PPC64 currently fails this test like:
FAIL: gdb.threads/step-over-trips-on-watchpoint.exp: displaced=on: no thread-specific bp: step: step
FAIL: gdb.threads/step-over-trips-on-watchpoint.exp: displaced=on: no thread-specific bp: next: next
FAIL: gdb.threads/step-over-trips-on-watchpoint.exp: displaced=on: no thread-specific bp: continue: continue (the program exited)
FAIL: gdb.threads/step-over-trips-on-watchpoint.exp: displaced=on: with thread-specific bp: step: step
FAIL: gdb.threads/step-over-trips-on-watchpoint.exp: displaced=on: with thread-specific bp: next: next
FAIL: gdb.threads/step-over-trips-on-watchpoint.exp: displaced=on: with thread-specific bp: continue: continue (the program exited)
The problem is that PPC is a non-continuable watchpoints architecture
and the displaced stepping code isn't coping with that correctly. On
such targets/architectures, a watchpoint traps _before_ the
instruction executes/completes. On a watchpoint trap, the PC points
at the instruction that triggers the watchpoint (side effects haven't
happened yet). In order to move past the watchpoint, GDB needs to
remove the watchpoint, single-step, and reinsert the watchpoint, just
like when stepping past a breakpoint.
The trouble is that if GDB is stepping over a breakpoint with
displaced stepping, and the instruction under the breakpoint triggers
a watchpoint, we get the watchpoint SIGTRAP, expecting a finished
(hard or software) step trap. Even though the thread's PC hasn't
advanced yet (must remove watchpoint for that), since we get a
SIGTRAP, displaced_step_fixup thinks the single-step finished
successfuly anyway, and calls gdbarch_displaced_step_fixup, which then
adjusts the thread's registers incorrectly.
The fix is to cancel the displaced step if we trip on a watchpoint.
handle_inferior_event then processes the watchpoint event, and starts
a new step-over, here:
...
/* At this point, we are stopped at an instruction which has
attempted to write to a piece of memory under control of
a watchpoint. The instruction hasn't actually executed
yet. If we were to evaluate the watchpoint expression
now, we would get the old value, and therefore no change
would seem to have occurred.
...
ecs->event_thread->stepping_over_watchpoint = 1;
keep_going (ecs);
return;
...
but this time, since we have a watchpoint to step over, watchpoints
are removed from the target, so the step-over succeeds.
The keep_going/resume changes are necessary because if we're stepping
over a watchpoint, we need to remove it from the target - displaced
stepping doesn't help, the copy of the instruction in the scratch pad
reads/writes to the same addresses, thus triggers the watchpoint
too... So without those changes we keep triggering the watchpoint
forever, never making progress. With non-stop that means we'll need
to pause all threads momentarily, which we can't today. We could
avoid that by removing the watchpoint _only_ from the thread that is
moving past the watchpoint, but GDB is not prepared for that today
either. For remote targets, that would need new packets, so good to
be able to step over it in-line as fallback anyway.
gdb/ChangeLog:
2015-04-10 Pedro Alves <palves@redhat.com>
* infrun.c (displaced_step_fixup): Switch to the event ptid
earlier. If the thread stopped for a watchpoint and the
target/arch has non-continuable watchpoints, cancel the displaced
step.
(resume): Don't start a displaced step if in-line step-over info
is valid.
TL;DR:
When stepping over a breakpoint with displaced stepping, the core must
be notified of all signals, otherwise the displaced step fixup code
confuses a breakpoint trap in the signal handler for the expected trap
indicating the displaced instruction was single-stepped
normally/successfully.
Detailed version:
Running sigstep.exp with displaced stepping on, against my x86
software single-step branch, I got:
FAIL: gdb.base/sigstep.exp: step on breakpoint, to handler: performing step
FAIL: gdb.base/sigstep.exp: next on breakpoint, to handler: performing next
FAIL: gdb.base/sigstep.exp: continue on breakpoint, to handler: performing continue
Turning on debug logs, we see:
(gdb) step
infrun: clear_proceed_status_thread (process 32147)
infrun: proceed (addr=0xffffffffffffffff, signal=GDB_SIGNAL_DEFAULT)
infrun: resume (step=1, signal=GDB_SIGNAL_0), trap_expected=1, current thread [process 32147] at 0x400842
displaced: stepping process 32147 now
displaced: saved 0x400622: 49 89 d1 5e 48 89 e2 48 83 e4 f0 50 54 49 c7 c0
displaced: %rip-relative addressing used.
displaced: using temp reg 2, old value 0x3615eafd37, new value 0x40084c
displaced: copy 0x400842->0x400622: c7 81 1c 08 20 00 00 00 00 00
displaced: displaced pc to 0x400622
displaced: run 0x400622: c7 81 1c 08
LLR: Preparing to resume process 32147, 0, inferior_ptid process 32147
LLR: PTRACE_CONT process 32147, 0 (resume event thread)
linux_nat_wait: [process -1], [TARGET_WNOHANG]
LLW: enter
LNW: waitpid(-1, ...) returned 32147, No child processes
LLW: waitpid 32147 received Alarm clock (stopped)
LLW: PTRACE_CONT process 32147, Alarm clock (preempt 'handle')
LNW: waitpid(-1, ...) returned 0, No child processes
LLW: exit (ignore)
sigchld
infrun: target_wait (-1.0.0, status) =
infrun: -1.0.0 [process -1],
infrun: status->kind = ignore
infrun: TARGET_WAITKIND_IGNORE
infrun: prepare_to_wait
linux_nat_wait: [process -1], [TARGET_WNOHANG]
LLW: enter
LNW: waitpid(-1, ...) returned 32147, No child processes
LLW: waitpid 32147 received Trace/breakpoint trap (stopped)
CSBB: process 32147 stopped by software breakpoint
LNW: waitpid(-1, ...) returned 0, No child processes
LLW: trap ptid is process 32147.
