The oops can be triggered in qemu using -no-hpet (but not nohpet) by
running a 32-bit program and reading a couple of pages before the vdso.
This should send SIGBUS instead of OOPSing.
The bug was introduced by:
commit 7a59ed415f
Author: Stefani Seibold <stefani@seibold.net>
Date: Mon Mar 17 23:22:09 2014 +0100
x86, vdso: Add 32 bit VDSO time support for 32 bit kernel
which is new in 3.15.
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Link: http://lkml.kernel.org/r/e99025d887d6670b6c4d81e6ccfeeb83770b21e9.1400109621.git.luto@amacapital.net
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Checkin:
b3b42ac2cb x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels
disabled 16-bit segments on 64-bit kernels due to an information
leak. However, it does seem that people are genuinely using Wine to
run old 16-bit Windows programs on Linux.
A proper fix for this ("espfix64") is coming in the upcoming merge
window, but as a temporary fix, create a sysctl to allow the
administrator to re-enable support for 16-bit segments.
It adds a "/proc/sys/abi/ldt16" sysctl that defaults to zero (off). If
you hit this issue and care about your old Windows program more than
you care about a kernel stack address information leak, you can do
echo 1 > /proc/sys/abi/ldt16
as root (add it to your startup scripts), and you should be ok.
The sysctl table is only added if you have COMPAT support enabled on
x86-64, but I assume anybody who runs old windows binaries very much
does that ;)
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Link: http://lkml.kernel.org/r/CA%2B55aFw9BPoD10U1LfHbOMpHWZkvJTkMcfCs9s3urPr1YyWBxw@mail.gmail.com
Cc: <stable@vger.kernel.org>
Pull x86 vdso fix from Peter Anvin:
"This is a single build fix for building with gold as opposed to GNU
ld. It got queued up separately and was expected to be pushed during
the merge window, but it got left behind"
* 'x86-vdso-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86, vdso: Make the vdso linker script compatible with Gold
Pull x86 vdso changes from Peter Anvin:
"This is the revamp of the 32-bit vdso and the associated cleanups.
This adds timekeeping support to the 32-bit vdso that we already have
in the 64-bit vdso. Although 32-bit x86 is legacy, it is likely to
remain in the embedded space for a very long time to come.
This removes the traditional COMPAT_VDSO support; the configuration
variable is reused for simply removing the 32-bit vdso, which will
produce correct results but obviously suffer a performance penalty.
Only one beta version of glibc was affected, but that version was
unfortunately included in one OpenSUSE release.
This is not the end of the vdso cleanups. Stefani and Andy have
agreed to continue work for the next kernel cycle; in fact Andy has
already produced another set of cleanups that came too late for this
cycle.
An incidental, but arguably important, change is that this ensures
that unused space in the VVAR page is properly zeroed. It wasn't
before, and would contain whatever garbage was left in memory by BIOS
or the bootloader. Since the VVAR page is accessible to user space
this had the potential of information leaks"
* 'x86-vdso-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (23 commits)
x86, vdso: Fix the symbol versions on the 32-bit vDSO
x86, vdso, build: Don't rebuild 32-bit vdsos on every make
x86, vdso: Actually discard the .discard sections
x86, vdso: Fix size of get_unmapped_area()
x86, vdso: Finish removing VDSO32_PRELINK
x86, vdso: Move more vdso definitions into vdso.h
x86: Load the 32-bit vdso in place, just like the 64-bit vdsos
x86, vdso32: handle 32 bit vDSO larger one page
x86, vdso32: Disable stack protector, adjust optimizations
x86, vdso: Zero-pad the VVAR page
x86, vdso: Add 32 bit VDSO time support for 64 bit kernel
x86, vdso: Add 32 bit VDSO time support for 32 bit kernel
x86, vdso: Patch alternatives in the 32-bit VDSO
x86, vdso: Introduce VVAR marco for vdso32
x86, vdso: Cleanup __vdso_gettimeofday()
x86, vdso: Replace VVAR(vsyscall_gtod_data) by gtod macro
x86, vdso: __vdso_clock_gettime() cleanup
x86, vdso: Revamp vclock_gettime.c
mm: Add new func _install_special_mapping() to mmap.c
x86, vdso: Make vsyscall_gtod_data handling x86 generic
...
