This adds a new QCatchSyscalls packet to enable 'catch syscall', and new
stop reasons "syscall_entry" and "syscall_return" for those events. It
is currently only supported on Linux x86 and x86_64.
gdb/ChangeLog:
2016-01-12 Josh Stone <jistone@redhat.com>
Philippe Waroquiers <philippe.waroquiers@skynet.be>
* NEWS (Changes since GDB 7.10): Mention QCatchSyscalls and the
syscall_entry and syscall_return stop reasons. Mention GDB
support for remote catch syscall.
* remote.c (PACKET_QCatchSyscalls): New enum.
(remote_set_syscall_catchpoint): New function.
(remote_protocol_features): New element for QCatchSyscalls.
(remote_parse_stop_reply): Parse syscall_entry/return stops.
(init_remote_ops): Install remote_set_syscall_catchpoint.
(_initialize_remote): Config QCatchSyscalls.
* linux-nat.h (struct lwp_info) <syscall_state>: Comment typo.
gdb/doc/ChangeLog:
2016-01-12 Josh Stone <jistone@redhat.com>
Philippe Waroquiers <philippe.waroquiers@skynet.be>
* gdb.texinfo (Remote Configuration): List the QCatchSyscalls packet.
(Stop Reply Packets): List the syscall entry and return stop reasons.
(General Query Packets): Describe QCatchSyscalls, and add it to the
table and the detailed list of stub features.
gdb/gdbserver/ChangeLog:
2016-01-12 Josh Stone <jistone@redhat.com>
Philippe Waroquiers <philippe.waroquiers@skynet.be>
* inferiors.h: Include "gdb_vecs.h".
(struct process_info): Add syscalls_to_catch.
* inferiors.c (remove_process): Free syscalls_to_catch.
* remote-utils.c (prepare_resume_reply): Report syscall_entry and
syscall_return stops.
* server.h (UNKNOWN_SYSCALL, ANY_SYSCALL): Define.
* server.c (handle_general_set): Handle QCatchSyscalls.
(handle_query): Report support for QCatchSyscalls.
* target.h (struct target_ops): Add supports_catch_syscall.
(target_supports_catch_syscall): New macro.
* linux-low.h (struct linux_target_ops): Add get_syscall_trapinfo.
(struct lwp_info): Add syscall_state.
* linux-low.c (handle_extended_wait): Mark syscall_state as an entry.
Maintain syscall_state and syscalls_to_catch across exec.
(get_syscall_trapinfo): New function, proxy to the_low_target.
(linux_low_ptrace_options): Enable PTRACE_O_TRACESYSGOOD.
(linux_low_filter_event): Toggle syscall_state entry/return for
syscall traps, and set it ignored for all others.
(gdb_catching_syscalls_p): New function.
(gdb_catch_this_syscall_p): New function.
(linux_wait_1): Handle SYSCALL_SIGTRAP.
(linux_resume_one_lwp_throw): Add PTRACE_SYSCALL possibility.
(linux_supports_catch_syscall): New function.
(linux_target_ops): Install it.
* linux-x86-low.c (x86_get_syscall_trapinfo): New function.
(the_low_target): Install it.
gdb/testsuite/ChangeLog:
2016-01-12 Josh Stone <jistone@redhat.com>
Philippe Waroquiers <philippe.waroquiers@skynet.be>
* gdb.base/catch-syscall.c (do_execve): New variable.
(main): Conditionally trigger an execve.
* gdb.base/catch-syscall.exp: Enable testing for remote targets.
(test_catch_syscall_execve): New, check entry/return across execve.
(do_syscall_tests): Call test_catch_syscall_execve.
Since we now rely on PTRACE_EVENT_CLONE being available (added in
Linux 2.5.46), we're relying on NPTL.
This commit removes the support for older LinuxThreads, as well as the
workarounds for vendor 2.4 kernels with NPTL backported.
- Rely on tkill being available.
- Assume gdb doesn't get cancel signals.
- Remove code that checks the LinuxThreads restart and cancel signals
in the inferior.
- Assume that __WALL is available.
- Assume that non-leader threads report WIFEXITED.
- Thus, no longer need to send signal 0 to check whether threads are
still alive.
- Update comments throughout.
Tested on x86_64 Fedora 20, native and gdbserver.
gdb/ChangeLog:
* configure.ac: Remove tkill checks.
* configure, config.in: Regenerate.
* linux-nat.c: Remove HAVE_TKILL_SYSCALL check. Update top level
comments.
(linux_nat_post_attach_wait): Remove 'cloned' parameter. Use
__WALL.
(attach_proc_task_lwp_callback): Don't set the cloned flag.
(linux_nat_attach): Adjust.
(kill_lwp): Remove HAVE_TKILL_SYSCALL check. No longer fall back
to 'kill'.
(linux_handle_extended_wait): Use __WALL. Don't set the cloned
flag.
(wait_lwp): Use __WALL. Update comments.
(running_callback, stop_and_resume_callback): Delete.
(linux_nat_filter_event): Don't stop and resume all lwps. Don't
check if the event LWP has previously exited.
(check_zombie_leaders): Update comments.
(linux_nat_wait_1): Use __WALL.
(kill_wait_callback): Don't handle clone processes separately.
Use __WALL instead.
(linux_thread_alive): Delete.
(linux_nat_thread_alive): Return true as long as the LWP is in the
LWP list.
(linux_nat_update_thread_list): Assume the kernel supports
PTRACE_EVENT_CLONE.
(get_signo): Delete.
(lin_thread_get_thread_signals): Remove LinuxThreads references.
No longer check __pthread_sig_restart / __pthread_sig_cancel in
the inferior.
* linux-nat.h (struct lwp_info) <cloned>: Delete field.
* linux-thread-db.c: Update comments.
(_initialize_thread_db): Remove LinuxThreads references.
* nat/linux-waitpid.c (my_waitpid): No longer emulate __WALL.
Pass down flags unmodified.
* linux-waitpid.h (my_waitpid): Update documentation.
gdb/gdbserver/ChangeLog:
* linux-low.c (linux_kill_one_lwp): Remove references to
LinuxThreads.
(kill_lwp): Remove HAVE_TKILL_SYSCALL check. No longer fall back
to 'kill'.
(linux_init_signals): Delete.
(initialize_low): Adjust.
* thread-db.c (thread_db_init): Remove LinuxThreads reference.
Before, on systems that did not support PTRACE_EVENT_CLONE, both GDB and
GDBServer coordinated with libthread_db.so to insert breakpoints at magic
locations in libpthread.so, in order to break at thread creation and
thread death.
Support for thread events was removed from GDBServer as patch:
https://sourceware.org/ml/gdb-patches/2015-11/msg00466.html
This patch removes support for thread events in GDB.
No regressions found on Ubuntu 14.04 x86_64.
gdb/ChangeLog:
* breakpoint.c (remove_thread_event_breakpoints): Remove.
* breakpoint.h (remove_thread_event_breakpoints): Remove
declaration.
* linux-nat.c (in_pid_list_p): Remove.
(lin_lwp_attach_lwp): Remove.
* linux-nat.h (lin_lwp_attach_lwp): Remove declaration.
* linux-thread-db.c (thread_db_use_events): Remove.
(struct thread_db_info) <td_create_bp_addr>: Remove.
<td_death_bp_addr>: Likewise.
<td_ta_event_addr_p>: Likewise.
<td_ta_set_event_p>: Likewise.
<td_ta_clear_event_p>: Likewise.
<td_ta_event_getmsg_p>: Likewise.
<td_thr_event_enable_p>: Likewise.
(attach_thread): Likewise.
(detach_thread): Likewise.
(have_threads_callback): Likewise.