LLW: exit
infrun: target_wait (-1.0.0, status) =
infrun: 32147.32147.0 [process 32147],
infrun: status->kind = stopped, signal = GDB_SIGNAL_TRAP
infrun: TARGET_WAITKIND_STOPPED
displaced: restored process 32147 0x400622
displaced: fixup (0x400842, 0x400622), insn = 0xc7 0x81 ...
displaced: restoring reg 2 to 0x3615eafd37
displaced: relocated %rip from 0x400717 to 0x400937
infrun: stop_pc = 0x400937
infrun: delayed software breakpoint trap, ignoring
infrun: no line number info
infrun: stop_waiting
0x0000000000400937 in __dso_handle ()
1: x/i $pc
=> 0x400937: and %ah,0xa0d64(%rip) # 0x4a16a1
(gdb) FAIL: gdb.base/sigstep.exp: displaced=on: step on breakpoint, to handler: performing step
What should have happened is that the breakpoint hit in the signal
handler should have been presented to the user. But note that
"preempt 'handle'" -- what happened instead is that
displaced_step_fixup confused the breakpoint in the signal handler for
the expected SIGTRAP indicating the displaced instruction was
single-stepped normally/successfully.
This should be affecting all software single-step targets in the same
way.
The fix is to make sure the core sees all signals when displaced
stepping, just like we already must see all signals when doing an
stepping over a breakpoint in-line. We now get:
infrun: target_wait (-1.0.0, status) =
infrun: 570.570.0 [process 570],
infrun: status->kind = stopped, signal = GDB_SIGNAL_ALRM
infrun: TARGET_WAITKIND_STOPPED
displaced: restored process 570 0x400622
infrun: stop_pc = 0x400842
infrun: random signal (GDB_SIGNAL_ALRM)
infrun: signal arrived while stepping over breakpoint
infrun: inserting step-resume breakpoint at 0x400842
infrun: resume (step=0, signal=GDB_SIGNAL_ALRM), trap_expected=0, current thread [process 570] at 0x400842
LLR: Preparing to resume process 570, Alarm clock, inferior_ptid process 570
LLR: PTRACE_CONT process 570, Alarm clock (resume event thread)
infrun: prepare_to_wait
linux_nat_wait: [process -1], [TARGET_WNOHANG]
LLW: enter
LNW: waitpid(-1, ...) returned 0, No child processes
LLW: exit (ignore)
infrun: target_wait (-1.0.0, status) =
infrun: -1.0.0 [process -1],
infrun: status->kind = ignore
sigchld
infrun: TARGET_WAITKIND_IGNORE
infrun: prepare_to_wait
linux_nat_wait: [process -1], [TARGET_WNOHANG]
LLW: enter
LNW: waitpid(-1, ...) returned 570, No child processes
LLW: waitpid 570 received Trace/breakpoint trap (stopped)
CSBB: process 570 stopped by software breakpoint
LNW: waitpid(-1, ...) returned 0, No child processes
LLW: trap ptid is process 570.
LLW: exit
infrun: target_wait (-1.0.0, status) =
infrun: 570.570.0 [process 570],
infrun: status->kind = stopped, signal = GDB_SIGNAL_TRAP
infrun: TARGET_WAITKIND_STOPPED
infrun: stop_pc = 0x400717
infrun: BPSTAT_WHAT_STOP_NOISY
infrun: stop_waiting
Breakpoint 3, handler (sig=14) at /home/pedro/gdb/mygit/src/gdb/testsuite/gdb.base/sigstep.c:35
35 done = 1;
Hardware single-step targets already behave this way, because the
Linux backends (both native and gdbserver) always report signals to
the core if the thread was single-stepping.
As mentioned in the new comment in do_target_resume, we can't fix this
by instead making the displaced_step_fixup phase skip fixing up the PC
if the single step stopped somewhere we didn't expect. Here's what
the backtrace would look like if we did that:
Breakpoint 3, handler (sig=14) at /home/pedro/gdb/mygit/src/gdb/testsuite/gdb.base/sigstep.c:35
35 done = 1;
1: x/i $pc
=> 0x400717 <handler+7>: movl $0x1,0x200943(%rip) # 0x601064 <done>
(gdb) bt
#0 handler (sig=14) at /home/pedro/gdb/mygit/src/gdb/testsuite/gdb.base/sigstep.c:35
#1 <signal handler called>
#2 0x0000000000400622 in _start ()
(gdb) FAIL: gdb.base/sigstep.exp: displaced=on: step on breakpoint, to handler: backtrace
gdb/ChangeLog:
2015-04-10 Pedro Alves <palves@redhat.com>
* infrun.c (displaced_step_in_progress): New function.
(do_target_resume): Advise target to report all signals if
displaced stepping.
gdb/testsuite/ChangeLog:
2015-04-10 Pedro Alves <palves@redhat.com>
* gdb.base/sigstep.exp (breakpoint_to_handler)
(breakpoint_to_handler_entry): New parameter 'displaced'. Use it.
Test "backtrace" in handler.
(breakpoint_over_handler): New parameter 'displaced'. Use it.
(top level): Add new "displaced" test axis to
breakpoint_to_handler, breakpoint_to_handler_entry and
breakpoint_over_handler.
The problem is that with hardware step targets and displaced stepping,
"signal FOO" when stopped at a breakpoint steps the breakpoint
instruction at the same time it delivers a signal. This results in
tp->stepped_breakpoint set, but no step-resume breakpoint set. When
the next stop event arrives, GDB crashes. Irrespective of whether we
should do something more/different to step past the breakpoint in this
scenario (e.g., PR 18225), it's just wrong to assume there'll be a
step-resume breakpoint set (and was not the original intention).
gdb/ChangeLog:
2015-04-10 Pedro Alves <palves@redhat.com>
PR gdb/18216
* infrun.c (process_event_stop_test): Don't assume a step-resume
is set if tp->stepped_breakpoint is true.
gdb/testsuite/ChangeLog:
2015-04-10 Pedro Alves <palves@redhat.com>
PR gdb/18216
* gdb.threads/multiple-step-overs.exp: Remove expected eof.
