[Crash-utility] Re: [PATCH] x86_64: Fix the bug of getting incorrect framesize

Date: Mon, 16 Sep 2024 19:44:58 +1200 From: Tao Liu <ltao(a)redhat.com&gt; Subject: [Crash-utility] [PATCH] x86_64: Fix the bug of getting incorrect framesize To: devel(a)lists.crash-utility.osci.io Cc: mycomplexlove(a)gmail.com Message-ID: <20240916074458.105832-1-ltao(a)redhat.com&gt; 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(a)redhat.com&gt; --- 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")) {

framesize = max; if (CRASHDEBUG(2) || (bt->flags & BT_FRAMESIZE_DEBUG)) -- 2.40.1