(have_threads): Likewise.
(enable_thread_event): Likewise.
(enable_thread_event_reporting): Likewise.
(try_thread_db_load_1): Remove td_ta_event_addr, td_ta_set_event,
td_ta_clear_event, td_ta_event_getmsg, td_thr_event_enable
initializations.
(try_thread_db_load_1): Remove enable_thread_event_reporting call.
(disable_thread_event_reporting): Remove.
(record_thread): Adapt to thread_db_use_event removal.
(detach_thread): Remove.
(thread_db_detach): Adapt to thread_db_use_event removal.
(check_event): Remove.
(thread_db_wait): Adapt to thread events support removal.
(thread_db_mourn_inferior): Likewise.
(find_new_threads_callback): Likewise.
(find_new_threads_once): Likewise.
(thread_db_update_thread_list): Likewise.
Nowadays, GDB calls target_can_download_tracepoint at the entry of
download_tracepoint_locations, which is called by.
update_global_location_list. Sometimes, it is not needed to call
target_can_download_tracepoint at all because there is no tracepoint
created. In remote target, target_can_download_tracepoint send
qTStatus to the remote in order to know whether tracepoint can be
downloaded or not. This means some redundant qTStatus packets are
sent.
This patch is to teach GDB to call target_can_download_tracepoint
lazily, only on the moment there are tracepoint to download.
gdb.perf/single-step.exp (with a local patch to measure RSP packets)
shows the number of RSP packets is reduced because there is no
tracepoint at all, so GDB doesn't send qTStatus any more.
# of RSP packets
original patched
single-step rsp 1000 7000 6000
single-step rsp 2000 14000 12000
single-step rsp 3000 21000 18000
single-step rsp 4000 28000 24000
gdb:
2015-09-10 Yao Qi <yao.qi@linaro.org>
* breakpoint.c (download_tracepoint_locations): New local
can_download_tracepoint. Check the result of
target_can_download_tracepoint and save it in
can_download_tracepoint if there are tracepoints to download.
* linux-nat.h (enum tribool): Move it to ...
* common/common-types.h: ... here.
have_ptrace_getregset is a tri-state variable (-1, 0, 1), and we have
some conditions like "if (have_ptrace_getregset)", which is not correct.
I'll explain why it is not correct in the following example. This fix
to this problem to replace the test (have_ptrace_getregset) to test
(have_ptrace_getregset == 1) or (have_ptrace_getregset == -1) etc.
However Doug thinks it hinders readability
https://sourceware.org/ml/gdb-patches/2015-05/msg00692.html so I decide
to add a new enum tribool and change have_ptrace_getregset to it, in
order to make these tests more readable.
have_ptrace_getregset is initialised to -1, and is adjusted to 0 or 1 in
$ARCH_linux_read_description according to the capability of the kernel.
However, it is possible that have_ptrace_getregset is used before it is
set to 0 or 1, which means it is still -1. This is shown below.
(gdb) run
Starting program: gdb/testsuite/gdb.base/break
Breakpoint 2, amd64_linux_fetch_inferior_registers (ops=0xceaa80, regcache=0xe72000, regnum=16) at git/gdb/amd64-linux-nat.c:128
128 {
top?p have_ptrace_getregset
$1 = TRIBOOL_UNKNOWN
top?c
Continuing.
Breakpoint 2, amd64_linux_fetch_inferior_registers (ops=0xceaa80, regcache=0xe72000, regnum=16) at git/gdb/amd64-linux-nat.c:128
128 {
top?c
Continuing.
Breakpoint 1, x86_linux_read_description (ops=0xceaa80) at git/gdb/x86-linux-nat.c:117
117 {
PTRACE_GETREGSET command is used even GDB doesn't know whether
PTRACE_GETREGSET is supported or not. It is wrong, but works on x86.
However it doesn't work on arm-linux if the kernel doesn't support
PTRACE_GETREGSET at all. We'll get:
(gdb) run
Starting program: gdb/testsuite/gdb.base/break
warning: Unable to fetch general register.
PC register is not available
gdb:
2015-06-23 Yao Qi <yao.qi@linaro.org>
* amd64-linux-nat.c (amd64_linux_fetch_inferior_registers):
Check whether have_ptrace_getregset is TRIBOOL_TRUE explicitly.
(amd64_linux_store_inferior_registers): Likewise.
* arm-linux-nat.c (fetch_fpregister): Likewise.
(fetch_fpregs, store_fpregister): Likewise.
(store_fpregister, store_fpregs): Likewise.
(fetch_register, fetch_regs): Likewise.
(store_register, store_regs): Likewise.
(fetch_vfp_regs, store_vfp_regs): Likewise.
(arm_linux_read_description): Check have_ptrace_getregset is
TRIBOOL_UNKNOWN. Set have_ptrace_getregset to TRIBOOL_TRUE
or TRIBOOL_FALSE.
* i386-linux-nat.c (fetch_xstateregs): Check
have_ptrace_getregset is not TRIBOOL_TRUE.
(store_xstateregs): Likewise.
* linux-nat.c (have_ptrace_getregset): Change its type to
enum tribool.
* linux-nat.h (tribool): New enum.
* x86-linux-nat.c (x86_linux_read_description): Use enum tribool.
Check whether have_ptrace_getregset is TRIBOOL_TRUE.
I'll let arm-linux-nat.c to use PTRACE_GETREGSET if kernel supports,
so this patch is to move have_ptrace_getregset from x86-linux-nat.c
to linux-nat.c.
gdb:
2015-06-01 Yao Qi <yao.qi@linaro.org>
* x86-linux-nat.c (have_ptrace_getregset): Move it to ...
* linux-nat.c: ... here.
* x86-linux-nat.h (have_ptrace_getregset): Move the declaration
to ...
* linux-nat.h: ... here.
Both GDB and gdbserver had linux_stop_lwp functions with identical
declarations. This commit moves these to nat/linux-nat.h to allow
shared code to use the function.
gdb/ChangeLog:
* linux-nat.h (linux_stop_lwp): Move declaration to...
* nat/linux-nat.h (linux_stop_lwp): New declaration.
gdb/gdbserver/ChangeLog:
* linux-low.h (linux_stop_lwp): Remove declaration.
This commit introduces a new function, iterate_over_lwps, that
shared Linux code can use to call a function for each LWP that
matches certain criteria. This function already existed in GDB
and was in use by GDB's various low-level Linux x86 debug register
setters. An equivalent was written for gdbserver and gdbserver's
low-level Linux x86 debug register setters were modified to use
it.
gdb/ChangeLog:
* linux-nat.h: Include nat/linux-nat.h.
(iterate_over_lwps): Move declaration to nat/linux-nat.h.
* nat/linux-nat.h (struct lwp_info): New forward declaration.
(iterate_over_lwps_ftype): New typedef.
(iterate_over_lwps): New declaration.
* linux-nat.h (iterate_over_lwps): Update comment. Use
iterate_over_lwps_ftype. Update callback return value check.
gdb/gdbserver/ChangeLog:
* linux-low.h: Include nat/linux-nat.h.
* linux-low.c (iterate_over_lwps_args): New structure.
(iterate_over_lwps_filter): New function.
(iterate_over_lwps): Likewise.
* linux-x86-low.c (update_debug_registers_callback):
Update signature to what iterate_over_lwps expects.
Remove PID check that iterate_over_lwps now performs.
(x86_dr_low_set_addr): Use iterate_over_lwps.
(x86_dr_low_set_control): Likewise.
TL;DR - GDB can hang if something refreshes the thread list out of the
target while the target is running. GDB hangs inside td_ta_thr_iter.
The fix is to not use that libthread_db function anymore.