Recent patch series "V2 All-stop on top of non-stop" causes a SIGSEGV
in the test case,
> -PASS: gdb.base/info-shared.exp: continue to breakpoint: library function #4
> +FAIL: gdb.base/info-shared.exp: continue to breakpoint: library function #4
>
> continue^M
> Continuing.^M
> ^M
> Program received signal SIGSEGV, Segmentation fault.^M
> 0x40021564 in ?? () gdb/testsuite/gdb.base/info-shared-solib1.so^M
> (gdb) FAIL: gdb.base/info-shared.exp: continue to breakpoint: library function #4
and an ARM displaced stepping bug is exposed. It can be reproduced by
the modified gdb.arch/arm-disp-step.exp as below,
continue^M
Continuing.^M
^M
Program received signal SIGSEGV, Segmentation fault.^M
0xa713cfcc in ?? ()^M
(gdb) FAIL: gdb.arch/arm-disp-step.exp: continue to breakpoint: continue to test_add_rn_pc_end
This patch is to fix it.
gdb:
2015-04-10 Yao Qi <yao.qi@linaro.org>
* arm-tdep.c (install_alu_reg): Update comment.
(thumb_copy_alu_reg): Remove local variable rn. Update
debugging message. Use r2 instead of r1 in the modified
instruction.
gdb/testsuite:
2015-04-10 Yao Qi <yao.qi@linaro.org>
* gdb.arch/arm-disp-step.S (main): Call test_add_rn_pc.
(test_add_rn_pc): New function.
* gdb.arch/arm-disp-step.exp (test_add_rn_pc): New proc.
(top level): Invoke test_add_rn_pc.
Running break-interp.exp with the target always in non-stop mode trips
on PR13858, as enabling non-stop also enables displaced stepping.
The problem is that when GDB doesn't know where the entry point is, it
doesn't know where to put the displaced stepping scratch pad. The
test added by this commit exercises this. Without the fix, we get:
(gdb) PASS: gdb.base/step-over-no-symbols.exp: displaced=on: break *$pc
set displaced-stepping on
(gdb) PASS: gdb.base/step-over-no-symbols.exp: displaced=on: set displaced-stepping on
stepi
0x00000000004005be in ?? ()
Entry point address is not known.
(gdb) PASS: gdb.base/step-over-no-symbols.exp: displaced=on: stepi
p /x $pc
$2 = 0x4005be
(gdb) PASS: gdb.base/step-over-no-symbols.exp: displaced=on: get after PC
FAIL: gdb.base/step-over-no-symbols.exp: displaced=on: advanced
The fix switches all GNU/Linux ports to get the entry point from
AT_ENTRY in the target auxiliary vector instead of from symbols. This
is currently only done by PPC when Cell debugging is enabled, but I
think all archs should be able to do the same. Note that
ppc_linux_displaced_step_location cached the result, I'm guessing to
avoid constantly re-fetching the auxv out of remote targets, but
that's no longer necessary nowadays, as the auxv blob is itself cached
in the inferior object. The ppc_linux_entry_point_addr global is
obviously bad for multi-process too nowadays.
Tested on x86-64 (-m64/-m32), PPC64 (-m64/-m32) and S/390 GNU/Linux.
Yao tested the new test on ARM as well.
gdb/ChangeLog:
2015-04-10 Pedro Alves <palves@redhat.com>
PR gdb/13858
* amd64-linux-tdep.c (amd64_linux_init_abi_common): Install
linux_displaced_step_location as gdbarch_displaced_step_location
hook.
* arm-linux-tdep.c (arm_linux_init_abi): Likewise.
* i386-linux-tdep.c (i386_linux_init_abi): Likewise.
* linux-tdep.c (linux_displaced_step_location): New function,
based on ppc_linux_displaced_step_location.
* linux-tdep.h (linux_displaced_step_location): New declaration.
* ppc-linux-tdep.c (ppc_linux_entry_point_addr): Delete.
(ppc_linux_inferior_created, ppc_linux_displaced_step_location):
Delete.
(ppc_linux_init_abi): Install linux_displaced_step_location as
gdbarch_displaced_step_location hook, even without Cell/B.E..
(_initialize_ppc_linux_tdep): Don't install
ppc_linux_inferior_created as inferior_created observer.
* s390-linux-tdep.c (s390_gdbarch_init): Install
linux_displaced_step_location as gdbarch_displaced_step_location
hook.
gdb/testsuite/
2015-04-10 Pedro Alves <palves@redhat.com>
PR gdb/13858
* gdb.base/step-over-no-symbols.exp: New file.
This commit introduces a new shared function to replace three
identical functions in various places in the codebase.
gdb/ChangeLog:
* common/common-remote-fileio.h (remote_fileio_to_fio_error):
New declaration.
* common/common-remote-fileio.c (remote_fileio_to_fio_error):
New function, factored out the named functions below.
* inf-child.c (gdb/fileio.h): Remove include.
(common-remote-fileio.h): New include.
(inf_child_errno_to_fileio_error): Remove function. Update
all callers to use remote_fileio_to_fio_error.
* remote-fileio.c (remote_fileio_errno_to_target): Likewise.
gdb/gdbserver/ChangeLog:
* hostio-errno.c (errno_to_fileio_error): Remove function.
Update caller to use remote_fileio_to_fio_error.
gdb/ChangeLog:
2015-04-09 Pedro Alves <palves@redhat.com>
* gnulib/update-gnulib.sh (aclocal version check): Filter out
"called too early to check prototype".
This patch is related to PR python/16699, and is an improvement over the
patch posted here:
<https://sourceware.org/ml/gdb-patches/2014-03/msg00301.html>
Keith noticed that, when using the "complete" command on GDB to complete
a Python command, some strange things could happen. In order to
understand what can go wrong, I need to explain how the Python
completion mechanism works.
