE. It's just the default behaviour when no
flags are specified.
Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Cc: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
We're about to add more options for commands behaviour, so let's give
a more generic name to the low-level kdb command registration function.
There are just various renames, no functional changes.
Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Cc: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
If the read loop in trace_buffers_splice_read() keeps failing due to
memory allocation failures without reading even a single page then this
function will keep busy looping.
Remove the risk for that by exiting the function if memory allocation
failures are seen.
Link: http://lkml.kernel.org/r/1415309167-2373-2-git-send-email-rabin@rab.in
Signed-off-by: Rabin Vincent <rabin@rab.in>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
On a !PREEMPT kernel, attempting to use trace-cmd results in a soft
lockup:
# trace-cmd record -e raw_syscalls:* -F false
NMI watchdog: BUG: soft lockup - CPU#0 stuck for 22s! [trace-cmd:61]
...
Call Trace:
[<ffffffff8105b580>] ? __wake_up_common+0x90/0x90
[<ffffffff81092e25>] wait_on_pipe+0x35/0x40
[<ffffffff810936e3>] tracing_buffers_splice_read+0x2e3/0x3c0
[<ffffffff81093300>] ? tracing_stats_read+0x2a0/0x2a0
[<ffffffff812d10ab>] ? _raw_spin_unlock+0x2b/0x40
[<ffffffff810dc87b>] ? do_read_fault+0x21b/0x290
[<ffffffff810de56a>] ? handle_mm_fault+0x2ba/0xbd0
[<ffffffff81095c80>] ? trace_event_buffer_lock_reserve+0x40/0x80
[<ffffffff810951e2>] ? trace_buffer_lock_reserve+0x22/0x60
[<ffffffff81095c80>] ? trace_event_buffer_lock_reserve+0x40/0x80
[<ffffffff8112415d>] do_splice_to+0x6d/0x90
[<ffffffff81126971>] SyS_splice+0x7c1/0x800
[<ffffffff812d1edd>] tracesys_phase2+0xd3/0xd8
The problem is this: tracing_buffers_splice_read() calls
ring_buffer_wait() to wait for data in the ring buffers. The buffers
are not empty so ring_buffer_wait() returns immediately. But
tracing_buffers_splice_read() calls ring_buffer_read_page() with full=1,
meaning it only wants to read a full page. When the full page is not
available, tracing_buffers_splice_read() tries to wait again with
ring_buffer_wait(), which again returns immediately, and so on.
Fix this by adding a "full" argument to ring_buffer_wait() which will
make ring_buffer_wait() wait until the writer has left the reader's
page, i.e. until full-page reads will succeed.
Link: http://lkml.kernel.org/r/1415645194-25379-1-git-send-email-rabin@rab.in
Cc: stable@vger.kernel.org # 3.16+
Fixes: b1169cc69b ("tracing: Remove mock up poll wait function")
Signed-off-by: Rabin Vincent <rabin@rab.in>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The file /sys/kernel/debug/tracing/eneabled_functions is used to debug
ftrace function hooks. Add to the output what function is being called
by the trampoline if the arch supports it.
Add support for this feature in x86_64.
Cc: H. Peter Anvin <hpa@linux.intel.com>
Tested-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Tested-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The current method of handling multiple function callbacks is to register
a list function callback that calls all the other callbacks based on
their hash tables and compare it to the function that the callback was
called on. But this is very inefficient.
For example, if you are tracing all functions in the kernel and then
add a kprobe to a function such that the kprobe uses ftrace, the
mcount trampoline will switch from calling the function trace callback
to calling the list callback that will iterate over all registered
ftrace_ops (in this case, the function tracer and the kprobes callback).
That means for every function being traced it checks the hash of the
ftrace_ops for function tracing and kprobes, even though the kprobes
is only set at a single function. The kprobes ftrace_ops is checked
for every function being traced!
Instead of calling the list function for functions that are only being
traced by a single callback, we can call a dynamically allocated
trampoline that calls the callback directly. The function graph tracer
already uses a direct call trampoline when it is being traced by itself
but it is not dynamically allocated. It's trampoline is static in the
kernel core. The infrastructure that called the function graph trampoline
can also be used to call a dynamically allocated one.
For now, only ftrace_ops that are not dynamically allocated can have
a trampoline. That is, users such as function tracer or stack tracer.
kprobes and perf allocate their ftrace_ops, and until there's a safe
way to free the trampoline, it can not be used. The dynamically allocated
ftrace_ops may, although, use the trampoline if the kernel is not
compiled with CONFIG_PREEMPT. But that will come later.
Tested-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Tested-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
ARM has some private syscalls (for example, set_tls(2)) which lie
outside the range of NR_syscalls. If any of these are called while
syscall tracing is being performed, out-of-bounds array access will
occur in the ftrace and perf sys_{enter,exit} handlers.
# trace-cmd record -e raw_syscalls:* true && trace-cmd report
...
true-653 [000] 384.675777: sys_enter: NR 192 (0, 1000, 3, 4000022, ffffffff, 0)
true-653 [000] 384.675812: sys_exit: NR 192 = 1995915264
true-653 [000] 384.675971: sys_enter: NR 983045 (76f74480, 76f74000, 76f74b28, 76f74480, 76f76f74, 1)
true-653 [000] 384.675988: sys_exit: NR 983045 = 0
...
# trace-cmd record -e syscalls:* true
[ 17.289329] Unable to handle kernel paging request at virtual address aaaaaace
[ 17.289590] pgd = 9e71c000
[ 17.289696] [aaaaaace] *pgd=00000000
[ 17.289985] Internal error: Oops: 5 [#1] PREEMPT SMP ARM
[ 17.290169] Modules linked in:
[ 17.290391] CPU: 0 PID: 704 Comm: true Not tainted 3.18.0-rc2+ #21
[ 17.290585] task: 9f4dab00 ti: 9e710000 task.ti: 9e710000
[ 17.290747] PC is at ftrace_syscall_enter+0x48/0x1f8
[ 17.290866] LR is at syscall_trace_enter+0x124/0x184
Fix this by ignoring out-of-NR_syscalls-bounds syscall numbers.
Commit cd0980fc8a "tracing: Check invalid syscall nr while tracing syscalls"
added the check for less than zero, but it should have also checked
for greater than NR_syscalls.
Link: http://lkml.kernel.org/p/1414620418-29472-1-git-send-email-rabin@rab.in
Fixes: cd0980fc8a "tracing: Check invalid syscall nr while tracing syscalls"
Cc: stable@vger.kernel.org # 2.6.33+
Signed-off-by: Rabin Vincent <rabin@rab.in>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
When modifying code, ftrace has several checks to make sure things
are being done correctly. One of them is to make sure any code it
modifies is exactly what it expects it to be before it modifies it.
In order to do so with the new trampoline logic, it must be able
to find out what trampoline a function is hooked to in order to
see if the code that hooks to it is what's expected.
The logic to find the trampoline from a record (accounting descriptor
for a function that is hooked) needs to only look at the "old_hash"
of an ops that is being modified. The old_hash is the list of function
an ops is hooked to before its update. Since a record would only be
pointing to an ops that is being modified if it was already hooked
before.
Currently, it can pick a modified ops based on its new functions it
will be hooked to, and this picks the wrong trampoline and causes
the check to fail, disabling ftrace.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
ftrace: squash into ordering of ops for modification
The code that checks for trampolines when modifying function hooks
tests against a modified ops "old_hash". But the ops old_hash pointer
is not being updated before the changes are made, making it possible
to not find the right hash to the callback and possibly causing
ftrace to break in accounting and disable itself.
Have the ops set its old_hash before the modifying takes place.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Pull scheduler updates from Ingo Molnar:
"The main changes in this cycle were:
- Optimized support for Intel "Cluster-on-Die" (CoD) topologies (Dave
Hansen)
- Various sched/idle refinements for better idle handling (Nicolas
Pitre, Daniel Lezcano, Chuansheng Liu, Vincent Guittot)
- sched/numa updates and optimizations (Rik van Riel)
- sysbench speedup (Vincent Guittot)
- capacity calculation cleanups/refactoring (Vincent Guittot)
- Various cleanups to thread group iteration (Oleg Nesterov)
- Double-rq-lock removal optimization and various refactorings
(Kirill Tkhai)
- various sched/deadline fixes
... and lots of other changes"
* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (72 commits)
sched/dl: Use dl_bw_of() under rcu_read_lock_sched()
sched/fair: Delete resched_cpu() from idle_balance()
sched, time: Fix build error with 64 bit cputime_t on 32 bit systems
sched: Improve sysbench performance by fixing spurious active migration
sched/x86: Fix up typo in topology detection
x86, sched: Add new topology for multi-NUMA-node CPUs
sched/rt: Use resched_curr() in task_tick_rt()
sched: Use rq->rd in sched_setaffinity() under RCU read lock
sched: cleanup: Rename 'out_unlock' to 'out_free_new_mask'
sched: Use dl_bw_of() under RCU read lock
sched/fair: Remove duplicate code from can_migrate_task()
sched, mips, ia64: Remove __ARCH_WANT_UNLOCKED_CTXSW
sched: print_rq(): Don't use tasklist_lock
sched: normalize_rt_tasks(): Don't use _irqsave for tasklist_lock, use task_rq_lock()
sched: Fix the task-group check in tg_has_rt_tasks()
sched/fair: Leverage the idle state info when choosing the "idlest" cpu
sched: Let the scheduler see CPU idle states
sched/deadline: Fix inter- exclusive cpusets migrations
sched/deadline: Clear dl_entity params when setscheduling to different class
sched/numa: Kill the wrong/dead TASK_DEAD check in task_numa_fault()
...
