This patch implements catchpoints for fork events on extended-remote
Linux targets.
Implementation appeared to be straightforward, requiring four new functions
in remote.c to implement insert/remove of fork/vfork catchpoints. These
functions are essentially stubs that just return 0 ('success') if the
required features are enabled. If the fork events are being reported, then
catchpoints are set and hit.
However, there are some extra issues that arise with catchpoints.
1) Thread creation reporting -- fork catchpoints are hit before the
follow_fork has been completed. When stopped at a fork catchpoint
in the native implementation, the new process is not 'reported'
until after the follow is done. It doesn't show up in the inferiors
list or the threads list. However, in the gdbserver case, an
'info threads' while stopped at a fork catchpoint will retrieve the
new thread info from the target and add it to GDB's data structures,
prior to the follow operations. Because of this premature report,
things on the GDB side eventually get very confused.
So in remote.c:remote_update_thread_list, we check to see if there
are any pending fork parent threads. If there are we remove the
related fork child thread from the thread list sent by the target.
2) Kill process before fork is followed -- on the native side in
linux-nat.c:linux_nat_kill, there is some code to handle the case where
a fork has occurred but follow_fork hasn't been called yet. It does
this by using the last status to determine if a follow is pending, and
if it is, to kill the child task. The use of last_status is fragile
in situations like non-stop mode where other events may have occurred
after the fork event. This patch identifies a fork parent
in remote.c:extended_remote_kill in a way similar to that used in
thread creation reporting above. If one is found, it kills the new
child as well.
Tested on x64 Ubuntu Lucid, native, remote, extended-remote. Tested the
case of killing the forking process before the fork has been followed
manually.
gdb/ChangeLog:
* remote.c (remote_insert_fork_catchpoint): New function.
(remote_remove_fork_catchpoint): New function.
(remote_insert_vfork_catchpoint): New function.
(remote_remove_vfork_catchpoint): New function.
(pending_fork_parent_callback): New function.
(remove_new_fork_child): New function.
(remote_update_thread_list): Call remote_notif_get_pending_events
and remove_new_fork_child.
(extended_remote_kill): Kill fork child when killing the
parent before follow_fork completes.
(init_extended_remote_ops): Initialize target vector with
new fork catchpoint functions.
This patch implements follow-fork for vfork on extended-remote Linux targets.
The implementation follows the native implementation as much as possible.
Most of the work is done on the GDB side in the existing code now in
infrun.c. GDBserver just has to report the events and do a little
bookkeeping.
Implementation includes:
* enabling VFORK events by adding ptrace options for VFORK and VFORK_DONE
to linux-low.c:linux_low_ptrace_options.
* handling VFORK and VFORK_DONE events in linux-low.c:handle_extended_wait
and reporting them to GDB.
* including VFORK and VFORK_DONE events in the predicate
linux-low.c:extended_event_reported.
* adding support for VFORK and VFORK_DONE events in RSP by adding stop
reasons "vfork" and "vforkdone" to the 'T' Stop Reply Packet in both
gdbserver/remote-utils.c and gdb/remote.c.
Tested on x64 Ubuntu Lucid, native, remote, extended-remote.
gdb/gdbserver/ChangeLog:
* linux-low.c (handle_extended_wait): Handle PTRACE_EVENT_FORK and
PTRACE_EVENT_VFORK_DONE.
(linux_low_ptrace_options, extended_event_reported): Add vfork
events.
* remote-utils.c (prepare_resume_reply): New stop reasons "vfork"
and "vforkdone" for RSP 'T' Stop Reply Packet.
* server.h (report_vfork_events): Declare
global variable.
gdb/ChangeLog:
* remote.c (remove_vfork_event_p): New function.
(remote_follow_fork): Add vfork event type to event checking.
(remote_parse_stop_reply): New stop reasons "vfork" and
"vforkdone" for RSP 'T' Stop Reply Packet.
This patch implements basic support for follow-fork and detach-on-fork on
extended-remote Linux targets. Only 'fork' is supported in this patch;
'vfork' support is added n a subsequent patch. This patch depends on
the previous patches in the patch series.
Sufficient extended-remote functionality has been implemented here to pass
gdb.base/multi-forks.exp, as well as gdb.base/foll-fork.exp with the
catchpoint tests commented out. Some other fork tests fail with this
patch because it doesn't provide the architecture support needed for
watchpoint inheritance or fork catchpoints.
The implementation follows the same general structure as for the native
implementation as much as possible.
This implementation includes:
* enabling fork events in linux-low.c in initialize_low and
linux_enable_extended_features
* handling fork events in gdbserver/linux-low.c:handle_extended_wait
- when a fork event occurs in gdbserver, we must do the full creation
of the new process, thread, lwp, and breakpoint lists. This is
required whether or not the new child is destined to be
detached-on-fork, because GDB will make target calls that require all
the structures. In particular we need the breakpoint lists in order
to remove the breakpoints from a detaching child. If we are not
detaching the child we will need all these structures anyway.
- as part of this event handling we store the target_waitstatus in a new
member of the parent lwp_info structure, 'waitstatus'. This
is used to store extended event information for reporting to GDB.
- handle_extended_wait is given a return value, denoting whether the
handled event should be reported to GDB. Previously it had only
handled clone events, which were never reported.
* using a new predicate in gdbserver to control handling of the fork event
(and eventually all extended events) in linux_wait_1. The predicate,
extended_event_reported, checks a target_waitstatus.kind for an
extended ptrace event.
* implementing a new RSP 'T' Stop Reply Packet stop reason: "fork", in
gdbserver/remote-utils.c and remote.c.
* implementing new target and RSP support for target_follow_fork with
target extended-remote. (The RSP components were actually defined in
patch 1, but they see their first use here).
- remote target routine remote_follow_fork, which just sends the 'D;pid'
detach packet to detach the new fork child cleanly. We can't just
call target_detach because the data structures for the forked child
have not been allocated on the host side.
Tested on x64 Ubuntu Lucid, native, remote, extended-remote.
gdb/gdbserver/ChangeLog:
* linux-low.c (handle_extended_wait): Implement return value,
rename argument 'event_child' to 'event_lwp', handle
PTRACE_EVENT_FORK, call internal_error for unrecognized event.
(linux_low_ptrace_options): New function.
(linux_low_filter_event): Call linux_low_ptrace_options,
use different argument fo linux_enable_event_reporting,
use return value from handle_extended_wait.
(extended_event_reported): New function.
(linux_wait_1): Call extended_event_reported and set
status to report fork events.
(linux_write_memory): Add pid to debug message.
(reset_lwp_ptrace_options_callback): New function.
(linux_handle_new_gdb_connection): New function.
(linux_target_ops): Initialize new structure member.
* linux-low.h (struct lwp_info) <waitstatus>: New member.
* lynx-low.c: Initialize new structure member.
* remote-utils.c (prepare_resume_reply): Implement stop reason
"fork" for "T" stop message.
* server.c (handle_query): Call handle_new_gdb_connection.
* server.h (report_fork_events): Declare global flag.
* target.h (struct target_ops) <handle_new_gdb_connection>:
New member.
(target_handle_new_gdb_connection): New macro.
* win32-low.c: Initialize new structure member.
gdb/ChangeLog:
* linux-nat.c (linux_nat_ptrace_options): New function.
(linux_init_ptrace, wait_lwp, linux_nat_filter_event):
Call linux_nat_ptrace_options and use different argument to
linux_enable_event_reporting.
(_initialize_linux_nat): Delete call to
linux_ptrace_set_additional_flags.
* nat/linux-ptrace.c (current_ptrace_options): Rename to
supported_ptrace_options.
(additional_flags): Delete variable.
(linux_check_ptrace_features): Use supported_ptrace_options.
(linux_test_for_tracesysgood, linux_test_for_tracefork):
Likewise, and remove additional_flags check.
(linux_enable_event_reporting): Change 'attached' argument to
'options'. Use supported_ptrace_options.
(ptrace_supports_feature): Change comment. Use
supported_ptrace_options.
(linux_ptrace_set_additional_flags): Delete function.
* nat/linux-ptrace.h (linux_ptrace_set_additional_flags):
Delete function prototype.
* remote.c (remote_fork_event_p): New function.
(remote_detach_pid): New function.
(remote_detach_1): Call remote_detach_pid, don't mourn inferior
if doing detach-on-fork.
(remote_follow_fork): New function.
(remote_parse_stop_reply): Handle new "T" stop reason "fork".
(remote_pid_to_str): Print "process" strings for pid/0/0 ptids.
(init_extended_remote_ops): Initialize to_follow_fork.
This patch implements a mechanism for GDB to determine whether fork
events are supported in gdbserver. This is a preparatory patch for
remote fork and exec event support.
Two new RSP packets are defined to represent fork and vfork event
support. These packets are used just like PACKET_multiprocess_feature
to denote whether the corresponding event is supported. GDB sends
fork-events+ and vfork-events+ to gdbserver to inquire about fork
event support. If the response enables these packets, then GDB
knows that gdbserver supports the corresponding events and will
enable them.
Target functions used to query for support are included along with
each new packet.
In order for gdbserver to know whether the events are supported at the
point where the qSupported packet arrives, the code in nat/linux-ptrace.c
had to be reorganized. Previously it would test for fork/exec event
support, then enable the events using the pid of the inferior. When the
qSupported packet arrives there may not be an inferior. So the mechanism
was split into two parts: a function that checks whether the events are
supported, called when gdbserver starts up, and another that enables the
events when the inferior stops for the first time.
Another gdbserver change was to add some global variables similar to
multi_process, one per new packet. These are used to control whether
the corresponding fork events are enabled. If GDB does not inquire
about the event support in the qSupported packet, then gdbserver will
not set these "report the event" flags. If the flags are not set, the
events are ignored like they were in the past. Thus, gdbserver will
never send fork event notification to an older GDB that doesn't
recognize fork events.
Tested on Ubuntu x64, native/remote/extended-remote, and as part of
subsequent patches in the series.
gdb/gdbserver/ChangeLog:
* linux-low.c (linux_supports_fork_events): New function.
(linux_supports_vfork_events): New function.
(linux_target_ops): Initialize new structure members.
(initialize_low): Call linux_check_ptrace_features.
* lynx-low.c (lynx_target_ops): Initialize new structure
members.
* server.c (report_fork_events, report_vfork_events):
New global flags.
(handle_query): Add new features to qSupported packet and
response.