When the user requests a completion of a Python command by using TAB,
GDB will first try to determine the right set of "brkchars" that will be
used when doing the completion. This is done by actually calling the
"complete" method of the Python class. Then, when we already know the
"brkchars" that will be used, we call the "complete" method again, for
the same values.
If you read the thread mentioned above, you will see that one of the
design decisions was to make the "cmdpy_completer_helper" (which is the
function the does the actual calling of the "complete" method) cache the
first result of the completion, since this result will be used in the
second call, to do the actual completion.
The problem is that the "complete" command does not process the
brkchars, and the current Python completion mechanism (improved by the
patch mentioned above) relies on GDB trying to determine the brkchars,
and then doing the completion itself. Therefore, when we use the
"complete" command instead of doing a TAB-completion on GDB, there is a
scenario where we can use the invalid cache of a previous Python command
that was completed before. For example:
(gdb) A <TAB>
(gdb) complete B
B value1
B value10
B value2
B value3
B value4
B value5
B value6
B value7
B value8
B value9
(gdb) B <TAB>
comp1 comp2 comp4 comp6 comp8
comp10 comp3 comp5 comp7 comp9
Here, we see that "complete B " gave a different result than "B <TAB>".
The reason for that is because "A <TAB>" was called before, and its
completion results were "value*", so when GDB tried to "complete B " it
wrongly answered with the results for A. The problem here is using a
wrong cache (A's cache) for completing B.
We tried to come up with a solution that would preserve the caching
mechanism, but it wasn't really possible. So I decided to completely
remove the cache, and doing the method calling twice for every
completion. This is not optimal, but I do not think it will impact
users noticeably.
It is worth mentioning another small issue that I found. The code was
doing:
wordobj = PyUnicode_Decode (word, sizeof (word), host_charset (), NULL);
which is totally wrong, because using "sizeof" here will lead to always
the same result. So I changed this to use "strlen". The testcase also
catches this problem.
Keith kindly expanded the existing testcase to cover the problem
described above, and everything is passing.
gdb/ChangeLog:
2015-04-08 Sergio Durigan Junior <sergiodj@redhat.com>
PR python/16699
* python/py-cmd.c (cmdpy_completer_helper): Adjust function to not
use a caching mechanism. Adjust comments and code to reflect
that. Replace 'sizeof' by 'strlen' when fetching 'wordobj'.
(cmdpy_completer_handle_brkchars): Adjust call to
cmdpy_completer_helper. Call Py_XDECREF for 'resultobj'.
(cmdpy_completer): Likewise.
gdb/testsuite/ChangeLog:
2015-04-08 Keith Seitz <keiths@redhat.com>
PR python/16699
* gdb.python/py-completion.exp: New tests for completion.
* gdb.python/py-completion.py (CompleteLimit1): New class.
(CompleteLimit2): Likewise.
(CompleteLimit3): Likewise.
(CompleteLimit4): Likewise.
(CompleteLimit5): Likewise.
(CompleteLimit6): Likewise.
(CompleteLimit7): Likewise.
Nowadays, in infrun.c:resume, the setting to 'step' variable is like:
if (use_displaced_stepping (gdbarch)
&& tp->control.trap_expected
&& sig == GDB_SIGNAL_0
&& !current_inferior ()->waiting_for_vfork_done)
{
}
/* Do we need to do it the hard way, w/temp breakpoints? */
else if (step)
step = maybe_software_singlestep (gdbarch, pc); <-- [1]
...
if (execution_direction != EXEC_REVERSE
&& step && breakpoint_inserted_here_p (aspace, pc))
{
...
if (gdbarch_cannot_step_breakpoint (gdbarch)) <-- [2]
step = 0;
}
spu doesn't have displaced stepping and uses software single step,
so 'step' is set to zero in [1], and [2] becomes unreachable as a
result. So don't have to call set_gdbarch_cannot_step_breakpoint
in spu_gdbarch_init.
gdb:
2015-04-08 Yao Qi <yao.qi@linaro.org>
* spu-tdep.c (spu_gdbarch_init): Don't call
set_gdbarch_cannot_step_breakpoint.
On GNU/Linux, if the running kernel supports clone events, then
linux-thread-db.c defers thread listing to the target beneath:
static void
thread_db_update_thread_list (struct target_ops *ops)
{
...
if (target_has_execution && !thread_db_use_events ())
ops->beneath->to_update_thread_list (ops->beneath);
else
thread_db_update_thread_list_td_ta_thr_iter (ops);
...
}
However, when live debugging, the target beneath, linux-nat.c, does
not implement the to_update_thread_list method. The result is that if
a thread is marked exited (because it can't be deleted right now,
e.g., it was the selected thread), then it won't ever be deleted,
until the process exits or is killed/detached.
A similar thing happens with the remote.c target. Because its
target_update_thread_list implementation skips exited threads when it
walks the current thread list looking for threads that no longer exits
on the target side, using ALL_NON_EXITED_THREADS_SAFE, stale exited
threads are never deleted.
This is not a big deal -- I can't think of any way this might be user
visible, other than gdb's memory growing a tiny bit whenever a thread
gets stuck in exited state. Still, might as well clean things up
properly.
All other targets use prune_threads, so are unaffected.
The fix adds a ALL_THREADS_SAFE macro, that like
ALL_NON_EXITED_THREADS_SAFE, walks the thread list and allows deleting
the iterated thread, and uses that in places that are walking the
thread list in order to delete threads. Actually, after converting
linux-nat.c and remote.c to use this, we find the only other user of
ALL_NON_EXITED_THREADS_SAFE is also walking the list to delete
threads. So we convert that too, and end up deleting
ALL_NON_EXITED_THREADS_SAFE.
Tested on x86_64 Fedora 20, native and gdbserver.
gdb/ChangeLog
2015-04-07 Pedro Alves <palves@redhat.com>
* gdbthread.h (ALL_NON_EXITED_THREADS_SAFE): Rename to ...
(ALL_THREADS_SAFE): ... this, and don't skip exited threads.