Long version:
Running the testsuite against my all-stop-on-top-of-non-stop series is
still exposing latent non-stop bugs.
I was originally seeing this with the multi-create.exp test, back when
we were still using libthread_db thread event breakpoints. The
all-stop-on-top-of-non-stop series forces a thread list refresh each
time GDB needs to start stepping over a breakpoint (to pause all
threads). That test hits the thread event breakpoint often, resulting
in a bunch of step-over operations, thus a bunch of thread list
refreshes while some threads in the target are running.
The commit adds a real non-stop mode test that triggers the issue,
based on multi-create.exp, that does an explicit "info threads" when a
breakpoint is hit. IOW, it does the same things the as-ns series was
doing when testing multi-create.exp.
The bug is a race, so it unfortunately takes several runs for the test
to trigger it. In fact, even when setting the test running in a loop,
it sometimes takes several minutes for it to trigger for me.
The race is related to libthread_db's td_ta_thr_iter. This is
libthread_db's entry point for walking the thread list of the
inferior.
Sometimes, when GDB refreshes the thread list from the target,
libthread_db's td_ta_thr_iter can somehow see glibc's thread list as a
cycle, and get stuck in an infinite loop.
The issue is that when a thread exits, its thread control structure in
glibc is moved from a "used" list to a "cache" list. These lists are
simply circular linked lists where the "next/prev" pointers are
embedded in the thread control structure itself. The "next" pointer
of the last element of the list points back to the list's sentinel
"head". There's only one set of "next/prev" pointers for both lists;
thus a thread can only be in one of the lists at a time, not in both
simultaneously.
So when thread C exits, simplifying, the following happens. A-C are
threads. stack_used and stack_cache are the list's heads.
Before:
stack_used -> A -> B -> C -> (&stack_used)
stack_cache -> (&stack_cache)
After:
stack_used -> A -> B -> (&stack_used)
stack_cache -> C -> (&stack_cache)
td_ta_thr_iter starts by iterating at the list's head's next, and
iterates until it sees a thread whose next pointer points to the
list's head again. Thus in the before case above, C's next points to
stack_used, indicating end of list. In the same case, the stack_cache
list is empty.
For each thread being iterated, td_ta_thr_iter reads the whole thread
object out of the inferior. This includes the thread's "next"
pointer.
In the scenario above, it may happen that td_ta_thr_iter is iterating
thread B and has already read B's thread structure just before thread
C exits and its control structure moves to the cached list.
Now, recall that td_ta_thr_iter is running in the context of GDB, and
there's no locking between GDB and the inferior. From it's local copy
of B, td_ta_thr_iter believes that the next thread after B is thread
C, so it happilly continues iterating to C, a thread that has already
exited, and is now in the stack cache list.
After iterating C, td_ta_thr_iter finds the stack_cache head, which
because it is not stack_used, td_ta_thr_iter assumes it's just another
thread. After this, unless the reverse race triggers, GDB gets stuck
in td_ta_thr_iter forever walking the stack_cache list, as no thread
in thatlist has a next pointer that points back to stack_used (the
terminating condition).
Before fully understanding the issue, I tried adding cycle detection
to GDB's td_ta_thr_iter callback. However, td_ta_thr_iter skips
calling the callback in some cases, which means that it's possible
that the callback isn't called at all, making it impossible for GDB to
break the loop. I did manage to get GDB stuck in that state more than
once.
Fortunately, we can avoid the issue altogether. We don't really need
td_ta_thr_iter for live debugging nowadays, given PTRACE_EVENT_CLONE.
We already know how to map and lwp id to a thread id without iterating
(thread_from_lwp), so use that more.
gdb/ChangeLog:
2015-02-20 Pedro Alves <palves@redhat.com>
* linux-nat.c (linux_handle_extended_wait): Call
thread_db_notice_clone whenever a new clone LWP is detected.
(linux_stop_and_wait_all_lwps, linux_unstop_all_lwps): New
functions.
* linux-nat.h (thread_db_attach_lwp): Delete declaration.
(thread_db_notice_clone, linux_stop_and_wait_all_lwps)
(linux_unstop_all_lwps): Declare.
* linux-thread-db.c (struct thread_get_info_inout): Delete.
(thread_get_info_callback): Delete.
(thread_from_lwp): Use td_thr_get_info and record_thread.
(thread_db_attach_lwp): Delete.
(thread_db_notice_clone): New function.
(try_thread_db_load_1): If /proc is mounted and shows the
process'es task list, walk over all LWPs and call thread_from_lwp
instead of relying on td_ta_thr_iter.
(attach_thread): Don't call check_thread_signals here. Split the
tail part of the function (which adds the thread to the core GDB
thread list) to ...
(record_thread): ... this function. Call check_thread_signals
here.
(thread_db_wait): Don't call thread_db_find_new_threads_1. Always
call thread_from_lwp.
(thread_db_update_thread_list): Rename to ...
(thread_db_update_thread_list_org): ... this.
(thread_db_update_thread_list): New function.
(thread_db_find_thread_from_tid): Delete.
(thread_db_get_ada_task_ptid): Simplify.
* nat/linux-procfs.c: Include <sys/stat.h>.
(linux_proc_task_list_dir_exists): New function.
* nat/linux-procfs.h (linux_proc_task_list_dir_exists): Declare.
gdb/gdbserver/ChangeLog:
2015-02-20 Pedro Alves <palves@redhat.com>
* thread-db.c: Include "nat/linux-procfs.h".
(thread_db_init): Skip listing new threads if the kernel supports
PTRACE_EVENT_CLONE and /proc/PID/task/ is accessible.
gdb/testsuite/ChangeLog:
2015-02-20 Pedro Alves <palves@redhat.com>
* gdb.threads/multi-create-ns-info-thr.exp: New file.
Running the testsuite with a series that reimplements user-visible
all-stop behavior on top of a target running in non-stop mode revealed
problems related to event starvation avoidance.
For example, I see
gdb.threads/signal-while-stepping-over-bp-other-thread.exp failing.
What happens is that GDB core never gets to see the signal event. It
ends up processing the events for the same threads over an over,
because Linux's waitpid(-1, ...) returns that first task in the task
list that has an event, starving threads on the tail of the task list.
So I wrote a non-stop mode test originally inspired by
signal-while-stepping-over-bp-other-thread.exp, to stress this
independently of all-stop on top of non-stop. Fixing it required the
changes described below. The test will be added in a following
commit.
1) linux-nat.c has code in place that picks an event LWP at random out
of all that have had events. This is because on the kernel side,
"waitpid(-1, ...)" just walks the task list linearly looking for the
first that had an event. But, this code is currently only used in
all-stop mode. So with a multi-threaded program that has multiple
events triggering debug events in parallel, GDB ends up starving some
threads.
To make the event randomization work in non-stop mode too, the patch
makes us pull out all the already pending events on the kernel side,
with waitpid, before deciding which LWP to report to the core.
There's some code in linux_wait that takes care of leaving events
pending if they were for LWPs the caller is not interested in. The
patch moves that to linux_nat_filter_event, so that we only have one
place that leaves events pending. With that in place, conceptually,
the flow is simpler and more normalized:
#1 - walk the LWP list looking for an LWP with a pending event to report.
#2 - if no pending event, pull events out of the kernel, and store
them in the LWP structures as pending.
#3- goto #1.
2) Then, currently the event randomization code only considers SIGTRAP
(or trap-like) events. That means that if e.g., have have multiple
threads stepping in parallel that hit a breakpoint that needs stepping
over, and one gets a signal, the signal may end up never getting
processed, because GDB will always be giving priority to the SIGTRAPs.
The patch fixes this by making the randomization code consider all
kinds of pending events.