(captured_main): Initialize new global variables.
* target.h (struct target_ops) <supports_fork_events>:
New member.
<supports_vfork_events>: New member.
(target_supports_fork_events): New macro.
(target_supports_vfork_events): New macro.
* win32-low.c (win32_target_ops): Initialize new structure
members.
gdb/ChangeLog:
* nat/linux-ptrace.c (linux_check_ptrace_features): Change
from static to extern.
* nat/linux-ptrace.h (linux_check_ptrace_features): Declare.
* remote.c (anonymous enum): <PACKET_fork_event_feature,
* PACKET_vfork_event_feature>: New enumeration constants.
(remote_protocol_features): Add table entries for new packets.
(remote_query_supported): Add new feature queries to qSupported
packet.
(_initialize_remote): Exempt new packets from the requirement
to have 'set remote' commands.
This commit allows GDB to determine filenames of main executables
when debugging using remote stubs without multiprocess extensions.
The qXfer:exec-file:read packet is extended to allow an empty
annex, with the meaning that the remote stub should supply the
filename of whatever it thinks is the current process.
gdb/ChangeLog:
* remote.c (remote_add_inferior): Call exec_file_locate_attach
for fake PIDs as well as real ones.
(remote_pid_to_exec_file): Send empty annex if PID is fake.
gdb/doc/ChangeLog:
* gdb.texinfo (General Query Packets): Document
qXfer:exec-file:read with empty annex.
gdb/gdbserver/ChangeLog:
* server.c (handle_qxfer_exec_file): Use current process
if annex is empty.
This commit modifies remote_add_inferior to take an extra argument
try_open_exec. If this is nonzero, remote_add_inferior will attempt
to open this inferior's executable as the main executable if no main
executable is open already. Callers are updated appropriately.
With this commit, remote debugging can now be initiated using only a
"target remote" or "target extended-remote" command; no "set sysroot"
or "file" commands are required, e.g.
bash$ gdb -q
(gdb) target remote | gdbserver - /bin/sh
Remote debugging using | gdbserver - /bin/sh
Process /bin/sh created; pid = 32166
stdin/stdout redirected
Remote debugging using stdio
Reading symbols from target:/bin/bash...
One testcase required updating as a result of this commit. The test
checked that GDB's "info files" command does not crash if no main
executable is open, and relied on GDB's inability to access the main
executable over the remote protocol. The test was updated to inhibit
this new behavior.
gdb/ChangeLog:
* remote.c (remote_add_inferior): New argument try_open_exec.
If nonzero, attempt to open the inferior's executable file as
the main executable if no main executable is open already.
All callers updated.
* NEWS: Mention that GDB now supports automatic location and
retrieval of executable + files from remote targets.
gdb/doc/ChangeLog:
* gdb.texinfo (Connecting to a Remote Target): Mention that
GDB can access program files from remote targets that support
qXfer:exec-file:read and Host I/O packets.
gdb/testsuite/ChangeLog:
* gdb.server/server-exec-info.exp: Inhibit GDB from accessing
the main executable over the remote protocol.
This commit adds a new packet "qXfer:exec-file:read" to the remote
protocol that can be used to obtain the pathname of the file that
was executed to create a process on the remote system. Support for
this packet is added to GDB and remote_ops.to_pid_to_exec_file is
implemented using it.
gdb/ChangeLog:
* target.h (TARGET_OBJECT_EXEC_FILE): New enum value.
* remote.c (PACKET_qXfer_exec_file): Likewise.
(remote_protocol_features): Register the
"qXfer:exec-file:read" feature.
(remote_xfer_partial): Handle TARGET_OBJECT_EXEC_FILE.
(remote_pid_to_exec_file): New function.
(init_remote_ops): Initialize to_pid_to_exec_file.
(_initialize_remote): Register new "set/show remote
pid-to-exec-file-packet" command.
* NEWS: Announce new qXfer:exec-file:read packet.
gdb/doc/ChangeLog:
* gdb.texinfo (Remote Configuration): Document the "set/show
remote pid-to-exec-file-packet" command.
(General Query Packets): Document the qXfer:exec-file:read
qSupported features. Document the qXfer:exec-file:read packet.
On GNU/Linux, if the running kernel supports clone events, then
linux-thread-db.c defers thread listing to the target beneath:
static void
thread_db_update_thread_list (struct target_ops *ops)
{
...
if (target_has_execution && !thread_db_use_events ())
ops->beneath->to_update_thread_list (ops->beneath);
else
thread_db_update_thread_list_td_ta_thr_iter (ops);
...
}
However, when live debugging, the target beneath, linux-nat.c, does
not implement the to_update_thread_list method. The result is that if
a thread is marked exited (because it can't be deleted right now,
e.g., it was the selected thread), then it won't ever be deleted,
until the process exits or is killed/detached.
A similar thing happens with the remote.c target. Because its
target_update_thread_list implementation skips exited threads when it
walks the current thread list looking for threads that no longer exits
on the target side, using ALL_NON_EXITED_THREADS_SAFE, stale exited
threads are never deleted.
This is not a big deal -- I can't think of any way this might be user
visible, other than gdb's memory growing a tiny bit whenever a thread
gets stuck in exited state. Still, might as well clean things up
properly.
All other targets use prune_threads, so are unaffected.
The fix adds a ALL_THREADS_SAFE macro, that like
ALL_NON_EXITED_THREADS_SAFE, walks the thread list and allows deleting
the iterated thread, and uses that in places that are walking the
thread list in order to delete threads. Actually, after converting
linux-nat.c and remote.c to use this, we find the only other user of
ALL_NON_EXITED_THREADS_SAFE is also walking the list to delete
threads. So we convert that too, and end up deleting
ALL_NON_EXITED_THREADS_SAFE.
Tested on x86_64 Fedora 20, native and gdbserver.
gdb/ChangeLog
2015-04-07 Pedro Alves <palves@redhat.com>
* gdbthread.h (ALL_NON_EXITED_THREADS_SAFE): Rename to ...
(ALL_THREADS_SAFE): ... this, and don't skip exited threads.
(delete_exited_threads): New declaration.
* infrun.c (follow_exec): Use ALL_THREADS_SAFE.
* linux-nat.c (linux_nat_update_thread_list): New function.
(linux_nat_add_target): Install it.
* remote.c (remote_update_thread_list): Use ALL_THREADS_SAFE.
* thread.c (prune_threads): Use ALL_THREADS_SAFE.
(delete_exited_threads): New function.
The functionality of "target:" sysroots is a superset of the
functionality of "remote:" sysroots. This commit causes the
"set sysroot" command to rewrite "remote:" sysroots as "target:"
sysroots and replaces "remote:" specific code with "target:"
specific code where still necessary.
gdb/ChangeLog:
* remote.h (REMOTE_SYSROOT_PREFIX): Remove definition.
(remote_filename_p): Remove declaration.
(remote_bfd_open): Likewise.
* remote.c (remote_bfd_iovec_open): Remove function.
(remote_bfd_iovec_close): Likewise.
(remote_bfd_iovec_pread): Likewise.
(remote_bfd_iovec_stat): Likewise.
(remote_filename_p): Likewise.
(remote_bfd_open): Likewise.
* symfile.h (gdb_bfd_open_maybe_remote): Remove declaration.
* symfile.c (separate_debug_file_exists): Use gdb_bfd_open.
(gdb_bfd_open_maybe_remote): Remove function.
(symfile_bfd_open): Replace remote filename check with
target filename check.
(reread_symbols): Use gdb_bfd_open.
* build-id.c (gdbcore.h): New include.
(build_id_to_debug_bfd): Use gdb_bfd_open.
* infcmd.c (attach_command_post_wait): Remove remote filename
check.
* solib.c (solib_find): Replace remote-specific handling with
target-specific handling. Update comments where necessary.
(solib_bfd_open): Replace remote-specific handling with
target-specific handling.
(gdb_sysroot_changed): New function.
(_initialize_solib): Call the above when gdb_sysroot changes.
* windows-tdep.c (gdbcore.h): New include.
(windows_xfer_shared_library): Use gdb_bfd_open.
This commit introduces a new target method target_filesystem_is_local
which can be used to determine whether or not the filesystem accessed
by the target_fileio_* methods is the local filesystem.
gdb/ChangeLog:
* target.h (struct target_ops) <to_filesystem_is_local>:
New field.
(target_filesystem_is_local): New macro.
* target-delegates.c: Regenerate.
* remote.c (remote_filesystem_is_local): New function.
(init_remote_ops): Initialize to_filesystem_is_local.
This commit introduces a new target method target_fileio_fstat
which can be used to retrieve information about files opened with
target_fileio_open.
gdb/ChangeLog:
* target.h (struct target_ops) <to_fileio_fstat>: New field.
(target_fileio_fstat): New declaration.
* target.c (target_fileio_fstat): New function.
* inf-child.c (inf_child_fileio_fstat): Likewise.
(inf_child_target): Initialize to_fileio_fstat.
* remote.c (init_remote_ops): Likewise.
gdb/ChangeLog:
* remote.c (remote_mourn_1): Remove function. Update all callers
to use remote_mourn.
(extended_remote_mourn_1): Remove function. Update all callers
to use extended_remote_mourn.
(extended_remote_attach_1): Remove function. Update all callers
to use extended_remote_attach.
All callers of target_async pass it the same callback
(inferior_event_handler). Since both common code and target backends
need to be able to put the target in and out of target async mode at
any given time, there's really no way that a different callback could
be passed. This commit simplifies things, and removes the indirection
altogether. Bonus: with this, gdb's target_async method ends up with
the same signature as gdbserver's.
Tested on x86_64 Fedora 20, native and gdbserver.
gdb/ChangeLog:
2015-03-25 Pedro Alves <palves@redhat.com>
* target.h <to_async>: Replace 'callback' and 'context' parameters
with boolean 'enable' parameter.
(target_async): Replace CALLBACK and CONTEXT parameters with
boolean ENABLE parameter.
* inf-loop.c (inferior_event_handler): Adjust.
* linux-nat.c (linux_nat_attach, linux_nat_resume)
(linux_nat_resume): Adjust.
(async_client_callback, async_client_context): Delete.
(handle_target_event): Call inferior_event_handler directly.
(linux_nat_async): Replace 'callback' and 'context' parameters
with boolean 'enable' parameter. Adjust. Remove references to
async_client_callback and async_client_context.