(delete_exited_threads): New declaration.
* infrun.c (follow_exec): Use ALL_THREADS_SAFE.
* linux-nat.c (linux_nat_update_thread_list): New function.
(linux_nat_add_target): Install it.
* remote.c (remote_update_thread_list): Use ALL_THREADS_SAFE.
* thread.c (prune_threads): Use ALL_THREADS_SAFE.
(delete_exited_threads): New function.
Although not currently possible in practice when we get here,
'resume_ptid' can also be a wildcard throughout this function. It's
clearer to fetch the regcache using the thread's ptid.
gdb/ChangeLog:
2015-04-07 Pedro Alves <pedro@codesourcery.com>
* infrun.c (resume) <displaced stepping debug output>: Get the
leader thread's regcache, not resume_ptid's.
gdb/ChangeLog:
* symtab.c (hash_symbol_entry): Hash STRUCT_DOMAIN symbols as
VAR_DOMAIN.
(symbol_cache_lookup): Clarify use of bsc_ptr, slot_ptr parameters.
Include symbol domain in debugging output.
Currently building gdb is impossible without an installed termcap or
curses library. But, GDB already has a very minimal termcap in the
tree to handle this situation for Windows -- gdb/stub-termcap.c. This
patch makes that the fallback for all hosts.
Testing this on GNU/Linux (by simply hacking away the termcap/curses
detection in gdb/configure.ac), we trip on:
../readline/libreadline.a(terminal.o): In function `_rl_init_terminal_io':
/home/pedro/gdb/mygit/src/readline/terminal.c:527: undefined reference to `PC'
/home/pedro/gdb/mygit/src/readline/terminal.c:528: undefined reference to `BC'
/home/pedro/gdb/mygit/src/readline/terminal.c:529: undefined reference to `UP'
/home/pedro/gdb/mygit/src/readline/terminal.c:538: undefined reference to `PC'
/home/pedro/gdb/mygit/src/readline/terminal.c:539: undefined reference to `BC'
/home/pedro/gdb/mygit/src/readline/terminal.c:540: undefined reference to `UP'
These are globals that are normally defined by termcap (or ncurses'
termcap emulation).
Now, we could just define replacements in stub-termcap.c, but
readline/terminal.c (at least the copy in our tree) has this:
#if !defined (__linux__) && !defined (NCURSES_VERSION)
# if defined (__EMX__) || defined (NEED_EXTERN_PC)
extern
# endif /* __EMX__ || NEED_EXTERN_PC */
char PC, *BC, *UP;
#endif /* !__linux__ && !NCURSES_VERSION */
which can result in readline defining the globals too. That will
usually work out in C, given that "-fcommon" is usually the default
for C compilers, but that won't work for C++, or C with -fno-common
(link fails with "multiple definition" errors)...
Mirroring those #ifdef conditions in the stub termcap screams
"brittle" to me -- I can see them changing in latter readline
versions.
Work around that by simply using __attribute__((weak)).
Windows/PE/COFF's do support weak, but not on gcc 3.4 based toolchains
(4.8.x does work). Given the file never needed the variables while it
was Windows-only, just continue not defining them there. All other
supported hosts should support this.
gdb/ChangeLog:
2015-04-06 Pedro Alves <palves@redhat.com>
Bernd Edlinger <bernd.edlinger@hotmail.de>
* configure.ac: Remove the mingw32-specific stub-termcap.o
fallback, and instead fallback to the stub termcap on all hosts.
* configure: Regenerate.
* stub-termcap.c [!__MINGW32__] (PC, BC, UP): Define as weak
symbols.
This paramater is no longer useful after the previous commit, so remove
it as a cleanup.
gdb/ChangeLog:
* gdbtypes.c (is_dynamic_type_internal): Remove the unused
"top_level" parameter.
(resolve_dynamic_type_internal): Remove the unused "top_level"
parameter. Update call to is_dynamic_type_internal.
(is_dynamic_type): Update call to is_dynamic_type_internal.
(resolve_dynamic_range): Update call to
resolve_dynamic_type_internal.
(resolve_dynamic_union): Likewise.
(resolve_dynamic_struct): Likewise.
(resolve_dynamic_type): Likewise.
Even when referenced types are dynamic, the corresponding referencing
type should not be considered as dynamic: it's only a pointer. This
prevents reference type for values not in memory to be resolved.
gdb/ChangeLog:
* gdbtypes.c (is_dynamic_type_internal): Remove special handling
of TYPE_CODE_REF types so that they are not considered as
dynamic depending on the referenced type.
(resolve_dynamic_type_internal): Likewise.
gdb/testsuite/ChangeLog:
* gdb.ada/funcall_ref.exp: New file.
* gdb.ada/funcall_ref/foo.adb: New file.
This commit makes GDB default to a sysroot of "target:".
One testcase needed updating as a result of this change.
gdb/ChangeLog:
* main.c (captured_main): Set gdb_sysroot to "target:"
if not otherwise set.
gdb/testsuite/ChangeLog:
* gdb.base/break-probes.exp: Cope with "target:" sysroot.
This commit adds support for filenames prefixed with "target:" to
exec_file_attach. This is required to correctly follow inferior
exec* calls when a gdb_sysroot prefixed with "target:" is set.
gdb/ChangeLog:
* exec.c (exec_file_attach): Support "target:" filenames.
This commit updates solib_find to strip the "target:" prefix from
gdb_sysroot when accessing local files. This ensures that the same
search algorithm is used for local files regardless of whether a
"target:" prefix was used or not. It also avoids cluttering GDB's
output with unnecessary "target:" prefixes on paths.
gdb/ChangeLog:
* solib.c (solib_find): Strip "target:" prefix from sysroot
if accessing local files.
symfile_bfd_open handled what were remote files as a special case.