3) If multiple threads hit a breakpoint, we report one of those, and
"cancel" the others. Cancelling means decrementing the PC, and
discarding the event. If the next time the LWP is resumed the
breakpoint is still installed, the LWP should hit it again, and we'll
report the hit then. The problem I found is that this delays threads
from advancing too much, with the kernel potentially ending up
scheduling the same threads over and over, and others not advancing.
So the patch switches away from cancelling the breakpoints, and
instead remembering that the LWP had stopped for a breakpoint. If on
resume the breakpoint is still installed, we report it. If it's no
longer installed, we discard the pending event then. This is actually
how GDBserver used to handle this before d50171e4 (Teach linux
gdbserver to step-over-breakpoints), but with the difference that back
then we'd delay adjusting the PC until resuming, which made it so that
"info threads" could wrongly see threads with unadjusted PCs.
gdb/
2015-01-09 Pedro Alves <palves@redhat.com>
* breakpoint.c (hardware_breakpoint_inserted_here_p): New
function.
* breakpoint.h (hardware_breakpoint_inserted_here_p): New
declaration.
* linux-nat.c (linux_nat_status_is_event): Move higher up in file.
(linux_resume_one_lwp): Store the thread's PC. Adjust to clear
stop_reason.
(check_stopped_by_watchpoint): New function.
(save_sigtrap): Reimplement.
(linux_nat_stopped_by_watchpoint): Adjust.
(linux_nat_lp_status_is_event): Delete.
(stop_wait_callback): Only call save_sigtrap after storing the
pending status.
(status_callback): If the thread had been stopped for a breakpoint
that has since been removed, discard the event and resume the LWP.
(count_events_callback, select_event_lwp_callback): Use
lwp_status_pending_p instead of linux_nat_lp_status_is_event.
(cancel_breakpoint): Rename to ...
(check_stopped_by_breakpoint): ... this. Record whether the LWP
stopped for a software breakpoint or hardware breakpoint.
(select_event_lwp): Only give preference to the stepping LWP in
all-stop mode. Adjust comments.
(stop_and_resume_callback): Remove references to new_pending_p.
(linux_nat_filter_event): Likewise. Leave exit events of the
leader thread pending here. Handle signal short circuiting here.
Only call save_sigtrap after storing the pending waitstatus.
(linux_nat_wait_1): Remove 'retry' label. Remove references to
new_pending. Don't handle leaving events the caller is not
interested in pending here, nor handle signal short-circuiting
here. Also give equal priority to all LWPs that have had events
in non-stop mode. If reporting a software breakpoint event,
unadjust the LWP's PC.
* linux-nat.h (enum lwp_stop_reason): New.
(struct lwp_info) <stop_pc>: New field.
(struct lwp_info) <stopped_by_watchpoint>: Delete field.
(struct lwp_info) <stop_reason>: New field.
* x86-linux-nat.c (x86_linux_prepare_to_resume): Adjust.
... instead of relying on libthread_db.
I wrote a test that attaches to a program that constantly spawns
short-lived threads, which exposed several issues. This is one of
them.
On Linux, we need to attach to all threads of a process (thread group)
individually. We currently rely on libthread_db to list the threads,
but that is problematic, because libthread_db relies on reading data
structures out of the inferior (which may well be corrupted). If
threads are being created or exiting just while we try to attach, we
may trip on inconsistencies in the inferior's thread list. To work
around that, when we see a seemingly corrupt list, we currently retry
a few times:
static void
thread_db_find_new_threads_2 (ptid_t ptid, int until_no_new)
{
...
if (until_no_new)
{
/* Require 4 successive iterations which do not find any new threads.
The 4 is a heuristic: there is an inherent race here, and I have
seen that 2 iterations in a row are not always sufficient to
"capture" all threads. */
...
That heuristic may well fail, and when it does, we end up with threads
in the program that aren't under GDB's control. That's obviously bad
and results in quite mistifying failures, like e.g., the process dying
for seeminly no reason when a thread that wasn't attached trips on a
breakpoint.
There's really no reason to rely on libthread_db for this nowadays
when we have /proc mounted. In that case, which is the usual case, we
can list the LWPs from /proc/PID/task/. In fact, GDBserver is already
doing this. The patch factors out that code that knows to walk the
task/ directory out of GDBserver, and makes GDB use it too.
Like GDBserver, the patch makes GDB attach to LWPs and _not_ wait for
them to stop immediately. Instead, we just tag the LWP as having an
expected stop. Because we can only set the ptrace options when the
thread stops, we need a new flag in the lwp structure to keep track of
whether we've already set the ptrace options, just like in GDBserver.
Note that nothing issues any ptrace command to the threads between the
PTRACE_ATTACH and the stop, so this is safe (unlike one scenario
described in gdbserver's linux-low.c).
When we attach to a program that has threads exiting while we attach,
it's easy to race with a thread just exiting as we try to attach to
it, like:
#1 - get current list of threads
#2 - attach to each listed thread
#3 - ooops, attach failed, thread is already gone
As this is pretty normal, we shouldn't be issuing a scary warning in
step #3.
When #3 happens, PTRACE_ATTACH usually fails with ESRCH, but sometimes
we'll see EPERM as well. That happens when the kernel still has the
thread in its task list, but the thread is marked as dead.
Unfortunately, EPERM is ambiguous and we'll get it also on other
scenarios where the thread isn't dead, and in those cases, it's useful
to get a warning. To distiguish the cases, when we get an EPERM
failure, we open /proc/PID/status, and check the thread's state -- if
the /proc file no longer exists, or the state is "Z (Zombie)" or "X
(Dead)", we ignore the EPERM error silently; otherwise, we'll warn.
Unfortunately, there seems to be a kernel race here. Sometimes I get
EPERM, and then the /proc state still indicates "R (Running)"... If
we wait a bit and retry, we do end up seeing X or Z state, or get an
ESRCH. I thought of making GDB retry the attach a few times, but even
with a 500ms wait and 4 retries, I still see the warning sometimes. I
haven't been able to identify the kernel path that causes this yet,
but in any case, it looks like a kernel bug to me. As this just
results failure to suppress a warning that we've been printing since
about forever anyway, I'm just making the test cope with it, and issue
an XFAIL.
gdb/gdbserver/
2015-01-09 Pedro Alves <palves@redhat.com>
* linux-low.c (linux_attach_fail_reason_string): Move to
nat/linux-ptrace.c, and rename.
(linux_attach_lwp): Update comment.
(attach_proc_task_lwp_callback): New function.
(linux_attach): Adjust to rename and use
linux_proc_attach_tgid_threads.
(linux_attach_fail_reason_string): Delete declaration.
gdb/
2015-01-09 Pedro Alves <palves@redhat.com>
* linux-nat.c (attach_proc_task_lwp_callback): New function.
(linux_nat_attach): Use linux_proc_attach_tgid_threads.
(wait_lwp, linux_nat_filter_event): If not set yet, set the lwp's
ptrace option flags.
* linux-nat.h (struct lwp_info) <must_set_ptrace_flags>: New
field.
* nat/linux-procfs.c: Include <dirent.h>.
(linux_proc_get_int): New parameter "warn". Handle it.
(linux_proc_get_tgid): Adjust.
(linux_proc_get_tracerpid): Rename to ...
(linux_proc_get_tracerpid_nowarn): ... this.
(linux_proc_pid_get_state): New function, factored out from
(linux_proc_pid_has_state): ... this. Add new parameter "warn"
and handle it.
(linux_proc_pid_is_gone): New function.
(linux_proc_pid_is_stopped): Adjust.
(linux_proc_pid_is_zombie_maybe_warn)
(linux_proc_pid_is_zombie_nowarn): New functions.