The new symbols provide the same API as the 64-bit variants, so they
should have the same symbol version name. This can't break
userspace, since these symbols are new for 32-bit Linux.
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Cc: Stefani Seibold <stefani@seibold.net>
Link: http://lkml.kernel.org/r/0a869bce03d25619565b1eee7d69a4fd15fd203a.1396124118.git.luto@amacapital.net
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
The .discard/.discard.* sections are used to generate intermediate
results for the assembler (effectively "test assembly".) The output
is waste and should not be retained.
Cc: Stefani Seibold <stefani@seibold.net>
Cc: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Link: http://lkml.kernel.org/n/tip-psizrnant8x3nrhbgvq2vekr@git.kernel.org
The size of the reserved memory for a 32 bit vdso must be the size of the
32 bit vDSO in pages + HPET page + VVAR page.
One page is not enough for this. Grrrr.... silly copy and paste bug,
was right in previous patch.
Signed-off-by: Stefani Seibold <stefani@seibold.net>
Cc: Andy Lutomirski <luto@amacapital.net>
Link: http://lkml.kernel.org/r/1395592694-20571-1-git-send-email-stefani@seibold.net
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
This replaces a decent amount of incomprehensible and buggy code
with much more straightforward code. It also brings the 32-bit vdso
more in line with the 64-bit vdsos, so maybe someday they can share
even more code.
This wastes a small amount of kernel .data and .text space, but it
avoids a couple of allocations on startup, so it should be more or
less a wash memory-wise.
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Cc: Stefani Seibold <stefani@seibold.net>
Link: http://lkml.kernel.org/r/b8093933fad09ce181edb08a61dcd5d2592e9814.1395352498.git.luto@amacapital.net
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
For the 32-bit VDSO, match the 64-bit VDSO in:
1. Disable the stack protector.
2. Use -fno-omit-frame-pointer for user space debugging sanity.
3. Use -foptimize-sibling-calls like the 64-bit VDSO does.
Reported-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Stefani Seibold <stefani@seibold.net>
Link: http://lkml.kernel.org/r/1395094933-14252-13-git-send-email-stefani@seibold.net
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
This patch add the VDSO time support for the IA32 Emulation Layer.
Due the nature of the kernel headers and the LP64 compiler where the
size of a long and a pointer differs against a 32 bit compiler, there
is some type hacking necessary for optimal performance.
The vsyscall_gtod_data struture must be a rearranged to serve 32- and
64-bit code access at the same time:
- The seqcount_t was replaced by an unsigned, this makes the
vsyscall_gtod_data intedepend of kernel configuration and internal functions.
- All kernel internal structures are replaced by fix size elements
which works for 32- and 64-bit access
- The inner struct clock was removed to pack the whole struct.
The "unsigned seq" would be handled by functions derivated from seqcount_t.
Signed-off-by: Stefani Seibold <stefani@seibold.net>
Link: http://lkml.kernel.org/r/1395094933-14252-11-git-send-email-stefani@seibold.net
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
This patch add the time support for 32 bit a VDSO to a 32 bit kernel.
For 32 bit programs running on a 32 bit kernel, the same mechanism is
used as for 64 bit programs running on a 64 bit kernel.
Reviewed-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Stefani Seibold <stefani@seibold.net>
Link: http://lkml.kernel.org/r/1395094933-14252-10-git-send-email-stefani@seibold.net
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
This patch cleans up the __vdso_gettimeofday() function a little.
It kicks out an unneeded ret local variable and makes the code faster
if only the timezone is needed (an admittedly rare case.)
Reviewed-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Stefani Seibold <stefani@seibold.net>
Link: http://lkml.kernel.org/r/1395094933-14252-7-git-send-email-stefani@seibold.net
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
There a currently more than 30 users of the gtod macro, so replace the
last VVAR(vsyscall_gtod_data) by gtod macro.
