Kernel v6.17-rc4 with STATIC_CALL_SELFTEST=y enabled fails to boot at early stage (PowerMac G4 DP)

[Christophe Leroy]

Hi Erhard,

Le 04/09/2025 à 00:44, Erhard Furtner a écrit :
> Greetings!
> 
> In a conversation with Andrew about his page table check code for 
> PowerPC he found out there seems to be a general problem of the code 
> patching code on ppc:
> 
>  > I note that STATIC_CALL_SELFTEST seems to fail, which could be but isn't
>  > necessarily related.
> 
>  > Specifically, it looks like code patching fails if the instruction 
> being patched
>  > is in an __init function, and in this case, that occurs due to
>  > page_table_check_pte_clear() being inlined into ptep_clear(), which 
> is in turn
>  > inlined into pte_clear_tests() in debug_vm_pgtable.c which is marked 
> __init.
>  > Very curious!
> 
> Indeed, when I enable STATIC_CALL_SELFTEST=y on my G4 the kernel fails 
> to boot at an early stage, the OpenFirmware console showing only:
> 
> done
> found display   : /pci at f0000000/ATY,AlteracParent at 10/ATY,Alterac_B at 1, 
> opening...
> 
> Without STATIC_CALL_SELFTEST the kernel boots just fine.
> 
> Kernel .config attached.

With your .config, on QEMU I get the following. I will investigate.

[    0.000000] Kernel panic - not syncing: arch_static_call_transform: 
patching failed func_a+0x0/0x10 at 0x0
[    0.000000] CPU: 0 UID: 0 PID: 0 Comm: swapper Not tainted 
6.17.0-rc4-PMacG4+ #1628 PREEMPTLAZY
[    0.000000] Hardware name: PowerMac3,1 7400 0xc0209 PowerMac
[    0.000000] Call Trace:
[    0.000000] [c0dd7e60] [c0810e54] dump_stack_lvl+0x70/0x8c (unreliable)
[    0.000000] [c0dd7e80] [c004b220] vpanic+0x114/0x2e4
[    0.000000] [c0dd7eb0] [c004b45c] arch_set_bit+0x0/0x38
[    0.000000] [c0dd7f00] [c00155fc] arch_static_call_transform+0xec/0x1e8
[    0.000000] [c0dd7f30] [c0176944] __static_call_init+0x110/0x288
[    0.000000] [c0dd7f80] [c0c19ab0] static_call_init+0x4c/0x9c
[    0.000000] [c0dd7fa0] [c0c02e00] start_kernel+0x7c/0x664
[    0.000000] [c0dd7ff0] [000035d0] 0x35d0
[    0.000000] Rebooting in 40 seconds..

Christophe