Converting from "remote:" files to "target:" made symfile_bfd_open
look like this:
if remote:
open bfd, check format, etc
return
local-specific stuff
open bfd, check format, etc
return
This commit rearranges symfile_bfd_open to remove the duplicated
code, like this:
if local:
local-specific stuff
open bfd, check format, etc
return
gdb/ChangeLog:
* symfile.c (symfile_bfd_open): Reorder to remove duplicated
checks and error messages.
The functionality of "target:" sysroots is a superset of the
functionality of "remote:" sysroots. This commit causes the
"set sysroot" command to rewrite "remote:" sysroots as "target:"
sysroots and replaces "remote:" specific code with "target:"
specific code where still necessary.
gdb/ChangeLog:
* remote.h (REMOTE_SYSROOT_PREFIX): Remove definition.
(remote_filename_p): Remove declaration.
(remote_bfd_open): Likewise.
* remote.c (remote_bfd_iovec_open): Remove function.
(remote_bfd_iovec_close): Likewise.
(remote_bfd_iovec_pread): Likewise.
(remote_bfd_iovec_stat): Likewise.
(remote_filename_p): Likewise.
(remote_bfd_open): Likewise.
* symfile.h (gdb_bfd_open_maybe_remote): Remove declaration.
* symfile.c (separate_debug_file_exists): Use gdb_bfd_open.
(gdb_bfd_open_maybe_remote): Remove function.
(symfile_bfd_open): Replace remote filename check with
target filename check.
(reread_symbols): Use gdb_bfd_open.
* build-id.c (gdbcore.h): New include.
(build_id_to_debug_bfd): Use gdb_bfd_open.
* infcmd.c (attach_command_post_wait): Remove remote filename
check.
* solib.c (solib_find): Replace remote-specific handling with
target-specific handling. Update comments where necessary.
(solib_bfd_open): Replace remote-specific handling with
target-specific handling.
(gdb_sysroot_changed): New function.
(_initialize_solib): Call the above when gdb_sysroot changes.
* windows-tdep.c (gdbcore.h): New include.
(windows_xfer_shared_library): Use gdb_bfd_open.
This commit updates gdb_bfd_open to access files using target
fileio functions if the supplied path starts with "target:"
and if the local and target filesystems are not the same.
This allows users to specify "set sysroot target:" and have
GDB access files locally or from the remote as appropriate.
The new functions in gdb_bfd.c are copies of functions from
remote.c. This duplication is intentional and will be removed
by the next commit in this series.
gdb/ChangeLog:
* gdb/gdb_bfd.h (TARGET_SYSROOT_PREFIX): New definition.
(is_target_filename): New declaration.
(gdb_bfd_has_target_filename): Likewise.
(gdb_bfd_open): Update documentation comment.
* gdb_bfd.c (target.h): New include.
(gdb/fileio.h): Likewise.
(is_target_filename): New function.
(gdb_bfd_has_target_filename): Likewise.
(fileio_errno_to_host): Likewise.
(gdb_bfd_iovec_fileio_open): Likewise.
(gdb_bfd_iovec_fileio_pread): Likewise.
(gdb_bfd_iovec_fileio_close): Likewise.
(gdb_bfd_iovec_fileio_fstat): Likewise.
(gdb_bfd_open): Use target fileio to access paths prefixed
with "target:" where necessary.
This commit introduces a new target method target_filesystem_is_local
which can be used to determine whether or not the filesystem accessed
by the target_fileio_* methods is the local filesystem.
gdb/ChangeLog:
* target.h (struct target_ops) <to_filesystem_is_local>:
New field.
(target_filesystem_is_local): New macro.
* target-delegates.c: Regenerate.
* remote.c (remote_filesystem_is_local): New function.
(init_remote_ops): Initialize to_filesystem_is_local.
This commit introduces a new target method target_fileio_fstat
which can be used to retrieve information about files opened with
target_fileio_open.
gdb/ChangeLog:
* target.h (struct target_ops) <to_fileio_fstat>: New field.
(target_fileio_fstat): New declaration.
* target.c (target_fileio_fstat): New function.
* inf-child.c (inf_child_fileio_fstat): Likewise.
(inf_child_target): Initialize to_fileio_fstat.
* remote.c (init_remote_ops): Likewise.
My all-stop-on-top-of-non-stop series manages to shows regressions due
to this latent bug. currently_stepping returns true if
stepped_breakpoint is set. Obviously we should clear
it before checking currently_stepping, not after.
Tested on x86_64 Fedora 20.
gdb/ChangeLog:
2015-04-01 Pedro Alves <palves@redhat.com>
* infrun.c (resume): Check currently_stepping after clearing
stepped_breakpoint, not before.
By inspection, I noticed a path where we return without discarding the
cleanups.
gdb/ChangeLog:
2015-04-01 Pedro Alves <palves@redhat.com>
* infrun.c (keep_going): Also discard cleanups if inserting
breakpoints fails.
Noticed that if an error is thrown out of target_wait, we miss running
finish_thread_state_cleanup.
Tested on x86_64 Fedora 20, with "maint set target-async off".
gdb/ChangeLog:
2015-04-01 Pedro Alves <palves@redhat.com>
* infrun.c (wait_for_inferior): Install the
finish_thread_state_cleanup cleanup across the whole function, not
just around handle_inferior_event.
We can use the recently added do_target_resume do simplify the code a
bit here.
Tested on x86_64 Fedora 20.
gdb/ChangeLog:
2015-04-01 Pedro Alves <palves@redhat.com>
* infrun.c (resume) <step past permanent breakpoint>: Use
do_target_resume.
My all-stop-on-top-of-non-stop series manages to trip on a bug in the
linux-nat.c backend while running the testsuite. If a thread is
discovered while threads are being momentarily paused (without the
core's intervention), the thread ends up stuck in THREAD_STOPPED
state, even though from the user's perspective, the thread is running
even while it is paused.
From inspection, in the current sources, this can happen if we call
stop_and_resume_callback, though there's no way to test that with
current Linux kernels.