(linux_nat_close): Adjust.
* record-btrace.c (record_btrace_async): Replace 'callback' and
'context' parameters with boolean 'enable' parameter. Adjust.
(record_btrace_resume): Adjust.
* record-full.c (record_full_async): Replace 'callback' and
'context' parameters with boolean 'enable' parameter. Adjust.
(record_full_resume, record_full_core_resume): Adjust.
* remote.c (struct remote_state) <async_client_callback,
async_client_context>: Delete fields.
(remote_start_remote, extended_remote_attach_1, remote_resume)
(extended_remote_create_inferior): Adjust.
(remote_async_serial_handler): Call inferior_event_handler
directly.
(remote_async): Replace 'callback' and 'context' parameters with
boolean 'enable' parameter. Adjust.
* top.c (gdb_readline_wrapper_cleanup, gdb_readline_wrapper):
Adjust.
* target-delegates.c: Regenerate.
The "set serial parity" command allows the user to control which
parity to use when communicating over a serial connection, rather
than having the parity hardcoded to none.
gdb/ChangeLog:
* NEWS: Mention set/show serial parity command.
* monitor.c (monitor_open): Call serial_setparity.
* remote.c (remote_open_1): Likewise.
* ser-base.c (ser_base_serparity): New function.
* ser-base.h (ser_base_setparity): Add declaration.
* ser-go32.c (dos_ops): Set "setparity" field.
* ser-mingw.c (ser_windows_raw): Do not set state.fParity and
state.Parity.
(ser_windows_setparity): New function.
(hardwire_ops): Add ser_windows_setparity.
(tty_ops): Add NULL for setparity field.
(pipe_ops): Add ser_base_setparity.
(tcp_ops): Likewise.
* ser-pipe.c (pipe_ops): Likewise.
* ser-tcp.c (tcp_ops): Likewise.
* ser-unix.c (hardwire_setparity): Add declaration.
(hardwire_raw): Don't reset PARENB flag.
(hardwire_setparity): New function.
(hardwire_ops): Add hardwire_setparity.
* serial.c (serial_setparity): New function.
(serial_parity): New global.
(parity_none, parity_odd, parity_even, parity_enums, parity):
New static globals.
(set_parity): New function.
(_initialize_serial): Add set/show serial parity commands.
* serial.h (GDBPARITY_NONE): Define.
(GDBPARITY_ODD): Define.
(GDBPARITY_EVEN): Define.
(serial_setparity) Add declaration.
(struct serial_ops): Add setparity field.
* target.h (serial_parity): Add declaration.
gdb/doc/ChangeLog:
* gdb.texinfo (Remote configuration): Document "set/show
serial parity" command.
This commit makes support for the "vFile:fstat" packet be detected
by probing rather than using qSupported, for consistency with the
other vFile: packets.
gdb/ChangeLog:
(remote_protocol_features): Remove the "vFile:fstat" feature.
(remote_hostio_fstat): Probe for "vFile:fstat" support.
gdb/doc/ChangeLog:
* gdb.texinfo (General Query Packets): Remove documentation
for now-removed vFile:fstat qSupported features.
gdb/gdbserver/ChangeLog:
* server.c (handle_query): Do not report vFile:fstat as supported.
This commit adds a new packet "vFile:fstat:" to the remote protocol
that can be used by to retrieve information about files that have
been previously opened using vFile:open. vFile:fstat: support is
added to GDB, and remote_bfd_iovec_stat is implemented using it. If
vFile:fstat: is not supported by the remote GDB creates a dummy result
by zeroing the supplied stat structure and setting its st_size field
to INT_MAX. This mimics GDB's previous behaviour, with the exception
that GDB did not previously zero the structure so all other fields
would have been returned unchanged, which is to say very likely
populated with random values from the stack.
gdb/ChangeLog:
* remote-fileio.h (remote_fileio_to_host_stat): New declaration.
* remote-fileio.c (remote_fileio_to_host_uint): New function.
(remote_fileio_to_host_ulong): Likewise.
(remote_fileio_to_host_mode): Likewise.
(remote_fileio_to_host_time): Likewise.
(remote_fileio_to_host_stat): Likewise.
* remote.c (PACKET_vFile_fstat): New enum value.
(remote_protocol_features): Register the "vFile:fstat" feature.
(remote_hostio_fstat): New function.
(remote_bfd_iovec_stat): Use the above.
(_initialize_remote): Register new "set/show remote
hostio-fstat-packet" command.
* symfile.c (separate_debug_file_exists): Update comment.
* NEWS: Announce new vFile:fstat packet.
gdb/doc/ChangeLog:
* gdb.texinfo (Remote Configuration): Document the
"set/show remote hostio-fstat-packet" command.
(General Query Packets): Document the vFile:fstat
qSupported features.
(Host I/O Packets): Document the vFile:fstat packet.
This patch splits the TRY_CATCH macro into three, so that we go from
this:
~~~
volatile gdb_exception ex;
TRY_CATCH (ex, RETURN_MASK_ERROR)
{
}
if (ex.reason < 0)
{
}
~~~
to this:
~~~
TRY
{
}
CATCH (ex, RETURN_MASK_ERROR)
{
}
END_CATCH
~~~
Thus, we'll be getting rid of the local volatile exception object, and
declaring the caught exception in the catch block.
This allows reimplementing TRY/CATCH in terms of C++ exceptions when
building in C++ mode, while still allowing to build GDB in C mode
(using setjmp/longjmp), as a transition step.
TBC, after this patch, is it _not_ valid to have code between the TRY
and the CATCH blocks, like:
TRY
{
}
// some code here.
CATCH (ex, RETURN_MASK_ERROR)
{
}
END_CATCH
Just like it isn't valid to do that with C++'s native try/catch.
By switching to creating the exception object inside the CATCH block
scope, we can get rid of all the explicitly allocated volatile
exception objects all over the tree, and map the CATCH block more
directly to C++'s catch blocks.
The majority of the TRY_CATCH -> TRY+CATCH+END_CATCH conversion was
done with a script, rerun from scratch at every rebase, no manual
editing involved. After the mechanical conversion, a few places
needed manual intervention, to fix preexisting cases where we were
using the exception object outside of the TRY_CATCH block, and cases
where we were using "else" after a 'if (ex.reason) < 0)' [a CATCH
after this patch]. The result was folded into this patch so that GDB
still builds at each incremental step.
END_CATCH is necessary for two reasons:
First, because we name the exception object in the CATCH block, which
requires creating a scope, which in turn must be closed somewhere.
Declaring the exception variable in the initializer field of a for
block, like:
#define CATCH(EXCEPTION, mask) \
for (struct gdb_exception EXCEPTION; \
exceptions_state_mc_catch (&EXCEPTION, MASK); \
EXCEPTION = exception_none)
would avoid needing END_CATCH, but alas, in C mode, we build with C90,
which doesn't allow mixed declarations and code.
Second, because when TRY/CATCH are wired to real C++ try/catch, as
long as we need to handle cleanup chains, even if there's no CATCH
block that wants to catch the exception, we need for stop at every
frame in the unwind chain and run cleanups, then rethrow. That will
be done in END_CATCH.
After we require C++, we'll still need TRY/CATCH/END_CATCH until
cleanups are completely phased out -- TRY/CATCH in C++ mode will
save/restore the current cleanup chain, like in C mode, and END_CATCH
catches otherwise uncaugh exceptions, runs cleanups and rethrows, so
that C++ cleanups and exceptions can coexist.
IMO, this still makes the TRY/CATCH code look a bit more like a
newcomer would expect, so IMO worth it even if we weren't considering
C++.
gdb/ChangeLog.
2015-03-07 Pedro Alves <palves@redhat.com>
* common/common-exceptions.c (struct catcher) <exception>: No
longer a pointer to volatile exception. Now an exception value.
<mask>: Delete field.
(exceptions_state_mc_init): Remove all parameters. Adjust.
(exceptions_state_mc): No longer pop the catcher here.
(exceptions_state_mc_catch): New function.
(throw_exception): Adjust.
* common/common-exceptions.h (exceptions_state_mc_init): Remove
all parameters.
(exceptions_state_mc_catch): Declare.
(TRY_CATCH): Rename to ...
(TRY): ... this. Remove EXCEPTION and MASK parameters.
(CATCH, END_CATCH): New.
All callers adjusted.
gdb/gdbserver/ChangeLog:
2015-03-07 Pedro Alves <palves@redhat.com>
Adjust all callers of TRY_CATCH to use TRY/CATCH/END_CATCH
instead.
This normalizes some exception catch blocks that check for ex.reason
to look like this:
~~~
volatile gdb_exception ex;
TRY_CATCH (ex, RETURN_MASK_ALL)
{
...
}
if (ex.reason < 0)
{
...
}
~~~
This is a preparation step for running a script that converts all
TRY_CATCH uses to look like this instead:
~~~
TRY
{
...
}
CATCH (ex, RETURN_MASK_ALL)
{
...
}
END_CATCH
~~~
The motivation for that change is being able to reimplent TRY/CATCH in
terms of C++ try/catch.
This commit makes it so that:
- no condition other than ex.reason < 0 is checked in the if
predicate
- there's no "else" block to check whether no exception was caught
- there's no code between the TRY_CATCH (TRY) block and the
'if (ex.reason < 0)' block (CATCH).
- the exception object is no longer referred to outside the if/catch
block. Note the local volatile exception objects that are
currently defined inside functions that use TRY_CATCH will
disappear. In cases it's more convenient to still refer to the
exception outside the catch block, a new non-volatile local is
added and copy to that object is made within the catch block.
The following patches should make this all clearer.
gdb/ChangeLog:
2015-03-07 Pedro Alves <palves@redhat.com>
* amd64-tdep.c (amd64_frame_cache, amd64_sigtramp_frame_cache)
(amd64_epilogue_frame_cache): Normal exception handling code.
* break-catch-throw.c (check_status_exception_catchpoint)
(re_set_exception_catchpoint): Ditto.
* cli/cli-interp.c (safe_execute_command):
* cli/cli-script.c (script_from_file): Ditto.
* compile/compile-c-symbols.c (generate_c_for_for_one_variable):
Ditto.
* compile/compile-object-run.c (compile_object_run): Ditto.
* cp-abi.c (baseclass_offset): Ditto.
* cp-valprint.c (cp_print_value): Ditto.
