From: Luis Machado <lgustavo@codesourcery.com>
To: <gdb-patches@sourceware.org>
Cc: <macro@linux-mips.org>
Subject: [PATCH, v2] Expect SI_KERNEL or TRAP_BRKPT si_code values for MIPS breakpoint traps
Date: Mon, 22 Feb 2016 12:57:00 -0000 [thread overview]
Message-ID: <1456145829-5052-1-git-send-email-lgustavo@codesourcery.com> (raw)
This is v2 of this patch. It was pre-approved by Maciej and i will commit
it soon if there are no objections.
---
While doing some MIPS/Linux tests, i've found a number of threading tests
failing due to spurious SIGTRAP's. Turns out those spurious SIGTRAP's were
actually software breakpoint hits that were supposed to be handled silently by
GDB/GDBserver, returning a swbreak event.
gdb.threads/continue-pending-status.exp is one of the testcases that show this
behavior.
--
Breakpoint 1, main () at gdb.threads/continue-pending-status.c:44^M
44 pthread_barrier_init (&barrier, NULL, NUM_THREADS);^M
(gdb) b continue-pending-status.c:36^M
Breakpoint 2 at 0x400a04: file gdb.threads/continue-pending-status.c, line 36.^M
(gdb) PASS: gdb.threads/continue-pending-status.exp: attempt 0: set break in tight loop
continue^M
Continuing.^M
[New Thread 5850]^M
[New Thread 5851]^M
[Switching to Thread 5850]^M
^M
Breakpoint 2, thread_function (arg=0x0) at gdb.threads/continue-pending-status.c:36^M
36 while (1); /* break here */^M
(gdb) PASS: gdb.threads/continue-pending-status.exp: attempt 0: continue to tight loop
print /x $_thread^M
$1 = 0x2^M
(gdb) PASS: gdb.threads/continue-pending-status.exp: attempt 0: get thread number
thread 3^M
[Switching to thread 3 (Thread 5851)]^M
36 while (1); /* break here */^M
(gdb) PASS: gdb.threads/continue-pending-status.exp: attempt 0: switch to non-event thread
delete breakpoints^M
Delete all breakpoints? (y or n) y^M
(gdb) info breakpoints^M
No breakpoints or watchpoints.^M
(gdb) continue^M
Continuing.^M
^M
Program received signal SIGTRAP, Trace/breakpoint trap.^M
<<<< This SIGTRAP was a pending breakpoint event that wasn't supposed to cause
<<<< a stop, but gdbserver did not figure out this was a breakpoint hit.
PASS: gdb.threads/continue-pending-status.exp: attempt 0: continue for ctrl-c
thread_function (arg=0x0) at gdb.threads/continue-pending-status.c:36^M
36 while (1); /* break here */^M
(gdb) FAIL: gdb.threads/continue-pending-status.exp: attempt 0: caught interrupt
--
I tracked this down to the lack of a proper definition of what MIPS' kernel
returns in the si_code for a software breakpoint trap.
Further discussion with MIPS maintainers showed that, historically, MIPS
kernels have never set a proper si_code and thus they use the default value of
SI_KERNEL.
There are plans to update the MIPS kernel to provide more meaningful si_code
values though, so we should expect both SI_KERNEL and TRAP_BRKPT from now
on, as GDB will handle both correctly, like powerpc.
With the following patch i have cleaner results for thread tests on
MIPS/Linux.
Regression-tested on a few MIPS boards.
OK?
gdb/ChangeLog:
2016-02-22 Luis Machado <lgustavo@codesourcery.com>
* nat/linux-ptrace.h: Check for both SI_KERNEL and TRAP_BRKPT si_code for
MIPS.
---
gdb/nat/linux-ptrace.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/gdb/nat/linux-ptrace.h b/gdb/nat/linux-ptrace.h
index ba58717..71b29dd 100644
--- a/gdb/nat/linux-ptrace.h
+++ b/gdb/nat/linux-ptrace.h
@@ -144,7 +144,7 @@ struct buffer;
instead of TRAP_BRKPT to abstract out these peculiarities. */
#if defined __i386__ || defined __x86_64__
# define GDB_ARCH_IS_TRAP_BRKPT(X) ((X) == SI_KERNEL)
-#elif defined __powerpc__
+#elif defined __powerpc__ || defined __mips__
# define GDB_ARCH_IS_TRAP_BRKPT(X) ((X) == SI_KERNEL || (X) == TRAP_BRKPT)
#else
# define GDB_ARCH_IS_TRAP_BRKPT(X) ((X) == TRAP_BRKPT)
--
1.9.1
next reply other threads:[~2016-02-22 12:57 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-22 12:57 Luis Machado [this message]
2016-02-22 13:16 ` Pedro Alves
2016-02-22 16:19 ` Maciej W. Rozycki
2016-02-24 11:57 ` Pedro Alves
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