code screem nasty warnings:
WARNING: CPU: 0 PID: 91 at kernel/sched/core.c:7253 __might_sleep+0x9a/0x378()
do not call blocking ops when !TASK_RUNNING; state=1 set at [<ffffffff8d79b511>] event_test_thread+0x48/0x93
Modules linked in:
CPU: 0 PID: 91 Comm: test-events Not tainted 3.17.0-rc7-00109-g2f85d18 #37
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.7.5-20140531_083030-gandalf 04/01/2014
0000000000000000 ffff880010ec3c80 ffffffff8c696943 ffff880010ec3cb8
ffffffff8be7cae5 ffffffff8bead236 0000000000000001 ffff88001161fa01
0000000000000001 0000000000000000 ffff880010ec3d20 ffffffff8be7cb46
Call Trace:
[<ffffffff8c696943>] dump_stack+0x19/0x1b
[<ffffffff8be7cae5>] warn_slowpath_common+0x8f/0xa8
[<ffffffff8bead236>] ? __might_sleep+0x9a/0x378
[<ffffffff8be7cb46>] warn_slowpath_fmt+0x48/0x50
[<ffffffff8be0dd55>] ? sched_clock+0x9/0xd
[<ffffffff8d79b511>] ? event_test_thread+0x48/0x93
[<ffffffff8d79b511>] ? event_test_thread+0x48/0x93
[<ffffffff8bead236>] __might_sleep+0x9a/0x378
[<ffffffff8c6a0227>] down_read+0x26/0x98
[<ffffffff8be8f503>] exit_signals+0x27/0x1c2
[<ffffffff8be7fedd>] do_exit+0x193/0x10bd
[<ffffffff8bfd1969>] ? kfree+0x4a0/0x4d7
[<ffffffff8d79b4c9>] ? event_trace_self_tests+0x6d7/0x6d7
[<ffffffff8d79b4c9>] ? event_trace_self_tests+0x6d7/0x6d7
[<ffffffff8bea4b65>] kthread+0x156/0x156
[<ffffffff8c69c0f8>] ? wait_for_common+0x3e/0x224
[<ffffffff8bea4a0f>] ? insert_kthread_work+0xe7/0xe7
[<ffffffff8c6a353a>] ret_from_fork+0x7a/0xb0
[<ffffffff8bea4a0f>] ? insert_kthread_work+0xe7/0xe7
---[ end trace 14d02ef17adbc114 ]---
These are triggered by some self tests that run at start up when
configure in. Although the code is technically correct, they are a little
sloppy and not very robust. They work now because it runs at boot up
and the tests do not call anything that might trigger a spurious
wake up. But that doesn't mean those tests wont change in the future.
It's best to clean them now to make sure the tests used to test the
internal workings of the system don't cause breakage themselves.
This also quiets the warnings made by the new checks.
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Merge tag 'trace-3.18-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull tracing fixes from Steven Rostedt:
"Seems that Peter Zijlstra added a new check that is making old code
scream nasty warnings:
WARNING: CPU: 0 PID: 91 at kernel/sched/core.c:7253 __might_sleep+0x9a/0x378()
do not call blocking ops when !TASK_RUNNING; state=1 set at [<ffffffff8d79b511>] event_test_thread+0x48/0x93
Call Trace:
__might_sleep+0x9a/0x378
down_read+0x26/0x98
exit_signals+0x27/0x1c2
do_exit+0x193/0x10bd
kthread+0x156/0x156
ret_from_fork+0x7a/0xb0
These are triggered by some self tests that run at start up when
configure in. Although the code is technically correct, they are a
little sloppy and not very robust. They work now because it runs at
boot up and the tests do not call anything that might trigger a
spurious wake up. But that doesn't mean those tests wont change in
the future.
It's best to clean them now to make sure the tests used to test the
internal workings of the system don't cause breakage themselves.
This also quiets the warnings made by the new checks"
* tag 'trace-3.18-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
tracing: Clean up scheduling in trace_wakeup_test_thread()
tracing: Robustify wait loop
of the trampoline logic.
The trampoline logic of 3.17 required a descriptor for every function
that is registered to be traced and uses a trampoline. Currently,
only the function graph tracer uses a trampoline, but if you were
to trace all 32,000 (give or take a few thousand) functions with the
function graph tracer, it would create 32,000 descriptors to let us
know that there's a trampoline associated with it. This takes up a bit
of memory when there's a better way to do it.
The redesign now reuses the ftrace_ops' (what registers the function graph
tracer) hash tables. The hash tables tell ftrace what the tracer
wants to trace or doesn't want to trace. There's two of them: one
that tells us what to trace, the other tells us what not to trace.
If the first one is empty, it means all functions should be traced,
otherwise only the ones that are listed should be. The second hash table
tells us what not to trace, and if it is empty, all functions may be
traced, and if there's any listed, then those should not be traced
even if they exist in the first hash table.
It took a bit of massaging, but now these hashes can be used to
keep track of what has a trampoline and what does not, and allows
the ftrace accounting to work. Now we can trace all functions when using
the function graph trampoline, and avoid needing to create any special
descriptors to hold all the functions that are being traced.
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Merge tag 'trace-3.18' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull tracing updates from Steven Rostedt:
"This set has a few minor updates, but the big change is the redesign
of the trampoline logic.
The trampoline logic of 3.17 required a descriptor for every function
that is registered to be traced and uses a trampoline. Currently,
only the function graph tracer uses a trampoline, but if you were to
trace all 32,000 (give or take a few thousand) functions with the
function graph tracer, it would create 32,000 descriptors to let us
know that there's a trampoline associated with it. This takes up a
bit of memory when there's a better way to do it.
The redesign now reuses the ftrace_ops' (what registers the function
graph tracer) hash tables. The hash tables tell ftrace what the
tracer wants to trace or doesn't want to trace. There's two of them:
one that tells us what to trace, the other tells us what not to trace.
If the first one is empty, it means all functions should be traced,
otherwise only the ones that are listed should be. The second hash
table tells us what not to trace, and if it is empty, all functions
may be traced, and if there's any listed, then those should not be
traced even if they exist in the first hash table.
It took a bit of massaging, but now these hashes can be used to keep
track of what has a trampoline and what does not, and allows the
ftrace accounting to work. Now we can trace all functions when using
the function graph trampoline, and avoid needing to create any special
descriptors to hold all the functions that are being traced"
* tag 'trace-3.18' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
ftrace: Only disable ftrace_enabled to test buffer in selftest
ftrace: Add sanity check when unregistering last ftrace_ops
kernel: trace_syscalls: Replace rcu_assign_pointer() with RCU_INIT_POINTER()
tracing: generate RCU warnings even when tracepoints are disabled
ftrace: Replace tramp_hash with old_*_hash to save space
ftrace: Annotate the ops operation on update
ftrace: Grab any ops for a rec for enabled_functions output
ftrace: Remove freeing of old_hash from ftrace_hash_move()
ftrace: Set callback to ftrace_stub when no ops are registered
ftrace: Add helper function ftrace_ops_get_func()
ftrace: Add separate function for non recursive callbacks
Peter's new debugging tool triggers when tasks exit with !TASK_RUNNING.
The code in trace_wakeup_test_thread() also has a single schedule() call
that should be encompassed by a loop.
This cleans up the code a little to make it a bit more robust and
also makes the return exit properly with TASK_RUNNING.
Link: http://lkml.kernel.org/p/20141008135216.76142204@gandalf.local.home
Reported-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Peter Zijlstra <peterz@infreadead.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The pending nested sleep debugging triggered on the potential stale
TASK_INTERRUPTIBLE in this code.
While there, fix the loop such that we won't revert to a while(1)
yield() 'spin' loop if we ever get a spurious wakeup.
And fix the actual issue by properly terminating the 'wait' loop by
setting TASK_RUNNING.
Link: http://lkml.kernel.org/p/20141008165110.GA14547@worktop.programming.kicks-ass.net
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Commit 651e22f270 "ring-buffer: Always reset iterator to reader page"
fixed one bug but in the process caused another one. The reset is to
update the header page, but that fix also changed the way the cached
reads were updated. The cache reads are used to test if an iterator
needs to be updated or not.
A ring buffer iterator, when created, disables writes to the ring buffer
but does not stop other readers or consuming reads from happening.
Although all readers are synchronized via a lock, they are only
synchronized when in the ring buffer functions. Those functions may
be called by any number of readers. The iterator continues down when
its not interrupted by a consuming reader. If a consuming read
occurs, the iterator starts from the beginning of the buffer.
