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From: Vimal Agrawal <avimalin@gmail.com>
Date: Tue, 14 Dec 2021 15:52:13 +0530
Message-ID: <CALkUMdRboO3aPqKmkYJ_pkjeC1_vXYkc6eCNhFBodVpeR27oXQ@mail.gmail.com>
Subject: Not able to decode local/ stack variables in vmcore
To: gdb@sourceware.org
Cc: Vimal Agrawal <vimal.agrawal@sophos.com>
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I don't see any option to see local variables in vmcore using crash
utility. Tried gdb as well. Gdb is not able to dump stack.

(gdb) bt

#0  sysrq_handle_crash (key=99) at drivers/tty/sysrq.c:147

Backtrace stopped: Cannot access memory at address 0xffffb8c6c132fe40

(gdb) x 0xffffb8c6c132fe40

0xffffb8c6c132fe40: Cannot access memory at address 0xffffb8c6c132fe40

(gdb) info reg rsp

rsp            0xffffb8c6c132fe38 0xffffb8c6c132fe38

(gdb)


I have loaded symbols on specific .text, .data and .bss load addresses
using following commands:
> gdb -c kcrash_vmcore
gdb> add-symbol-file ~/crash3/vmlinux 0xffffffff97000000 -s .data
0xffffffff97c00000 -s .bss 0xffffffff97fa5000

I could decode .text and global .data symbols but not stack addresses
and local variables.
I have tried enabling CONFIG_FRAME_POINTER and also tried the latest
version of gdb and crash as well but no help.

Can someone please suggest and comment if this is indeed possible with
gdb/crash to decode local variables from vmcore?

Vimal Agrawal