(While trying to come up with test to exercise this, I stumbled on:
https://sourceware.org/ml/gdb-patches/2015-03/msg00850.html
... which does include a non-trivial test, so I think I can still
claim I come out net positive. :-) )
Tested on x86_64 Fedora 20.
gdb/ChangeLog:
2015-04-01 Pedro Alves <palves@redhat.com>
* linux-nat.c (linux_handle_extended_wait): Always call set_running.
On GNU/Linux, if the target reuses the TID of a thread that GDB still
has in its list marked as THREAD_EXITED, GDB crashes, like:
(gdb) continue
Continuing.
src/gdb/thread.c:789: internal-error: set_running: Assertion `tp->state != THREAD_EXITED' failed.
A problem internal to GDB has been detected,
further debugging may prove unreliable.
Quit this debugging session? (y or n) FAIL: gdb.threads/tid-reuse.exp: continue to breakpoint: after_reuse_time (GDB internal error)
Here:
(top-gdb) bt
#0 internal_error (file=0x953dd8 "src/gdb/thread.c", line=789, fmt=0x953da0 "%s: Assertion `%s' failed.")
at src/gdb/common/errors.c:54
#1 0x0000000000638514 in set_running (ptid=..., running=1) at src/gdb/thread.c:789
#2 0x00000000004bda42 in linux_handle_extended_wait (lp=0x16f5760, status=0, stopping=0) at src/gdb/linux-nat.c:2114
#3 0x00000000004bfa24 in linux_nat_filter_event (lwpid=20570, status=198015) at src/gdb/linux-nat.c:3127
#4 0x00000000004c070e in linux_nat_wait_1 (ops=0xe193d0, ptid=..., ourstatus=0x7fffffffd2c0, target_options=1) at src/gdb/linux-nat.c:3478
#5 0x00000000004c1015 in linux_nat_wait (ops=0xe193d0, ptid=..., ourstatus=0x7fffffffd2c0, target_options=1) at src/gdb/linux-nat.c:3722
#6 0x00000000004c92d2 in thread_db_wait (ops=0xd80b60 <thread_db_ops>, ptid=..., ourstatus=0x7fffffffd2c0, options=1)
at src/gdb/linux-thread-db.c:1525
#7 0x000000000066db43 in delegate_wait (self=0xd80b60 <thread_db_ops>, arg1=..., arg2=0x7fffffffd2c0, arg3=1) at src/gdb/target-delegates.c:116
#8 0x000000000067e54b in target_wait (ptid=..., status=0x7fffffffd2c0, options=1) at src/gdb/target.c:2206
#9 0x0000000000625111 in fetch_inferior_event (client_data=0x0) at src/gdb/infrun.c:3275
#10 0x0000000000648a3b in inferior_event_handler (event_type=INF_REG_EVENT, client_data=0x0) at src/gdb/inf-loop.c:56
#11 0x00000000004c2ecb in handle_target_event (error=0, client_data=0x0) at src/gdb/linux-nat.c:4655
I managed to come up with a test that reliably reproduces this. It
spawns enough threads for the pid number space to wrap around, so
could potentially take a while. On my box that's 4 seconds; on
gcc110, a PPC box which has max_pid set to 65536, it's over 10
seconds. So I made the test compute how long that would take, and cap
the time waited if it would be unreasonably long.
Tested on x86_64 Fedora 20.
gdb/ChangeLog:
2015-04-01 Pedro Alves <palves@redhat.com>
* linux-thread-db.c (record_thread): Readd the thread to gdb's
list if it was marked exited.
gdb/testsuite/ChangeLog:
2015-04-01 Pedro Alves <palves@redhat.com>
* gdb.threads/tid-reuse.c: New file.
* gdb.threads/tid-reuse.exp: New file.
This patch, as the subject says, extends GDB so that it is able to use
the contents of the file /proc/PID/coredump_filter when generating a
corefile. This file contains a bit mask that is a representation of
the different types of memory mappings in the Linux kernel; the user
can choose to dump or not dump a certain type of memory mapping by
enabling/disabling the respective bit in the bit mask. Currently,
here is what is supported:
bit 0 Dump anonymous private mappings.
bit 1 Dump anonymous shared mappings.
bit 2 Dump file-backed private mappings.
bit 3 Dump file-backed shared mappings.
bit 4 (since Linux 2.6.24)
Dump ELF headers.
bit 5 (since Linux 2.6.28)
Dump private huge pages.
bit 6 (since Linux 2.6.28)
Dump shared huge pages.
(This table has been taken from core(5), but you can also read about it
on Documentation/filesystems/proc.txt inside the Linux kernel source
tree).
The default value for this file, used by the Linux kernel, is 0x33,
which means that bits 0, 1, 4 and 5 are enabled. This is also the
default for GDB implemented in this patch, FWIW.
Well, reading the file is obviously trivial. The hard part, mind you,
is how to determine the types of the memory mappings. For that, I
extended the code of gdb/linux-tdep.c:linux_find_memory_regions_full and
made it rely *much more* on the information gathered from
/proc/<PID>/smaps. This file contains a "verbose dump" of the
inferior's memory mappings, and we were not using as much information as
we could from it. If you want to read more about this file, take a look
at the proc(5) manpage (I will also write a blog post soon about
everything I had to learn to get this patch done, and when I it is ready
I will post it here).
With Oleg Nesterov's help, we could improve the current algorithm for
determining whether a memory mapping is anonymous/file-backed,
private/shared. GDB now also respects the MADV_DONTDUMP flag and does
not dump the memory mapping marked as so, and will always dump
"[vsyscall]" or "[vdso]" mappings (just like the Linux kernel).
In a nutshell, what the new code is doing is:
- If the mapping is associated to a file whose name ends with
" (deleted)", or if the file is "/dev/zero", or if it is "/SYSV%08x"
(shared memory), or if there is no file associated with it, or if
the AnonHugePages: or the Anonymous: fields in the /proc/PID/smaps
have contents, then GDB considers this mapping to be anonymous.