The way the iterator sees that a consuming read has happened since
its last read is by checking the reader "cache". The cache holds the
last counts of the read and the reader page itself.
Commit 651e22f270 changed what was saved by the cache_read when
the rb_iter_reset() occurred, making the iterator never match the cache.
Then if the iterator calls rb_iter_reset(), it will go into an
infinite loop by checking if the cache doesn't match, doing the reset
and retrying, just to see that the cache still doesn't match! Which
should never happen as the reset is suppose to set the cache to the
current value and there's locks that keep a consuming reader from
having access to the data.
Fixes: 651e22f270 "ring-buffer: Always reset iterator to reader page"
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Tasks get their end of stack set to STACK_END_MAGIC with the
aim to catch stack overruns. Currently this feature does not
apply to init_task. This patch removes this restriction.
Note that a similar patch was posted by Prarit Bhargava
some time ago but was never merged:
http://marc.info/?l=linux-kernel&m=127144305403241&w=2
Signed-off-by: Aaron Tomlin <atomlin@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Michael Ellerman <mpe@ellerman.id.au>
Cc: aneesh.kumar@linux.vnet.ibm.com
Cc: dzickus@redhat.com
Cc: bmr@redhat.com
Cc: jcastillo@redhat.com
Cc: jgh@redhat.com
Cc: minchan@kernel.org
Cc: tglx@linutronix.de
Cc: hannes@cmpxchg.org
Cc: Alex Thorlton <athorlton@sgi.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Daeseok Youn <daeseok.youn@gmail.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Fabian Frederick <fabf@skynet.be>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Michael Opdenacker <michael.opdenacker@free-electrons.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Seiji Aguchi <seiji.aguchi@hds.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Vladimir Davydov <vdavydov@parallels.com>
Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Cc: linuxppc-dev@lists.ozlabs.org
Link: http://lkml.kernel.org/r/1410527779-8133-2-git-send-email-atomlin@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The ftrace_enabled variable is set to zero in the self tests to keep
delayed functions from being traced and messing with the checks. This
only needs to be done when the checks are being performed, otherwise,
if ftrace_enabled is off when calls back to the utility that is being
tested, it can cause errors to happen and the tests can fail with
false positives.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
When the last ftrace_ops is unregistered, all the function records should
have a zeroed flags value. Make sure that is the case when the last ftrace_ops
is unregistered.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The uses of "rcu_assign_pointer()" are NULLing out the pointers.
According to RCU_INIT_POINTER()'s block comment:
"1. This use of RCU_INIT_POINTER() is NULLing out the pointer"
it is better to use it instead of rcu_assign_pointer() because it has a
smaller overhead.
The following Coccinelle semantic patch was used:
@@
@@
- rcu_assign_pointer
+ RCU_INIT_POINTER
(..., NULL)
Link: http://lkml.kernel.org/p/20140822142822.GA32391@ada
Signed-off-by: Andreea-Cristina Bernat <bernat.ada@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Allowing function callbacks to declare their own trampolines requires
that each ftrace_ops that has a trampoline must have some sort of
accounting that keeps track of which ops has a trampoline attached
to a record.
The easy way to solve this was to add a "tramp_hash" that created a
hash entry for every function that a ops uses with a trampoline.
But since we can have literally tens of thousands of functions being
traced, that means we need tens of thousands of descriptors to map
the ops to the function in the hash. This is quite expensive and
can cause enabling and disabling the function graph tracer to take
some time to start and stop. It can take up to several seconds to
disable or enable all functions in the function graph tracer for this
reason.
The better approach albeit more complex, is to keep track of how ops
are being enabled and disabled, and use that along with the counting
of the number of ops attached to records, to determive what ops has
a trampoline attached to a record at enabling and disabling of
tracing.
To do this, the tramp_hash has been replaced with an old_filter_hash
and old_notrace_hash, which get the copy of the ops filter_hash and
notrace_hash respectively. The old hashes is kept until the ops has
been modified or removed and the old hashes are used with the logic
of the accounting to determine the ops that have the trampoline of
a record. The reason this has less of a footprint is due to the trick
that an "empty" hash in the filter_hash means "all functions" and
an empty hash in the notrace hash means "no functions" in the hash.
This is much more efficienct, doesn't have the delay, and takes up
much less memory, as we do not need to map all the functions but
just figure out which functions are mapped at the time it is
enabled or disabled.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Add three new flags for ftrace_ops:
FTRACE_OPS_FL_ADDING
FTRACE_OPS_FL_REMOVING
FTRACE_OPS_FL_MODIFYING
These will be set for the ftrace_ops when they are first added
to the function tracing, being removed from function tracing
or just having their functions changed from function tracing,
respectively.
This will be needed to remove the tramp_hash, which can grow quite
big. The tramp_hash is used to note what functions a ftrace_ops
is using a trampoline for. Denoting which ftrace_ops is being
modified, will allow us to use the ftrace_ops hashes themselves,
which are much smaller as they have a global flag to denote if
a ftrace_ops is tracing all functions, as well as a notrace hash
if the ftrace_ops is tracing all but a few. The tramp_hash just
creates a hash item for every function, which can go into the 10s
of thousands if all functions are using the ftrace_ops trampoline.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
When dumping the enabled_functions, use the first op that is
found with a trampoline to the record, as there should only be
one, as only one ops can be registered to a function that has
a trampoline.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
ftrace_hash_move() currently frees the old hash that is passed to it
after replacing the pointer with the new hash. Instead of having the
function do that chore, have the caller perform the free.
This lets the ftrace_hash_move() be used a bit more freely, which
is needed for changing the way the trampoline logic is done.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The clean up that adds the helper function ftrace_ops_get_func()
caused the default function to not change when DYNAMIC_FTRACE was not
set and no ftrace_ops were registered. Although static tracing is
not very useful (not having DYNAMIC_FTRACE set), it is still supported
and we don't want to break it.
Clean up the if statement even more to specifically have the default
function call ftrace_stub when no ftrace_ops are registered. This
fixes the small bug for static tracing as well as makes the code a
bit more understandable.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Add the helper function to what the mcount trampoline is to call
for a ftrace_ops function. This helper will be used by arch code
in the future to set up dynamic trampolines. But as this does the
same tests that are performed in choosing what function to call for
the default mcount trampoline, might as well use it to clean up
the existing code.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Instead of using the generic list function for callbacks that
are not recursive, call a new helper function from the mcount
trampoline called ftrace_ops_recur_func() that will do the recursion
checking for the callback.
This eliminates an indirection as well as will help in future code
that will use dynamically allocated trampolines.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Epoll on trace_pipe can sometimes hang in a weird case. If the ring buffer is
empty when we set waiters_pending but an event shows up exactly at that moment
we can miss being woken up by the ring buffers irq work. Since
ring_buffer_empty() is inherently racey we will sometimes think that the buffer
is not empty. So we don't get woken up and we don't think there are any events
even though there were some ready when we added the watch, which makes us hang.
This patch fixes this by making sure that we are actually on the wait list
before we set waiters_pending, and add a memory barrier to make sure
ring_buffer_empty() is going to be correct.
Link: http://lkml.kernel.org/p/1408989581-23727-1-git-send-email-jbacik@fb.com
Cc: stable@vger.kernel.org # 3.10+
Cc: Martin Lau <kafai@fb.com>
Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
In __ftrace_replace_code(), when converting the call to a nop in a function
it needs to compare against the "curr" (current) value of the ftrace ops, and
not the "new" one. It currently does not affect x86 which is the only arch
to do the trampolines with function graph tracer, but when other archs that do
depend on this code implement the function graph trampoline, it can crash.
Here's an example when ARM uses the trampolines (in the future):
------------[ cut here ]------------
WARNING: CPU: 0 PID: 9 at kernel/trace/ftrace.c:1716 ftrace_bug+0x17c/0x1f4()
Modules linked in: omap_rng rng_core ipv6
CPU: 0 PID: 9 Comm: migration/0 Not tainted 3.16.0-test-10959-gf0094b28f303-dirty #52
[<c02188f4>] (unwind_backtrace) from [<c021343c>] (show_stack+0x20/0x24)
[<c021343c>] (show_stack) from [<c095a674>] (dump_stack+0x78/0x94)
[<c095a674>] (dump_stack) from [<c02532a0>] (warn_slowpath_common+0x7c/0x9c)
[<c02532a0>] (warn_slowpath_common) from [<c02532ec>] (warn_slowpath_null+0x2c/0x34)
[<c02532ec>] (warn_slowpath_null) from [<c02cbac4>] (ftrace_bug+0x17c/0x1f4)
[<c02cbac4>] (ftrace_bug) from [<c02cc44c>] (ftrace_replace_code+0x80/0x9c)
[<c02cc44c>] (ftrace_replace_code) from [<c02cc658>] (ftrace_modify_all_code+0xb8/0x164)
[<c02cc658>] (ftrace_modify_all_code) from [<c02cc718>] (__ftrace_modify_code+0x14/0x1c)
[<c02cc718>] (__ftrace_modify_code) from [<c02c7244>] (multi_cpu_stop+0xf4/0x134)
[<c02c7244>] (multi_cpu_stop) from [<c02c6e90>] (cpu_stopper_thread+0x54/0x130)
[<c02c6e90>] (cpu_stopper_thread) from [<c0271cd4>] (smpboot_thread_fn+0x1ac/0x1bc)
[<c0271cd4>] (smpboot_thread_fn) from [<c026ddf0>] (kthread+0xe0/0xfc)
[<c026ddf0>] (kthread) from [<c020f318>] (ret_from_fork+0x14/0x20)
---[ end trace dc9ce72c5b617d8f ]---
[ 65.047264] ftrace failed to modify [<c0208580>] asm_do_IRQ+0x10/0x1c
[ 65.054070] actual: 85:1b:00:eb
Fixes: 7413af1fb7 "ftrace: Make get_ftrace_addr() and get_ftrace_addr_old() global"
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The latest rewrite of ftrace removed the separate ftrace_ops of
the function tracer and the function graph tracer and had them
share the same ftrace_ops. This simplified the accounting by removing
the multiple layers of functions called, where the global_ops func
would call a special list that would iterate over the other ops that
were registered within it (like function and function graph), which
itself was registered to the ftrace ops list of all functions
currently active. If that sounds confusing, the code that implemented
it was also confusing and its removal is a good thing.