* exceptions.c (catch_exceptions_with_msg):
* frame-unwind.c (frame_unwind_try_unwinder): Ditto.
* frame.c (get_frame_address_in_block_if_available): Ditto.
* i386-tdep.c (i386_frame_cache, i386_epilogue_frame_cache)
(i386_sigtramp_frame_cache): Ditto.
* infcmd.c (post_create_inferior): Ditto.
* linespec.c (parse_linespec, find_linespec_symbols):
* p-valprint.c (pascal_object_print_value): Ditto.
* parse.c (parse_expression_for_completion): Ditto.
* python/py-finishbreakpoint.c (bpfinishpy_init): Ditto.
* remote.c (remote_get_noisy_reply): Ditto.
* s390-linux-tdep.c (s390_frame_unwind_cache): Ditto.
* solib-svr4.c (solib_svr4_r_map): Ditto.
This commit introduces a new inline common function "startswith"
which takes two string arguments and returns nonzero if the first
string starts with the second. It also updates the 295 places
where this logic was written out longhand to use the new function.
gdb/ChangeLog:
* common/common-utils.h (startswith): New inline function.
All places where this logic was used updated to use the above.
This adjusts target remote to tell the core whether a trap was caused
by a breakpoint.
To that end, the patch teaches GDB about new RSP stop reasons "T05
swbreak" and "T05 hwbreak", that remote targets report back to GDB,
similarly to how "T05 watch" indicates a stop caused by a watchpoint.
Because targets that can report these events are expected to
themselves adjust the PC after a software breakpoint, these new stop
reasons must only be reported if the stub is talking to a GDB that
understands them. Because of that, the use of the new stop reasons
needs to be handshaked on initial connection, using the qSupported
mechanism. GDB simply sends "swbreak+" in its qSupports query, and
the stub reports back "swbreak+" too.
Because these new stop reasons are required to fix a fundamental
non-stop mode problem, this commit extends the remote non-stop intro
section in the manual, documenting the events as required.
To be clear, GDB will still cope with remote targets that don't
support these new stop reasons; it will behave just like today.
Tested on x86-64 Fedora 20, native and gdbserver.
gdb/ChangeLog:
2015-03-04 Pedro Alves <palves@redhat.com>
* NEWS: Mention the new "swbreak" and "hwbreak" stop reasons.
* remote.c (struct remote_state) <remote_stopped_by_watchpoint_p>:
Delete field.
<stop_reason>: New field.
(PACKET_swbreak_feature, PACKET_hwbreak_feature): New enum values.
(packet_set_cmd_state): New function.
(remote_protocol_features): Register the "swbreak" and "hwbreak"
features.
(remote_query_supported): If not disabled with the corresponding
"set remote foo-packet" command, report support for the swbreak
and hwbreak features.
(struct stop_reply) <remote_stopped_by_watchpoint_p>: Delete
field.
<stop_reason>: New field.
(remote_parse_stop_reply): Handle "swbreak" and "hwbreak".
(remote_wait_as): Adjust.
(remote_stopped_by_sw_breakpoint)
(remote_supports_stopped_by_sw_breakpoint)
(remote_stopped_by_hw_breakpoint)
(remote_supports_stopped_by_hw_breakpoint): New functions.
(remote_stopped_by_watchpoint): New function.
(init_remote_ops): Install them.
(_initialize_remote): Register new "set/show remote
swbreak-feature-packet" and "set/show remote
swbreak-feature-packet" commands.
gdb/doc/ChangeLog:
2015-03-04 Pedro Alves <palves@redhat.com>
* gdb.texinfo (Remote Configuration): Document the "set/show
remote swbreak-feature-packet" and "set/show remote
hwbreak-feature-packet" commands.
(Packets) <Z0>: Add cross link to the "swbreak" stop reason's
decription.
(Stop Reply Packets): Document the swbreak and hwbreak stop
reasons.
(General Query Packets): Document the swbreak and hwbreak
qSupported features.
(Remote Non-Stop): Explain that swbreak and hwbreak are required.
This patch renames symbols that happen to have names which are
reserved keywords in C++.
Most of this was generated with Tromey's cxx-conversion.el script.
Some places where later hand massaged a bit, to fix formatting, etc.
And this was rebased several times meanwhile, along with re-running
the script, so re-running the script from scratch probably does not
result in the exact same output. I don't think that matters anyway.
gdb/
2015-02-27 Tom Tromey <tromey@redhat.com>
Pedro Alves <palves@redhat.com>
Rename symbols whose names are reserved C++ keywords throughout.
gdb/gdbserver/
2015-02-27 Tom Tromey <tromey@redhat.com>
Pedro Alves <palves@redhat.com>
Rename symbols whose names are reserved C++ keywords throughout.
Fixes building gdb on x86_64-apple-darwin14 with clang, which produces
a number of warnings from -Wformat-nonliteral.
Ref: https://sourceware.org/ml/gdb/2015-02/msg00047.html
gdb/ChangeLog:
2015-02-26 Pedro Alves <palves@redhat.com>
* auto-load.h (file_is_auto_load_safe): Add ATTRIBUTE_PRINTF.
* complaints.c (vcomplaint): Pass argument FMT directly to
printf-like functions instead of complaint->fmt.
* ctf.c (ctf_save_write_metadata): Add ATTRIBUTE_PRINTF.
* darwin-nat.c (inferior_debug): Add ATTRIBUTE_PRINTF.
* compile/compile-loc2c.c (pushf, unary, binary): Add
ATTRIBUTE_PRINTF.
(do_compile_dwarf_expr_to_c): Pass string literal as format string
to pushf.
(BINARY): Pass string literal as format string to 'binary'.
* compile/compile-object-load.c (link_callbacks_einfo): Add
ATTRIBUTE_PRINTF.
* guile/guile-internal.h (gdbscm_printf): Add ATTRIBUTE_PRINTF.
We need to be careful with parsing optional stop reasons that start
with an hex character ("awatch", "core"), as GDBs that aren't aware of
them parse them as real numbers. That's silly of course, given that
there should be a colon after those magic "numbers". So if strtol on
"abbz:" doesn't return "first invalid char" pointing to the colon, we
know that "abbz" isn't really a register number. It must be optional
stop info we don't know about. This adjusts GDB to work that way,
removing the need for the special casing done upfront:
/* If this packet is an awatch packet, don't parse the 'a'
as a register number. */
if (strncmp (p, "awatch", strlen("awatch")) != 0
&& strncmp (p, "core", strlen ("core") != 0))
For as long as we care about compatibility with GDB 7.9, we'll need to
continue to be careful about this, so I added a comment.
Tested on x86_64 Fedora 20, native gdbserver.
gdb/ChangeLog:
2015-02-23 Pedro Alves <palves@redhat.com>
* remote.c (skip_to_semicolon): New function.
(remote_parse_stop_reply) <T stop reply>: Use it. Don't
special case the stop reasons that look like hex numbers
upfront. Instead handle real register numbers after matching
all the known stop reasons.
We were comparing a pointer against a char on remote.c. 'dcb' filed a
bug to inform us about that. I pushed the following patch under the
obvious rule.
gdb/ChangeLog:
2015-02-09 Sergio Durigan Junior <sergiodj@redhat.com>
PR remote/17946
* gdb/remote.c (remote_parse_stop_reply): Fix wrong comparison
of pointer against char.
Allow the size of the branch trace ring buffer to be defined by the
user. The specified buffer size will be used when BTS tracing is
enabled for new threads.
The obtained buffer size may differ from the requested size. The
actual buffer size for the current thread is shown in the "info record"
command.
Bigger buffers mean longer traces, but also longer processing time.
2015-02-09 Markus Metzger <markus.t.metzger@intel.com>
* btrace.c (parse_xml_btrace_conf_bts): Add size.
(btrace_conf_bts_attributes): New.
(btrace_conf_children): Add attributes.
* common/btrace-common.h (btrace_config_bts): New.
(btrace_config)<bts>: New.
(btrace_config): Update comment.
* nat/linux-btrace.c (linux_enable_btrace, linux_enable_bts):
Use config.
* features/btrace-conf.dtd: Increment version. Add size
attribute to bts element.
* record-btrace.c (set_record_btrace_bts_cmdlist,
show_record_btrace_bts_cmdlist): New.
(record_btrace_adjust_size, record_btrace_print_bts_conf,
record_btrace_print_conf, cmd_set_record_btrace_bts,
cmd_show_record_btrace_bts): New.
(record_btrace_info): Call record_btrace_print_conf.
(_initialize_record_btrace): Add commands.
* remote.c: Add PACKET_Qbtrace_conf_bts_size enum.
(remote_protocol_features): Add Qbtrace-conf:bts:size packet.
(btrace_sync_conf): Synchronize bts size.
(_initialize_remote): Add Qbtrace-conf:bts:size packet.
* NEWS: Announce new commands and new packets.
doc/
* gdb.texinfo (Branch Trace Configuration Format): Add size.
(Process Record and Replay): Describe new set|show commands.
(General Query Packets): Describe Qbtrace-conf:bts:size packet.
testsuite/
* gdb.btrace/buffer-size: New.
gdbserver/
* linux-low.c (linux_low_btrace_conf): Print size.
* server.c (handle_btrace_conf_general_set): New.
(hanle_general_set): Call handle_btrace_conf_general_set.
(handle_query): Report Qbtrace-conf:bts:size as supported.
Add a struct to describe the branch trace configuration and use it for
enabling branch tracing.
The user will be able to set configuration fields for each tracing format
to be used for new threads.
The actual configuration that is active for a given thread will be shown
in the "info record" command.
At the moment, the configuration struct only contains a format field
that is set to the only available format.
The format is the only configuration option that can not be set via set
commands. It is given as argument to the "record btrace" command when
starting recording.
2015-02-09 Markus Metzger <markus.t.metzger@intel.com>
* Makefile.in (XMLFILES): Add btrace-conf.dtd.
* x86-linux-nat.c (x86_linux_enable_btrace): Update parameters.
(x86_linux_btrace_conf): New.
(x86_linux_create_target): Initialize to_btrace_conf.
* nat/linux-btrace.c (linux_enable_btrace): Update parameters.
Check format. Split into this and ...
(linux_enable_bts): ... this.
(linux_btrace_conf): New.
(perf_event_skip_record): Renamed into ...
(perf_event_skip_bts_record): ... this. Updated users.
(linux_disable_btrace): Split into this and ...