(linux_proc_pid_is_zombie): Use
linux_proc_pid_is_zombie_maybe_warn.
(linux_proc_attach_tgid_threads): New function.
* nat/linux-procfs.h (linux_proc_get_tgid): Update comment.
(linux_proc_get_tracerpid): Rename to ...
(linux_proc_get_tracerpid_nowarn): ... this, and update comment.
(linux_proc_pid_is_gone): New declaration.
(linux_proc_pid_is_zombie): Update comment.
(linux_proc_pid_is_zombie_nowarn): New declaration.
(linux_proc_attach_lwp_func): New typedef.
(linux_proc_attach_tgid_threads): New declaration.
* nat/linux-ptrace.c (linux_ptrace_attach_fail_reason): Adjust to
use nowarn functions.
(linux_ptrace_attach_fail_reason_string): Move here from
gdbserver/linux-low.c and rename.
(ptrace_supports_feature): If the current ptrace options are not
known yet, check them now, instead of asserting.
* nat/linux-ptrace.h (linux_ptrace_attach_fail_reason_string):
Declare.
While reviewing the native AArch64 patch, I noticed a problem:
On 02/06/2013 08:46 PM, Pedro Alves wrote:
>
>> > +static void
>> > +aarch64_linux_prepare_to_resume (struct lwp_info *lwp)
>> > +{
>> > + struct arch_lwp_info *info = lwp->arch_private;
>> > +
>> > + /* NULL means this is the main thread still going through the shell,
>> > + or, no watchpoint has been set yet. In that case, there's
>> > + nothing to do. */
>> > + if (info == NULL)
>> > + return;
>> > +
>> > + if (DR_HAS_CHANGED (info->dr_changed_bp)
>> > + || DR_HAS_CHANGED (info->dr_changed_wp))
>> > + {
>> > + int tid = GET_LWP (lwp->ptid);
>> > + struct aarch64_debug_reg_state *state = aarch64_get_debug_reg_state ();
> Hmm. This is always fetching the debug_reg_state of
> the current inferior, but may not be the inferior of lwp.
> I see the same bug on x86. Sorry about that. I'll fix it.
A natural fix would be to make xxx_get_debug_reg_state take an
inferior argument, but that doesn't work because of the case where we
detach breakpoints/watchpoints from the child fork, at a time there's
no inferior for the child fork at all. We do a nasty hack in
i386_inferior_data_get, but that relies on all callers pointing the
current inferior to the correct inferior, which isn't actually being
done by all callers, and I don't think we want to enforce that -- deep
in the bowls of linux-nat.c, there are many cases we resume lwps
behind the scenes, and it's be better to not have that code rely on
global state (as it doesn't today).
The fix is to decouple the watchpoints code from inferiors, making it
track target processes instead. This way, we can freely keep track of
the watchpoint mirrors for these processes behind the core's back.
Checkpoints also play dirty tricks with swapping the process behind
the inferior, so they get special treatment too in the patch (which
just amounts to calling a new hook). Instead of the old hack in
i386_inferior_data_get, where we returned a copy of the current
inferior's debug registers mirror, as soon as we detect a fork in the
target, we copy the debug register mirror from the parent to the child
process.
I don't have an old kernel handy to test, but I stepped through gdb doing
the watchpoint removal in the fork child in the watchpoint-fork test
seeing that the debug registers end up cleared in the child.
I didn't find the need for linux_nat_iterate_watchpoint_lwps. If
we use plain iterate_over_lwps instead, what happens is that
when removing watchpoints, that iterate_over_lwps doesn't actually
iterate over anything, since the fork child is not added to the
lwp list until later, at detach time, in linux_child_follow_fork.
And if we don't iterate over that lwp, we don't mark its debug
registers as needing update. But linux_child_follow_fork takes
care of doing that explicitly:
child_lp = add_lwp (inferior_ptid);
child_lp->stopped = 1;
child_lp->last_resume_kind = resume_stop;
make_cleanup (delete_lwp_cleanup, child_lp);
/* CHILD_LP has new PID, therefore linux_nat_new_thread is not called for it.
See i386_inferior_data_get for the Linux kernel specifics.
Ensure linux_nat_prepare_to_resume will reset the hardware debug
registers. It is done by the linux_nat_new_thread call, which is
being skipped in add_lwp above for the first lwp of a pid. */
gdb_assert (num_lwps (GET_PID (child_lp->ptid)) == 1);
if (linux_nat_new_thread != NULL)
linux_nat_new_thread (child_lp);
if (linux_nat_prepare_to_resume != NULL)
linux_nat_prepare_to_resume (child_lp);
ptrace (PTRACE_DETACH, child_pid, 0, 0);
so unless I'm missing something (quite possible) it ends up all
the same. But, the !detach-on-fork, and the "follow-fork child" paths
should also call linux_nat_new_thread, and they don't presently. It
seems to me in those cases we're not clearing debug regs correctly
when that's needed. Instead of copying that bit that works around
add_lwp bypassing the linux_nat_new_thread call, I thought it'd
be better to add an add_initial_lwp call to be used in the case we
really need to bypass linux_nat_new_thread, and make
add_lwp always call linux_nat_new_thread.
i386_cleanup_dregs is rewritten to forget about the current process
debug mirrors, which takes cares of other i386 ports. Only a couple
of extra tweaks here and there were needed, as some targets wheren't
actually calling i386_cleanup_dregs.
Tested on Fedora 17 x86_64 -m64/-m32.
GDBserver already fetches the i386_debug_reg_state from the right
process, and, it doesn't handle forks at all, so no fix is needed over
there.
gdb/
2013-02-13 Pedro Alves <palves@redhat.com>
* amd64-linux-nat.c (update_debug_registers_callback):
Update comment.
(amd64_linux_dr_set_control, amd64_linux_dr_set_addr): Use
iterate_over_lwps.
(amd64_linux_prepare_to_resume): Pass the lwp's pid to
i386_debug_reg_state.
(amd64_linux_new_fork): New function.
(_initialize_amd64_linux_nat): Install amd64_linux_new_fork as
linux_nat_new_fork hook, and i386_forget_process as
linux_nat_forget_process hook.
* i386-linux-nat.c (update_debug_registers_callback):
Update comment.
(amd64_linux_dr_set_control, amd64_linux_dr_set_addr): Use
iterate_over_lwps.
(i386_linux_prepare_to_resume): Pass the lwp's pid to
i386_debug_reg_state.
(i386_linux_new_fork): New function.
(_initialize_i386_linux_nat): Install i386_linux_new_fork as
linux_nat_new_fork hook, and i386_forget_process as
linux_nat_forget_process hook.
* i386-nat.c (i386_init_dregs): Delete.
(i386_inferior_data, struct i386_inferior_data):
Delete.
(struct i386_process_info): New.
(i386_process_list): New global.
(i386_find_process_pid, i386_add_process, i386_process_info_get):
New functions.
(i386_inferior_data_get): Delete.
(i386_process_info_get): New function.
(i386_debug_reg_state): New parameter 'pid'. Reimplement.
(i386_forget_process): New function.
(i386_cleanup_dregs): Rewrite.
(i386_update_inferior_debug_regs, i386_insert_watchpoint)
(i386_remove_watchpoint, i386_region_ok_for_watchpoint)
(i386_stopped_data_address, i386_insert_hw_breakpoint)
(i386_remove_hw_breakpoint): Adjust to pass the current process id
to i386_debug_reg_state.
(i386_use_watchpoints): Don't register inferior data.
* i386-nat.h (i386_debug_reg_state): Add new 'pid' parameter, and
adjust comment.
(i386_forget_process): Declare.
* linux-fork.c (delete_fork): Call linux_nat_forget_process.
