On Thu, 15 Jun 2023 14:40:47 +0530, Aditya Gupta wrote:

ppc_save_regs() skips one stack frame while saving the CPU register states.
Instead of saving current R1, it pulls the previous stack frame pointer.

When vmcores caused by direct panic call (such as `echo c >
/proc/sysrq-trigger`), are debugged with gdb, gdb fails to show the
backtrace correctly. On further analysis, it was found that it was because
of mismatch between r1 and NIP.

[...]

Applied to powerpc/next.

[1/1] powerpc: update ppc_save_regs to save current r1 in pt_regs
      https://git.kernel.org/powerpc/c/b684c09f09e7a6af3794d4233ef785819e72db79

cheers