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gdbserver/Linux: Use TRAP_BRKPT/TRAP_HWBPT

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This patch adjusts gdbserver's Linux backend to tell gdbserver core
(and ultimately GDB) whether a trap was caused by a breakpoint.

It teaches the backend to get that information out of the si_code of
the SIGTRAP siginfo.

gdb/gdbserver/ChangeLog:
2015-03-04  Pedro Alves  <palves@redhat.com>

        * linux-low.c (check_stopped_by_breakpoint) [USE_SIGTRAP_SIGINFO]:
	Decide whether a breakpoint triggered based on the SIGTRAP's
	siginfo.si_code.
        (thread_still_has_status_pending_p) [USE_SIGTRAP_SIGINFO]: Don't check whether a
        breakpoint is inserted if relying on SIGTRAP's siginfo.si_code.
	(linux_low_filter_event): Check for breakpoints before checking
	watchpoints.
	(linux_wait_1): Don't re-increment the PC if relying on SIGTRAP's
	siginfo.si_code.
        (linux_stopped_by_sw_breakpoint)
        (linux_supports_stopped_by_sw_breakpoint)
        (linux_stopped_by_hw_breakpoint)
        (linux_supports_stopped_by_hw_breakpoint): New functions.
        (linux_target_ops): Install new target methods.
This commit is contained in:
Pedro Alves 2015-03-04 20:41:17 +00:00
parent 1ec68e26c9
commit 3e572f7104
2 changed files with 133 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

17
gdb/gdbserver/ChangeLog
View File

@ -1,3 +1,20 @@
2015-03-04 Pedro Alves <palves@redhat.com>
* linux-low.c (check_stopped_by_breakpoint) [USE_SIGTRAP_SIGINFO]:
Decide whether a breakpoint triggered based on the SIGTRAP's
siginfo.si_code.
(thread_still_has_status_pending_p) [USE_SIGTRAP_SIGINFO]: Don't check whether a
breakpoint is inserted if relying on SIGTRAP's siginfo.si_code.
(linux_low_filter_event): Check for breakpoints before checking
watchpoints.
(linux_wait_1): Don't re-increment the PC if relying on SIGTRAP's
siginfo.si_code.
(linux_stopped_by_sw_breakpoint)
(linux_supports_stopped_by_sw_breakpoint)
(linux_stopped_by_hw_breakpoint)
(linux_supports_stopped_by_hw_breakpoint): New functions.
(linux_target_ops): Install new target methods.
2015-03-04 Pedro Alves <palves@redhat.com>
* remote-utils.c (prepare_resume_reply): Report swbreak/hbreak.