* linux-nat.c (linux_nat_new_fork, linux_nat_forget_process_hook):
New static globals.
(linux_child_follow_fork): Don't call linux_nat_new_thread here.
(add_initial_lwp): New, factored out from ...
(add_lwp): ... this. Don't check the number of lwps before
calling linux_nat_new_thread.
(linux_nat_iterate_watchpoint_lwps): Delete.
(linux_nat_attach): Use add_initial_lwp instead of add_lwp.
(linux_handle_extended_wait): Call the linux_nat_new_fork hook on
forks and vforks.
(linux_nat_wait_1): Use add_initial_lwp instead of add_lwp for the
initial lwp.
(linux_nat_kill, linux_nat_mourn_inferior): Call
linux_nat_forget_process.
(linux_nat_set_new_fork, linux_nat_set_forget_process)
(linux_nat_forget_process): New functions.
* linux-nat.h (linux_nat_iterate_watchpoint_lwps_ftype): Delete
type.
(linux_nat_iterate_watchpoint_lwps): Delete declaration.
(linux_nat_new_fork_ftype, linux_nat_forget_process_ftype): New
types.
(linux_nat_set_new_fork, linux_nat_set_forget_process)
(linux_nat_forget_process): New declarations.
* amd64fbsd-nat.c (super_mourn_inferior): New global.
(amd64fbsd_mourn_inferior): New function.
(_initialize_amd64fbsd_nat): Override to_mourn_inferior.
* windows-nat.c (windows_detach): Call i386_cleanup_dregs.
Two modifications:
1. The addition of 2013 to the copyright year range for every file;
2. The use of a single year range, instead of potentially multiple
year ranges, as approved by the FSF.
Code cleanup for the next patch.
* arm-linux-nat.c (arm_linux_stopped_data_address): Change variable
siginfo_p to siginfo, update its users incl. the linux_nat_get_siginfo
call for it.
* ia64-linux-nat.c (ia64_linux_stopped_data_address): Likewise.
(ia64_linux_stopped_data_address):
* linux-nat.c (linux_nat_get_siginfo): Add parameter siginfo, change
the return value.
* linux-nat.h (linux_nat_get_siginfo): Likewise.
* ppc-linux-nat.c (ppc_linux_stopped_data_address): Change variable
siginfo_p to siginfo, update its users incl. the linux_nat_get_siginfo
call for it.
Fix watchpoints across inferior fork.
* amd64-linux-nat.c (update_debug_registers_callback): Update the
comment for linux_nat_iterate_watchpoint_lwps.
(amd64_linux_dr_set_control, amd64_linux_dr_set_addr): Use
linux_nat_iterate_watchpoint_lwps.
(amd64_linux_prepare_to_resume): New comment on Linux kernel.
* i386-linux-nat.c (update_debug_registers_callback): Update the
comment for linux_nat_iterate_watchpoint_lwps.
(i386_linux_dr_set_control, i386_linux_dr_set_addr): Use
linux_nat_iterate_watchpoint_lwps.
(i386_linux_prepare_to_resume): New comment on Linux kernel.
* i386-nat.c: Include inferior.h.
(dr_mirror): Remove.
(i386_inferior_data, struct i386_inferior_data)
(i386_inferior_data_get): New.
(i386_debug_reg_state): Use i386_inferior_data_get.
(i386_cleanup_dregs, i386_update_inferior_debug_regs)
(i386_insert_watchpoint, i386_remove_watchpoint)
(i386_stopped_data_address, i386_insert_hw_breakpoint)
(i386_remove_hw_breakpoint): New variable state, use
i386_debug_reg_state instead of DR_MIRROR.
* linux-nat.c (delete_lwp): New declaration.
(num_lwps): Move here from downwards.
(delete_lwp_cleanup): New.
(linux_child_follow_fork): Create new child_lp, call
linux_nat_new_thread and linux_nat_prepare_to_resume before calling
PTRACE_DETACH.
(num_lwps): Move upwards.
(linux_nat_iterate_watchpoint_lwps): New.
* linux-nat.h (linux_nat_iterate_watchpoint_lwps_ftype): New.
(linux_nat_iterate_watchpoint_lwps_ftype): New declaration.
gdb/testsuite/
Fix watchpoints across inferior fork.
* gdb.threads/watchpoint-fork-child.c: New file.
* gdb.threads/watchpoint-fork-mt.c: New file.
* gdb.threads/watchpoint-fork-parent.c: New file.
* gdb.threads/watchpoint-fork-st.c: New file.
* gdb.threads/watchpoint-fork.exp: New file.
* gdb.threads/watchpoint-fork.h: New file.
* linux-nat.h (enum resume_kind): New.
(struct lwp_info) <last_resume_kind>: New field.
(linux_child_follow_fork): Set last_resume_kind to resume_stop on
the new lwp.
(add_lwp): Set last_resume_kind as resume_continue by default.
(lin_lwp_attach_lwp): Set last_resume_kind as resume_stop.
(resume_lwp): New, factored out from resume_callback. Also check
for pending status in lp->waitstatus.
(resume_callback): Reimplement.
(resume_clear_callback): Set last_resume_kind as resume_stop.
(resume_set_callback): Set last_resume_kind as resume_continue.
(linux_nat_resume, linux_handle_extended_wait): Set
last_resume_kind.
(running_callback): Also check lp->waitstatus for pending events.
(select_singlestep_lwp_callback): Check that lp->last_resume_kind
is resume_step.
(stop_and_resume_callback): Don't re-resume if the core wanted the
lwp stopped. Use resume_lwp instead of resume_callback. Avoid
using an invalidated pointer.
(linux_nat_filter_event): Don't discard SIGSTOPs as delayed
SIGSTOPs if the core wanted the LWP to stop.
(linux_nat_wait_1) Don't consume a pending SIGSTOP if the core
wanted the lwp to stop. If the core wanted the lwp to stop, and
the lwp stopped with a SIGSTOP, report a TARGET_SIGNAL_0 instead
of TARGET_SIGNAL_STOP.
(linux_nat_stop_lwp): Don't synchronously wait for the lwp to stop
here. Instead, signal the lwp, and set the last_resume_kind to
resume_stop.
* amd64-linux-tdep.c: Include xml-syscall.h header, define the XML
syscall name for the architecture.
(amd64_linux_get_syscall_number): New function.
(amd64_linux_init_abi): Register the correct functions for syscall
catchpoint; set the correct syscall file name.
* breakpoint.c: New include: xml-syscall.h.
(set_raw_breakpoint_without_location): Setting the parameters
for the catch syscall feature.
(insert_catch_syscall): New.
(remove_catch_syscall): New.
(breakpoint_hit_catch_syscall): New.
(print_it_catch_syscall): New.
(print_one_catch_syscall): New.
(print_mention_catch_syscall): New.
(catch_syscall_breakpoint_ops): New.
(syscall_catchpoint_p): New.
(create_catchpoint_without_mention): New.
(create_catchpoint): Modified in order to use
create_catchpoint_without_mention.
(create_syscall_event_catchpoint): New.
(clean_up_filters): New.
(catch_syscall_split_args): New.
(catch_syscall_command_1): New.
(delete_breakpoint): Add cleanup for catch syscall.
(is_syscall_catchpoint_enabled): New.
(catch_syscall_enabled): New.
(catching_syscall_number): New.
(catch_syscall_completer): New completer function.
(add_catch_command): Add the completer function for catchpoints.
* breakpoint.h (syscalls_to_be_caught): New vector.
(catch_syscall_enabled): New.
(catching_syscall_number): New.
* gdbarch.c: Regenerated.
* gdbarch.h: Regenerated.
* gdbarch.sh: Add syscall catchpoint functions and structures.