(linux_disable_bts): ... this.
(linux_read_btrace): Check format.
* nat/linux-btrace.h (linux_enable_btrace): Update parameters.
(linux_btrace_conf): New.
(btrace_target_info)<ptid>: Moved.
(btrace_target_info)<conf>: New.
(btrace_target_info): Split into this and ...
(btrace_tinfo_bts): ... this. Updated users.
* btrace.c (btrace_enable): Update parameters.
(btrace_conf, parse_xml_btrace_conf_bts, parse_xml_btrace_conf)
(btrace_conf_children, btrace_conf_attributes)
(btrace_conf_elements): New.
* btrace.h (btrace_enable): Update parameters.
(btrace_conf, parse_xml_btrace_conf): New.
* common/btrace-common.h (btrace_config): New.
* feature/btrace-conf.dtd: New.
* record-btrace.c (record_btrace_conf): New.
(record_btrace_cmdlist): New.
(record_btrace_enable_warn, record_btrace_open): Pass
&record_btrace_conf.
(record_btrace_info): Print recording format.
(cmd_record_btrace_bts_start): New.
(cmd_record_btrace_start): Call cmd_record_btrace_bts_start.
(_initialize_record_btrace): Add "record btrace bts" subcommand.
Add "record bts" alias command.
* remote.c (remote_state)<btrace_config>: New.
(remote_btrace_reset, PACKET_qXfer_btrace_conf): New.
(remote_protocol_features): Add qXfer:btrace-conf:read.
(remote_open_1): Call remote_btrace_reset.
(remote_xfer_partial): Handle TARGET_OBJECT_BTRACE_CONF.
(btrace_target_info)<conf>: New.
(btrace_sync_conf, btrace_read_config): New.
(remote_enable_btrace): Update parameters. Call btrace_sync_conf and
btrace_read_conf.
(remote_btrace_conf): New.
(init_remote_ops): Initialize to_btrace_conf.
(_initialize_remote): Add qXfer:btrace-conf packet.
* target.c (target_enable_btrace): Update parameters.
(target_btrace_conf): New.
* target.h (target_enable_btrace): Update parameters.
(target_btrace_conf): New.
(target_object)<TARGET_OBJECT_BTRACE_CONF>: New.
(target_ops)<to_enable_btrace>: Update parameters and comment.
(target_ops)<to_btrace_conf>: New.
* target-delegates: Regenerate.
* target-debug.h (target_debug_print_const_struct_btrace_config_p)
(target_debug_print_const_struct_btrace_target_info_p): New.
NEWS: Announce new command and new packet.
doc/
* gdb.texinfo (Process Record and Replay): Describe the "record
btrace bts" command.
(General Query Packets): Describe qXfer:btrace-conf:read packet.
(Branch Trace Configuration Format): New.
gdbserver/
* linux-low.c (linux_low_enable_btrace): Update parameters.
(linux_low_btrace_conf): New.
(linux_target_ops)<to_btrace_conf>: Initialize.
* server.c (current_btrace_conf): New.
(handle_btrace_enable): Rename to ...
(handle_btrace_enable_bts): ... this. Pass ¤t_btrace_conf
to target_enable_btrace. Update comment. Update users.
(handle_qxfer_btrace_conf): New.
(qxfer_packets): Add btrace-conf entry.
(handle_query): Report qXfer:btrace-conf:read as supported packet.
* target.h (target_ops)<enable_btrace>: Update parameters and comment.
(target_ops)<read_btrace_conf>: New.
(target_enable_btrace): Update parameters.
(target_read_btrace_conf): New.
testsuite/
* gdb.btrace/delta.exp: Update "info record" output.
* gdb.btrace/enable.exp: Update "info record" output.
* gdb.btrace/finish.exp: Update "info record" output.
* gdb.btrace/instruction_history.exp: Update "info record" output.
* gdb.btrace/next.exp: Update "info record" output.
* gdb.btrace/nexti.exp: Update "info record" output.
* gdb.btrace/step.exp: Update "info record" output.
* gdb.btrace/stepi.exp: Update "info record" output.
* gdb.btrace/nohist.exp: Update "info record" output.
Add a format argument to the various supports_btrace functions to check
for support of a specific btrace format. This is to prepare for a new
format.
Removed two redundant calls. The check will be made in the subsequent
btrace_enable call.
2015-02-09 Markus Metzger <markus.t.metzger@intel.com>
* btrace.c (btrace_enable): Pass BTRACE_FORMAT_BTS.
* record-btrace.c (record_btrace_open): Remove call to
target_supports_btrace.
* remote.c (remote_supports_btrace): Update parameters.
* target.c (target_supports_btrace): Update parameters.
* target.h (to_supports_btrace, target_supports_btrace): Update
parameters.
* target-delegates.c: Regenerate.
* target-debug.h (target_debug_print_enum_btrace_format): New.
* nat/linux-btrace.c
(kernel_supports_btrace): Rename into ...
(kernel_supports_bts): ... this. Update users. Update warning text.
(intel_supports_btrace): Rename into ...
(intel_supports_bts): ... this. Update users.
(cpu_supports_btrace): Rename into ...
(cpu_supports_bts): ... this. Update users.
(linux_supports_btrace): Update parameters. Split into this and ...
(linux_supports_bts): ... this.
* nat/linux-btrace.h (linux_supports_btrace): Update parameters.
gdbserver/
* server.c (handle_btrace_general_set): Remove call to
target_supports_btrace.
(supported_btrace_packets): New.
(handle_query): Call supported_btrace_packets.
* target.h: include btrace-common.h.
(btrace_target_info): Removed.
(supports_btrace, target_supports_btrace): Update parameters.
Add a structure to hold the branch trace data and an enum to describe
the format of that data. So far, only BTS is supported. Also added
a NONE format to indicate that no branch trace data is available.
This will make it easier to support different branch trace formats in
the future.
2015-02-09 Markus Metzger <markus.t.metzger@intel.com>
* Makefile.in (SFILES): Add common/btrace-common.c.
(COMMON_OBS): Add common/btrace-common.o.
(btrace-common.o): Add build rules.
* btrace.c (parse_xml_btrace): Update parameters.
(parse_xml_btrace_block): Set format field.
(btrace_add_pc, btrace_fetch): Use struct btrace_data.
(do_btrace_data_cleanup, make_cleanup_btrace_data): New.
(btrace_compute_ftrace): Split into this and...
(btrace_compute_ftrace_bts): ...this.
(btrace_stitch_trace): Split into this and...
(btrace_stitch_bts): ...this.
* btrace.h (parse_xml_btrace): Update parameters.
(make_cleanup_btrace_data): New.
* common/btrace-common.c: New.
* common/btrace-common.h: Include common-defs.h.
(btrace_block_s): Update comment.
(btrace_format): New.
(btrace_format_string): New.
(btrace_data_bts): New.
(btrace_data): New.
(btrace_data_init, btrace_data_fini, btrace_data_empty): New.
* remote.c (remote_read_btrace): Update parameters.
* target.c (target_read_btrace): Update parameters.
* target.h (target_read_btrace): Update parameters.
(target_ops)<to_read_btrace>: Update parameters.
* x86-linux-nat.c (x86_linux_read_btrace): Update parameters.
* target-delegates.c: Regenerate.
* target-debug (target_debug_print_struct_btrace_data_p): New.
* nat/linux-btrace.c (linux_read_btrace): Split into this and...
(linux_read_bts): ...this.
* nat/linux-btrace.h (linux_read_btrace): Update parameters.
gdbserver/
* Makefile.in (SFILES): Add common/btrace-common.c.
(OBS): Add common/btrace-common.o.
(btrace-common.o): Add build rules.
* linux-low: Include btrace-common.h.
(linux_low_read_btrace): Use struct btrace_data. Call
btrace_data_init and btrace_data_fini.
The sigall-reverse.exp test occasionally fails with something like this:
(gdb) PASS: gdb.reverse/sigall-reverse.exp: send signal TERM
continue
Continuing.
The next instruction is syscall exit_group. It will make the program exit. Do you want to stop the program?([y] or n) FAIL: gdb.reverse/sigall-reverse.exp: continue to signal exit (timeout)
FAIL: gdb.reverse/sigall-reverse.exp: reverse to handler of TERM (timeout)
FAIL: gdb.reverse/sigall-reverse.exp: reverse to gen_TERM (timeout)
This is another event-loop/async related problem exposed by the patch
that made 'query' use gdb_readline_wrapper (588dcc3edb).
The problem is that even though gdb_readline_wrapper disables
target-async while the secondary prompt is in progress, the record
target's async event source is left marked. So when
gdb_readline_wrapper nests an event loop to process input, it may
happen that that event loop ends up processing a target event while
GDB is not really ready for it. Here's the relevant part of the
backtrace showing the root issue in action:
...
#14 0x000000000061cb48 in fetch_inferior_event (client_data=0x0) at src/gdb/infrun.c:4158
#15 0x0000000000642917 in inferior_event_handler (event_type=INF_REG_EVENT, client_data=0x0) at src/gdb/inf-loop.c:57
#16 0x000000000077ca5c in record_full_async_inferior_event_handler (data=0x0) at src/gdb/record-full.c:791
#17 0x0000000000640fdf in invoke_async_event_handler (data=...) at src/gdb/event-loop.c:1067
#18 0x000000000063fb01 in process_event () at src/gdb/event-loop.c:339
#19 0x000000000063fb2a in gdb_do_one_event () at src/gdb/event-loop.c:360
#20 0x000000000074d607 in gdb_readline_wrapper (prompt=0x3588f40 "The next instruction is syscall exit_group. It will make the program exit. Do you want to stop the program?([y] or n) ") at src/gdb/top.c:842
#21 0x0000000000750bd9 in defaulted_query (ctlstr=0x8c6588 "The next instruction is syscall exit_group. It will make the program exit. Do you want to stop the program?", defchar=121 'y', args=0x7fff70524410) at src/gdb/utils.c:1279
#22 0x0000000000750e4c in yquery (ctlstr=0x8c6588 "The next instruction is syscall exit_group. It will make the program exit. Do you want to stop the program?") at src/gdb/utils.c:1358
#23 0x00000000004b020e in record_linux_system_call (syscall=gdb_sys_exit_group, regcache=0x3529450, tdep=0xd6c840 <amd64_linux_record_tdep>) at src/gdb/linux-record.c:1933
With my all-stop-on-top-of-non-stop series, I'm also seeing
gdb.server/ext-attach.exp fail occasionally due to the same issue.
