Since the starvation avoidance series
(https://sourceware.org/ml/gdb-patches/2014-12/msg00631.html), both
GDB and GDBserver pull all events out of ptrace before deciding which
event to process.
There's one problem with that though. Because we resume new threads
immediately when we see a PTRACE_EVENT_CLONE event, if the program
constantly spawns threads fast enough, new threads can spawn threads
faster we can pull events out of the kernel, and thus we'd get stuck
in an infinite loop, never returning any event to the core to process.
I occasionally see this happen with the
attach-many-short-lived-threads.exp test against gdbserver.
The fix is to delay resuming new threads until we've pulled out all
events out of the kernel.
On native, we already have the resume_stopped_resumed_lwps function
that knows to resume LWPs that are stopped with no event to report to
the core. So the patch just adds another use. GDBserver didn't have
the equivalent yet, so the patch adds one.
Tested on x86_64 Fedora 20, native and gdbserver (remote and
extended-remote).
gdb/gdbserver/ChangeLog:
2015-02-04 Pedro Alves <palves@redhat.com>
* linux-low.c (handle_extended_wait): Don't resume LWPs here.
(resume_stopped_resumed_lwps): New function.
(linux_wait_for_event_filtered): Use it.
gdb/ChangeLog:
2015-02-04 Pedro Alves <palves@redhat.com>
* linux-nat.c (handle_extended_wait): Don't resume LWPs here.
(wait_lwp): Don't call wait_lwp if linux_handle_extended_wait
returns true.
(resume_stopped_resumed_lwps): Don't check whether the thread is
marked as executing.
(linux_nat_wait_1): Use resume_stopped_resumed_lwps.
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.
linux_nat_is_async_p currently always returns true, even when the
target is _not_ async. That confuses
gdb_readline_wrapper/gdb_readline_wrapper_cleanup, which
force-disables target-async while the secondary prompt is active. As
a result, when gdb_readline_wrapper returns, the target is left async,
even through it was sync to begin with.
That can result in weird bugs, like the one the test added by this
commit exposes.
Ref: https://sourceware.org/ml/gdb-patches/2015-01/msg00592.html
gdb/ChangeLog:
2015-01-23 Pedro Alves <palves@redhat.com>
* linux-nat.c (linux_is_async_p): New macro.
(linux_nat_is_async_p):
(linux_nat_terminal_inferior): Check whether the target can async
instead of whether it is already async.
(linux_nat_terminal_ours): Don't check whether the target is
async.
(linux_async_pipe): Use linux_is_async_p.
gdb/testsuite/ChangeLog:
2015-01-23 Pedro Alves <palves@redhat.com>
* gdb.threads/continue-pending-after-query.c: New file.
* gdb.threads/continue-pending-after-query.exp: New file.
This patch moves the shared code present on
gdb/linux-nat.c:linux_nat_create_inferior and
gdb/gdbserver/linux-low.c:linux_create_inferior to
nat/linux-personality.c. This code is responsible for disabling
address space randomization based on user setting, and using
<sys/personality.h> to do that. I decided to put the prototype of the
maybe_disable_address_space_randomization on nat/linux-osdata.h
because it seemed the best place to put it.
I regression-tested this patch on Fedora 20 x86_64, and found no
regressions.
gdb/ChangeLog
2015-01-15 Sergio Durigan Junior <sergiodj@redhat.com>
* Makefile.in (HFILES_NO_SRCDIR): Add nat/linux-personality.h.
(linux-personality.o): New rule.
* common/common-defs.h: Include <stdint.h>.
* config/aarch64/linux.mh (NATDEPFILES): Include
linux-personality.o.
* config/alpha/alpha-linux.mh (NATDEPFILES): Likewise.
* config/arm/linux.mh (NATDEPFILES): Likewise.
* config/i386/linux64.mh (NATDEPFILES): Likewise.
* config/i386/linux.mh (NATDEPFILES): Likewise.
* config/ia64/linux.mh (NATDEPFILES): Likewise.
* config/m32r/linux.mh (NATDEPFILES): Likewise.
* config/m68k/linux.mh (NATDEPFILES): Likewise.
* config/mips/linux.mh (NATDEPFILES): Likewise.
* config/pa/linux.mh (NATDEPFILES): Likewise.
* config/powerpc/linux.mh (NATDEPFILES): Likewise.
* config/powerpc/ppc64-linux.mh (NATDEPFILES): Likewise.
* config/powerpc/spu-linux.mh (NATDEPFILES): Likewise.
* config/s390/linux.mh (NATDEPFILES): Likewise.
* config/sparc/linux64.mh (NATDEPFILES): Likewise.
* config/sparc/linux.mh (NATDEPFILES): Likewise.
* config/tilegx/linux.mh (NATDEPFILES): Likewise.
* config/xtensa/linux.mh (NATDEPFILES): Likewise.
* defs.h: Remove #include <stdint.h> (moved to
common/common-defs.h).
* linux-nat.c: Include nat/linux-personality.h. Remove #include
<sys/personality.h>; do not define ADDR_NO_RANDOMIZE (moved to
nat/linux-personality.c).
(linux_nat_create_inferior): Remove code to disable address space
randomization (moved to nat/linux-personality.c). Create cleanup
to disable address space randomization.
* nat/linux-personality.c: New file.
* nat/linux-personality.h: Likewise.
gdb/gdbserver/ChangeLog
2015-01-15 Sergio Durigan Junior <sergiodj@redhat.com>
* Makefile.in (SFILES): Add linux-personality.c.
(linux-personality.o): New rule.
* configure.srv (srv_linux_obj): Add linux-personality.o to the
list of objects to be built.
* linux-low.c: Include nat/linux-personality.h.
(linux_create_inferior): Remove code to disable address space
randomization (moved to ../nat/linux-personality.c). Create
cleanup to disable address space randomization.
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.
