* Re: [PATCH] Make mips-linux signal frame unwinding more robust.
2010-02-25 18:48 ` [PATCH] Make mips-linux signal frame unwinding more robust David Daney
@ 2010-02-26 18:22 ` David Daney
2010-02-26 20:50 ` Daniel Jacobowitz
0 siblings, 1 reply; 3+ messages in thread
From: David Daney @ 2010-02-26 18:22 UTC (permalink / raw)
To: gdb-patches; +Cc: Joel Brobecker, Pinski, Andrew, Ralf Baechle, linux-mips
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On 02/25/2010 10:48 AM, David Daney wrote:
> On 02/25/2010 09:47 AM, Joel Brobecker wrote:
[...]
>>
>> I don't know mips-linux, but something looked funny to me: You avoid
>> the use of SIGFRAME_CODE_OFFSET to compute the address where the
>> sigcontext
>> structure is located, but you still use it to compute the frame base
>> address (used when building the frame ID). Is the frame base address
>> still a constant offset from FUNC, or does the frame ID base address
>> also needs to be changed.
>
> Right, I missed that part. When it started working, I stopped patching.
> I will take another look at that part.
>
>
Here is the revised patch fixing the issue Joel noted.
From the original message:
The current signal frame unwinding code in mips-linux-tdep.c assumes
a constant offset from the signal return trampoline to the signal
frame. The assumption does not hold for all kernels. Specifically
those that have to be compiled with ICACHE_REFILLS_WORKAROUND_WAR
set (SGI O2 for example). In the near future, it is likely that the
assumption will cease to hold universally, as we are attempting to
move the signal return trampoline off the stack entirely.
The libgcc unwinder already gets this right by using the signal
frame's SP to locate the sigcontext.
This patch makes gdb follow suit and find the sigcontext_base using
the signal frame's SP rather than an offset from the trampoline.
Tested on mips64-linux with no regressions (and more than 100
improvements).
OK to commit?
How about on the 7.1 branch?
2010-02-26 David Daney <ddaney.caviumnetworks.com>
* mips-linux-tdep.c: Update struct sigframe comments.
(SIGFRAME_CODE_OFFSET): Delete macro.
(mips_linux_o32_sigframe_init): Calculate sigcontext_base using
this_frame's sp.
(mips_linux_n32n64_sigframe_init): Same.
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Index: gdb/mips-linux-tdep.c
===================================================================
RCS file: /cvs/src/src/gdb/mips-linux-tdep.c,v
retrieving revision 1.81
diff -u -p -r1.81 mips-linux-tdep.c
--- gdb/mips-linux-tdep.c 1 Jan 2010 07:31:37 -0000 1.81
+++ gdb/mips-linux-tdep.c 25 Feb 2010 20:27:05 -0000
@@ -797,7 +797,7 @@ static const struct tramp_frame mips_lin
struct sigframe {
u32 sf_ass[4]; [argument save space for o32]
- u32 sf_code[2]; [signal trampoline]
+ u32 sf_code[2]; [signal trampoline or fill]
struct sigcontext sf_sc;
sigset_t sf_mask;
};
@@ -827,7 +827,7 @@ static const struct tramp_frame mips_lin
struct rt_sigframe {
u32 rs_ass[4]; [argument save space for o32]
- u32 rs_code[2] [signal trampoline]
+ u32 rs_code[2] [signal trampoline or fill]
struct siginfo rs_info;
struct ucontext rs_uc;
};
@@ -842,7 +842,6 @@ static const struct tramp_frame mips_lin
}; */
/* *INDENT-ON* */
-#define SIGFRAME_CODE_OFFSET (4 * 4)
#define SIGFRAME_SIGCONTEXT_OFFSET (6 * 4)
#define RTSIGFRAME_SIGINFO_SIZE 128
@@ -871,14 +870,15 @@ mips_linux_o32_sigframe_init (const stru
{
struct gdbarch *gdbarch = get_frame_arch (this_frame);
int ireg, reg_position;
- CORE_ADDR sigcontext_base = func - SIGFRAME_CODE_OFFSET;
+ CORE_ADDR frame_sp = get_frame_sp (this_frame);
+ CORE_ADDR sigcontext_base;
const struct mips_regnum *regs = mips_regnum (gdbarch);
CORE_ADDR regs_base;
if (self == &mips_linux_o32_sigframe)
- sigcontext_base += SIGFRAME_SIGCONTEXT_OFFSET;
+ sigcontext_base = frame_sp + SIGFRAME_SIGCONTEXT_OFFSET;
else
- sigcontext_base += RTSIGFRAME_SIGCONTEXT_OFFSET;
+ sigcontext_base = frame_sp + RTSIGFRAME_SIGCONTEXT_OFFSET;
/* I'm not proud of this hack. Eventually we will have the
infrastructure to indicate the size of saved registers on a
@@ -947,9 +947,7 @@ mips_linux_o32_sigframe_init (const stru
sigcontext_base + SIGCONTEXT_BADVADDR);
/* Choice of the bottom of the sigframe is somewhat arbitrary. */
- trad_frame_set_id (this_cache,
- frame_id_build (func - SIGFRAME_CODE_OFFSET,
- func));
+ trad_frame_set_id (this_cache, frame_id_build (frame_sp, func));
}
/* *INDENT-OFF* */
@@ -957,7 +955,7 @@ mips_linux_o32_sigframe_init (const stru
struct rt_sigframe_n32 {
u32 rs_ass[4]; [ argument save space for o32 ]
- u32 rs_code[2]; [ signal trampoline ]
+ u32 rs_code[2]; [ signal trampoline or fill ]
struct siginfo rs_info;
struct ucontextn32 rs_uc;
};
@@ -1038,13 +1036,14 @@ mips_linux_n32n64_sigframe_init (const s
{
struct gdbarch *gdbarch = get_frame_arch (this_frame);
int ireg, reg_position;
- CORE_ADDR sigcontext_base = func - SIGFRAME_CODE_OFFSET;
+ CORE_ADDR frame_sp = get_frame_sp (this_frame);
+ CORE_ADDR sigcontext_base;
const struct mips_regnum *regs = mips_regnum (gdbarch);
if (self == &mips_linux_n32_rt_sigframe)
- sigcontext_base += N32_SIGFRAME_SIGCONTEXT_OFFSET;
+ sigcontext_base = frame_sp + N32_SIGFRAME_SIGCONTEXT_OFFSET;
else
- sigcontext_base += N64_SIGFRAME_SIGCONTEXT_OFFSET;
+ sigcontext_base = frame_sp + N64_SIGFRAME_SIGCONTEXT_OFFSET;
if (mips_linux_restart_reg_p (gdbarch))
trad_frame_set_reg_addr (this_cache,
@@ -1082,9 +1081,7 @@ mips_linux_n32n64_sigframe_init (const s
sigcontext_base + N64_SIGCONTEXT_LO);
/* Choice of the bottom of the sigframe is somewhat arbitrary. */
- trad_frame_set_id (this_cache,
- frame_id_build (func - SIGFRAME_CODE_OFFSET,
- func));
+ trad_frame_set_id (this_cache, frame_id_build (frame_sp, func));
}
static void
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