The first part of the fix is for target_async implementations to make
sure to remove/unmark all target-related event sources from the event
loop.
Tested on x86_64 Fedora 20, native and gdbserver.
gdb/
2015-02-03 Pedro Alves <palves@redhat.com>
* event-loop.c (clear_async_event_handler): New function.
* event-loop.h (clear_async_event_handler): New declaration.
* record-btrace.c (record_btrace_async): New function.
(init_record_btrace_ops): Install record_btrace_async.
* record-full.c (record_full_async): New function.
(record_full_resume): Don't mark the async event source here.
(init_record_full_ops): Install record_full_async.
(record_full_core_resume): Don't mark the async event source here.
(init_record_full_core_ops): Install record_full_async.
* remote.c (remote_async): Mark and clear the async stop reply
queue event-loop token as appropriate.
In all these cases we're interested in whether the target is currently
async, with its event sources installed in the event loop, not whether
it can async if needed. Also, I'm not seeing the point of the
target_async call from within linux_nat_wait. That's normally done on
resume instead, which this target already does.
Tested on x86_64 Fedora 20, native and gdbserver.
gdb/
2015-02-03 Pedro Alves <palves@redhat.com>
* linux-nat.c (linux_child_follow_fork, linux_nat_wait_1): Use
target_is_async_p instead of target_can_async.
(linux_nat_wait): Use target_is_async_p instead of
target_can_async. Don't enable async here.
* remote.c (interrupt_query, remote_wait, putpkt_binary): Use
target_is_async_p instead of target_can_async.
In https://sourceware.org/ml/gdb-patches/2014-10/msg00652.html, Sandra
shows a target that was broken by the recent update_thread_list
optimization:
(gdb) target remote qa8-centos32-cs:10514
...
(gdb) continue
Continuing.
Cannot execute this command without a live selected thread.
(gdb)
The error means that the current thread is in "exited" state when the
continue command is processed. The root of the problem was found
here:
> Sending packet: $Hg0#df...Packet received:
...
> Sending packet: $?#3f...Packet received: S00
> Sending packet: $qfThreadInfo#bb...Packet received: l
> Sending packet: $Hc-1#09...Packet received:
> Sending packet: $qC#b4...Packet received: unset
This target doesn't really support threads (no thread indication in
stop reply packets; no support for qC), but then supports
qfThreadInfo, and returns an empty thread list to GDB.
See https://sourceware.org/ml/gdb-patches/2014-10/msg00665.html for
why the target does that.
As remote_update_thread_list deletes threads from GDB's list that are
not found in the thread list that the target reports, the result is
that GDB deletes the "fake" main thread that GDB added itself. (As
that thread is currently selected, it is marked "exited" instead of
being deleted straight away.)
This commit avoids deleting the main thread in this scenario.
gdb/
2014-10-27 Pedro Alves <palves@redhat.com>
* remote.c (remote_thread_alive): New, factored out from ...
(remote_thread_alive): ... this.
(remote_update_thread_list): Bail out before deleting threads if
the target returned an empty list, and, the current thread has a
magic/fake ptid.
clear_threads_listing_context is used for thread listing methods other
than the xml based, but it's only defined when HAVE_LIBEXPAT is defined.
gdb/
2014-10-17 Pedro Alves <palves@redhat.com>
* remote.c (clear_threads_listing_context): Move higher up, out of
the HAVE_LIBEXPAT guard.
This commit avoids the prune_threads call in the remote target's
target_update_thread_list's implementation, eliminating all the "thread
alive" RSP traffic (one packet per thread) whenever we fetch the
thread list.
IOW, this:
Sending packet: $Tp2141.2150#82...Packet received: OK
Sending packet: $Tp2141.214f#b7...Packet received: OK
Sending packet: $Tp2141.2141#82...Packet received: OK
... more T packets; it's one per previously known live thread ...
Sending packet: $qXfer:threads:read::0,fff#03...Packet received: l<threads>\n<thread id="p2141.2141" core="2"/>\n<thread id="p2141.214f" core="1"/>\n<thread id="p2141.2150" core="2"/>\n</threads>\n
Becomes:
Sending packet: $qXfer:threads:read::0,fff#03...Packet received: l<threads>\n<thread id="p2141.2141" core="2"/>\n<thread id="p2141.214f" core="1"/>\n<thread id="p2141.2150" core="2"/>\n</threads>\n
Tested on x86_64 Fedora 20, native gdbserver:
- tests the qXfer:threads:read method.
Tested on x86_64 Fedora 20, native gdbserver with qXfer:threads:read
force-disabled in gdbserver:
- So that GDB falls back to the qfThreadInfo/qsThreadInfo method.
And also manually smoked tested force disabling both
qXfer:threads:read and qfThreadInfo/qsThreadInfo in gdbserver.
gdb/
2014-10-15 Pedro Alves <palves@redhat.com>
* gdbthread.h (ALL_NON_EXITED_THREADS_SAFE): New macro.
* remote.c (remote_update_thread_list): Skip calling prune_threads
if any thread listing method is supported, and instead walk over
the set of remote threads listed, deleting those that are not
found in GDB's thread list.
When GDB wants to sync the thread list with the target's (e.g., due to
"info threads"), it calls update_thread_list:
update_thread_list (void)
{
prune_threads ();
target_find_new_threads ();
update_threads_executing ();
}
And then prune_threads does:
prune_threads (void)
{
struct thread_info *tp, *next;
for (tp = thread_list; tp; tp = next)
{
next = tp->next;
if (!thread_alive (tp))
delete_thread (tp->ptid);
}
}
Calling thread_live on each thread one by one is expensive.
E.g., on Linux, it ends up doing kill(SIG0) once for each thread. Not
a big deal, but still a bunch of syscalls...
With the remote target, it's cumbersome. That thread_alive call ends
up generating one T packet per thread:
Sending packet: $Tp2141.2150#82...Packet received: OK
Sending packet: $Tp2141.214f#b7...Packet received: OK
Sending packet: $Tp2141.2141#82...Packet received: OK
Sending packet: $qXfer:threads:read::0,fff#03...Packet received: l<threads>\n<thread id="p2141.2141" core="2"/>\n<thread id="p2141.214f" core="1"/>\n<thread id="p2141.2150" core="2"/>\n</threads>\n
That seems a bit silly when target_find_new_threads method
implementations will always fetch the whole current set of target
threads, and then add those that are not in GDB's thread list, to
GDB's thread list.
This patch thus pushes down the responsibility of pruning dead threads
to the target_find_new_threads method instead, so a target may
implement pruning dead threads however it wants.
Once we do that, target_find_new_threads becomes a misnomer, so the
patch renames it to target_update_thread_list.
The patch doesn't attempt to do any optimization to any target yet.
It simply exports prune_threads, and makes all implementations of
target_update_thread_list call that. It's meant to be a no-op.
gdb/
2014-10-15 Pedro Alves <palves@redhat.com>
* ada-tasks.c (print_ada_task_info, task_command_1): Adjust.
* bsd-uthread.c (bsd_uthread_find_new_threads): Rename to ...
(bsd_uthread_update_thread_list): ... this. Call prune_threads.
(bsd_uthread_target): Adjust.
* corelow.c (core_open): Adjust.
* dec-thread.c (dec_thread_find_new_threads): Update comment.
(dec_thread_update_thread_list): New function.
(init_dec_thread_ops): Adjust.
* gdbthread.h (prune_threads): New declaration.
* linux-thread-db.c (thread_db_find_new_threads): Rename to ...
(thread_db_update_thread_list): ... this. Call prune_threads.
(init_thread_db_ops): Adjust.
* nto-procfs.c (procfs_find_new_threads): Rename to ...
(procfs_update_thread_list): ... this. Call prune_threads.
(procfs_attach, procfs_create_inferior, init_procfs_targets):
Adjust.
* obsd-nat.c (obsd_find_new_threads): Rename to ...
(obsd_update_thread_list): ... this. Call prune_threads.
(obsd_add_target): Adjust.
* procfs.c (procfs_target): Adjust.
(procfs_notice_thread): Update comment.
(procfs_find_new_threads): Rename to ...
(procfs_update_thread_list): ... this. Call prune_threads.
* ravenscar-thread.c (ravenscar_update_inferior_ptid): Update
comment.
(ravenscar_wait): Adjust.
(ravenscar_find_new_threads): Rename to ...
(ravenscar_update_thread_list): ... this. Call prune_threads.
(init_ravenscar_thread_ops): Adjust.
* record-btrace.c (record_btrace_find_new_threads): Rename to ...
(record_btrace_update_thread_list): ... this. Adjust comment.
(init_record_btrace_ops): Adjust.
* remote.c (remote_threads_info): Rename to ...
(remote_update_thread_list): ... this. Call prune_threads.
(remote_start_remote, extended_remote_attach_1, init_remote_ops):
Adjust.
* sol-thread.c (check_for_thread_db): Adjust.
(sol_find_new_threads_callback): Rename to ...
(sol_update_thread_list_callback): ... this.
(sol_find_new_threads): Rename to ...
(sol_update_thread_list): ... this. Call prune_threads. Adjust.
(sol_get_ada_task_ptid, init_sol_thread_ops): Adjust.
* target-delegates.c: Regenerate.
* target.c (target_find_new_threads): Rename to ...
(target_update_thread_list): ... this.
* target.h (struct target_ops): Rename to_find_new_threads field
to to_update_thread_list.
(target_find_new_threads): Rename to ...
(target_update_thread_list): ... this.
* thread.c (prune_threads): Make extern.
(update_thread_list): Adjust.
We have three methods to list the current remote thread list:
1. The qXfer:threads:read method (the preferred one nowadays), builds a
remote thread list while parsing the XML, and then after the XML
parsing is done, goes over the built list and adds threads GDB doesn't
know about yet to GDB's list.
2. If the qXfer method isn't available, we fallback to using the
qfThreadInfo/qsThreadInfo packets. When we do this, we adds threads
to GDB's list immediately as we parse the qfThreadInfo/qsThreadInfo
packet replies.
3. And then if the previous method isn't available either, we try the
old deprecated qL packet. This path is already looking somewhat
broken for not using remote_notice_new_inferior to add threads to
GDB's list.
This patch makes all variants work in two passes, like the qXfer
method, and then makes all variants share the code path that adds
threads to GDB's list.