A subsequent patch will make the Linux backend's target_wait method
pull all events out of the kernel (with waitpid) and store them as
pending status in the LWP structure if no pending status was already
available. Then, the backend goes over the pending statuses and pick
one to report to the core.
With that, the existing thread-execl.exp test exposes a bug, like:
(gdb) set scheduler-locking on
(gdb) PASS: gdb.threads/thread-execl.exp: schedlock on: set scheduler-locking on
next
FAIL: gdb.threads/thread-execl.exp: schedlock on: get to main in new image (timeout)
Recall that when the non-leader thread execs, all threads in the
process die, the execing thread changes its pid to the tgid, and then
waitpid returns an exec event to the tgid. If GDB didn't resume the
leader LWP, then GDB sees an event for an LWP that was supposedly
stopped, and thus not marked as resumed. Because the code that picks
a pending event to report to the core ignores not-resumed LWPs:
/* Return non-zero if LP has a wait status pending. */
static int
status_callback (struct lwp_info *lp, void *data)
{
/* Only report a pending wait status if we pretend that this has
indeed been resumed. */
if (!lp->resumed)
return 0;
the event ends up pending forever, thus the timeout.
gdb/
2015-01-09 Pedro Alves <palves@redhat.com>
* linux-nat.c (linux_handle_extended_wait) <PTRACE_EVENT_EXEC>:
Set the LWP's 'resumed' flag.
Whenever we resume an LWP, we must clear a few flags and flush the
LWP's register cache. We actually currently flush the register cache
of all LWPs, but that's unnecessary. This patch makes us flush the
register cache of only the LWP that is resumed. Instead of open
coding all that in many places, we use a helper function.
Likewise, we have two fields in the LWP structure where a pending
status may be recorded. Add a helper predicate that checks both and
use it throughout instead of open coding the checks.
gdb/
2015-01-09 Pedro Alves <palves@redhat.com>
* linux-nat.c (linux_resume_one_lwp): New function.
(resume_lwp): Use lwp_status_pending_p and linux_resume_one_lwp.
(linux_nat_resume): Use lwp_status_pending_p and
linux_resume_one_lwp.
(linux_handle_syscall_trap): Use linux_resume_one_lwp.
(linux_handle_extended_wait): Use linux_resume_one_lwp.
(status_callback, running_callback): Use lwp_status_pending_p.
(lwp_status_pending_p): New function.
(stop_and_resume_callback): Use lwp_status_pending_p.
(linux_nat_filter_event): Use linux_resume_one_lwp.
(linux_nat_wait_1): Always use status_callback to look for an LWP
with a pending status. Use linux_resume_one_lwp.
(resume_stopped_resumed_lwps): Use lwp_status_pending_p and
linux_resume_one_lwp.
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 GNU/Linux, attaching to a multi-threaded program sometimes prints
out warnings like:
...
[New LWP 20700]
warning: unable to open /proc file '/proc/-1/status'
[New LWP 20850]
[New LWP 21019]
...
That happens because when a thread exits, and is joined, glibc does:
nptl/pthread_join.c:
pthread_join ()
{
...
if (__glibc_likely (result == 0))
{
/* We mark the thread as terminated and as joined. */
pd->tid = -1;
...
/* Free the TCB. */
__free_tcb (pd);
}
So if we attach or interrupt the program (which does an implicit "info
threads") at just the right (or rather, wrong) time, we can find and
return threads in the libthread_db/pthreads thread list with kernel
thread ID -1. I've filed glibc PR nptl/17707 for this. You'll find
more info there.
This patch handles this as a special case in GDB.
This is actually more than just a cosmetic issue. lin_lwp_attach_lwp
will think that this -1 is an LWP we're not attached to yet, and after
failing to attach will try to check we were already attached to the
process, using a waitpid call, which in this case ends up being
"waitpid (-1, ...", which obviously results in GDB potentially
discarding an event when it shouldn't...
Tested on x86_64 Fedora 20, native and gdbserver.
gdb/gdbserver/
2015-01-09 Pedro Alves <palves@redhat.com>
* thread-db.c (find_new_threads_callback): Ignore thread if the
kernel thread ID is -1.
gdb/
2015-01-09 Pedro Alves <palves@redhat.com>
* linux-nat.c (lin_lwp_attach_lwp): Assert that the lwp id we're
about to wait for is > 0.
* linux-thread-db.c (find_new_threads_callback): Ignore thread if
the kernel thread ID is -1.
... 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.
This patch enhances GDB on GNU/Linux systems in the situation where
we are debugging an inferior that was created from GDB (as opposed
to attached to), by asking the kernel to kill the inferior if GDB
terminates without doing it itself.
This would typically happen when GDB encounters a problem and
crashes, or when it gets killed by an external process. This can
be observed by starting a program under GDB, and then killing
GDB with signal 9. After GDB is killed, the inferior still remains.
This patch also fixes GDBserver similarly.
This fix is conditional on the kernel supporting the PTRACE_O_EXITKILL
feature. On older kernels, the behavior remains unchanged.
gdb/ChangeLog:
* nat/linux-ptrace.h (PTRACE_O_EXITKILL): Define if not
already defined.
(linux_enable_event_reporting): Add parameter "attached".
* nat/linux-ptrace.c (linux_test_for_exitkill): New forward
declaration. New function.
(linux_check_ptrace_features): Add linux_test_for_exitkill call.
(linux_enable_event_reporting): Add new parameter "attached".
Do not call ptrace with the PTRACE_O_EXITKILL if ATTACHED is
nonzero.
* linux-nat.c (linux_init_ptrace): Add parameter "attached".
Use it. Update function description.
(linux_child_post_attach, linux_child_post_startup_inferior):
Update call to linux_enable_event_reporting.
gdb/gdbserver/ChangeLog:
* linux-low.c (linux_low_filter_event): Update call to
linux_enable_event_reporting following the addition of
a new parameter to that function.
Tested on x86_64-linux, native and native-gdbserver.
I also verified by hand that the inferior gets killed when killing
GDB in the "run" case, while the inferior remains in the "attach"
case. Same for GDBserver.