There is a special case in this, though: if the memory mapping is a
file-backed one, but *also* contains "Anonymous:" or
"AnonHugePages:" pages, then GDB considers this mapping to be *both*
anonymous and file-backed, just like the Linux kernel does. What
that means is simple: this mapping will be dumped if the user
requested anonymous mappings *or* if the user requested file-backed
mappings to be present in the corefile.
It is worth mentioning that, from all those checks described above,
the most fragile is the one to see if the file name ends with
" (deleted)". This does not necessarily mean that the mapping is
anonymous, because the deleted file associated with the mapping may
have been a hard link to another file, for example. The Linux
kernel checks to see if "i_nlink == 0", but GDB cannot easily do
this check (as it has been discussed, GDB would need to run as root,
and would need to check the contents of the /proc/PID/map_files/
directory in order to determine whether the deleted was a hardlink
or not). Therefore, we made a compromise here, and we assume that
if the file name ends with " (deleted)", then the mapping is indeed
anonymous. FWIW, this is something the Linux kernel could do
better: expose this information in a more direct way.
- If we see the flag "sh" in the VmFlags: field (in /proc/PID/smaps),
then certainly the memory mapping is shared (VM_SHARED). If we have
access to the VmFlags, and we don't see the "sh" there, then
certainly the mapping is private. However, older Linux kernels (see
the code for more details) do not have the VmFlags field; in that
case, we use another heuristic: if we see 'p' in the permission
flags, then we assume that the mapping is private, even though the
presence of the 's' flag there would mean VM_MAYSHARE, which means
the mapping could still be private. This should work OK enough,
however.
Finally, it is worth mentioning that I added a new command, 'set
use-coredump-filter on/off'. When it is 'on', it will read the
coredump_filter' file (if it exists) and use its value; otherwise, it
will use the default value mentioned above (0x33) to decide which memory
mappings to dump.
gdb/ChangeLog:
2015-03-31 Sergio Durigan Junior <sergiodj@redhat.com>
Jan Kratochvil <jan.kratochvil@redhat.com>
Oleg Nesterov <oleg@redhat.com>
PR corefiles/16092
* linux-tdep.c: Include 'gdbcmd.h' and 'gdb_regex.h'.
New enum identifying the various options of the coredump_filter
file.
(struct smaps_vmflags): New struct.
(use_coredump_filter): New variable.
(decode_vmflags): New function.
(mapping_is_anonymous_p): Likewise.
(dump_mapping_p): Likewise.
(linux_find_memory_regions_full): New variables
'coredumpfilter_name', 'coredumpfilterdata', 'pid', 'filterflags'.
Removed variable 'modified'. Read /proc/<PID>/smaps file; improve
parsing of its information. Implement memory mapping filtering
based on its contents.
(show_use_coredump_filter): New function.
(_initialize_linux_tdep): New command 'set use-coredump-filter'.
* NEWS: Mention the possibility of using the
'/proc/PID/coredump_filter' file when generating a corefile.
Mention new command 'set use-coredump-filter'.
gdb/doc/ChangeLog:
2015-03-31 Sergio Durigan Junior <sergiodj@redhat.com>
PR corefiles/16092
* gdb.texinfo (gcore): Mention new command 'set
use-coredump-filter'.
(set use-coredump-filter): Document new command.
gdb/testsuite/ChangeLog:
2015-03-31 Sergio Durigan Junior <sergiodj@redhat.com>
PR corefiles/16092
* gdb.base/coredump-filter.c: New file.
* gdb.base/coredump-filter.exp: Likewise.
When loading a corefile that has some inaccessible memory region(s),
GDB complains about it:
(gdb) core /my/corefile
[New LWP 28468]
Cannot access memory at address 0x355fc21148
Cannot access memory at address 0x355fc21140
(gdb)
However, despite not seeing the message "Core was generated by...", it
is still possible to inspect the corefile using regular GDB commands.
The reason for that is because read_memory_unsigned_integer throws an
exception when it cannot read the memory region, but
solib_svr4_r_ldsomap was not catching it. The fix is to catch the
exception and act accordingly.
Tested on Fedora 20 x86_64, no regressions found.
gdb/ChangeLog:
2015-03-31 Sergio Durigan Junior <sergiodj@redhat.com>
* solib-svr4.c (solib_svr4_r_ldsomap): Catch possible exception by
read_memory_unsigned_integer.
This patch adds cpu information on linux based on /proc/cpuinfo as :
cpus Listing of all cpus/cores on the system
This patch also reorders the info os commands so that they are listed
in alphabetical order.
gdb/ChangeLog:
* NEWS: Mention info os cpus support.
* gdb/nat/linux-osdata.c (linux_xfer_osdata_cpus): New function.
(struct osdata_type): Add cpus entry, reorder the entries in
alphabetical order.
gdb/doc/ChangeLog:
* gdb.texinfo (Operating System Auxiliary Information): Add info os cpus
documentation, reorder the info os entries in alphabetical order.
This allows triplets where the vendor is not set.
gdb/ChangeLog:
2015-03-31 Matthias Klose <doko@ubuntu.com>
* compile/compile.c (compile_to_object): Allow triplets with or
without vendor set.
gdb/ChangeLog:
* remote.c (remote_mourn_1): Remove function. Update all callers
to use remote_mourn.
(extended_remote_mourn_1): Remove function. Update all callers
to use extended_remote_mourn.
(extended_remote_attach_1): Remove function. Update all callers
to use extended_remote_attach.
Simon Marchi:
I think this patch is wrong. Starting with that commit (f30d5c7),
some tests (e.g. mi-break.exp) started to fail for me, because
of gdb segfaulting.
The address of expr is passed to the cleanup. When the cleanup is ran,
expr is no longer in scope, so what is at that address is probably not
safe to use anymore. That's my guess.
gdb/ChangeLog
2015-03-27 Jan Kratochvil <jan.kratochvil@redhat.com>
Revert:
2015-03-26 Jan Kratochvil <jan.kratochvil@redhat.com>
Code cleanup.
* printcmd.c (print_command_1): Move expr variable scope.