The problem with this change was that it assumed that the function
and function graph tracer can never be used at the same time.
This is mostly true, but there is an exception. That is when the
function profiler uses the function graph tracer to profile.
The function profiler can be activated the same time as the function
tracer, and this breaks the assumption and the result is that ftrace
will crash (it detects the error and shuts itself down, it does not
cause a kernel oops).
To solve this issue, a previous change allowed the hash tables
for the functions traced by a ftrace_ops to be a pointer and let
multiple ftrace_ops share the same hash. This allows the function
and function_graph tracer to have separate ftrace_ops, but still
share the hash, which is what is done.
Now the function and function graph tracers have separate ftrace_ops
again, and the function tracer can be run while the function_profile
is active.
Cc: stable@vger.kernel.org # 3.16 (apply after 3.17-rc4 is out)
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Now that a ftrace_hash can be shared by multiple ftrace_ops, they can dec
the rec->flags by more than once (one per those that share the ftrace_hash).
This means that the tramp_hash may not have a hash item when it was added.
For example, if two ftrace_ops share a hash for a ftrace record, and the
first ops has a trampoline, when it adds itself it will set the rec->flags
TRAMP flag and increments its nr_trampolines counter. When the second ops
is added, it must clear that tramp flag but also decrement the other ops
that shares its hash. As the update to the function callbacks has not yet
been performed, the other ops will not have the tramp hash set yet and it
can not be used to know to decrement its nr_trampolines.
Luckily, the tramp_hash does not need to be used. As the ftrace_mutex is
held, a ops with a trampoline to a record during an update of another ops
that shares the record will have its func_hash pointing to it. Since a
trampoline can only be set for a record if only one ops is attached to it,
we can just check if the record has a trampoline (the FTRACE_FL_TRAMP flag
is set) and then find the ops that has this record in its hashes.
Also added some output to help debug when things go wrong.
Cc: stable@vger.kernel.org # 3.16+ (apply after 3.17-rc4 is out)
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
When updating what an ftrace_ops traces, if it is registered (that is,
actively tracing), and that ftrace_ops uses the shared global_ops
local_hash, then we need to update all tracers that are active and
also share the global_ops' ftrace_hash_ops.
Cc: stable@vger.kernel.org # 3.16 (apply after 3.17-rc4 is out)
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Currently the top level debug file system function tracer shares its
ftrace_ops with the function graph tracer. This was thought to be fine
because the tracers are not used together, as one can only enable
function or function_graph tracer in the current_tracer file.
But that assumption proved to be incorrect. The function profiler
can use the function graph tracer when function tracing is enabled.
Since all function graph users uses the function tracing ftrace_ops
this causes a conflict and when a user enables both function profiling
as well as the function tracer it will crash ftrace and disable it.
The quick solution so far is to move them as separate ftrace_ops like
it was earlier. The problem though is to synchronize the functions that
are traced because both function and function_graph tracer are limited
by the selections made in the set_ftrace_filter and set_ftrace_notrace
files.
To handle this, a new structure is made called ftrace_ops_hash. This
structure will now hold the filter_hash and notrace_hash, and the
ftrace_ops will point to this structure. That will allow two ftrace_ops
to share the same hashes.
Since most ftrace_ops do not share the hashes, and to keep allocation
simple, the ftrace_ops structure will include both a pointer to the
ftrace_ops_hash called func_hash, as well as the structure itself,
called local_hash. When the ops are registered, the func_hash pointer
will be initialized to point to the local_hash within the ftrace_ops
structure. Some of the ftrace internal ftrace_ops will be initialized
statically. This will allow for the function and function_graph tracer
to have separate ops but still share the same hash tables that determine
what functions they trace.
Cc: stable@vger.kernel.org # 3.16 (apply after 3.17-rc4 is out)
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
rarely ever hit, and requires the user to do something that users rarely
do. It took a few special test cases to even trigger this bug,
and one of them was just one test in the process of finishing up as another
one started.
Both bugs have to do with the ring buffer iterator rb_iter_peek(), but one
is more indirect than the other.
The fist bug fix is simply an increase in the safety net loop counter.
The counter makes sure that the rb_iter_peek() only iterates the number
of times we expect it can, and no more. Well, there was one way it could
iterate one more than we expected, and that caused the ring buffer
to shutdown with a nasty warning. The fix was simply to up that counter by
one.
The other bug has to be with rb_iter_reset() (called by rb_iter_peek()).
This happens when a user reads both the trace_pipe and trace files.
The trace_pipe is a consuming read and does not use the ring buffer
iterator, but the trace file is not a consuming read and does use the
ring buffer iterator. When the trace file is being read, if it detects
that a consuming read occurred, it resets the iterator and starts over.
But the reset code that does this (rb_iter_reset()), checks if the
reader_page is linked to the ring buffer or not, and will look into
the ring buffer itself if it is not. This is wrong, as it should always
try to read the reader page first. Not to mention, the code that looked
into the ring buffer did it wrong, and used the header_page "read" offset
to start reading on that page. That offset is bogus for pages in the
writable ring buffer, and was corrupting the iterator, and it would start
returning bogus events.
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Merge tag 'trace-fixes-3.16' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull trace file read iterator fixes from Steven Rostedt:
"This contains a fix for two long standing bugs. Both of which are
rarely ever hit, and requires the user to do something that users
rarely do. It took a few special test cases to even trigger this bug,
and one of them was just one test in the process of finishing up as
another one started.
Both bugs have to do with the ring buffer iterator rb_iter_peek(), but
one is more indirect than the other.
The fist bug fix is simply an increase in the safety net loop counter.
The counter makes sure that the rb_iter_peek() only iterates the
number of times we expect it can, and no more. Well, there was one
way it could iterate one more than we expected, and that caused the
ring buffer to shutdown with a nasty warning. The fix was simply to
up that counter by one.
The other bug has to be with rb_iter_reset() (called by
rb_iter_peek()). This happens when a user reads both the trace_pipe
and trace files. The trace_pipe is a consuming read and does not use
the ring buffer iterator, but the trace file is not a consuming read
and does use the ring buffer iterator. When the trace file is being
read, if it detects that a consuming read occurred, it resets the
iterator and starts over. But the reset code that does this
(rb_iter_reset()), checks if the reader_page is linked to the ring
buffer or not, and will look into the ring buffer itself if it is not.
This is wrong, as it should always try to read the reader page first.
Not to mention, the code that looked into the ring buffer did it
wrong, and used the header_page "read" offset to start reading on that
page. That offset is bogus for pages in the writable ring buffer, and
was corrupting the iterator, and it would start returning bogus
events"
* tag 'trace-fixes-3.16' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
ring-buffer: Always reset iterator to reader page
ring-buffer: Up rb_iter_peek() loop count to 3
When performing a consuming read, the ring buffer swaps out a
page from the ring buffer with a empty page and this page that
was swapped out becomes the new reader page. The reader page
is owned by the reader and since it was swapped out of the ring
buffer, writers do not have access to it (there's an exception
to that rule, but it's out of scope for this commit).
When reading the "trace" file, it is a non consuming read, which
means that the data in the ring buffer will not be modified.
When the trace file is opened, a ring buffer iterator is allocated
and writes to the ring buffer are disabled, such that the iterator
will not have issues iterating over the data.
Although the ring buffer disabled writes, it does not disable other
reads, or even consuming reads. If a consuming read happens, then
the iterator is reset and starts reading from the beginning again.