(get_syscall_number): New.
(UNKNOWN_SYSCALL): New definition.
* i386-linux-nat.c (i386_linux_resume): Select the proper request
to be made for ptrace() considering if we are catching syscalls
or not.
* i386-linux-tdep.c: Include xml-syscall.h header, define the XML
syscall name for the architecture.
(i386_linux_get_syscall_number): New.
(i386_linux_init_abi): Register the correct functions for syscall
catchpoint; set the correct syscall file name.
* inf-child.c (inf_child_set_syscall_catchpoint): New.
(inf_child_target): Assign default values to target_ops.
* inf-ptrace.c (inf_ptrace_resume): Select the proper request
to be made for ptrace() considering if we are catching syscalls
or not.
* inferior.h (struct inferior): Included new variables
any_syscall_count, syscalls_counts and total_syscalls_count,
used to keep track of requested syscall catchpoints.
* infrun.c (resume): Add syscall catchpoint.
(deal_with_syscall_event): New.
(handle_inferior_event): Add syscall entry/return events.
(inferior_has_called_syscall): New.
* linux-nat.c: Define some helpful variables to track wether we have
support for the needed ptrace option.
(linux_test_for_tracesysgood): New.
(linux_supports_tracesysgood): New.
(linux_enable_tracesysgood): New.
(linux_enable_event_reporting): Save the current used ptrace
options.
(linux_child_post_attach): Calling linux_enable_tracesysgood.
(linux_child_post_startup_inferior): Likewise.
(linux_child_set_syscall_catchpoint): New function.
(linux_handle_extended_wait): Handle the case which the inferior stops
because it has called or returned from a syscall.
(linux_target_install_ops): Install the necessary functions to handle
syscall catchpoints.
* linux-nat.h (struct lwp_info): Include syscall_state into the
structure, which indicates if we are in a syscall entry or return.
* ppc-linux-tdep.c: Include xml-syscall.h header, define the XML
syscall filename for the arch.
(ppc_linux_get_syscall_number): New.
(ppc_linux_init_abi): Register the correct functions for syscall
catchpoint; setting the correct name for the XML syscall file.
* target.c (update_current_target): Update/copy functions related to
syscall catchpoint.
(target_waitstatus_to_string): Add syscall catchpoint entry/return
events.
* target.h (struct target_waitstatus): Add syscall number.
(struct syscall): New struct to hold information about syscalls
in the system.
(struct target_ops): Add ops for syscall catchpoint.
(inferior_has_called_syscall): New.
(target_set_syscall_catchpoint): New.
* xml-support.c (xml_fetch_content_from_file): New function,
transferred from xml-tdesc.c.
* xml-support.h (xml_fetch_content_from_file): New.
* xml-tdesc.c (fetch_xml_from_file): Function removed;
transferred to xml-support.c.
(file_read_description_xml): Updated to use the new
xml_fetch_content_from_file function.
* syscalls/gdb-syscalls.dtd: New definition file for syscall's XML
support.
* syscalls/amd64-linux.xml: New file containing information about
syscalls for GNU/Linux systems that use amd64 architecture.
* syscalls/i386-linux.xml: New file containing information about
syscalls for GNU/Linux systems that use i386 architecture.
* syscalls/ppc-linux.xml: New file containing information about
syscalls for GNU/Linux systems that use PPC architecture.
* syscalls/ppc64-linux.xml: New file containing information about
syscalls for GNU/Linux systems that use PPC64 architecture.
* xml-syscall.c: New file containing functions for manipulating
syscall's XML files.
* xml-syscall.h: New file, exporting the functions above mentioned.
* Makefile.in: Support for relocatable GDB datadir and XML
syscall.
* NEWS: Added information about the catch syscall feature.
* doc/gdb.texinfo (Set Catchpoints): Documentation about the new
feature.
* testsuite/Makefile.in: Inclusion of catch-syscall object.
* testsuite/gdb.base/catch-syscall.c: New file.
* testsuite/gdb.base/catch-syscall.exp: New file.
* linux-nat.c (linux_proc_get_tgid): New.
* linux-thread-db.c (struct thread_db_info): New field
`need_stale_parent_threads_check'.
(add_thread_db_info): Set it.
(find_new_threads_callback): Ignore stale fork parent threads.
(thread_db_resume): New.
(init_thread_db_ops): Install thread_db_resume.
is the first inferior.
(startup_inferior): If the target support multi-process, tell it
to resume only the new process.
* linux-nat.c (num_lwps): Delete global.
(purge_lwp_list): New function.
(num_lwps): New function.
(add_lwp, delete_lwp): Adjust.
(ptid_match): New.
(iterate_over_lwps): Add filter argument. Handle it.
(linux_nat_attach): Remove FIXME note.
(linux_nat_detach): Adjust to iterate over threads of the inferior
we're detaching from. Adjust to num_lwps being a function. Don't
assume the head of the lwp list is the main thread of the process
we're detaching from. Don't destroy the LWP list.
(resume_callback): Add debug output.
(linux_nat_resume): Handle resuming a single inferior. Allow a
wildcard resume in non-stop mode.
(linux_handle_extended_wait): Don't assume inferior_ptid is the
correct inferior of the parent LWP.
(status_callback): Also check lp->waitstatus.
(select_event_lwp): Add new filter parameter. Handle it.
(linux_nat_filter_event): Adjust to num_lwps being a function.
(linux_nat_wait_1): When adding the first lwp of the inferior, use
an is_lwp check instead of checking for the number of lwps.
(linux_nat_wait_1): Handle waiting for a specific tgid. Handle
pending process exit statuses.
(linux_nat_mourn_inferior): Don't destroy all the LWP info.
Instead delete LWPs of the inferior that we're mourning. Don't
unregister from the event loop here.
(linux_nat_pid_to_str): Use `num_lwps'.
(linux_nat_make_corefile_notes): Adjust to walk over lwps of a
single inferior.
(linux_nat_is_async_p): Check if async was masked out.
(linux_multi_process): New global.
(linux_nat_supports_multi_process): New.
(linux_nat_stop_lwp): Remove LWP filtering. It is done by the
caller.
(linux_nat_stop): Adjust to make iterate_over_lwps itself do the
LWP filtering.
(linux_nat_close): New.
(linux_nat_add_target): Register linux_nat_close and
linux_nat_supports_multi_process.
* linux-nat.h (iterate_over_lwps): Add filter argument.
* linux-thread-db.c (thread_db_handle): Delete.
(proc_handle, thread_agent, td_init_p, td_ta_new_p)
(td_ta_map_id2thr_p, td_ta_map_lwp2thr_p, td_ta_thr_iter_p)
(td_ta_event_addr_p, td_ta_set_event_p, td_ta_event_getmsg_p)
(td_thr_validate_p, td_thr_get_info_p, td_thr_event_enable_p)
(td_thr_tls_get_addr_p, td_create_bp_addr, td_death_bp_addr): No
longer globals, moved to...
(struct thread_db_info): ... this new structure.
(thread_db_list): New.
(add_thread_db_info, get_thread_db_info, delete_thread_db_info):
New.
(have_threads_callback): Filter out threads of all inferiors but
the one specified by the ARGS argument.
(have_threads): Add ptid argument specifying the inferior we're
interested in. Handle it.
(struct thread_get_info_inout): New.
(thread_get_info_callback, thread_from_lwp): Adjust to use it.
(thread_db_attach_lwp): Check that inferior of the passed in
thread is using thread-db. Adjust.
(enable_thread_event): Remove thread_agent parameter. Instead,
get it from the per-inferior thread-db info.
(dladdr_to_soname): Move higher up.
(enable_thread_event_reporting): Adjust to use per-inferior
thread-db info.
