On Mon, Sep 16, 2024 at 3:46 PM <devel-request@xxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
Date: Mon, 16 Sep 2024 19:44:58 +1200
From: Tao Liu <ltao@xxxxxxxxxx>
Subject: [PATCH] x86_64: Fix the bug of getting
incorrect framesize
To: devel@xxxxxxxxxxxxxxxxxxxxxxxxxxx
Cc: mycomplexlove@xxxxxxxxx
Message-ID: <20240916074458.105832-1-ltao@xxxxxxxxxx>
Content-Type: text/plain; charset="US-ASCII"; x-default=true
Previously, "retq" is used to determine the end of a function, so the end
of framesize calculation. However "ret" might be outputted by gdb rather
than "retq", as a result, the framesize is returned incorrectly, and bogus
stack trace will be outputted.
Without the patch:
$ crash -d 3 vmcore vmlinux
crash> bt
0xffffffff92da7545 <copy_process+5>: push %rbp [framesize: 8]
...
0xffffffff92da7561 <copy_process+33>: sub $0x238,%rsp [framesize: 624]
...
0xffffffff92da776a <copy_process+554>: pop %r15 [framesize: 8]
0xffffffff92da776c <copy_process+556>: pop %rbp [framesize: 0]
0xffffffff92da776d <copy_process+557>: ret
crash> bt -D dump
framesize_cache_entries:
...
[ 3]: ffffffff92dadcbd 0 CF (copy_process+26493)
crash> bt
...
#9 [ffff888263157bc0] copy_process at ffffffff92dadcbd
#10 [ffff888263157d20] __mutex_init at ffffffff92ed8dd5
#11 [ffff888263157d38] __alloc_file at ffffffff93458397
#12 [ffff888263157d60] alloc_empty_file at ffffffff934585d2
#13 [ffff888263157da8] __alloc_fd at ffffffff934b5ead
#14 [ffff888263157e38] _do_fork at ffffffff92dae7a1
#15 [ffff888263157f28] do_syscall_64 at ffffffff92c085f4
Stack #10 ~ #13 are bogus and misleading.
With the patch:
...
0xffffffff92da776d <copy_process+557>: ret [framesize restored to: 624]
crash> bt -D dump
...
[ 3]: ffffffff92dadcbd 624 CF (copy_process+26493)
crash> bt
...
#9 [ffff888263157bc0] copy_process at ffffffff92dadcbd
#10 [ffff888263157e38] _do_fork at ffffffff92dae7a1
#11 [ffff888263157f28] do_syscall_64 at ffffffff92c085f4
Signed-off-by: Tao Liu <ltao@xxxxxxxxxx>
---
x86_64.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/x86_64.c b/x86_64.c
index 469d26b..7aa9430 100644
--- a/x86_64.c
+++ b/x86_64.c
@@ -8781,7 +8781,8 @@ x86_64_get_framesize(struct bt_info *bt, ulong textaddr, ulong rsp, char *stack_
if (CRASHDEBUG(2) || (bt->flags & BT_FRAMESIZE_DEBUG))
fprintf(fp, "%s\t[framesize: %d]\n",
strip_linefeeds(buf2), framesize);
- } else if (STRNEQ(arglist[instr], "retq")) {
+ } else if (STRNEQ(arglist[instr], "retq") ||
+ STRNEQ(arglist[instr], "ret")) {
Thank you for the fix, Tao.
This looks good. Applied:
Lianbo
if (!exception) {
framesize = max;
if (CRASHDEBUG(2) || (bt->flags & BT_FRAMESIZE_DEBUG))
--
2.40.1
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