Reviewed-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Stefani Seibold <stefani@seibold.net>
Link: http://lkml.kernel.org/r/1395094933-14252-6-git-send-email-stefani@seibold.net
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
This patch is a small code cleanup for the __vdso_clock_gettime() function.
It removes the unneeded return values from do_monotonic_coarse() and
do_realtime_coarse() and add a fallback label for doing the kernel
gettimeofday() system call.
Reviewed-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Stefani Seibold <stefani@seibold.net>
Link: http://lkml.kernel.org/r/1395094933-14252-5-git-send-email-stefani@seibold.net
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
This intermediate patch revamps the vclock_gettime.c by moving some functions
around. It is only for spliting purpose, to make whole the 32 bit vdso timer
patch easier to review.
Reviewed-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Stefani Seibold <stefani@seibold.net>
Link: http://lkml.kernel.org/r/1395094933-14252-4-git-send-email-stefani@seibold.net
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
The compat vDSO is a complicated hack that's needed to maintain
compatibility with a small range of glibc versions.
This removes it and replaces it with a much simpler hack: a config
option to disable the 32-bit vDSO by default.
This also changes the default value of CONFIG_COMPAT_VDSO to n --
users configuring kernels from scratch almost certainly want that
choice.
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Link: http://lkml.kernel.org/r/4bb4690899106eb11430b1186d5cc66ca9d1660c.1394751608.git.luto@amacapital.net
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
The VDSO does not play well with LTO, so just disable LTO for it.
Also pass a 32bit linker flag for the 32bit version.
[ hpa: change braces to parens to match kernel Makefile style ]
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Link: http://lkml.kernel.org/r/1391846481-31491-1-git-send-email-ak@linux.intel.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Pull x86 cleanups from Ingo Molnar:
"Misc cleanups"
* 'x86-cleanups-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86, cpu, amd: Fix a shadowed variable situation
um, x86: Fix vDSO build
x86: Delete non-required instances of include <linux/init.h>
x86, realmode: Pointer walk cleanups, pull out invariant use of __pa()
x86/traps: Clean up error exception handler definitions
Linus disliked the _no_lockdep() naming, so instead
use the more-consistent raw_* prefix to the non-lockdep
enabled seqcount methods.
This also adds raw_ methods for the write operations
as well, which will be utilized in a following patch.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Krzysztof Hałasa <khalasa@piap.pl>
Cc: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Cc: Willy Tarreau <w@1wt.eu>
Link: http://lkml.kernel.org/r/1388704274-5278-1-git-send-email-john.stultz@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
None of these files are actually using any __init type directives
and hence don't need to include <linux/init.h>. Most are just a
left over from __devinit and __cpuinit removal, or simply due to
code getting copied from one driver to the next.
[ hpa: undid incorrect removal from arch/x86/kernel/head_32.S ]
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Link: http://lkml.kernel.org/r/1389054026-12947-1-git-send-email-paul.gortmaker@windriver.com
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Currently seqlocks and seqcounts don't support lockdep.
After running across a seqcount related deadlock in the timekeeping
code, I used a less-refined and more focused variant of this patch
to narrow down the cause of the issue.
This is a first-pass attempt to properly enable lockdep functionality
on seqlocks and seqcounts.
Since seqcounts are used in the vdso gettimeofday code, I've provided
non-lockdep accessors for those needs.
I've also handled one case where there were nested seqlock writers
and there may be more edge cases.
Comments and feedback would be appreciated!
Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Li Zefan <lizefan@huawei.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: netdev@vger.kernel.org
Link: http://lkml.kernel.org/r/1381186321-4906-3-git-send-email-john.stultz@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Linux as a guest on KVM hypervisor, the only user of the pvclock
vsyscall interface, does not require notification on task migration
because:
1. cpu ID number maps 1:1 to per-CPU pvclock time info.
2. per-CPU pvclock time info is updated if the
underlying CPU changes.
3. that version is increased whenever underlying CPU
changes.
Which is sufficient to guarantee nanoseconds counter
is calculated properly.