This patch introduces find_inferior_ptid to replace the common idiom
find_inferior_pid (ptid_get_pid (...));
It replaces all the instances of that idiom that I found with the new
function.
No significant changes before/after the patch in the regression suite
on amd64 linux.
gdb/ChangeLog:
* inferior.c (find_inferior_ptid): New function.
* inferior.h (find_inferior_ptid): New declaration.
* ada-tasks.c (ada_get_task_number): Use find_inferior_ptid.
* corelow.c (core_pid_to_str): Same.
* darwin-nat.c (darwin_resume): Same.
* infrun.c (fetch_inferior_event): Same.
(get_inferior_stop_soon): Same.
(handle_inferior_event): Same.
(handle_signal_stop): Same.
* linux-nat.c (resume_lwp): Same.
(stop_wait_callback): Same.
* mi/mi-interp.c (mi_new_thread): Same.
(mi_thread_exit): Same.
* proc-service.c (ps_pglobal_lookup): Same.
* record-btrace.c (record_btrace_step_thread): Same.
* remote-sim.c (gdbsim_close_inferior): Same.
(gdbsim_resume): Same.
(gdbsim_stop): Same.
* sol2-tdep.c (sol2_core_pid_to_str): Same.
* target.c (memory_xfer_partial_1): Same.
(default_thread_address_space): Same.
* thread.c (thread_change_ptid): Same.
(switch_to_thread): Same.
(do_restore_current_thread_cleanup): Same.
This patch reorganizes the code that implements follow-fork and
detach-on-fork in preparation for implementation of those features for the
extended-remote target. The function linux-nat.c:linux_child_follow_fork
contained target-independent code mixed in with target-dependent code. The
target-independent pieces need to be accessible for the host-side
implementation of follow-fork for extended-remote Linux targets.
The changes are fairly mechanical. A new routine, follow_fork_inferior,
is implemented in infrun.c, containing those parts of
linux_child_follow_fork that manage inferiors and the inferior list. The
parts of linux_child_follow_fork that deal with LWPs and target-specifics
were left in-place. Although the order of some operations was changed, the
resulting functionality was not.
Modifications were made to the other native target follow-fork functions,
inf_ttrace_follow_fork and inf_ptrace_follow_fork, that should allow them
to work with follow_fork_inferior. Some other adjustments were necessary
in inf-ttrace.c. The changes to inf-ttrace.c and inf-ptrace.c were not
tested.
gdb/ChangeLog:
* inf-ptrace.c (inf_ptrace_follow_fork): Remove target-independent
code so as to work with follow_fork_inferior.
* inf-ttrace.c (inf_ttrace_follow_fork): Ditto.
(inf_ttrace_create_inferior): Remove reference to
inf_ttrace_vfork_ppid.
(inf_ttrace_attach): Ditto.
(inf_ttrace_detach): Ditto.
(inf_ttrace_kill): Use current_inferior instead of
inf_ttrace_vfork_ppid.
(inf_ttrace_wait): Eliminate use of inf_ttrace_vfork_ppid, report
TARGET_WAITKIND_VFORK_DONE event, delete HACK that switched the
inferior away from the parent.
* infrun.c (follow_fork): Call follow_fork_inferior instead of
target_follow_fork.
(follow_fork_inferior): New function.
(follow_inferior_reset_breakpoints): Make function static.
* infrun.h (follow_inferior_reset_breakpoints): Remove declaration.
* linux-nat.c (linux_child_follow_fork): Move target-independent
code to infrun.c:follow_fork_inferior.
Now that all Linux targets use the regset iterator, the fall back to
the deprecated target method is dropped.
gdb/ChangeLog:
* linux-nat.c (linux_nat_collect_thread_registers): Remove.
(linux_nat_make_corefile_notes): Remove.
(linux_target_install_ops): Do not set target method
'make_corefile_notes'.
* linux-tdep.c (struct linux_corefile_thread_data)<collect>:
Remove field.
(linux_corefile_thread_callback): Instead of args->collect, call
linux_collect_thread_registers.
(linux_make_corefile_notes): Remove 'collect' parameter. Return
NULL unless there is a regset iterator.
(linux_make_corefile_notes_1): Remove.
(linux_init_abi): Replace reference to linux_make_corefile_notes_1
by linux_make_corefile_notes.
* linux-tdep.h (linux_make_corefile_notes): Remove prototype.
This commit implements functions for identifying and extracting extended
ptrace event information from a Linux wait status. These are just
convenience functions intended to hide the ">> 16" used to extract the
event from the wait status word, replacing the hard-coded shift with a more
descriptive function call. This is preparatory work for implementation of
follow-fork and detach-on-fork for extended-remote linux targets.
gdb/ChangeLog:
* linux-nat.c (linux_handle_extended_wait): Call
linux_ptrace_get_extended_event.
(wait_lwp): Call linux_is_extended_waitstatus.
(linux_nat_filter_event): Call linux_ptrace_get_extended_event
and linux_is_extended_waitstatus.
* nat/linux-ptrace.c (linux_test_for_tracefork): Call
linux_ptrace_get_extended_event.
(linux_ptrace_get_extended_event): New function.
(linux_is_extended_waitstatus): New function.
* nat/linux-ptrace.h (linux_ptrace_get_extended_event)
(linux_is_extended_waitstatus): New declarations.
gdb/gdbserver/ChangeLog:
* linux-low.c (handle_extended_wait): Call
linux_ptrace_get_extended_event.
(get_stop_pc, get_detach_signal, linux_low_filter_event): Call
linux_is_extended_waitstatus.
---
This is an obvious replacement of "fprintf (stderr..." by
"fprintf_unfiltered (gdb_stdlog...", which is the standard to use in
these cases.
gdb/ChangeLog:
2014-09-16 Sergio Durigan Junior <sergiodj@redhat.com>
PR cli/7233
* linux-nat.c (linux_nat_wait_1): Replace "fprintf (stderr..." by
"fprintf_unfiltered (gdb_stdlog...)".
