Re: [PATCH] powerpc/970: fix nap return address corruption on async interrupt exit

[Madhavan Srinivasan]

On Tue, 07 Jul 2026 22:54:30 +0530, Mukesh Kumar Chaurasiya (IBM) wrote:
> On PowerMac G5 (PPC970, CONFIG_PPC_970_NAP) the system panics shortly
> after boot with symptoms including instruction fetch faults, kernel data
> access faults, and stack corruption, predominantly on SMP and always
> somewhere inside softirq processing.
> 
> The PPC970 idle path works by setting _TLF_NAPPING in the current
> thread's local flags before entering the MSR_POW nap loop.  When any
> async interrupt wakes the CPU, nap_adjust_return() is expected to detect
> _TLF_NAPPING, clear it, and rewrite regs->NIP to power4_idle_nap_return
> so that the interrupt returns cleanly to the caller of power4_idle_nap()
> rather than back into the nap spin loop.
> 
> [...]

Applied to powerpc/fixes.

[1/1] powerpc/970: fix nap return address corruption on async interrupt exit
      https://git.kernel.org/powerpc/c/bddf7540099bf653eaea339e886add6f62555cf3

cheers