My tests would sometimes trigger this bug on my i386 box:
WARNING: CPU: 0 PID: 5175 at kernel/trace/trace.c:1527 __trace_find_cmdline+0x66/0xaa()
Modules linked in:
CPU: 0 PID: 5175 Comm: grep Not tainted 3.16.0-rc3-test+ #8
Hardware name: /DG965MQ, BIOS MQ96510J.86A.0372.2006.0605.1717 06/05/2006
00000000 00000000 f09c9e1c c18796b3 c1b5d74c f09c9e4c c103a0e3 c1b5154b
f09c9e78 00001437 c1b5d74c 000005f7 c10bd85a c10bd85a c1cac57c f09c9eb0
ed0e0000 f09c9e64 c103a185 00000009 f09c9e5c c1b5154b f09c9e78 f09c9e80^M
Call Trace:
[<c18796b3>] dump_stack+0x4b/0x75
[<c103a0e3>] warn_slowpath_common+0x7e/0x95
[<c10bd85a>] ? __trace_find_cmdline+0x66/0xaa
[<c10bd85a>] ? __trace_find_cmdline+0x66/0xaa
[<c103a185>] warn_slowpath_fmt+0x33/0x35
[<c10bd85a>] __trace_find_cmdline+0x66/0xaa^M
[<c10bed04>] trace_find_cmdline+0x40/0x64
[<c10c3c16>] trace_print_context+0x27/0xec
[<c10c4360>] ? trace_seq_printf+0x37/0x5b
[<c10c0b15>] print_trace_line+0x319/0x39b
[<c10ba3fb>] ? ring_buffer_read+0x47/0x50
[<c10c13b1>] s_show+0x192/0x1ab
[<c10bfd9a>] ? s_next+0x5a/0x7c
[<c112e76e>] seq_read+0x267/0x34c
[<c1115a25>] vfs_read+0x8c/0xef
[<c112e507>] ? seq_lseek+0x154/0x154
[<c1115ba2>] SyS_read+0x54/0x7f
[<c188488e>] syscall_call+0x7/0xb
---[ end trace 3f507febd6b4cc83 ]---
>>>> ##### CPU 1 buffer started ####
Which was the __trace_find_cmdline() function complaining about the pid
in the event record being negative.
After adding more test cases, this would trigger more often. Strangely
enough, it would never trigger on a single test, but instead would trigger
only when running all the tests. I believe that was the case because it
required one of the tests to be shutting down via delayed instances while
a new test started up.
After spending several days debugging this, I found that it was caused by
the iterator becoming corrupted. Debugging further, I found out why
the iterator became corrupted. It happened with the rb_iter_reset().
As consuming reads may not read the full reader page, and only part
of it, there's a "read" field to know where the last read took place.
The iterator, must also start at the read position. In the rb_iter_reset()
code, if the reader page was disconnected from the ring buffer, the iterator
would start at the head page within the ring buffer (where writes still
happen). But the mistake there was that it still used the "read" field
to start the iterator on the head page, where it should always start
at zero because readers never read from within the ring buffer where
writes occur.
I originally wrote a patch to have it set the iter->head to 0 instead
of iter->head_page->read, but then I questioned why it wasn't always
setting the iter to point to the reader page, as the reader page is
still valid. The list_empty(reader_page->list) just means that it was
successful in swapping out. But the reader_page may still have data.
There was a bug report a long time ago that was not reproducible that
had something about trace_pipe (consuming read) not matching trace
(iterator read). This may explain why that happened.
Anyway, the correct answer to this bug is to always use the reader page
an not reset the iterator to inside the writable ring buffer.
Cc: stable@vger.kernel.org # 2.6.28+
Fixes: d769041f86 "ring_buffer: implement new locking"
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
After writting a test to try to trigger the bug that caused the
ring buffer iterator to become corrupted, I hit another bug:
WARNING: CPU: 1 PID: 5281 at kernel/trace/ring_buffer.c:3766 rb_iter_peek+0x113/0x238()
Modules linked in: ipt_MASQUERADE sunrpc [...]
CPU: 1 PID: 5281 Comm: grep Tainted: G W 3.16.0-rc3-test+ #143
Hardware name: To Be Filled By O.E.M. To Be Filled By O.E.M./To be filled by O.E.M., BIOS SDBLI944.86P 05/08/2007
0000000000000000 ffffffff81809a80 ffffffff81503fb0 0000000000000000
ffffffff81040ca1 ffff8800796d6010 ffffffff810c138d ffff8800796d6010
ffff880077438c80 ffff8800796d6010 ffff88007abbe600 0000000000000003
Call Trace:
[<ffffffff81503fb0>] ? dump_stack+0x4a/0x75
[<ffffffff81040ca1>] ? warn_slowpath_common+0x7e/0x97
[<ffffffff810c138d>] ? rb_iter_peek+0x113/0x238
[<ffffffff810c138d>] ? rb_iter_peek+0x113/0x238
[<ffffffff810c14df>] ? ring_buffer_iter_peek+0x2d/0x5c
[<ffffffff810c6f73>] ? tracing_iter_reset+0x6e/0x96
[<ffffffff810c74a3>] ? s_start+0xd7/0x17b
[<ffffffff8112b13e>] ? kmem_cache_alloc_trace+0xda/0xea
[<ffffffff8114cf94>] ? seq_read+0x148/0x361
[<ffffffff81132d98>] ? vfs_read+0x93/0xf1
[<ffffffff81132f1b>] ? SyS_read+0x60/0x8e
[<ffffffff8150bf9f>] ? tracesys+0xdd/0xe2
Debugging this bug, which triggers when the rb_iter_peek() loops too
many times (more than 2 times), I discovered there's a case that can
cause that function to legitimately loop 3 times!
rb_iter_peek() is different than rb_buffer_peek() as the rb_buffer_peek()
only deals with the reader page (it's for consuming reads). The
rb_iter_peek() is for traversing the buffer without consuming it, and as
such, it can loop for one more reason. That is, if we hit the end of
the reader page or any page, it will go to the next page and try again.
That is, we have this:
1. iter->head > iter->head_page->page->commit
(rb_inc_iter() which moves the iter to the next page)
try again
2. event = rb_iter_head_event()
event->type_len == RINGBUF_TYPE_TIME_EXTEND
rb_advance_iter()
try again
3. read the event.
But we never get to 3, because the count is greater than 2 and we
cause the WARNING and return NULL.
Up the counter to 3.
Cc: stable@vger.kernel.org # 2.6.37+
Fixes: 69d1b839f7 "ring-buffer: Bind time extend and data events together"
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Pull timer and time updates from Thomas Gleixner:
"A rather large update of timers, timekeeping & co
- Core timekeeping code is year-2038 safe now for 32bit machines.
Now we just need to fix all in kernel users and the gazillion of
user space interfaces which rely on timespec/timeval :)
- Better cache layout for the timekeeping internal data structures.
- Proper nanosecond based interfaces for in kernel users.
- Tree wide cleanup of code which wants nanoseconds but does hoops
and loops to convert back and forth from timespecs. Some of it
definitely belongs into the ugly code museum.
- Consolidation of the timekeeping interface zoo.
- A fast NMI safe accessor to clock monotonic for tracing. This is a
long standing request to support correlated user/kernel space
traces. With proper NTP frequency correction it's also suitable
for correlation of traces accross separate machines.
- Checkpoint/restart support for timerfd.
- A few NOHZ[_FULL] improvements in the [hr]timer code.
- Code move from kernel to kernel/time of all time* related code.
- New clocksource/event drivers from the ARM universe. I'm really
impressed that despite an architected timer in the newer chips SoC
manufacturers insist on inventing new and differently broken SoC
specific timers.
[ Ed. "Impressed"? I don't think that word means what you think it means ]
- Another round of code move from arch to drivers. Looks like most
of the legacy mess in ARM regarding timers is sorted out except for
a few obnoxious strongholds.
- The usual updates and fixlets all over the place"
* 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (114 commits)
timekeeping: Fixup typo in update_vsyscall_old definition
clocksource: document some basic timekeeping concepts
timekeeping: Use cached ntp_tick_length when accumulating error
timekeeping: Rework frequency adjustments to work better w/ nohz
timekeeping: Minor fixup for timespec64->timespec assignment
ftrace: Provide trace clocks monotonic
timekeeping: Provide fast and NMI safe access to CLOCK_MONOTONIC
seqcount: Add raw_write_seqcount_latch()
seqcount: Provide raw_read_seqcount()
timekeeping: Use tk_read_base as argument for timekeeping_get_ns()
timekeeping: Create struct tk_read_base and use it in struct timekeeper
timekeeping: Restructure the timekeeper some more
clocksource: Get rid of cycle_last
clocksource: Move cycle_last validation to core code
clocksource: Make delta calculation a function
wireless: ath9k: Get rid of timespec conversions
drm: vmwgfx: Use nsec based interfaces
drm: i915: Use nsec based interfaces
timekeeping: Provide ktime_get_raw()
hangcheck-timer: Use ktime_get_ns()
...
Pull perf changes from Ingo Molnar:
"Kernel side changes:
- Consolidate the PMU interrupt-disabled code amongst architectures
(Vince Weaver)
- misc fixes
Tooling changes (new features, user visible changes):
- Add support for pagefault tracing in 'trace', please see multiple
examples in the changeset messages (Stanislav Fomichev).