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 patch removes some GDBSERVER checks from nat/linux-ptrace.c.
Currently the code uses a compile-time check to decide whether some
flags should be used. This changes the code to instead let users of
the module specify an additional set of flags; and then changes gdb's
linux-nat.c to call this function. At some later date, when the back
ends are fully merged, we will be able to remove this function again.
gdb/
2014-07-24 Tom Tromey <tromey@redhat.com>
Gary Benson <gbenson@redhat.com>
* nat/linux-ptrace.c (additional_flags): New global.
(linux_test_for_tracesysgood, linux_test_for_tracefork): Use
additional_flags; don't check GDBSERVER.
(linux_ptrace_set_additional_flags): New function.
* nat/linux-ptrace.h (linux_ptrace_set_additional_flags):
Declare.
* linux-nat.c (_initialize_linux_nat): Call
linux_ptrace_set_additional_flags.
Since we use tkill everywhere, using kill to try to kill each lwp
individually looks suspiciously odd. We should really be using tgkill
everywhere, but at least while we don't get there this makes us
consistent.
gdb/gdbserver/
2014-07-16 Pedro Alves <palves@redhat.com>
* linux-low.c (linux_kill_one_lwp): Use kill_lwp, not kill.
gdb/
2014-07-16 Pedro Alves <palves@redhat.com>
* linux-nat.c (kill_callback): Use kill_lwp, not kill.
The fix that went into GDBserver is also needed on the GDB side.
Although most compilers follow right-to-left evaluation order, the
order of evaluation of a function call's arguments is really
unspecified. target_pid_to_str may well clobber errno when we get to
evaluate the third argument to fprintf_unfiltered.
gdb/
2014-07-15 Pedro Alves <palves@redhat.com>
* linux-nat.c (kill_callback): Save errno and work with saved
copy.
I'm seeing a ton of new FAILs in fork-related tests. Like, these and
many more:
+FAIL: gdb.base/disp-step-syscall.exp: vfork: continue to vfork (2nd time) (timeout)
+FAIL: gdb.base/disp-step-syscall.exp: vfork: display/i $pc (timeout)
...
-PASS: gdb.base/foll-vfork.exp: exec: vfork parent follow, through step: step
+FAIL: gdb.base/foll-vfork.exp: exec: vfork parent follow, through step: step (timeout)
-PASS: gdb.base/foll-vfork.exp: exec: vfork parent follow, to bp: continue to bp
+FAIL: gdb.base/foll-vfork.exp: exec: vfork parent follow, to bp: continue to bp (timeout)
...
FAIL: gdb.threads/watchpoint-fork.exp: parent: multithreaded: breakpoint (A) after the first fork (timeout)
FAIL: gdb.threads/watchpoint-fork.exp: parent: multithreaded: watchpoint A after the first fork (timeout)
FAIL: gdb.base/fileio.exp: System(3) call (timeout)
FAIL: gdb.threads/watchpoint-fork.exp: parent: multithreaded: watchpoint B after the first fork (timeout)
-PASS: gdb.base/multi-forks.exp: run to exit 2
+FAIL: gdb.base/multi-forks.exp: run to exit 2 (timeout)
...
PASS: gdb.base/watch-vfork.exp: Watchpoint on global variable (hw)
-PASS: gdb.base/watch-vfork.exp: Watchpoint triggers after vfork (hw)
+FAIL: gdb.base/watch-vfork.exp: Watchpoint triggers after vfork (hw) (timeout)
PASS: gdb.base/watch-vfork.exp: Watchpoint on global variable (sw)
-PASS: gdb.base/watch-vfork.exp: Watchpoint triggers after vfork (sw)
+FAIL: gdb.base/watch-vfork.exp: Watchpoint triggers after vfork (sw) (timeout)
Three issues with
https://sourceware.org/ml/gdb-patches/2014-06/msg00348.html
(c077881a).
- The inner 'status' local is shadowing the outer 'status' local,
thus PTRACE_DETACH is never seeing the status it intends to pass on
the inferior.
- With that fixed, we then try to pass down the SIGTRAP that results
from the step to the inferior. Need to filter out signals that are
in nopass state.
- For software single-step archs, the current code is equivalent to:
int status = 0;
if (WIFSTOPPED (status))
ptrace (PTRACE_DETACH, child_pid, 0, WSTOPSIG (status));
... and status == 0 is WIFEXITED, not WIFSTOPPED, so we're never
detaching.
gdb/
2014-06-09 Pedro Alves <palves@redhat.com>
* linux-nat.c (linux_child_follow_fork): Initialize status with
W_STOPCODE (0) instead of 0. Remove shodowing 'status' local from
inner block. Only pass the signal to PTRACE_DETACH if in pass
state.
https://sourceware.org/ml/gdb-patches/2014-04/msg00047.html
Got gdb.base/watch-vfork.exp: Watchpoint triggers after vfork (sw)
(timeout) with Linux 2.6.32 and older version.
The rootcause is after the test use "set can-use-hw-watchpoints 0" let GDB
doesn't use hardware breakpoint and set a watchpoint on "global", GDB
continue will keep single step inside function "vfork".
The Linux 2.6.32 and older version doesn't have commit
6580807da14c423f0d0a708108e6df6ebc8bc83d (get more info please goto
http://git.kernel.org/cgit/linux/kernel/git/stable/linux-stable.git/commit/?id=6580807da14c423f0d0a708108e6df6ebc8bc83d).
When the function "vfork" do syscall, the single step flag TIF_SINGLESTEP
will copy to child process.
Then GDB detach it, child process and parent process will be hanged.
So I make a patch that do a single step before detach. Then TIF_SINGLESTEP
of child process in old Linux kernel will be cleared before detach.
Child process in new Linux kernel will not be affected by this single step.
2014-06-08 Hui Zhu <hui@codesourcery.com>
* common/linux-ptrace.c (linux_disable_event_reporting): New
function.