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Gleb Natapov <gleb@redhat.com>
vread_hpet() uses "0xf0" as the offset of the hpet counter. To
clarify the meaning of this code, it should use symbolic name,
HPET_COUNTER, instead.
Signed-off-by: Satoru Takeuchi <takeuchi_satoru@jp.fujitsu.com>
Cc: H. Peter Anvin <hpa@linux.intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull KVM updates from Marcelo Tosatti:
"Considerable KVM/PPC work, x86 kvmclock vsyscall support,
IA32_TSC_ADJUST MSR emulation, amongst others."
Fix up trivial conflict in kernel/sched/core.c due to cross-cpu
migration notifier added next to rq migration call-back.
* tag 'kvm-3.8-1' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (156 commits)
KVM: emulator: fix real mode segment checks in address linearization
VMX: remove unneeded enable_unrestricted_guest check
KVM: VMX: fix DPL during entry to protected mode
x86/kexec: crash_vmclear_local_vmcss needs __rcu
kvm: Fix irqfd resampler list walk
KVM: VMX: provide the vmclear function and a bitmap to support VMCLEAR in kdump
x86/kexec: VMCLEAR VMCSs loaded on all cpus if necessary
KVM: MMU: optimize for set_spte
KVM: PPC: booke: Get/set guest EPCR register using ONE_REG interface
KVM: PPC: bookehv: Add EPCR support in mtspr/mfspr emulation
KVM: PPC: bookehv: Add guest computation mode for irq delivery
KVM: PPC: Make EPCR a valid field for booke64 and bookehv
KVM: PPC: booke: Extend MAS2 EPN mask for 64-bit
KVM: PPC: e500: Mask MAS2 EPN high 32-bits in 32/64 tlbwe emulation
KVM: PPC: Mask ea's high 32-bits in 32/64 instr emulation
KVM: PPC: e500: Add emulation helper for getting instruction ea
KVM: PPC: bookehv64: Add support for interrupt handling
KVM: PPC: bookehv: Remove GET_VCPU macro from exception handler
KVM: PPC: booke: Fix get_tb() compile error on 64-bit
KVM: PPC: e500: Silence bogus GCC warning in tlb code
...
Update the x86_64 arch_get_unmapped_area[_topdown] functions to make use
of vm_unmapped_area() instead of implementing a brute force search.
Signed-off-by: Michel Lespinasse <walken@google.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Improve performance of time system calls when using Linux pvclock,
by reading time info from fixmap visible copy of pvclock data.
Originally from Jeremy Fitzhardinge.
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Switch x86_64 to using sub-ns precise vsyscall
Cc: Tony Luck <tony.luck@intel.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Rename checking_wrmsrl() to wrmsrl_safe(), to match the naming
convention used by all the other MSR access functions/macros.
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Pull x32 support for x86-64 from Ingo Molnar:
"This tree introduces the X32 binary format and execution mode for x86:
32-bit data space binaries using 64-bit instructions and 64-bit kernel
syscalls.
This allows applications whose working set fits into a 32 bits address
space to make use of 64-bit instructions while using a 32-bit address
space with shorter pointers, more compressed data structures, etc."
Fix up trivial context conflicts in arch/x86/{Kconfig,vdso/vma.c}
* 'x86-x32-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (71 commits)
x32: Fix alignment fail in struct compat_siginfo
x32: Fix stupid ia32/x32 inversion in the siginfo format
x32: Add ptrace for x32
x32: Switch to a 64-bit clock_t
x32: Provide separate is_ia32_task() and is_x32_task() predicates
x86, mtrr: Use explicit sizing and padding for the 64-bit ioctls
x86/x32: Fix the binutils auto-detect
x32: Warn and disable rather than error if binutils too old
x32: Only clear TIF_X32 flag once
x32: Make sure TS_COMPAT is cleared for x32 tasks
fs: Remove missed ->fds_bits from cessation use of fd_set structs internally
fs: Fix close_on_exec pointer in alloc_fdtable
x32: Drop non-__vdso weak symbols from the x32 VDSO
x32: Fix coding style violations in the x32 VDSO code
x32: Add x32 VDSO support
x32: Allow x32 to be configured
x32: If configured, add x32 system calls to system call tables
x32: Handle process creation
x32: Signal-related system calls
x86: Add #ifdef CONFIG_COMPAT to <asm/sys_ia32.h>
...
