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Honour software single step in fallback of displaced stepping

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Hi,
When I run gdb.threads/non-stop-fair-events.exp on arm-linux target,
I see the following message in the debugging log,

  displaced: breakpoint is gone: Thread 22518, step(1)^M
  Sending packet: $vCont;s:p57f3.57f6#9d...
                  ^^^^^^^^^
GDB sends vCont;s by mistake, and GDBserver fails on assert.  GDB
doesn't consider software single step in infrun.c:displaced_step_fixup,

	  /* Go back to what we were trying to do.  */
	  step = currently_stepping (tp);

	  if (debug_displaced)
	    fprintf_unfiltered (gdb_stdlog,
				"displaced: breakpoint is gone: %s, step(%d)\n",
				target_pid_to_str (tp->ptid), step);

	  target_resume (ptid, step, GDB_SIGNAL_0);

The patch is to let GDB consider software single step here.  It fixes
fails in gdb.threads/non-stop-fair-events.exp on arm.

gdb:

2015-04-16  Yao Qi  <yao.qi@linaro.org>

	* infrun.c (maybe_software_singlestep): Declare.
	(displaced_step_fixup): Call maybe_software_singlestep.
This commit is contained in:
Yao Qi
2015-04-16 13:48:10 +01:00
parent af9fd6f863
commit 8550d3b32f
2 changed files with 11 additions and 2 deletions
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8
gdb/infrun.c
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@@ -98,6 +98,8 @@ static void insert_step_resume_breakpoint_at_caller (struct frame_info *);
static void insert_longjmp_resume_breakpoint (struct gdbarch *, CORE_ADDR);
static int maybe_software_singlestep (struct gdbarch *gdbarch, CORE_ADDR pc);
/* When set, stop the 'step' command if we enter a function which has
no line number information. The normal behavior is that we step
over such function. */
@@ -1863,6 +1865,7 @@ displaced_step_fixup (ptid_t event_ptid, enum gdb_signal signal)
regcache = get_thread_regcache (ptid);
actual_pc = regcache_read_pc (regcache);
aspace = get_regcache_aspace (regcache);
gdbarch = get_regcache_arch (regcache);
if (breakpoint_here_p (aspace, actual_pc))
{
@@ -1873,8 +1876,6 @@ displaced_step_fixup (ptid_t event_ptid, enum gdb_signal signal)
displaced_step_prepare (ptid);
gdbarch = get_regcache_arch (regcache);
if (debug_displaced)
{
CORE_ADDR actual_pc = regcache_read_pc (regcache);
@@ -1907,6 +1908,9 @@ displaced_step_fixup (ptid_t event_ptid, enum gdb_signal signal)
/* Go back to what we were trying to do. */
step = currently_stepping (tp);
if (step)
step = maybe_software_singlestep (gdbarch, actual_pc);
if (debug_displaced)
fprintf_unfiltered (gdb_stdlog,
"displaced: breakpoint is gone: %s, step(%d)\n",