* common/linux-ptrace.h (linux_disable_event_reporting): New
declaration.
* linux-nat.c (linux_child_follow_fork): Do a single step before
detach.
This constifies the "args" argument to the target_ops to_attach
method.
I updated all instances of the method. I could not compile all of
them but I hand-inspected them. In all cases either the argument is
ignored, or it is passed to parse_pid_to_attach. (linux-nat does some
extra stuff, but that one I built...)
If you want to try it on your host of choice, please do so.
The code in parse_pid_to_attach seems a little bogus to me. If there
is a platform with a broken strtoul, we have better methods for fixing
the issue now. However, I left the code as is since it is clearly ok
to do so.
Built and regtested on x86-64 Fedora 20.
2014-06-04 Tom Tromey <tromey@redhat.com>
* procfs.c (procfs_attach): Make "args" const.
* windows-nat.c (windows_attach): Make "args" const.
* nto-procfs.c (procfs_attach): Make "args" const.
* inf-ttrace.c (inf_ttrace_attach): Make "args" const.
* go32-nat.c (go32_attach): Make "args" const.
* gnu-nat.c (gnu_attach): Make "args" const.
* darwin-nat.c (darwin_attach): Make "args" const.
* inf-ptrace.c (inf_ptrace_attach): Make "args" const.
* linux-nat.c (linux_nat_attach): Make "args" const.
* remote.c (extended_remote_attach_1, extended_remote_attach):
Make "args" const.
* target.h (struct target_ops) <to_attach>: Make "args" const.
(find_default_attach): Likewise.
* utils.c (parse_pid_to_attach): Make "args" const.
* utils.h (parse_pid_to_attach): Update.
linux_nat_resume is not considering that linux_ops->to_resume may throw:
/* Mark LWP as not stopped to prevent it from being continued by
linux_nat_resume_callback. */
lp->stopped = 0;
if (resume_many)
iterate_over_lwps (ptid, linux_nat_resume_callback, NULL);
If something within linux_nat_resume_callback throws, GDB leaves the
lwp_info as if the inferior was resumed, while it actually wasn't.
A couple examples, there are possibly others:
- i386_linux_resume calls target_read which calls QUIT.
- if the actual ptrace resumption fails in inf_ptrace_resume,
perror_with_name is called.
If the user tries to kill the inferior at this point (or quit, which
offers to kill), GDB locks up trying to stop the lwp -- if it is
already stopped no new waitpid event gets generated for it.
Fix this by setting the stopped flag earlier, as soon as we collect a
stop event with waitpid, and clearing it always only after resuming
the lwp successfully.
Tested on x86_64 Fedora 20. Confirmed the lock-up disappears using a
local hack that forces an error in inf_ptrace_resume.
Also fixes a little "set debug lin-lwp" annoyance. Currently we always see:
Continuing.
LLR: Preparing to resume process 6802, 0, inferior_ptid Thread 0x7ffff7fc7740 (LWP 6802)
^^^^^^^^
RC: Resuming sibling Thread 0x7ffff77c5700 (LWP 6807), 0, resume
RC: Resuming sibling Thread 0x7ffff7fc6700 (LWP 6806), 0, resume
RC: Not resuming sibling Thread 0x7ffff7fc7740 (LWP 6802) (not stopped)
^^^^^^^^^^^^^^^^^^^^^^^
LLR: PTRACE_CONT process 6802, 0 (resume event thread)
This patch gets rid of the "Not resuming sibling" line.
2014-05-29 Pedro Alves <palves@redhat.com>
PR gdb/15713
* linux-nat.c (linux_nat_resume_callback): Rename the second
parameter to 'except'. Skip LP if it points to EXCEPT.
(linux_nat_resume): Don't mark the event lwp as not stopped
before resuming sibling lwps. Instead ask
linux_nat_resume_callback to skip the event lwp. Mark it as not
stopped after actually resuming it.
(linux_handle_syscall_trap): Mark the lwp as not stopped after
resuming it.
(wait_lwp): Mark the lwp as stopped here.
(stop_wait_callback): Mark the lwp as not stopped right after
resuming it. Don't mark lwps as stopped here.
(linux_nat_filter_event): Mark the lwp as stopped earlier.
(linux_nat_wait_1): Don't mark dead lwps as stopped here.
Move infrun.c declarations out of inferior.h to a new infrun.h file.
Tested by building on:
i686-w64-mingw32, enable-targets=all
x86_64-linux, enable-targets=all
i586-pc-msdosdjgpp
And also grepped the whole tree for each symbol moved to find where
infrun.h might be necessary.
gdb/
2014-05-22 Pedro Alves <palves@redhat.com>
* inferior.h (debug_infrun, debug_displaced, stop_on_solib_events)
(sync_execution, sched_multi, step_stop_if_no_debug, non_stop)
(disable_randomization, enum exec_direction_kind)
(execution_direction, stop_registers, start_remote)
(clear_proceed_status, proceed, resume, user_visible_resume_ptid)
(wait_for_inferior, normal_stop, get_last_target_status)
(prepare_for_detach, fetch_inferior_event, init_wait_for_inferior)
(insert_step_resume_breakpoint_at_sal)
(follow_inferior_reset_breakpoints, stepping_past_instruction_at)
(set_step_info, print_stop_event, signal_stop_state)
(signal_print_state, signal_pass_state, signal_stop_update)
(signal_print_update, signal_pass_update)
(update_signals_program_target, clear_exit_convenience_vars)
(displaced_step_dump_bytes, update_observer_mode)
(signal_catch_update, gdb_signal_from_command): Move
declarations ...
* infrun.h: ... to this new file.
* amd64-tdep.c: Include infrun.h.
* annotate.c: Include infrun.h.
* arch-utils.c: Include infrun.h.
* arm-linux-tdep.c: Include infrun.h.
* arm-tdep.c: Include infrun.h.
* break-catch-sig.c: Include infrun.h.