Pull timer core updates from Thomas Gleixner.
* 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
ia64: vsyscall: Add missing paranthesis
alarmtimer: Don't call rtc_timer_init() when CONFIG_RTC_CLASS=n
x86: vdso: Put declaration before code
x86-64: Inline vdso clock_gettime helpers
x86-64: Simplify and optimize vdso clock_gettime monotonic variants
kernel-time: fix s/then/than/ spelling errors
time: remove no_sync_cmos_clock
time: Avoid scary backtraces when warning of > 11% adj
alarmtimer: Make sure we initialize the rtctimer
ntp: Fix leap-second hrtimer livelock
x86, tsc: Skip refined tsc calibration on systems with reliable TSC
rtc: Provide flag for rtc devices that don't support UIE
ia64: vsyscall: Use seqcount instead of seqlock
x86: vdso: Use seqcount instead of seqlock
x86: vdso: Remove bogus locking in update_vsyscall_tz()
time: Remove bogus comments
time: Fix change_clocksource locking
time: x86: Fix race switching from vsyscall to non-vsyscall clock
The motivation for this patchset was that I was looking at a way for a
qemu-kvm process, to exclude the guest memory from its core dump, which
can be quite large. There are already a number of filter flags in
/proc/<pid>/coredump_filter, however, these allow one to specify 'types'
of kernel memory, not specific address ranges (which is needed in this
case).
Since there are no more vma flags available, the first patch eliminates
the need for the 'VM_ALWAYSDUMP' flag. The flag is used internally by
the kernel to mark vdso and vsyscall pages. However, it is simple
enough to check if a vma covers a vdso or vsyscall page without the need
for this flag.
The second patch then replaces the 'VM_ALWAYSDUMP' flag with a new
'VM_NODUMP' flag, which can be set by userspace using new madvise flags:
'MADV_DONTDUMP', and unset via 'MADV_DODUMP'. The core dump filters
continue to work the same as before unless 'MADV_DONTDUMP' is set on the
region.
The qemu code which implements this features is at:
http://people.redhat.com/~jbaron/qemu-dump/qemu-dump.patch
In my testing the qemu core dump shrunk from 383MB -> 13MB with this
patch.
I also believe that the 'MADV_DONTDUMP' flag might be useful for
security sensitive apps, which might want to select which areas are
dumped.
This patch:
The VM_ALWAYSDUMP flag is currently used by the coredump code to
indicate that a vma is part of a vsyscall or vdso section. However, we
can determine if a vma is in one these sections by checking it against
the gate_vma and checking for a non-NULL return value from
arch_vma_name(). Thus, freeing a valuable vma bit.
Signed-off-by: Jason Baron <jbaron@redhat.com>
Acked-by: Roland McGrath <roland@hack.frob.com>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Avi Kivity <avi@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We used to store the wall-to-monotonic offset and the realtime base.
It's faster to precompute the monotonic base.
This is about a 3% speedup on Sandy Bridge for CLOCK_MONOTONIC.
It's much more impressive for CLOCK_MONOTONIC_COARSE.
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: John Stultz <john.stultz@linaro.org>
The update of the vdso data happens under xtime_lock, so adding a
nested lock is pointless. Just use a seqcount to sync the readers.
Reviewed-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>
When switching from a vsyscall capable to a non-vsyscall capable
clocksource, there was a small race, where the last vsyscall
gettimeofday before the switch might return a invalid time value
using the new non-vsyscall enabled clocksource values after the
switch is complete.
This is due to the vsyscall code checking the vclock_mode once
outside of the seqcount protected section. After it reads the
vclock mode, it doesn't re-check that the sampled clock data
that is obtained in the seqcount critical section still matches.
