This is the mail archive of the gdb-patches@sourceware.org mailing list for the GDB project.


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

[PATCH 2/2] Fix gdb.threads/multiple-step-overs.exp fails on arm


Hi,
Some tests in gdb.threads/multiple-step-overs.exp fail on arm target
when the displaced stepping on, but they pass when displaced stepping
is off.

 FAIL: gdb.threads/multiple-step-overs.exp: displaced=on: step: step
 FAIL: gdb.threads/multiple-step-overs.exp: displaced=on: next: next
 FAIL: gdb.threads/multiple-step-overs.exp: displaced=on: continue: continue
 FAIL: gdb.threads/multiple-step-overs.exp: displaced=on: signal thr1: continue to sigusr1_handler

when displaced stepping is on,

Sending packet: $vCont;c#a8...infrun: infrun_async(1)^M <--- [1]
infrun: prepare_to_wait^M
infrun: target_wait (-1.0.0, status) =^M
infrun:   -1.0.0 [Thread 0],^M
infrun:   status->kind = ignore^M
infrun: TARGET_WAITKIND_IGNORE^M
infrun: prepare_to_wait^M
Packet received: T05swbreak:;0b:f8faffbe;0d:409ee7b6;0f:d0880000;thread:p635.636;core:0;^M
infrun: target_wait (-1.0.0, status) =^M
infrun:   1589.1590.0 [Thread 1590],^M
infrun:   status->kind = stopped, signal = GDB_SIGNAL_TRAP^M
infrun: TARGET_WAITKIND_STOPPED^M
infrun: stop_pc = 0x88d0^M
infrun: context switch^M
infrun: Switching context from Thread 1591 to Thread 1590^

GDB resumes the whole process (all threads) rather than the specific
thread it wants to single step (as shown in [1]).  That is wrong.

when displaced stepping is off, GDB behaves correctly, only resumes
the specific thread (as shown in [2]).

Sending packet: $vCont;c:p611.613#b2...infrun: infrun_async(1)^M <-- [2]
infrun: prepare_to_wait^M
infrun: target_wait (-1.0.0, status) =^M
infrun:   -1.0.0 [Thread 0],^M
infrun:   status->kind = ignore^M
infrun: TARGET_WAITKIND_IGNORE^M
infrun: prepare_to_wait^M
Packet received: T05swbreak:;0b:f8faffbe;0d:409e67b6;0f:48880000;thread:p611.613;core:1;^M
infrun: target_wait (-1.0.0, status) =^M
infrun:   1553.1555.0 [Thread 1555],^M
infrun:   status->kind = stopped, signal = GDB_SIGNAL_TRAP^M
infrun: TARGET_WAITKIND_STOPPED^M
infrun: clear_step_over_info^M
infrun: stop_pc = 0x8848

The current logic in GDB on deciding the set of threads to resume is:

  /* Decide the set of threads to ask the target to resume.  */
  if ((step || thread_has_single_step_breakpoints_set (tp))
      && tp->control.trap_expected)
    {
      /* We're allowing a thread to run past a breakpoint it has
	 hit, by single-stepping the thread with the breakpoint
	 removed.  In which case, we need to single-step only this
	 thread, and keep others stopped, as they can miss this
	 breakpoint if allowed to run.  */
      resume_ptid = inferior_ptid;
    }
  else
    resume_ptid = internal_resume_ptid (user_step);

it doesn't handle the case correctly that GDB continue (instead of
single step) the thread for displaced stepping.

I also update the comment below to reflect the code.  I remove the
"with the breakpoint removed" comment, because GDB doesn't remove
breakpoints in displaced stepping, so we don't have to worry that
other threads may miss the breakpoint.

Patch is regression tested on both x86_64-linux and arm-linux.

gdb:

2015-10-28  Yao Qi  <yao.qi@linaro.org>

	* infrun.c (resume): Check displaced_step_in_progress_thread
	when deciding the set of threads to resume.
---
 gdb/infrun.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/gdb/infrun.c b/gdb/infrun.c
index 0265d35..c619b61 100644
--- a/gdb/infrun.c
+++ b/gdb/infrun.c
@@ -2631,14 +2631,12 @@ resume (enum gdb_signal sig)
   gdb_assert (!(thread_has_single_step_breakpoints_set (tp) && step));
 
   /* Decide the set of threads to ask the target to resume.  */
-  if ((step || thread_has_single_step_breakpoints_set (tp))
+  if ((step || thread_has_single_step_breakpoints_set (tp)
+       || displaced_step_in_progress_thread (tp->ptid))
       && tp->control.trap_expected)
     {
       /* We're allowing a thread to run past a breakpoint it has
-	 hit, by single-stepping the thread with the breakpoint
-	 removed.  In which case, we need to single-step only this
-	 thread, and keep others stopped, as they can miss this
-	 breakpoint if allowed to run.  */
+	 hit, by single-stepping (in-line or out-of-line) the thread.  */
       resume_ptid = inferior_ptid;
     }
   else
-- 
1.9.1


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]