* breakpoint.c: Include infrun.h.
* common/agent.c: Include infrun.h instead of inferior.h.
* corelow.c: Include infrun.h.
* event-top.c: Include infrun.h.
* go32-nat.c: Include infrun.h.
* i386-tdep.c: Include infrun.h.
* inf-loop.c: Include infrun.h.
* infcall.c: Include infrun.h.
* infcmd.c: Include infrun.h.
* infrun.c: Include infrun.h.
* linux-fork.c: Include infrun.h.
* linux-nat.c: Include infrun.h.
* linux-thread-db.c: Include infrun.h.
* monitor.c: Include infrun.h.
* nto-tdep.c: Include infrun.h.
* procfs.c: Include infrun.h.
* record-btrace.c: Include infrun.h.
* record-full.c: Include infrun.h.
* remote-m32r-sdi.c: Include infrun.h.
* remote-mips.c: Include infrun.h.
* remote-notif.c: Include infrun.h.
* remote-sim.c: Include infrun.h.
* remote.c: Include infrun.h.
* reverse.c: Include infrun.h.
* rs6000-tdep.c: Include infrun.h.
* s390-linux-tdep.c: Include infrun.h.
* solib-irix.c: Include infrun.h.
* solib-osf.c: Include infrun.h.
* solib-svr4.c: Include infrun.h.
* target.c: Include infrun.h.
* top.c: Include infrun.h.
* windows-nat.c: Include infrun.h.
* mi/mi-interp.c: Include infrun.h.
* mi/mi-main.c: Include infrun.h.
* python/py-threadevent.c: Include infrun.h.
Sometimes it's useful to be able to disable the automatic connection
to the native target. E.g., sometimes GDB disconnects from the
extended-remote target I was debugging, without me noticing it, and
then I do "run". That starts the program locally, and only after a
little head scratch session do I figure out the program is running
locally instead of remotely as intended. Same thing with "attach",
"info os", etc.
With the patch, we now can have this instead:
(gdb) set auto-connect-native-target off
(gdb) target extended-remote :9999
...
*gdb disconnects*
(gdb) run
Don't know how to run. Try "help target".
To still be able to connect to the native target with
auto-connect-native-target set to off, I've made "target native" work
instead of erroring out as today.
Before:
(gdb) target native
Use the "run" command to start a native process.
After:
(gdb) target native
Done. Use the "run" command to start a process.
(gdb) maint print target-stack
The current target stack is:
- native (Native process)
- exec (Local exec file)
- None (None)
(gdb) run
Starting program: ./a.out
...
I've also wanted this for the testsuite, when running against the
native-extended-gdbserver.exp board (runs against gdbserver in
extended-remote mode). With a non-native-target board, it's always a
bug to launch a program with the native target. Turns out we still
have one such case this patch catches:
(gdb) break main
Breakpoint 1 at 0x4009e5: file ../../../src/gdb/testsuite/gdb.base/coremaker.c, line 138.
(gdb) run
Don't know how to run. Try "help target".
(gdb) FAIL: gdb.base/corefile.exp: run: with core
On the patch itself, probably the least obvious bit is the need to go
through all targets, and move the unpush_target call to after the
generic_mourn_inferior call instead of before. This is what
inf-ptrace.c does too, ever since multi-process support was added.
The reason inf-ptrace.c does things in that order is that in the
current multi-process/single-target model, we shouldn't unpush the
target if there are still other live inferiors being debugged. The
check for that is "have_inferiors ()" (a misnomer nowadays...), which
does:
have_inferiors (void)
{
for (inf = inferior_list; inf; inf = inf->next)
if (inf->pid != 0)
return 1;
It's generic_mourn_inferior that ends up clearing inf->pid, so we need
to call it before the have_inferiors check. To make all native
targets behave the same WRT to explicit "target native", I've added an
inf_child_maybe_unpush_target function that targets call instead of
calling unpush_target directly, and as that includes the
have_inferiors check, I needed to adjust the targets.
Tested on x86_64 Fedora 20, native, and also with the
extended-gdbserver board.
Confirmed a cross build of djgpp gdb still builds.
Smoke tested a cross build of Windows gdb under Wine.
Untested otherwise.
gdb/
2014-05-21 Pedro Alves <palves@redhat.com>
* inf-child.c (inf_child_ops, inf_child_explicitly_opened): New
globals.
(inf_child_open_target): New function.
(inf_child_open): Use inf_child_open_target to push the target
instead of erroring out.
(inf_child_disconnect, inf_child_close)
(inf_child_maybe_unpush_target): New functions.
(inf_child_target): Install inf_child_disconnect and
inf_child_close. Store a pointer to the returned object.
* inf-child.h (inf_child_open_target, inf_child_maybe_unpush): New
declarations.
* target.c (auto_connect_native_target): New global.
(show_default_run_target): New function.
(find_default_run_target): Return NULL if automatically connecting
to the native target is disabled.
(_initialize_target): Install set/show auto-connect-native-target.
* NEWS: Mention "set auto-connect-native-target", and "target
native".
* linux-nat.c (super_close): New global.
(linux_nat_close): Call super_close.
(linux_nat_add_target): Store a pointer to the base class's
to_close method.
* inf-ptrace.c (inf_ptrace_mourn_inferior, inf_ptrace_detach): Use
inf_child_maybe_unpush.
* inf-ttrace.c (inf_ttrace_him): Don't push the target if it is
already pushed.
(inf_ttrace_mourn_inferior): Only unpush the target after mourning
the inferior. Use inf_child_maybe_unpush_target.
(inf_ttrace_attach): Don't push the target if it is already
pushed.
(inf_ttrace_detach): Use inf_child_maybe_unpush_target.
* darwin-nat.c (darwin_mourn_inferior): Only unpush the target
after mourning the inferior. Use inf_child_maybe_unpush_target.
(darwin_attach_pid): Don't push the target if it is already
pushed.