The fix is to sample vclock_mode inside the protected section,
and as long as it isn't VCLOCK_NONE, return the calculated
value. If it has changed and is now VCLOCK_NONE, fall back
to the syscall gettime calculation.
v2:
* Cleanup checks as suggested by tglx
* Also fix same issue present in gettimeofday path
CC: Andy Lutomirski <luto@amacapital.net>
CC: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Drop the legacy weak symbols that don't carry the __vdso prefix from
the x32 VDSO. This is a new ABI and we don't need to support that
legacy; the actual libc will export the proper symbols.
Suggested-by: Andy Lutomirski <luto@mit.edu>
Link: http://lkml.kernel.org/r/4F42E171.9080005@mit.edu
Cc: H. J. Lu <hjl.tools@gmail.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Move the prototype for x32_setup_additional_pages() to a header file,
and adjust the coding style to match standard.
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: H. J. Lu <hjl.tools@gmail.com>
Add support for the x32 VDSO. The x32 VDSO takes advantage of the
similarity between the x86-64 and the x32 ABIs to contain the same
content, only the container is different, as the x32 VDSO obviously is
an x32 shared object.
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
* 'x86-cpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86, amd: Include linux/elf.h since we use stuff from asm/elf.h
x86: cache_info: Update calculation of AMD L3 cache indices
x86: cache_info: Kill the atomic allocation in amd_init_l3_cache()
x86: cache_info: Kill the moronic shadow struct
x86: cache_info: Remove bogus free of amd_l3_cache data
x86, amd: Include elf.h explicitly, prepare the code for the module.h split
x86-32, amd: Move va_align definition to unbreak 32-bit build
x86, amd: Move BSP code to cpu_dev helper
x86: Add a BSP cpu_dev helper
x86, amd: Avoid cache aliasing penalties on AMD family 15h
* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
x86-32, vdso: On system call restart after SYSENTER, use int $0x80
x86, UV: Remove UV delay in starting slave cpus
x86, olpc: Wait for last byte of EC command to be accepted
When we enter a 32-bit system call via SYSENTER or SYSCALL, we shuffle
the arguments to match the int $0x80 calling convention. This was
probably a design mistake, but it's what it is now. This causes
errors if the system call as to be restarted.
For SYSENTER, we have to invoke the instruction from the vdso as the
return address is hardcoded. Accordingly, we can simply replace the
jump in the vdso with an int $0x80 instruction and use the slower
entry point for a post-restart.
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Link: http://lkml.kernel.org/r/CA%2B55aFztZ=r5wa0x26KJQxvZOaQq8s2v3u50wCyJcA-Sc4g8gQ@mail.gmail.com
Cc: <stable@kernel.org>
This patch provides performance tuning for the "Bulldozer" CPU. With its
shared instruction cache there is a chance of generating an excessive
number of cache cross-invalidates when running specific workloads on the
cores of a compute module.
This excessive amount of cross-invalidations can be observed if cache
lines backed by shared physical memory alias in bits [14:12] of their
virtual addresses, as those bits are used for the index generation.
This patch addresses the issue by clearing all the bits in the [14:12]
slice of the file mapping's virtual address at generation time, thus
forcing those bits the same for all mappings of a single shared library
across processes and, in doing so, avoids instruction cache aliases.
It also adds the command line option "align_va_addr=(32|64|on|off)" with
which virtual address alignment can be enabled for 32-bit or 64-bit x86
individually, or both, or be completely disabled.
This change leaves virtual region address allocation on other families
and/or vendors unaffected.
Signed-off-by: Borislav Petkov <borislav.petkov@amd.com>
Link: http://lkml.kernel.org/r/1312550110-24160-2-git-send-email-bp@amd64.org
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Andy Lutomirski
Linus Torvalds
H. Peter Anvin
Stefani Seibold
Andi Kleen
John Stultz
Paul Gortmaker
Marcelo Tosatti
Joe Perches
Satoru Takeuchi
Michel Lespinasse
H. Peter Anvin
Jason Baron
Andy Lutomirski
Thomas Gleixner
H. J. Lu
Borislav Petkov