Tested on x86_64 Fedora 20 with native gdbserver.
gdb/
2014-10-15 Pedro Alves <palves@redhat.com>
* remote.c (remote_get_threadlist, remote_threadlist_iterator):
Add describing comment. Return -1 if the qL packet is not
supported.
(struct thread_item, thread_item_t): Move higher up in
the file. Add comments.
(struct threads_parsing_context): Move higher up in
the file, add comments, and remote to ...
(struct threads_listing_context): ... this.
(remote_newthread_step): Don't add the thread to GDB's thread
database here. Instead push it to the thread_listing_context
list.
(remote_find_new_threads): Rename to ...
(remote_get_threads_with_ql): ... this. Add target_ops and
targets_listing_context parameters. Pass down context.
(start_thread): Adjust.
(clear_threads_parsing_context): Rename to ...
(clear_threads_listing_context): ... this.
(remote_get_threads_with_qxfer): New, with parts salvaged from old
remote_threads_info.
(remote_get_threads_with_qthreadinfo): Ditto.
(remote_threads_info): Reimplement.
This change:
commit b775012e84
Author: Luis Machado <luisgpm@br.ibm.com>
Date: Fri Feb 24 15:10:59 2012 +0000
2012-02-24 Luis Machado <lgustavo@codesourcery.com>
* remote.c (remote_supports_cond_breakpoints): New forward
declaration.
[...]
changed the way breakpoints are inserted and removed such that
`insert_bp_location' can now be called with the breakpoint being handled
already in place, while previously the call was only ever made for
breakpoints that have not been put in place. This in turn caused an
issue for software breakpoints and targets for which a breakpoint's
`placed_address' may not be the same as the original requested address.
The issue is `insert_bp_location' overwrites the previously adjusted
value in `placed_address' with the original address, that is only
replaced back with the correct adjusted address later on when
`gdbarch_breakpoint_from_pc' is called. Meanwhile there's a window
where the value in `placed_address' does not correspond to data stored
in `shadow_contents', leading to incorrect instruction bytes being
supplied when `one_breakpoint_xfer_memory' is called to supply the
instruction overlaid by the breakpoint.
And this is exactly what happens on the MIPS target with software
breakpoints placed in microMIPS code. In this case not only
`placed_address' is not the original address because of the ISA bit, but
`mips_breakpoint_from_pc' has to read the original instruction to
determine which one of the two software breakpoint instruction encodings
to choose as well. The 16-bit encoding is used to replace 16-bit
instructions and similarly the 32-bit one is used with 32-bit
instructions, to satisfy branch delay slot size requirements.
The mismatch between `placed_address' and the address data in
`shadow_contents' has been obtained from leads to the wrong encoding
being used in some cases, which in the case of a 32-bit software
breakpoint instruction replacing a 16-bit instruction causes corruption
to the adjacent following instruction and leads the debug session astray
if execution reaches there e.g. with a jump.
To address this problem I made the change below, that adds a
`reqstd_address' field to `struct bp_target_info' and leaves
`placed_address' unchanged once it has been set. This ensures data in
`shadow_contents' is always consistent with `placed_address'.
This approach also has this good side effect that all the places that
examine the breakpoint's address see a consistent value, either
`reqstd_address' or `placed_address', as required. Currently some
places see either the original or the adjusted address in
`placed_address', depending on whether they have been called before
`gdbarch_remote_breakpoint_from_pc' or afterwards. This is in
particular true for subsequent calls to
`gdbarch_remote_breakpoint_from_pc' itself, e.g. from
`one_breakpoint_xfer_memory'. This is also important for places like
`find_single_step_breakpoint' where a breakpoint's address is compared
to the raw value of $pc.
* breakpoint.h (bp_target_info): Add `reqstd_address' member,
update comments.
* breakpoint.c (one_breakpoint_xfer_memory): Use `reqstd_address'
for the breakpoint's address. Don't preinitialize `placed_size'.
(insert_bp_location): Set `reqstd_address' rather than
`placed_address'.
(bp_target_info_copy_insertion_state): Also copy `placed_address'.
(bkpt_insert_location): Use `reqstd_address' for the breakpoint's
address.
(bkpt_remove_location): Likewise.
(deprecated_insert_raw_breakpoint): Likewise.
(deprecated_remove_raw_breakpoint): Likewise.
(find_single_step_breakpoint): Likewise.
* mem-break.c (default_memory_insert_breakpoint): Use
`reqstd_address' for the breakpoint's address. Don't set
`placed_address' or `placed_size' if breakpoint contents couldn't
have been determined.
* remote.c (remote_insert_breakpoint): Use `reqstd_address' for
the breakpoint's address.
(remote_insert_hw_breakpoint): Likewise. Don't set
`placed_address' or `placed_size' if breakpoint couldn't have been
set.
* aarch64-linux-nat.c (aarch64_linux_insert_hw_breakpoint): Use
`reqstd_address' for the breakpoint's address.
* arm-linux-nat.c (arm_linux_hw_breakpoint_initialize): Likewise.
* ia64-tdep.c (ia64_memory_insert_breakpoint): Likewise.
* m32r-tdep.c (m32r_memory_insert_breakpoint): Likewise.
* microblaze-linux-tdep.c
(microblaze_linux_memory_remove_breakpoint): Likewise.
* monitor.c (monitor_insert_breakpoint): Likewise.
* nto-procfs.c (procfs_insert_breakpoint): Likewise.
(procfs_insert_hw_breakpoint): Likewise.
* ppc-linux-nat.c (ppc_linux_insert_hw_breakpoint): Likewise.
* ppc-linux-tdep.c (ppc_linux_memory_remove_breakpoint): Likewise.
* remote-m32r-sdi.c (m32r_insert_breakpoint): Likewise.
* remote-mips.c (mips_insert_breakpoint): Likewise.
* x86-nat.c (x86_insert_hw_breakpoint): Likewise.
By default, GDB removes all breakpoints from the target when the
target stops and the prompt is given back to the user. This is useful
in case GDB crashes while the user is interacting, as otherwise,
there's a higher chance breakpoints would be left planted on the
target.
But, as long as any thread is running free, we need to make sure to
keep breakpoints inserted, lest a thread misses a breakpoint. With
that in mind, in preparation for non-stop mode, we added a "breakpoint
always-inserted on" mode. This traded off the extra crash protection
for never having threads miss breakpoints, and in addition is more
efficient if there's a ton of breakpoints to remove/insert at each
user command (e.g., at each "step").
When we added non-stop mode, and for a period, we required users to
manually set "always-inserted on" when they enabled non-stop mode, as
otherwise GDB removes all breakpoints from the target as soon as any
thread stops, which means the other threads still running will miss
breakpoints. The test added by this patch exercises this.
That soon revealed a nuisance, and so later we added an extra
"breakpoint always-inserted auto" mode, that made GDB behave like
"always-inserted on" when non-stop was enabled, and "always-inserted
off" when non-stop was disabled. "auto" was made the default at the
same time.
In hindsight, this "auto" setting was unnecessary, and not the ideal
solution. Non-stop mode does depends on breakpoints always-inserted
mode, but only as long as any thread is running. If no thread is
running, no breakpoint can be missed. The same is true for all-stop
too. E.g., if, in all-stop mode, and the user does:
(gdb) c&
(gdb) b foo
That breakpoint at "foo" should be inserted immediately, but it
currently isn't -- currently it'll end up inserted only if the target
happens to trip on some event, and is re-resumed, e.g., an internal
breakpoint triggers that doesn't cause a user-visible stop, and so we
end up in keep_going calling insert_breakpoints. The test added by
this patch also covers this.
IOW, no matter whether in non-stop or all-stop, if the target fully
stops, we can remove breakpoints. And no matter whether in all-stop
or non-stop, if any thread is running in the target, then we need
breakpoints to be immediately inserted. And then, if the target has
global breakpoints, we need to keep breakpoints even when the target
is stopped.
So with that in mind, and aiming at reducing all-stop vs non-stop
differences for all-stop-on-stop-of-non-stop, this patch fixes
"breakpoint always-inserted off" to not remove breakpoints from the
target until it fully stops, and then removes the "auto" setting as
unnecessary. I propose removing it straight away rather than keeping
it as an alias, unless someone complains they have scripts that need
it and that can't adjust.
Tested on x86_64 Fedora 20.
gdb/
2014-09-22 Pedro Alves <palves@redhat.com>
* NEWS: Mention merge of "breakpoint always-inserted" modes "off"
and "auto" merged.
* breakpoint.c (enum ugll_insert_mode): New enum.
(always_inserted_mode): Now a plain boolean.
(show_always_inserted_mode): No longer handle AUTO_BOOLEAN_AUTO.
(breakpoints_always_inserted_mode): Delete.
(breakpoints_should_be_inserted_now): New function.
(insert_breakpoints): Pass UGLL_INSERT to
update_global_location_list instead of calling
insert_breakpoint_locations manually.
(create_solib_event_breakpoint_1): New, factored out from ...
(create_solib_event_breakpoint): ... this.
(create_and_insert_solib_event_breakpoint): Use
create_solib_event_breakpoint_1 instead of calling
insert_breakpoint_locations manually.
(update_global_location_list): Change parameter type from boolean
to enum ugll_insert_mode. All callers adjusted. Adjust to use
breakpoints_should_be_inserted_now and handle UGLL_INSERT.
(update_global_location_list_nothrow): Change parameter type from
boolean to enum ugll_insert_mode.
(_initialize_breakpoint): "breakpoint always-inserted" option is
now a boolean command. Update help text.
* breakpoint.h (breakpoints_always_inserted_mode): Delete declaration.
(breakpoints_should_be_inserted_now): New declaration.
* infrun.c (handle_inferior_event) <TARGET_WAITKIND_LOADED>:
Remove breakpoints_always_inserted_mode check.
(normal_stop): Adjust to use breakpoints_should_be_inserted_now.
* remote.c (remote_start_remote): Likewise.
gdb/doc/
2014-09-22 Pedro Alves <palves@redhat.com>
* gdb.texinfo (Set Breaks): Document that "set breakpoint
always-inserted off" is the default mode now. Delete
documentation of "set breakpoint always-inserted auto".
gdb/testsuite/
2014-09-22 Pedro Alves <palves@redhat.com>
* gdb.threads/break-while-running.exp: New file.
