[Crash-utility] Re: [PATCH v3] ppc64: Fix bt printing error stack trace

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 <ltao(a)redhat.com&gt; Suggested-by: Aditya Gupta <adityag(a)linux.ibm.com&gt; --- v1 Discussion: https://www.mail-archive.com/devel@lists.crash-utility.osci.io/msg01181.html v2 No discussion: https://www.mail-archive.com/devel@lists.crash-utility.osci.io/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(-)