On 25/11/06 04:06PM, Tao Liu wrote:
> A error stack trace of bt cmd observed:
>
> crash> bt 1
> PID: 1 TASK: c000000003714b80 CPU: 2 COMMAND: "systemd"
> #0 [c0000000037735c0] _end at c0000000037154b0 (unreliable)
> #1 [c000000003773770] __switch_to at c00000000001fa9c
> #2 [c0000000037737d0] __schedule at c00000000112e4ec
> #3 [c0000000037738b0] schedule at c00000000112ea80
> ...
>
> The #0 stack trace is incorrect, the function address shouldn't exceed _end.
> The reason is for kernel commit cd52414d5a6c ("powerpc/64: ELFv2 use
> minimal stack frames in int and switch frame sizes"), the offset of pt_regs
> to sp changed from STACK_FRAME_OVERHEAD, i.e 112, to STACK_SWITCH_FRAME_REGS.
> For CONFIG_PPC64_ELF_ABI_V1, it's 112, for ABI_V2, it's 48. So the nip will
> read a wrong value from stack when ABI_V2 enabled.
>
> After the patch:
> crash> bt 1
> PID: 1 TASK: c000000003714b80 CPU: 2 COMMAND: "systemd"
> #0 [c0000000037737d0] __schedule at c00000000112e4ec
> #1 [c0000000037738b0] schedule at c00000000112ea80
> ...
>
> Signed-off-by: Tao Liu <[email protected]>
> Suggested-by: Aditya Gupta <[email protected]>
> ---
>
> v1 Discussion:
> https://www.mail-archive.com/[email protected]/msg01181.html
> v2 No discussion:
> https://www.mail-archive.com/[email protected]/msg01170.html
> v3 -> v2: Rebase to top-most of upstream patch
>
> Regarding to v1's discussion, we cannot run abiv1 program on abiv2
> kernel, it's because abiv1 is big-endian and abiv2 is little-endian, and
> abiv2, or ppc64le kernel doesn't support big-endian, or abiv1 program
> cannot run upon it, see the following:
>
> $ file blkid
> blkid: ELF 64-bit MSB executable, 64-bit PowerPC or cisco 7500, Power ELF V1
> ABI, version 1 (GNU/Linux), statically linked, for GNU/Linux 3.2.0,
> BuildID[sha1]=b36e8a2a5e4d27039591a35fca38fa48735f5540, stripped
> $ ~/qemu-10.1.2/build/qemu-ppc64 ./blkid
> /dev/mapper/root: UUID="..." TYPE="xfs"
> /dev/sda3: UUID="..." TYPE="LVM2_member" PARTUUID="..."
> /dev/sda2: UUID="..." TYPE="xfs" PARTUUID="..."
> /dev/mapper/swap: UUID="..." TYPE="swap"
> /dev/mapper/home: UUID="..." TYPE="xfs"
> /dev/sda1: PARTUUID="..."
> $ ./blkid
> -bash: ./blkid: cannot execute binary file: Exec format error
> $ uname -a
> Linux 6.12.0-150.el10.ppc64le #1 SMP Fri Oct 31 06:58:14 EDT 2025 ppc64le
> GNU/Linux
> $ file /bin/bash
> /bin/bash: ELF 64-bit LSB pie executable, 64-bit PowerPC or cisco 7500,
> OpenPOWER ELF V2 ABI, version 1 (SYSV), dynamically linked, interpreter
> /lib64/ld64.so.2, BuildID[sha1]=9ab800028ced16c5974f5b19cb6ed754178802a8, for
> GNU/Linux 3.10.0, stripped
>
> The abiv1 program blkid cannot be run on this machine, except with the
> help of qemu. So from my view, we don't need to consider the case that abiv2
> kernel might containing a abiv1 program or .ko.
>
> Please feel free to correct me if I'm wrong. @Aditya Gupta
>
> ---
> defs.h | 3 ++-
> netdump.c | 14 ++++++++++----
> ppc64.c | 34 +++++++++++++++++++++++++++++++---
> symbols.c | 5 +++--
> 4 files changed, 46 insertions(+), 10 deletions(-)
The patch looks good to me, also verified it with SLES and other vmcores
I had with 5.14 and 6.14 kernel, kdump-compressed/ELF formats.
Sorry for the delayed response, not actively working on crash from
sometime, and thanks for the patch Tao !
Reviewed-by: Aditya Gupta <[email protected]>
Thanks,
- Aditya G
--
Crash-utility mailing list -- [email protected]
To unsubscribe send an email to [email protected]
https://${domain_name}/admin/lists/devel.lists.crash-utility.osci.io/
Contribution Guidelines: https://github.com/crash-utility/crash/wiki