* gdb.threads/break-while-running.c: New file.
The code becomes dead as GDB evolves. In 2003, Andrew Cagney post patch
https://sourceware.org/ml/gdb-patches/2003-10/msg00511.html to add target
read/write partial methods. They support query buffer size when both
OFFSET and LEN is zero, and it was used in avr-tdep.c and kod.c. Then,
Daniel added target_read_object_alloc and avr-tdep.c switches to use that
in patch https://sourceware.org/ml/gdb-patches/2006-07/msg00009.html
From then on, GDB on longer queries the buffer size, so the code
returning packet size in remote_xfer_partial became dead.
PR 17060 is duplicated of PR 9053, so I mention the latter in the
ChangeLog entry. Rebuild GDB with this patch. OK to apply?
I'll mark PR 17060 as duplicated once the patch is applied.
gdb:
2014-08-09 Yao Qi <yao@codesourcery.com>
PR remote/9053
* remote.c (remote_xfer_partial): Remove dead code.
I run splint in gdb source and get the following warnings:
../../../git/gdb/corelow.c:740: Return value type int does not match declared type enum target_xfer_status: 0
'TARGET_XFER_EOF' (enum target_xfer_status) is expected to be returned,
but 0 is returned. This patch is to replace 0 with TARGET_XFER_EOF
in the implementations of to_xfer_partial.
gdb:
2014-08-07 Yao Qi <yao@codesourcery.com>
* corelow.c (core_xfer_partial): Replace 0 with TARGET_XFER_EOF.
* remote-m32r-sdi.c (m32r_xfer_memory): Likewise.
* remote.c (remote_read_bytes): Likewise.
This makes target_ops::to_open take a const string and then fixes the
fallout.
There were a few of these I could not build. However I eyeballed it
and in any case the fixes should generally be trivial.
This is based on the patch to fix up the target debugging for to_open,
because that changes gdb to not directly install to_open as the target
command
2014-07-30 Tom Tromey <tromey@redhat.com>
* bsd-kvm.c (bsd_kvm_open): Constify.
* corelow.c (core_open): Constify.
* ctf.c (ctf_open): Constify.
* dbug-rom.c (dbug_open): Constify.
* exec.c (exec_open): Constify.
* m32r-rom.c (m32r_open, mon2000_open): Constify.
* microblaze-rom.c (picobug_open): Constify.
* nto-procfs.c (procfs_open_1, procfs_open, procfs_native_open):
Constify.
* ppcbug-rom.c (ppcbug_open0, ppcbug_open1): Constify.
* record-btrace.c (record_btrace_open): Constify.
* record-full.c (record_full_core_open_1, record_full_open_1)
(record_full_open): Constify.
* remote-m32r-sdi.c (m32r_open): Constify.
* remote-mips.c (common_open, mips_open, pmon_open, ddb_open)
(rockhopper_open, lsi_open): Constify.
* remote-sim.c (gdbsim_open): Constify.
* remote.c (remote_open, extended_remote_open, remote_open_1):
Constify.
* target.h (struct target_ops) <to_open>: Make "arg" const.
* tracefile-tfile.c (tfile_open): Constify.
Currently, GDB can pass a signal to the wrong thread in several
different but related scenarios.
E.g., if thread 1 stops for signal SIGFOO, the user switches to thread
2, and then issues "continue", SIGFOO is actually delivered to thread
2, not thread 1. This obviously messes up programs that use
pthread_kill to send signals to specific threads.
This has been a known issue for a long while. Back in 2008 when I
made stop_signal be per-thread (2020b7ab), I kept the behavior -- see
code in 'proceed' being removed -- wanting to come back to it later.
The time has finally come now.
The patch fixes this -- on resumption, intercepted signals are always
delivered to the thread that had intercepted them.
Another example: if thread 1 stops for a breakpoint, the user switches
to thread 2, and then issues "signal SIGFOO", SIGFOO is actually
delivered to thread 1, not thread 2, because 'proceed' first switches
to thread 1 to step over its breakpoint... If the user deletes the
breakpoint before issuing "signal FOO", then the signal is delivered
to thread 2 (the current thread).
"signal SIGFOO" can be used for two things: inject a signal in the
program while the program/thread had stopped for none, bypassing
"handle nopass"; or changing/suppressing a signal the program had
stopped for. These scenarios are really two faces of the same coin,
and GDB can't really guess what the user is trying to do. GDB might
have intercepted signals in more than one thread even (see the new
signal-command-multiple-signals-pending.exp test). At least in the
inject case, it's obviously clear to me that the user means to deliver
the signal to the currently selected thread, so best is to make the
command's behavior consistent and easy to explain.
Then, if the user is trying to suppress/change a signal the program
had stopped for instead of injecting a new signal, but, the user had
changed threads meanwhile, then she will be surprised that with:
(gdb) continue
Thread 1 stopped for signal SIGFOO.
(gdb) thread 2
(gdb) signal SIGBAR
... GDB actually delivers SIGFOO to thread 1, and SIGBAR to thread 2
(with scheduler-locking off, which is the default, because then
"signal" or any other resumption command resumes all threads).
So the patch makes GDB detect that, and ask for confirmation:
(gdb) thread 1
[Switching to thread 1 (Thread 10979)]
(gdb) signal SIGUSR2
Note:
Thread 3 previously stopped with signal SIGUSR2, User defined signal 2.
Thread 2 previously stopped with signal SIGUSR1, User defined signal 1.
Continuing thread 1 (the current thread) with specified signal will
still deliver the signals noted above to their respective threads.
Continue anyway? (y or n)
All these scenarios are covered by the new tests.
Tested on x86_64 Fedora 20, native and gdbserver.
gdb/
2014-07-25 Pedro Alves <palves@redhat.com>
* NEWS: Mention signal passing and "signal" command changes.
* gdbthread.h (struct thread_suspend_state) <stop_signal>: Extend
comment.
* breakpoint.c (until_break_command): Adjust clear_proceed_status
call.
* infcall.c (run_inferior_call): Adjust clear_proceed_status call.
* infcmd.c (proceed_thread_callback, continue_1, step_once)
(jump_command): Adjust clear_proceed_status call.
(signal_command): Warn if other thread that are resumed have
signals that will be delivered. Adjust clear_proceed_status call.
(until_next_command, finish_command)
(proceed_after_attach_callback, attach_command_post_wait)
(attach_command): Adjust clear_proceed_status call.
* infrun.c (proceed_after_vfork_done): Likewise.
(proceed_after_attach_callback): Adjust comment.
(clear_proceed_status_thread): Clear stop_signal if not in pass
state.
(clear_proceed_status_callback): Delete.
(clear_proceed_status): New 'step' parameter. Only clear the
proceed status of threads the command being prepared is about to
resume.
(proceed): If passed in an explicit signal, override stop_signal
with it. Don't pass the last stop signal to the thread we're
resuming.
(init_wait_for_inferior): Adjust clear_proceed_status call.
(switch_back_to_stepped_thread): Clear the signal if it should not
be passed.
* infrun.h (clear_proceed_status): New 'step' parameter.
(user_visible_resume_ptid): Add comment.
* linux-nat.c (linux_nat_resume_callback): Don't check whether the
signal is in pass state.
* remote.c (append_pending_thread_resumptions): Likewise.
* mi/mi-main.c (proceed_thread): Adjust clear_proceed_status call.
gdb/doc/
2014-07-25 Pedro Alves <palves@redhat.com>
Eli Zaretskii <eliz@gnu.org>
* gdb.texinfo (Signaling) <signal command>: Explain what happens
with multi-threaded programs.
gdb/testsuite/
2014-07-25 Pedro Alves <palves@redhat.com>
* gdb.threads/signal-command-handle-nopass.c: New file.
* gdb.threads/signal-command-handle-nopass.exp: New file.
* gdb.threads/signal-command-multiple-signals-pending.c: New file.
* gdb.threads/signal-command-multiple-signals-pending.exp: New file.
* gdb.threads/signal-delivered-right-thread.c: New file.
* gdb.threads/signal-delivered-right-thread.exp: New file.
This does some more constification in remote.c.
2014-07-24 Tom Tromey <tromey@redhat.com>
* remote.c (remote_serial_open, print_packet, putpkt)
(putpkt_binary): Constify.
* remote.h (putpkt): Update.
When debugging a remote bare-metal target with "target
extended-remote" + attach, GDB won't send a qSymbol packet to initiate
symbol lookup. This happens because all the previous places in which
GDB might have done this are guarded by conditions that don't hold in
the said scenario: there are no shared libraries, no vsyscall page and
the binary file didn't change in the time passed between the "file"
and the "attach" commands.
To solve this problem remote_check_symbols is called in the
target_post_attach hook.
gdb/
2014-07-11 Adrian Sendroiu <adrian.sendroiu@freescale.com>
* remote.c (extended_remote_post_attach): New function.
(init_extended_remote_ops): Install it as to_post_attach method.
On Windows, with "maint set target-async on" (the default since
a09dd441), Ctrl-C fails to stop a remote target.
With maint target-async on, the SIGINT signal handler doesn't send the
remote interrupt request immediately. Instead, it marks an async
handler as ready, and then the main event loop wakes up and notices
that the SIGINT async signal handler token was set, and calls the
corresponding event handler, which sends the remote interrupt request.
On POSIX-like systems, the SIGINT signal makes the select/poll in the
main event loop wake up / return with EINTR. However, on Windows,
signal handlers run on a separate thread, and Windows doesn't really
have a concept of EINTR. So, just marking the async handler
(effectively just setting a flag) does not wake up gdb_select.
Instead, we need to call gdb_call_async_signal_handler from the signal
handler. The Windows version (in mingw-hdep.c) sets a Windows event
that gdb_select's WaitForMultipleObjects is waiting for.
Confirmed that with this, Ctrl-C interrupts the remote target on
Windows. Also regression tested on x86_64 Fedora 20 against
GDBserver.
gdb/
2014-07-07 Pedro Alves <palves@redhat.com>
* remote.c (async_handle_remote_sigint)
(async_handle_remote_sigint_twice): Call
gdb_call_async_signal_handler instead of
mark_async_signal_handler.
Don Breazeal
Gary Benson
Pedro Alves
Yury Grechishchev
Sergio Durigan Junior
Markus Metzger
Joel Brobecker
Maciej W. Rozycki
Yao Qi
Tom Tromey
Doug Evans
Adrian Sendroiu