Handle MIPS Linux SIGTRAP siginfo.si_code values
Commit Message
On 04/05/2016 05:57 PM, Maciej W. Rozycki wrote:
> FYI, the kernel change has now made it upstream:
>
> commit 3b143cca6e1397188f507a6c727f4108861ceb8b
> Author: Maciej W. Rozycki <macro@imgtec.com>
> Date: Fri Mar 4 01:44:28 2016 +0000
>
> MIPS: traps: Correct the SIGTRAP debug ABI in `do_watch' and `do_trap_or_bp'
>
> and will be present starting from Linux 4.6.0 release.
>
Thanks Maciej,
Here's the same patch with updated comments. I've pushed this to both master
and the 7.11 branch.
I've filed https://sourceware.org/bugzilla/show_bug.cgi?id=19958
(Breakpoints/watchpoints broken on MIPS Linux <= 4.5), as necessary
according to our branch backporting procedure.
From f25c3723b2251e33e725afa52280fde679f3e600 Mon Sep 17 00:00:00 2001
From: Pedro Alves <palves@redhat.com>
Date: Fri, 15 Apr 2016 23:52:00 +0100
Subject: [PATCH] MIPS/Linux: Also recognize TRAP_BRKPT and TRAP_HWBKPT
This makes the MIPS Linux backends recognize TRAP_BRKPT and
TRAP_HWBKPT in siginfo.si_code in addition to SI_KERNEL, since Linux
4.6 now reports the finer-grained si_code values too.
Refs:
https://sourceware.org/ml/gdb-patches/2016-02/msg00756.html
https://sourceware.org/ml/gdb-patches/2016-04/msg00090.html
On kernels that report SI_KERNEL (<= 4.5), we'll enter the "ambiguous"
path of save_stop_reason:
if (GDB_ARCH_IS_TRAP_BRKPT (siginfo.si_code)
&& GDB_ARCH_IS_TRAP_HWBKPT (siginfo.si_code))
{
/* The si_code is ambiguous on this arch -- check debug
registers. */
if (!check_stopped_by_watchpoint (lp))
lp->stop_reason = TARGET_STOPPED_BY_SW_BREAKPOINT;
}
while on kernels that report the finer-grained si_code values (>= 4.6),
we'll enter the corresponding branches:
else if (GDB_ARCH_IS_TRAP_BRKPT (siginfo.si_code))
{
}
else if (GDB_ARCH_IS_TRAP_HWBKPT (siginfo.si_code))
{
...
gdb/ChangeLog:
2016-04-15 Pedro Alves <palves@redhat.com>
* nat/linux-ptrace.h [__mips__] (GDB_ARCH_IS_TRAP_BRKPT): Also
accept TRAP_BRKPT.
[__mips__] (GDB_ARCH_IS_TRAP_HWBKPT): Also accept TRAP_HWBKPT.
---
gdb/nat/linux-ptrace.h | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)
@@ -140,8 +140,8 @@ struct buffer;
in SPU code on a Cell/B.E. However, SI_KERNEL is never seen
on a SIGTRAP for any other reason.
- The MIPS kernel uses SI_KERNEL for all kernel generated traps.
- Since:
+ The MIPS kernel up until 4.5 used SI_KERNEL for all kernel
+ generated traps. Since:
- MIPS doesn't do hardware single-step.
- We don't need to care about exec SIGTRAPs --- we assume
@@ -152,6 +152,9 @@ struct buffer;
software breakpoints and hardware watchpoints, which can be done by
peeking the debug registers.
+ Beginning with Linux 4.6, the MIPS port reports proper TRAP_BRKPT and
+ TRAP_HWBKPT codes, so we also match them.
+
The generic Linux target code should use GDB_ARCH_IS_TRAP_* instead
of TRAP_* to abstract out these peculiarities. */
#if defined __i386__ || defined __x86_64__
@@ -161,8 +164,8 @@ struct buffer;
# define GDB_ARCH_IS_TRAP_BRKPT(X) ((X) == SI_KERNEL || (X) == TRAP_BRKPT)
# define GDB_ARCH_IS_TRAP_HWBKPT(X) ((X) == TRAP_HWBKPT)
#elif defined __mips__
-# define GDB_ARCH_IS_TRAP_BRKPT(X) ((X) == SI_KERNEL)
-# define GDB_ARCH_IS_TRAP_HWBKPT(X) ((X) == SI_KERNEL)
+# define GDB_ARCH_IS_TRAP_BRKPT(X) ((X) == SI_KERNEL || (X) == TRAP_BRKPT)
+# define GDB_ARCH_IS_TRAP_HWBKPT(X) ((X) == SI_KERNEL || (X) == TRAP_HWBKPT)
#else
# define GDB_ARCH_IS_TRAP_BRKPT(X) ((X) == TRAP_BRKPT)
# define GDB_ARCH_IS_TRAP_HWBKPT(X) ((X) == TRAP_HWBKPT)