* gnu-nat.c (gnu_mourn_inferior): Only unpush the target after
mourning the inferior. Use inf_child_maybe_unpush_target.
(gnu_detach): Use inf_child_maybe_unpush_target.
* go32-nat.c (go32_create_inferior): Don't push the target if it
is already pushed.
(go32_mourn_inferior): Use inf_child_maybe_unpush_target.
* nto-procfs.c (procfs_is_nto_target): Adjust comment.
(procfs_open): Rename to ...
(procfs_open_1): ... this. Add target_ops parameter. Adjust
comments. Can target_preopen before changing node. Call
inf_child_open_target to push the target explicitly.
(procfs_attach): Don't push the target if it is already pushed.
(procfs_detach): Use inf_child_maybe_unpush_target.
(procfs_create_inferior): Don't push the target if it is already
pushed.
(nto_native_ops): New global.
(procfs_open): Reimplement.
(procfs_native_open): New function.
(init_procfs_targets): Install procfs_native_open as to_open of
"target native". Store a pointer to the "native" target in
nto_native_ops.
* procfs.c (procfs_attach): Don't push the target if it is already
pushed.
(procfs_detach): Use inf_child_maybe_unpush_target.
(procfs_mourn_inferior): Only unpush the target after mourning the
inferior. Use inf_child_maybe_unpush_target.
(procfs_init_inferior): Don't push the target if it is already
pushed.
* windows-nat.c (do_initial_windows_stuff): Don't push the target
if it is already pushed.
(windows_detach): Use inf_child_maybe_unpush_target.
(windows_mourn_inferior): Only unpush the target after mourning
the inferior. Use inf_child_maybe_unpush_target.
gdb/doc/
2014-05-21 Pedro Alves <palves@redhat.com>
* gdb.texinfo (Starting): Document "set/show
auto-connect-native-target".
(Target Commands): Document "target native".
gdb/testsuite/
2014-05-21 Pedro Alves <palves@redhat.com>
* boards/gdbserver-base.exp (GDBFLAGS): Set to "set
auto-connect-native-target off".
* gdb.base/auto-connect-native-target.c: New file.
* gdb.base/auto-connect-native-target.exp: New file.
On Linux, we need to explicitly ptrace attach to all lwps of a
process. Because GDB might not be connected yet when an attach is
requested, and thus it may not be possible to activate thread_db, as
that requires access to symbols (IOW, gdbserver --attach), a while ago
we make linux_attach loop over the lwps as listed by /proc/PID/task to
find the lwps to attach to.
linux_attach_lwp_1 has:
...
if (initial)
/* If lwp is the tgid, we handle adding existing threads later.
Otherwise we just add lwp without bothering about any other
threads. */
ptid = ptid_build (lwpid, lwpid, 0);
else
{
/* Note that extracting the pid from the current inferior is
safe, since we're always called in the context of the same
process as this new thread. */
int pid = pid_of (current_inferior);
ptid = ptid_build (pid, lwpid, 0);
}
That "safe" comment referred to linux_attach_lwp being called by
thread-db.c. But this was clearly missed when a new call to
linux_attach_lwp_1 was added to linux_attach. As a result,
current_inferior will be set to some random process, and non-initial
lwps of the second inferior get assigned the pid of the wrong
inferior. E.g., in the case of attaching to two inferiors, for the
second inferior (and so on), non-initial lwps of the second inferior
get assigned the pid of the first inferior. This doesn't trigger on
the first inferior, when current_inferior is NULL, add_thread switches
the current inferior to the newly added thread.
Rather than making linux_attach switch current_inferior temporarily
(thus avoiding further reliance on global state), or making
linux_attach_lwp_1 get the tgid from /proc, which add extra syscalls,
and will be wrong in case of the user having originally attached
directly to a non-tgid lwp, and then that lwp spawning new clones (the
ptid.pid field of further new clones should be the same as the
original lwp's pid, which is not the tgid), we note that callers of
linux_attach_lwp/linux_attach_lwp_1 always have the right pid handy
already, so they can pass it down along with the lwpid.
The only other reason for the "initial" parameter is to error out
instead of warn in case of attach failure, when we're first attaching
to a process. There are only three callers of
linux_attach_lwp/linux_attach_lwp_1, and each wants to print a
different warn/error string, so we can just move the error/warn out of
linux_attach_lwp_1 to the callers, thus getting rid of the "initial"
parameter.
There really nothing gdbserver-specific about attaching to two
threaded processes, so this adds a new test under gdb.multi/. The
test passes cleanly against the native GNU/Linux target, but
fails/triggers the bug against GDBserver (before the patch), with the
native-extended-remote board (as plain remote doesn't support
multi-process).
Tested on x86_64 Fedora 17, with the native-extended-gdbserver board.
gdb/gdbserver/
2014-04-25 Pedro Alves <palves@redhat.com>
PR server/16255
* linux-low.c (linux_attach_fail_reason_string): New function.
(linux_attach_lwp): Delete.
(linux_attach_lwp_1): Rename to ...
(linux_attach_lwp): ... this. Take a ptid instead of a pid as
argument. Remove "initial" parameter. Return int instead of
void. Don't error or warn here.
(linux_attach): Adjust to call linux_attach_lwp. Call error on
failure to attach to the tgid. Call warning when failing to
attach to an lwp.
* linux-low.h (linux_attach_lwp): Take a ptid instead of a pid as
argument. Remove "initial" parameter. Return int instead of
void. Don't error or warn here.
(linux_attach_fail_reason_string): New declaration.
* thread-db.c (attach_thread): Adjust to linux_attach_lwp's
interface change. Use linux_attach_fail_reason_string.
gdb/
2014-04-25 Pedro Alves <palves@redhat.com>
PR server/16255
* common/linux-ptrace.c (linux_ptrace_attach_warnings): Rename to ...
(linux_ptrace_attach_fail_reason): ... this. Remove "warning: "
and newline from built string.
* common/linux-ptrace.h (linux_ptrace_attach_warnings): Rename to ...