- Add pagefault statistics in 'trace' (Stanislav Fomichev)
- Add header for columns in 'top' and 'report' TUI browsers (Jiri
Olsa)
- Add pagefault statistics in 'trace' (Stanislav Fomichev)
- Add IO mode into timechart command (Stanislav Fomichev)
- Fallback to syscalls:* when raw_syscalls:* is not available in the
perl and python perf scripts. (Daniel Bristot de Oliveira)
- Add --repeat global option to 'perf bench' to be used in benchmarks
such as the existing 'futex' one, that was modified to use it
instead of a local option. (Davidlohr Bueso)
- Fix fd -> pathname resolution in 'trace', be it using /proc or a
vfs_getname probe point. (Arnaldo Carvalho de Melo)
- Add suggestion of how to set perf_event_paranoid sysctl, to help
non-root users trying tools like 'trace' to get a working
environment. (Arnaldo Carvalho de Melo)
- Updates from trace-cmd for traceevent plugin_kvm plus args cleanup
(Steven Rostedt, Jan Kiszka)
- Support S/390 in 'perf kvm stat' (Alexander Yarygin)
Tooling infrastructure changes:
- Allow reserving a row for header purposes in the hists browser
(Arnaldo Carvalho de Melo)
- Various fixes and prep work related to supporting Intel PT (Adrian
Hunter)
- Introduce multiple debug variables control (Jiri Olsa)
- Add callchain and additional sample information for python scripts
(Joseph Schuchart)
- More prep work to support Intel PT: (Adrian Hunter)
- Polishing 'script' BTS output
- 'inject' can specify --kallsym
- VDSO is per machine, not a global var
- Expose data addr lookup functions previously private to 'script'
- Large mmap fixes in events processing
- Include standard stringify macros in power pc code (Sukadev
Bhattiprolu)
Tooling cleanups:
- Convert open coded equivalents to asprintf() (Andy Shevchenko)
- Remove needless reassignments in 'trace' (Arnaldo Carvalho de Melo)
- Cache the is_exit syscall test in 'trace) (Arnaldo Carvalho de
Melo)
- No need to reimplement err() in 'perf bench sched-messaging', drop
barf(). (Davidlohr Bueso).
- Remove ev_name argument from perf_evsel__hists_browse, can be
obtained from the other parameters. (Jiri Olsa)
Tooling fixes:
- Fix memory leak in the 'sched-messaging' perf bench test.
(Davidlohr Bueso)
- The -o and -n 'perf bench mem' options are mutually exclusive, emit
error when both are specified. (Davidlohr Bueso)
- Fix scrollbar refresh row index in the ui browser, problem exposed
now that headers will be added and will be allowed to be switched
on/off. (Jiri Olsa)
- Handle the num array type in python properly (Sebastian Andrzej
Siewior)
- Fix wrong condition for allocation failure (Jiri Olsa)
- Adjust callchain based on DWARF debug info on powerpc (Sukadev
Bhattiprolu)
- Fix a risk for doing free on uninitialized pointer in traceevent
lib (Rickard Strandqvist)
- Update attr test with PERF_FLAG_FD_CLOEXEC flag (Jiri Olsa)
- Enable close-on-exec flag on perf file descriptor (Yann Droneaud)
- Fix build on gcc 4.4.7 (Arnaldo Carvalho de Melo)
- Event ordering fixes (Jiri Olsa)"
* 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (123 commits)
Revert "perf tools: Fix jump label always changing during tracing"
perf tools: Fix perf usage string leftover
perf: Check permission only for parent tracepoint event
perf record: Store PERF_RECORD_FINISHED_ROUND only for nonempty rounds
perf record: Always force PERF_RECORD_FINISHED_ROUND event
perf inject: Add --kallsyms parameter
perf tools: Expose 'addr' functions so they can be reused
perf session: Fix accounting of ordered samples queue
perf powerpc: Include util/util.h and remove stringify macros
perf tools: Fix build on gcc 4.4.7
perf tools: Add thread parameter to vdso__dso_findnew()
perf tools: Add dso__type()
perf tools: Separate the VDSO map name from the VDSO dso name
perf tools: Add vdso__new()
perf machine: Fix the lifetime of the VDSO temporary file
perf tools: Group VDSO global variables into a structure
perf session: Add ability to skip 4GiB or more
perf session: Add ability to 'skip' a non-piped event stream
perf tools: Pass machine to vdso__dso_findnew()
perf tools: Add dso__data_size()
...
As he found some small bugs that went into 3.16, and these changes were
based on that, I had to apply his changes to a separate branch than
my main development branch.
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Merge tag 'trace-3.17-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull tracing filter cleanups from Steven Rostedt:
"Oleg Nesterov did several clean ups with the tracing filter code. As
he found some small bugs that went into 3.16, and these changes were
based on that, I had to apply his changes to a separate branch than my
main development branch.
This was based on work that was already pulled into 3.16, and is a
separate pull request to keep from having local merges in my pull
request"
* tag 'trace-3.17-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
tracing: Kill "filter_string" arg of replace_preds()
tracing: Change apply_subsystem_event_filter() paths to check file->system == dir
tracing: Kill ftrace_event_call->files
tracing/uprobes: Kill the dead TRACE_EVENT_FL_USE_CALL_FILTER logic
tracing: Kill call_filter_disable()
tracing: Kill destroy_call_preds()
tracing: Kill destroy_preds() and destroy_file_preds()
to the ftrace function callback infrastructure. It's introducing a
way to allow different functions to call directly different trampolines
instead of all calling the same "mcount" one.
The only user of this for now is the function graph tracer, which always
had a different trampoline, but the function tracer trampoline was called
and did basically nothing, and then the function graph tracer trampoline
was called. The difference now, is that the function graph tracer
trampoline can be called directly if a function is only being traced by
the function graph trampoline. If function tracing is also happening on
the same function, the old way is still done.
The accounting for this takes up more memory when function graph tracing
is activated, as it needs to keep track of which functions it uses.
I have a new way that wont take as much memory, but it's not ready yet
for this merge window, and will have to wait for the next one.
Another big change was the removal of the ftrace_start/stop() calls that
were used by the suspend/resume code that stopped function tracing when
entering into suspend and resume paths. The stop of ftrace was done
because there was some function that would crash the system if one called
smp_processor_id()! The stop/start was a big hammer to solve the issue
at the time, which was when ftrace was first introduced into Linux.
Now ftrace has better infrastructure to debug such issues, and I found
the problem function and labeled it with "notrace" and function tracing
can now safely be activated all the way down into the guts of suspend
and resume.
Other changes include clean ups of uprobe code.
Clean up of the trace_seq() code.
And other various small fixes and clean ups to ftrace and tracing.
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Merge tag 'trace-3.17' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull tracing updates from Steven Rostedt:
"This pull request has a lot of work done. The main thing is the
changes to the ftrace function callback infrastructure. It's
introducing a way to allow different functions to call directly
different trampolines instead of all calling the same "mcount" one.
The only user of this for now is the function graph tracer, which
always had a different trampoline, but the function tracer trampoline
was called and did basically nothing, and then the function graph
tracer trampoline was called. The difference now, is that the
function graph tracer trampoline can be called directly if a function
is only being traced by the function graph trampoline. If function
tracing is also happening on the same function, the old way is still
done.
The accounting for this takes up more memory when function graph
tracing is activated, as it needs to keep track of which functions it
uses. I have a new way that wont take as much memory, but it's not
ready yet for this merge window, and will have to wait for the next
one.
Another big change was the removal of the ftrace_start/stop() calls
that were used by the suspend/resume code that stopped function
tracing when entering into suspend and resume paths. The stop of
ftrace was done because there was some function that would crash the
system if one called smp_processor_id()! The stop/start was a big
hammer to solve the issue at the time, which was when ftrace was first
introduced into Linux. Now ftrace has better infrastructure to debug
such issues, and I found the problem function and labeled it with
"notrace" and function tracing can now safely be activated all the way
down into the guts of suspend and resume
Other changes include clean ups of uprobe code, clean up of the
trace_seq() code, and other various small fixes and clean ups to
ftrace and tracing"
* tag 'trace-3.17' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (57 commits)
ftrace: Add warning if tramp hash does not match nr_trampolines
ftrace: Fix trampoline hash update check on rec->flags
ring-buffer: Use rb_page_size() instead of open coded head_page size
ftrace: Rename ftrace_ops field from trampolines to nr_trampolines
tracing: Convert local function_graph functions to static
ftrace: Do not copy old hash when resetting
tracing: let user specify tracing_thresh after selecting function_graph
ring-buffer: Always run per-cpu ring buffer resize with schedule_work_on()
tracing: Remove function_trace_stop and HAVE_FUNCTION_TRACE_MCOUNT_TEST
s390/ftrace: remove check of obsolete variable function_trace_stop
arm64, ftrace: Remove check of obsolete variable function_trace_stop
Blackfin: ftrace: Remove check of obsolete variable function_trace_stop
metag: ftrace: Remove check of obsolete variable function_trace_stop
microblaze: ftrace: Remove check of obsolete variable function_trace_stop
MIPS: ftrace: Remove check of obsolete variable function_trace_stop
parisc: ftrace: Remove check of obsolete variable function_trace_stop
sh: ftrace: Remove check of obsolete variable function_trace_stop
sparc64,ftrace: Remove check of obsolete variable function_trace_stop
tile: ftrace: Remove check of obsolete variable function_trace_stop
ftrace: x86: Remove check of obsolete variable function_trace_stop
...