122
gdb/gdbserver/linux-low.c
View File

@ -493,6 +493,9 @@ check_stopped_by_breakpoint (struct lwp_info *lwp)
CORE_ADDR pc;
CORE_ADDR sw_breakpoint_pc;
struct thread_info *saved_thread;
#if USE_SIGTRAP_SIGINFO
siginfo_t siginfo;
#endif
if (the_low_target.get_pc == NULL)
return 0;
@ -504,6 +507,54 @@ check_stopped_by_breakpoint (struct lwp_info *lwp)
saved_thread = current_thread;
current_thread = get_lwp_thread (lwp);
#if USE_SIGTRAP_SIGINFO
if (ptrace (PTRACE_GETSIGINFO, lwpid_of (current_thread),
(PTRACE_TYPE_ARG3) 0, &siginfo) == 0)
{
if (siginfo.si_signo == SIGTRAP)
{
if (siginfo.si_code == GDB_ARCH_TRAP_BRKPT)
{
if (debug_threads)
{
struct thread_info *thr = get_lwp_thread (lwp);
debug_printf ("CSBB: Push back software breakpoint for %s\n",
target_pid_to_str (ptid_of (thr)));
}
/* Back up the PC if necessary. */
if (pc != sw_breakpoint_pc)
{
struct regcache *regcache
= get_thread_regcache (current_thread, 1);
(*the_low_target.set_pc) (regcache, sw_breakpoint_pc);
}
lwp->stop_pc = sw_breakpoint_pc;
lwp->stop_reason = TARGET_STOPPED_BY_SW_BREAKPOINT;
current_thread = saved_thread;
return 1;
}
else if (siginfo.si_code == TRAP_HWBKPT)
{
if (debug_threads)
{
struct thread_info *thr = get_lwp_thread (lwp);
debug_printf ("CSBB: Push back hardware "
"breakpoint/watchpoint for %s\n",
target_pid_to_str (ptid_of (thr)));
}
lwp->stop_pc = pc;
lwp->stop_reason = TARGET_STOPPED_BY_HW_BREAKPOINT;
current_thread = saved_thread;
return 1;
}
}
}
#else
/* We may have just stepped a breakpoint instruction. E.g., in
non-stop mode, GDB first tells the thread A to step a range, and
then the user inserts a breakpoint inside the range. In that
@ -548,6 +599,7 @@ check_stopped_by_breakpoint (struct lwp_info *lwp)
current_thread = saved_thread;
return 1;
}
#endif
current_thread = saved_thread;
return 0;
@ -1242,6 +1294,8 @@ thread_still_has_status_pending_p (struct thread_info *thread)
lwpid_of (thread));
discard = 1;
}
#if !USE_SIGTRAP_SIGINFO
else if (lp->stop_reason == TARGET_STOPPED_BY_SW_BREAKPOINT
&& !(*the_low_target.breakpoint_at) (pc))
{
@ -1258,6 +1312,7 @@ thread_still_has_status_pending_p (struct thread_info *thread)
lwpid_of (thread));
discard = 1;
}
#endif
current_thread = saved_thread;
@ -1875,15 +1930,24 @@ linux_low_filter_event (int lwpid, int wstat)
return NULL;
}
if (WIFSTOPPED (wstat) && WSTOPSIG (wstat) == SIGTRAP
&& check_stopped_by_watchpoint (child))
;
else if (WIFSTOPPED (wstat) && linux_wstatus_maybe_breakpoint (wstat))
/* Check first whether this was a SW/HW breakpoint before checking
watchpoints, because at least s390 can't tell the data address of
hardware watchpoint hits, and returns stopped-by-watchpoint as
long as there's a watchpoint set. */
if (WIFSTOPPED (wstat) && linux_wstatus_maybe_breakpoint (wstat))
{
if (check_stopped_by_breakpoint (child))
have_stop_pc = 1;
}
/* Note that TRAP_HWBKPT can indicate either a hardware breakpoint
or hardware watchpoint. Check which is which if we got
TARGET_STOPPED_BY_HW_BREAKPOINT. */
if (WIFSTOPPED (wstat) && WSTOPSIG (wstat) == SIGTRAP
&& (child->stop_reason == TARGET_STOPPED_BY_NO_REASON
|| child->stop_reason == TARGET_STOPPED_BY_HW_BREAKPOINT))
check_stopped_by_watchpoint (child);
if (!have_stop_pc)
child->stop_pc = get_pc (child);
@ -2938,8 +3002,10 @@ linux_wait_1 (ptid_t ptid,
ourstatus->kind = TARGET_WAITKIND_STOPPED;
/* Now that we've selected our final event LWP, un-adjust its PC if
it was a software breakpoint. */
if (event_child->stop_reason == TARGET_STOPPED_BY_SW_BREAKPOINT)
it was a software breakpoint, and the client doesn't know we can
adjust the breakpoint ourselves. */
if (event_child->stop_reason == TARGET_STOPPED_BY_SW_BREAKPOINT
&& !swbreak_feature)
{
int decr_pc = the_low_target.decr_pc_after_break;
@ -4901,6 +4967,46 @@ linux_remove_point (enum raw_bkpt_type type, CORE_ADDR addr,
return 1;
}
/* Implement the to_stopped_by_sw_breakpoint target_ops
method. */
static int
linux_stopped_by_sw_breakpoint (void)
{
struct lwp_info *lwp = get_thread_lwp (current_thread);
return (lwp->stop_reason == TARGET_STOPPED_BY_SW_BREAKPOINT);
}
/* Implement the to_supports_stopped_by_sw_breakpoint target_ops
method. */
static int
linux_supports_stopped_by_sw_breakpoint (void)
{
return USE_SIGTRAP_SIGINFO;
}
/* Implement the to_stopped_by_hw_breakpoint target_ops
method. */
static int
linux_stopped_by_hw_breakpoint (void)
{
struct lwp_info *lwp = get_thread_lwp (current_thread);
return (lwp->stop_reason == TARGET_STOPPED_BY_HW_BREAKPOINT);
}
/* Implement the to_supports_stopped_by_hw_breakpoint target_ops
method. */
static int
linux_supports_stopped_by_hw_breakpoint (void)
{
return USE_SIGTRAP_SIGINFO;
}
static int
linux_stopped_by_watchpoint (void)
{
@ -6087,6 +6193,10 @@ static struct target_ops linux_target_ops = {
linux_supports_z_point_type,
linux_insert_point,
linux_remove_point,
linux_stopped_by_sw_breakpoint,
linux_supports_stopped_by_sw_breakpoint,
linux_stopped_by_hw_breakpoint,
linux_supports_stopped_by_hw_breakpoint,
linux_stopped_by_watchpoint,
linux_stopped_data_address,
#if defined(__UCLIBC__) && defined(HAS_NOMMU) \