On Wed, Jun 25, 2025 at 12:04 PM <devel-requ...@lists.crash-utility.osci.io>
wrote:

> Date: Wed, 25 Jun 2025 16:01:58 +1200
> From: Tao Liu <l...@redhat.com>
> Subject: [Crash-utility] [PATCH v4 0/5] gdb multi-stack unwinding
>         support
> To: devel@lists.crash-utility.osci.io
> Cc: Tao Liu <l...@redhat.com>
> Message-ID: <20250625040203.60334-1-l...@redhat.com>
> Content-Type: text/plain; charset="US-ASCII"; x-default=true
>
> This patchset is based on Alexy's work [1], and is the follow-up of the
> previous "gdb stack unwinding support for crash utility" patchset.
>
> Currently gdb target analyzes only one task at a time and it backtraces
> only straight stack until end of the stack. If stacks were concatenated
> during exceptions or interrupts, gdb bt will show only the topmost one.
>
> This patchset will introduce multiple stacks support for gdb stack
> unwinding,
> which can be observed as a different threads from gdb perspective. A
> short usage is as follows:
>
>     'set <PID>'        - to switch to a specific task
>     'gdb info threads' - to see list of in-kernel stacks of this task.
>     'gdb thread <ID>'  - to switch to the stack.
>     'gdb bt'           - to unwind it.
>
> E.g, with the patchset:
>
> crash> bt
> PID: 17636    TASK: ffff88032e0742c0  CPU: 11   COMMAND: "kworker/11:4"
>  #0 [ffff88037fca6b58] machine_kexec at ffffffff8103cef2
>  #1 [ffff88037fca6ba8] crash_kexec at ffffffff810c9aa3
>  #2 [ffff88037fca6c70] panic at ffffffff815f0444
>  ...
>  #9 [ffff88037fca6ec8] do_nmi at ffffffff815fd980
> #10 [ffff88037fca6ef0] end_repeat_nmi at ffffffff815fcec1
>     [exception RIP: memcpy+13]
>     RIP: ffffffff812f5b1d  RSP: ffff88034f2a9728  RFLAGS: 00010046
>     RAX: ffffc900139fe000  RBX: ffff880374b7a1b0  RCX: 0000000000000030
>     RBP: ffff88034f2a9778   R8: 000000007fffffff   R9: 00000000ffffffff
>     ...
>     ORIG_RAX: ffffffffffffffff  CS: 0010  SS: 0018
> --- <NMI exception stack> ---
> #11 [ffff88034f2a9728] memcpy at ffffffff812f5b1d
> #12 [ffff88034f2a9728] mga_dirty_update at ffffffffa024ad2b [mgag200]
> #13 [ffff88034f2a9780] mga_imageblit at ffffffffa024ae3f [mgag200]
> #14 [ffff88034f2a97a0] bit_putcs at ffffffff813424ef
> ...
>
> crash> info threads
>   Id   Target Id                    Frame
> * 1    17636 kworker/11:4 (stack 0) crash_setup_regs (oldregs=0x0,
> newregs=0xffff88037fca6bb0)
>   2    17636 kworker/11:4 (stack 1) 0xffffffff812f5b1d in memcpy ()
>
> crash> thread 2
> crash> gdb bt
> #0  0xffffffff812f5b1d in memcpy () at arch/x86/lib/memcpy_64.S:69
> ...
>
> There are 2 stacks of the current task, and we can list/switch-to/unwind
> each stack.
>
> [1]:
> https://www.mail-archive.com/devel@lists.crash-utility.osci.io/msg01204.html
>
> v2 -> v1: 1) Rebase this patchset onto gdb-16.2 [2].
>           2) Improved the silent_call_bt() to catch the error FATAL.
>
> [2]:
> https://www.mail-archive.com/devel@lists.crash-utility.osci.io/msg01354.html
>
> v3 -> v2: 1) Rebase this patchset to crash v9.0.0.
>           2) Fix v2's segfault in cmd "bt -E".
>           3) Elimit repeat stacks by adding constraints before
>              gdb_add_substack().
>
> v4 -> v3: 1) Fix compiling warning of silent_call_bt()
>           2) Add known issue link found in ppc arch.
>
>
Thank you for the update, Tao.

For the v4: Ack

Thanks
Lianbo

Tao Liu (5):
>   Add multi-threads support in crash target
>   Call cmd_bt silently after "set pid"
>   x86_64: Add gdb multi-stack unwind support
>   arm64: Add gdb multi-stack unwind support
>   ppc64: Add gdb multi-stack unwind support
>
>  arm64.c         | 102 +++++++++++++++++++++++++++++++++--
>  crash_target.c  |  49 +++++++++++++++--
>  defs.h          |   3 +-
>  gdb_interface.c |   6 +--
>  kernel.c        |  44 +++++++++++++++
>  ppc64.c         |  78 ++++++++++++++++++++++++---
>  task.c          |   4 +-
>  x86_64.c        | 138 +++++++++++++++++++++++++++++++++++++++++++++---
>  8 files changed, 394 insertions(+), 30 deletions(-)
>
> --
> 2.47.0
>
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