There's no need to check cloned event's permission once the
parent was already checked.
Also the code is checking 'current' process permissions, which
is not owner process for cloned events, thus could end up with
wrong permission check result.
Reported-by: Alexander Yarygin <yarygin@linux.vnet.ibm.com>
Tested-by: Alexander Yarygin <yarygin@linux.vnet.ibm.com>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/1405079782-8139-1-git-send-email-jolsa@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
After adding all the records to the tramp_hash, add a check that makes
sure that the number of records added matches the number of records
expected to match and do a WARN_ON and disable ftrace if they do
not match.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
In the loop of ftrace_save_ops_tramp_hash(), it adds all the recs
to the ops hash if the rec has only one callback attached and the
ops is connected to the rec. It gives a nasty warning and shuts down
ftrace if the rec doesn't have a trampoline set for it. But this
can happen with the following scenario:
# cd /sys/kernel/debug/tracing
# echo schedule do_IRQ > set_ftrace_filter
# mkdir instances/foo
# echo schedule > instances/foo/set_ftrace_filter
# echo function_graph > current_function
# echo function > instances/foo/current_function
# echo nop > instances/foo/current_function
The above would then trigger the following warning and disable
ftrace:
------------[ cut here ]------------
WARNING: CPU: 0 PID: 3145 at kernel/trace/ftrace.c:2212 ftrace_run_update_code+0xe4/0x15b()
Modules linked in: ipt_MASQUERADE sunrpc ip6t_REJECT nf_conntrack_ipv6 nf_defrag_ip [...]
CPU: 1 PID: 3145 Comm: bash Not tainted 3.16.0-rc3-test+ #136
Hardware name: To Be Filled By O.E.M. To Be Filled By O.E.M./To be filled by O.E.M., BIOS SDBLI944.86P 05/08/2007
0000000000000000 ffffffff81808a88 ffffffff81502130 0000000000000000
ffffffff81040ca1 ffff880077c08000 ffffffff810bd286 0000000000000001
ffffffff81a56830 ffff88007a041be0 ffff88007a872d60 00000000000001be
Call Trace:
[<ffffffff81502130>] ? dump_stack+0x4a/0x75
[<ffffffff81040ca1>] ? warn_slowpath_common+0x7e/0x97
[<ffffffff810bd286>] ? ftrace_run_update_code+0xe4/0x15b
[<ffffffff810bd286>] ? ftrace_run_update_code+0xe4/0x15b
[<ffffffff810bda1a>] ? ftrace_shutdown+0x11c/0x16b
[<ffffffff810bda87>] ? unregister_ftrace_function+0x1e/0x38
[<ffffffff810cc7e1>] ? function_trace_reset+0x1a/0x28
[<ffffffff810c924f>] ? tracing_set_tracer+0xc1/0x276
[<ffffffff810c9477>] ? tracing_set_trace_write+0x73/0x91
[<ffffffff81132383>] ? __sb_start_write+0x9a/0xcc
[<ffffffff8120478f>] ? security_file_permission+0x1b/0x31
[<ffffffff81130e49>] ? vfs_write+0xac/0x11c
[<ffffffff8113115d>] ? SyS_write+0x60/0x8e
[<ffffffff81508112>] ? system_call_fastpath+0x16/0x1b
---[ end trace 938c4415cbc7dc96 ]---
------------[ cut here ]------------
Link: http://lkml.kernel.org/r/20140723120805.GB21376@redhat.com
Reported-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
There's a helper function to get a ring buffer page size (the number
of bytes of data recorded on the page), called rb_page_size().
Use that instead of open coding it.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Expose the new NMI safe accessor to clock monotonic to the tracer.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Having two fields within the same struct that is off by one character
can be confusing and error prone. Rename the counter "trampolines"
to "nr_trampolines" to explicitly show it is a counter and not to
be confused by the "trampoline" field.
Suggested-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The "uptime" trace clock added in:
commit 8aacf017b0
tracing: Add "uptime" trace clock that uses jiffies
has wraparound problems when the system has been up more
than 1 hour 11 minutes and 34 seconds. It converts jiffies
to nanoseconds using:
(u64)jiffies_to_usecs(jiffy) * 1000ULL
but since jiffies_to_usecs() only returns a 32-bit value, it
truncates at 2^32 microseconds. An additional problem on 32-bit
systems is that the argument is "unsigned long", so fixing the
return value only helps until 2^32 jiffies (49.7 days on a HZ=1000
system).
Avoid these problems by using jiffies_64 as our basis, and
not converting to nanoseconds (we do convert to clock_t because
user facing API must not be dependent on internal kernel
HZ values).
Link: http://lkml.kernel.org/p/99d63c5bfe9b320a3b428d773825a37095bf6a51.1405708254.git.tony.luck@intel.com
Cc: stable@vger.kernel.org # 3.10+
Fixes: 8aacf017b0 "tracing: Add "uptime" trace clock that uses jiffies"
Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Do not waste time copying the old hash if the hash is going to be
reset. Just allocate a new hash and free the old one, as that is
the same result as copying te old one and then resetting it.
Link: http://lkml.kernel.org/p/1405384820-48837-1-git-send-email-wangnan0@huawei.com
Signed-off-by: Wang Nan <wangnan0@huawei.com>
[ SDR: Removed unused ftrace_filter_reset() function ]
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Currently, tracing_thresh works only if we specify it before selecting
function_graph tracer. If we do the opposite, tracing_thresh will change
it's value, but it will not be applied.
To fix it, we add update_thresh callback which is called whenever
tracing_thresh is updated and for function_graph tracer we register
handler which reinitializes tracer depending on tracing_thresh.
Link: http://lkml.kernel.org/p/20140718111727.GA3206@stfomichev-desktop.yandex.net
Signed-off-by: Stanislav Fomichev <stfomichev@yandex-team.ru>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The code for resizing the trace ring buffers has to run the per-cpu
resize on the CPU itself. The code was using preempt_off() and
running the code for the current CPU directly, otherwise calling
schedule_work_on().
At least on RT this could result in the following:
|BUG: sleeping function called from invalid context at kernel/rtmutex.c:673
|in_atomic(): 1, irqs_disabled(): 0, pid: 607, name: bash
|3 locks held by bash/607:
|CPU: 0 PID: 607 Comm: bash Not tainted 3.12.15-rt25+ #124
|(rt_spin_lock+0x28/0x68)
|(free_hot_cold_page+0x84/0x3b8)
|(free_buffer_page+0x14/0x20)
|(rb_update_pages+0x280/0x338)
|(ring_buffer_resize+0x32c/0x3dc)
|(free_snapshot+0x18/0x38)
|(tracing_set_tracer+0x27c/0x2ac)
probably via
|cd /sys/kernel/debug/tracing/
|echo 1 > events/enable ; sleep 2
|echo 1024 > buffer_size_kb
If we just always use schedule_work_on(), there's no need for the
preempt_off(). So do that.
Link: http://lkml.kernel.org/p/1405537633-31518-1-git-send-email-cminyard@mvista.com
Reported-by: Stanislav Meduna <stano@meduna.org>
Signed-off-by: Corey Minyard <cminyard@mvista.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
All users of function_trace_stop and HAVE_FUNCTION_TRACE_MCOUNT_TEST have
been removed. We can safely remove them from the kernel.
Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
function_trace_stop is no longer used to stop function tracing.
Remove the check from __ftrace_ops_list_func().
Also, call FTRACE_WARN_ON() instead of setting function_trace_stop
if a ops has no func to call.
Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
When function tracing is being updated function_trace_stop is set to
keep from tracing the updates. This was fine when function tracing
was done from stop machine. But it is no longer done that way and
this can cause real tracing to be missed.
Remove it.
Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
All archs now use ftrace_graph_is_dead() to stop function graph
tracing. Remove the usage of ftrace_stop() as that is no longer
needed.
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
ftrace_stop() is going away as it disables parts of function tracing
that affects users that should not be affected. But ftrace_graph_stop()
is built on ftrace_stop(). Here's another example of killing all of
function tracing because something went wrong with function graph
tracing.
Instead of disabling all users of function tracing on function graph
error, disable only function graph tracing.
A new function is created called ftrace_graph_is_dead(). This is called
in strategic paths to prevent function graph from doing more harm and
allowing at least a warning to be printed before the system crashes.
NOTE: ftrace_stop() is still used until all the archs are converted over
to use ftrace_graph_is_dead(). After that, ftrace_stop() will be removed.
Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Cosmetic, but replace_preds() doesn't need/use "char *filter_string".
Remove it to microsimplify the code.
Link: http://lkml.kernel.org/p/20140715184832.GA20519@redhat.com
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
filter_free_subsystem_preds(), filter_free_subsystem_filters() and
replace_system_preds() can simply check file->system->subsystem and
avoid strcmp(call->class->system).
Better yet, we can pass "struct ftrace_subsystem_dir *dir" instead of
event_subsystem and just check file->system == dir.