(linux_ptrace_attach_fail_reason): ... this.
* linux-nat.c (linux_nat_attach): Adjust to use
linux_ptrace_attach_fail_reason.
gdb/testsuite/
2014-04-25 Simon Marchi <simon.marchi@ericsson.com>
Pedro Alves <palves@redhat.com>
PR server/16255
* gdb.multi/multi-attach.c: New file.
* gdb.multi/multi-attach.exp: New file.
ps -e | grep a.out
28886 pts/12 00:00:00 a.out
gdb -p 28886
Loaded symbols for /lib64/ld-linux-x86-64.so.2
0x0000003b0ccbc970 in __nanosleep_nocancel () from /lib64/libc.so.6
../../binutils-gdb/gdb/cleanups.c:265: internal-warning: restore_my_cleanups has found a stale cleanup
A problem internal to GDB has been detected,
further debugging may prove unreliable.
Quit this debugging session? (y or n)
The backtrace of this issue:
(gdb) bt
file=0x8b0c10 "s' failed.", line=265, fmt=0x8b0c38 "nutils-gdb/gdb/cleanups.c",
ap=0x7fff803e3ed8) at ../../binutils-gdb/gdb/utils.c:748
fmt=0x8b0c38 "nutils-gdb/gdb/cleanups.c", ap=0x7fff803e3ed8)
at ../../binutils-gdb/gdb/utils.c:799
string=0x8b0c38 "nutils-gdb/gdb/cleanups.c") at ../../binutils-gdb/gdb/utils.c:809
at ../../binutils-gdb/gdb/cleanups.c:265
at ../../binutils-gdb/gdb/cleanups.c:276
at ../../binutils-gdb/gdb/exceptions.c:142
at ../../binutils-gdb/gdb/exceptions.c:203
command=0x5d5fb8 <attach_command_continuation_free_args+18>, arg=0x7fff803e525b "2914",
from_tty=1, mask=RETURN_MASK_ALL) at ../../binutils-gdb/gdb/exceptions.c:549
---Type <return> to continue, or q <return> to quit---
func_args=0x7fff803e4280, errstring=0x8cf2e4 "/local/bin", mask=RETURN_MASK_ALL)
at ../../binutils-gdb/gdb/exceptions.c:522
This is a new issue. It is introduced by commit https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;a=commit;h=8bc2fe488957946d2cdccda3ce8d4f39e4003ea0
It removed the discard_cleanups (back_to) inside attach_command.
Then restore_my_cleanups will throw a internal_warning.
https://sourceware.org/ml/gdb-patches/2014-03/msg00374.html
2014-03-21 Hui Zhu <hui@codesourcery.com>
Pedro Alves <palves@redhat.com>
* darwin-nat.c (darwin_pid_to_exec_file): Change xmalloc to
static buffer.
* fbsd-nat.c (fbsd_pid_to_exec_file): Ditto.
* linux-nat.c (linux_child_pid_to_exec_file): Ditto.
* nbsd-nat.c (nbsd_pid_to_exec_file): Ditto.
Looking at target_terminal_inferior etc. in async mode, I realized
that the naming of the terminal_inferior, terminal_ours,
etc. functions doesn't really give a clue that they're meant for the
native target only. This patch renames them. There's already
child_terminal_info using the child_ prefix, and, they're most
prominently installed by inf-child.c, so I went with the child_
prefix. I dropped "inferior" from a couple to make the name match the
corresponding target method.
Tested on x86_64 Fedora 17, and cross built for mingw. I didn't test
gnu-nat.c, but I think the change is as obvious as it gets. I grepped
the tree looking for other potential spots that would need adjustment
but this is all I found. If something breaks, it should be trivial to
fix.
gdb/
2014-03-14 Pedro Alves <palves@redhat.com>
* inferior.h (terminal_ours_for_output): Rename to ...
(child_terminal_ours_for_output): ... this.
(terminal_save_ours): Rename to ...
(child_terminal_save_ours): ... this.
(terminal_ours): Rename to ...
(child_terminal_ours): ... this.
(terminal_inferior): Rename to ...
(child_terminal_inferior): ... this.
(terminal_init_inferior): Rename to ...
(child_terminal_init_inferior): ... this.
(terminal_init_inferior_with_pgrp): Rename to ...
(child_terminal_init_inferior_with_pgrp): ... this.
* inflow.c (terminal_init_inferior_with_pgrp): Rename to ...
(child_terminal_init_with_pgrp): ... this.
(terminal_save_ours): Rename to ...
(child_terminal_save_ours): ... this.
(terminal_init_inferior): Rename to ...
(child_terminal_init): ... this. Adjust.
(terminal_inferior): Rename to ...
(child_terminal_inferior): ... this.
(terminal_ours_for_output): Rename to ...
(child_terminal_ours_for_output): ... this. Adjust.
(terminal_ours): Rename to ...
(child_terminal_ours): ... this.
(terminal_ours_1): Rename to ...
(child_terminal_ours_1): ... this. Adjust.
* linux-nat.c (linux_nat_terminal_inferior): Adjust.
* windows-nat.c (do_initial_windows_stuff): Adjust.
* gnu-nat.c (gnu_terminal_init_inferior): Rename to ...
(gnu_terminal_init): ... this. Adjust.
(gnu_target): Adjust.
* inf-child.c (inf_child_target): Adjust.
So that gdbserver's Linux backend can use it too.
gdb/
2014-02-27 Pedro Alves <palves@redhat.com>
PR 12702
* linux-nat.c (status_to_str): Moved to nat/linux-waitpid.c.
* nat/linux-waitpid.c: Include string.h.
(status_to_str): Moved here and made extern.
* nat/linux-waitpid.h (status_to_str): New declaration.
Pedro Alves
Sergio Durigan Junior
Joel Brobecker
Simon Marchi
Doug Evans
Gary Benson
Don Breazeal
Andreas Arnez
Doug Evans
Tom Tromey
Hui Zhu