(try_thread_db_load_1): Replace `handle' parameter by a
thread_db_info parameter. Adjust to use per-inferior thread-db
info.
(try_thread_db_load): Adjust to use per-inferior thread-db info.
(thread_db_load, disable_thread_event_reporting): Ditto.
(check_for_thread_db): Remove conditional reporting of which
libthread_db is in use.
(thread_db_new_objfile): Add comment about inferior_ptid.
(attach_thread): Adjust to use per-inferior thread-db info.
(thread_db_detach): Adjust to use per-inferior thread-db info.
Remove thread event breakpoints of the current inferior. Only
unpush the thread-db target if there are no more processes using
it.
(check_event): Adjust to use per-inferior thread-db info.
(thread_db_wait): Adjust to use per-inferior thread-db info. Only
unpush the thread-db target if there are no more processes using
it.
(thread_db_mourn_inferior): Adjust to use per-inferior thread-db
info. Mark breakpoints of the current inferior out before
deleting them. Only unpush the thread-db target if there are no
more processes using it.
(find_new_threads_callback): Adjust to use per-inferior thread_db
info.
(thread_db_find_new_threads_1): Add new ptid argument. Adjust to
use per-inferior thread-db info.
(thread_db_find_new_threads): Adjust to use per-inferior thread-db
info.
(thread_db_get_thread_local_address): Adjust.
(thread_db_get_ada_task_ptid): Adjust.
* inf-ptrace.c (inf_ptrace_mourn_inferior): Only unpush the target
if there no more processes left to debug.
* thread.c (set_running, set_executing): Handle resuming all
threads of a single inferior.
* mi/mi-interp.c (mi_output_running_pid): New.
(mi_inferior_count): New.
(mi_on_resume): For backwards compatibility, if resuming all
threads of an inferior, and there is only one inferior, output
"all".
(linux_nat_has_pending_sigint): New function, based on
linux_nat_has_pending.
(set_ignore_sigint, maybe_clear_ignore_sigint): New functions.
(stop_wait_callback): Remove flush_mask handling. Honor
ignore_sigint. Call maybe_clear_ignore_sigint. Pass NULL
to recursive calls.
(linux_nat_has_pending, flush_callback): Remove.
(linux_nat_filter_event): Check for ignore_sigint.
(linux_nat_wait): Remove flush_mask support and call to
flush_callback. Use set_ignore_sigint and maybe_clear_ignore_sigint.
* linux-nat.h (struct lwp_info): Add ignore_sigint field.
* gdb.threads/manythreads.exp: Use remote_expect instead of after.
Add a test for duplicated SIGINTs.
* linux-nat.c (linux_test_for_tracefork): Block events while we're
here.
(get_pending_status): Implement non-stop mode.
(linux_nat_detach): Stop threads before detaching.
(linux_nat_resume): In non-stop mode, always resume only a single
PTID.
(linux_handle_extended_wait): On a clone event, in non-stop mode,
add new lwp to GDB's thread table, and mark as running, executing
and stopped appropriately.
(linux_nat_filter_event): Don't assume there are other running
threads when a thread exits.
(linux_nat_wait): Mark the main thread as running and executing.
In non-stop mode, don't stop all lwps.
(linux_nat_kill): Stop lwps before killing them.
(linux_nat_thread_alive): Use signal 0 to detect if a thread is
alive.
(send_sigint_callback): New.
(linux_nat_stop): New.
(linux_nat_add_target): Set to_stop to linux_nat_stop.
* linux-nat.h (thread_db_attach_lwp): Declare.
* linux-thread-db.c (thread_get_info_callback): Check for new
threads if we have none.
(thread_from_lwp, enable_thread_event): Set proc_handle.pid to the
stopped lwp. Check for new threads if we have none.
(thread_db_attach_lwp): New.
(thread_db_init): Set proc_handle.pid to inferior_ptid.
(check_event): Set proc_handle.pid to the stopped lwp.
(thread_db_find_new_threads): Set proc_handle.pid to any stopped
lwp available, bail out if there is none.
* linux-fork.c (linux_fork_killall): Use SIGKILL instead of
PTRACE_KILL.
* gdbthread.h (add_thread_with_info): New.
* linux-thread-db.c: Add some documentation.
(GET_LWP, GET_PID, GET_THREAD, is_lwp, is_thread, BUILD_LWP): Delete.
(struct private_thread_info): Remove th_valid and ti_valid.
Replace ti with tid.
(thread_get_info_callback): Do not add TID to the new ptid. Do
not cache th or ti.
(thread_db_map_id2thr, lwp_from_thread): Delete functions.
(thread_from_lwp): Assert that the LWP is set. Do not add TID to the
new PTID.
(attach_thread): Handle an already-existing thread. Use
add_thread_with_info. Cache the th and tid.
(detach_thread): Verify that private was set. Remove verbose
argument and printing. Update caller.
(thread_db_detach): Do not adjust inferior_ptid.
(clear_lwpid_callback, thread_db_resume, thread_db_kill): Delete.
(check_event, find_new_threads_callback): Do not add TID to the new PTID.
(thread_db_wait): Do not use lwp_from_thread.
(thread_db_pid_to_str): Use the cached TID.
(thread_db_extra_thread_info): Check that private is set.
(same_ptid_callback): Delete.
(thread_db_get_thread_local_address): Do not use it or check
is_thread. Check that private is set. Assume that the thread
handle is already cached.
(init_thread_db_ops): Remove to_resume and to_kill.
* thread.c (add_thread_with_info): New.
(add_thread): Use it.
* linux-nat.c (find_thread_from_lwp): Delete.
(exit_lwp): Do not use it. Check print_thread_events. Print before
deleting the thread.
(GET_PID, GET_LWP, BUILD_LWP, is_lwp): Move to...
* linux-nat.h (GET_PID, GET_LWP, BUILD_LWP, is_lwp): ...here.
* inf-ttrace.c (inf_ttrace_wait): Use print_thread_events and
printf_unfiltered for thread exits.
* procfs.c (procfs_wait): Likewise.
2008-03-21 Pedro Alves <pedro@codesourcery.com>
* gdb.threads/fork-child-threads.exp: Test next over fork.
* thread.c (add_thread_silent): Renamed
from add_thread.
(print_thread_events): New variable definition.
(show_print_thread_events): New function.
(_initialize_thread): Add "set print thread-events" and
"show print thread-events" commands.
(add_thread): Announce new thread.
* gdbthread.h (add_thread_silent): Declare.
(print_thread_events): New variable declaration.
* inf-ttrace.c (inf_ttrace_wait): Don't
inform about new thread, as add_thread is always
called too, and will take care of that.
* infrun.c (handle_inferior_event): Likewise.
* procfs.c (procfs_wait): Likewise.
* remote.c (remote_currthread): Likewise.
* sol-thread.c (sol_thread_wait): Likewise.
* win32-nat.c (get_win32_debug_event): Likewise.
* linux-thread-db.c (attach_thread): Likewise.
Remove the verbose parameter.
(check_event): Make detach_thread be verbose
only if print_thread_events is set.
* linux-nat.c (lin_lwp_attach_lwp): Don't inform
about new thread. This is called only from
linux-thread-db.c:attach_thread, which will take care.
Remove the verbose parameter.
* linux-nat.h (lin_lwp_attach_lwp): Adjust prototype.
Josh Stone
Joel Brobecker
Pedro Alves
Antoine Tremblay
Yao Qi
Simon Marchi
Gary Benson
Luis Machado
Joel Brobecker
Jan Kratochvil
Thomas Schwinge
Michael Snyder
Ulrich Weigand
Vladimir Prus
Sergio Durigan Junior
Daniel Jacobowitz