Thanks to Namhyung Kim who pointed out that replace_system_preds() can
be changed too.
Link: http://lkml.kernel.org/p/20140715184829.GA20516@redhat.com
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
alloc_trace_uprobe() sets TRACE_EVENT_FL_USE_CALL_FILTER for unknown
reason and this is simply wrong. Fortunately this has no effect because
register_uprobe_event() clears call->flags after that.
Kill both. This trace_uprobe was kzalloc'ed and we rely on this fact
anyway.
Link: http://lkml.kernel.org/p/20140715184824.GA20505@redhat.com
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
It seems that the only purpose of call_filter_disable() is to
make filter_disable() less clear and symmetrical, remove it.
Link: http://lkml.kernel.org/p/20140715184821.GA20498@redhat.com
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Remove destroy_call_preds(). Its only caller, __trace_remove_event_call(),
can use free_event_filter() and nullify ->filter by hand.
Perhaps we could keep this trivial helper although imo it is pointless, but
then it should be static in trace_events.c.
Link: http://lkml.kernel.org/p/20140715184816.GA20495@redhat.com
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
destroy_preds() makes no sense.
The only caller, event_remove(), actually wants destroy_file_preds().
__trace_remove_event_call() does destroy_call_preds() which takes care
of call->filter.
And after the previous change we can simply remove destroy_preds() from
event_remove(), we are going to call remove_event_from_tracers() which
in turn calls remove_event_file_dir()->free_event_filter().
Link: http://lkml.kernel.org/p/20140715184813.GA20488@redhat.com
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Currently if an arch supports function graph tracing, the core code will
just assign the function graph trampoline to the function graph addr that
gets called.
But as the old method for function graph tracing always calls the function
trampoline first and that calls the function graph trampoline, some
archs may have the function graph trampoline dependent on operations that
were done in the function trampoline. This causes function graph tracer
to break on those archs.
Instead of having the default be to set the function graph ftrace_ops
to the function graph trampoline, have it instead just set it to zero
which will keep it from jumping to a trampoline that is not set up
to be jumped directly too.
Link: http://lkml.kernel.org/r/53BED155.9040607@nvidia.com
Reported-by: Tuomas Tynkkynen <ttynkkynen@nvidia.com>
Tested-by: Tuomas Tynkkynen <ttynkkynen@nvidia.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
ring_buffer_poll_wait() should always put the poll_table to its wait_queue
even there is immediate data available. Otherwise, the following epoll and
read sequence will eventually hang forever:
1. Put some data to make the trace_pipe ring_buffer read ready first
2. epoll_ctl(efd, EPOLL_CTL_ADD, trace_pipe_fd, ee)
3. epoll_wait()
4. read(trace_pipe_fd) till EAGAIN
5. Add some more data to the trace_pipe ring_buffer
6. epoll_wait() -> this epoll_wait() will block forever
~ During the epoll_ctl(efd, EPOLL_CTL_ADD,...) call in step 2,
ring_buffer_poll_wait() returns immediately without adding poll_table,
which has poll_table->_qproc pointing to ep_poll_callback(), to its
wait_queue.
~ During the epoll_wait() call in step 3 and step 6,
ring_buffer_poll_wait() cannot add ep_poll_callback() to its wait_queue
because the poll_table->_qproc is NULL and it is how epoll works.
~ When there is new data available in step 6, ring_buffer does not know
it has to call ep_poll_callback() because it is not in its wait queue.
Hence, block forever.
Other poll implementation seems to call poll_wait() unconditionally as the very
first thing to do. For example, tcp_poll() in tcp.c.
Link: http://lkml.kernel.org/p/20140610060637.GA14045@devbig242.prn2.facebook.com
Cc: stable@vger.kernel.org # 2.6.27
Fixes: 2a2cc8f7c4 "ftrace: allow the event pipe to be polled"
Reviewed-by: Chris Mason <clm@fb.com>
Signed-off-by: Martin Lau <kafai@fb.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The TRACE_ITER_PRINTK check in __trace_puts/__trace_bputs is missing,
so add it, to be consistent with __trace_printk/__trace_bprintk.
Those functions are all called by the same function: trace_printk().
Link: http://lkml.kernel.org/p/51E7A7D6.8090900@huawei.com
Cc: stable@vger.kernel.org # 3.11+
Signed-off-by: zhangwei(Jovi) <jovi.zhangwei@huawei.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Running my ftrace tests on PowerPC, it failed the test that checks
if function_graph tracer is affected by the stack tracer. It was.
Looking into this, I found that the update_function_graph_func()
must be called even if the trampoline function is not changed.
This is because archs like PowerPC do not support ftrace_ops being
passed by assembly and instead uses a helper function (what the
trampoline function points to). Since this function is not changed
even when multiple ftrace_ops are added to the code, the test that
falls out before calling update_function_graph_func() will miss that
the update must still be done.
Call update_function_graph_function() for all calls to
update_ftrace_function()
Cc: stable@vger.kernel.org # 3.3+
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Currently trace option stacktrace is not applicable for
trace_printk with constant string argument, the reason is
in __trace_puts/__trace_bputs ftrace_trace_stack is missing.
In contrast, when using trace_printk with non constant string
argument(will call into __trace_printk/__trace_bprintk), then
trace option stacktrace is workable, this inconstant result
will confuses users a lot.
Link: http://lkml.kernel.org/p/51E7A7C9.9040401@huawei.com
Cc: stable@vger.kernel.org # 3.10+
Signed-off-by: zhangwei(Jovi) <jovi.zhangwei@huawei.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Disabling reading and writing to the trace file should not be able to
disable all function tracing callbacks. There's other users today
(like kprobes and perf). Reading a trace file should not stop those
from happening.
Cc: stable@vger.kernel.org # 3.0+
Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
When there's no entry in set_ftrace_notrace, it'll print nothing, but
it's better to print something like below like set_graph_notrace does:
#### no functions disabled ####
Link: http://lkml.kernel.org/p/1402644246-4649-1-git-send-email-namhyung@kernel.org
Reported-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
When there's no entry in set_graph_notrace, it'll print below message
#### all functions enabled ####
While this is technically correct, it's better to print like below:
#### no functions disabled ####
Link: http://lkml.kernel.org/p/1402590233-22321-3-git-send-email-namhyung@kernel.org
Reported-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The ftrace_graph_notrace option is for specifying notrace filter for
function graph tracer at boot time. It can be altered after boot
using set_graph_notrace file on the debugfs.
Link: http://lkml.kernel.org/p/1402590233-22321-2-git-send-email-namhyung@kernel.org
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
It seems like it's a leftover from commit 4104d326b6 ("ftrace:
Remove global function list and call function directly"). As it
isn't updated at all, checking its value is meaningless.
Let's get rid of it.
Link: http://lkml.kernel.org/p/1402584972-17824-1-git-send-email-namhyung@kernel.org
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
There's several locations in the kernel that open code the calculation
of the next location in the trace_seq buffer. This is usually done with
p->buffer + p->len
Instead of having this open coded, supply a helper function in the
header to do it for them. This function is called trace_seq_buffer_ptr().
Link: http://lkml.kernel.org/p/20140626220129.452783019@goodmis.org
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
trace_seq_reserve() has no users in the kernel, it just wastes space.
Remove it.
Cc: Eduard - Gabriel Munteanu <eduard.munteanu@linux360.ro>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Currently trace_seq_putmem_hex() can only take as a parameter a pointer
to something that is 8 bytes or less, otherwise it will overflow the
buffer. This is protected by a macro that encompasses the call to
trace_seq_putmem_hex() that has a BUILD_BUG_ON() for the variable before
it is passed in. This is not very robust and if trace_seq_putmem_hex() ever
gets used outside that macro it will cause issues.
Instead of only being able to produce a hex output of memory that is for
a single word, change it to be more robust and allow any size input.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
For using trace_seq_*() functions in NMI context, I posted a patch to move
it to the lib/ directory. This caused Andrew Morton to take a look at the code.
He went through and gave a lot of comments about missing kernel doc,
inconsistent types for the save variable, mix match of EXPORT_SYMBOL_GPL()
and EXPORT_SYMBOL() as well as missing EXPORT_SYMBOL*()s. There were
a few comments about the way variables were being compared (int vs uint).
All these were good review comments and should be implemented regardless of
if trace_seq.c should be moved to lib/ or not.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Linus Torvalds
Steven Rostedt (Red Hat)
Rafael J. Wysocki
Arianna Avanzini
Al Viro
Dan Carpenter
Byungchul Park
Masami Hiramatsu
Jiri Kosina
Frans Klaver
Markus Elfring
Daniel Bristot de Oliveira
Rasmus Villemoes
Daniel Thompson
Luis Claudio R. Goncalves
Jiang Liu
Oleg Nesterov
Anton Vorontsov
Rabin Vincent
Peter Zijlstra
Aaron Tomlin
Kirill Tkhai
Andreea-Cristina Bernat
Josef Bacik
Jiri Olsa
Thomas Gleixner
Tony Luck
Wang Nan
Stanislav Fomichev
Corey Minyard
Martin Lau
zhangwei(Jovi)
Namhyung Kim
Fabian Frederick