[PATCH] powerpc/8xx: Fix kernel DTLB miss on dcbz

[Michael Ellerman]

On Sat, 05 Oct 2024 10:53:29 +0200, Christophe Leroy wrote:
> Following OOPS is encountered while loading test_bpf module
> on powerpc 8xx:
> 
> [  218.835567] BUG: Unable to handle kernel data access on write at 0xcb000000
> [  218.842473] Faulting instruction address: 0xc0017a80
> [  218.847451] Oops: Kernel access of bad area, sig: 11 [#1]
> [  218.852854] BE PAGE_SIZE=16K PREEMPT CMPC885
> [  218.857207] SAF3000 DIE NOTIFICATION
> [  218.860713] Modules linked in: test_bpf(+) test_module
> [  218.865867] CPU: 0 UID: 0 PID: 527 Comm: insmod Not tainted 6.11.0-s3k-dev-09856-g3de3d71ae2e6-dirty #1280
> [  218.875546] Hardware name: MIAE 8xx 0x500000 CMPC885
> [  218.880521] NIP:  c0017a80 LR: beab859c CTR: 000101d4
> [  218.885584] REGS: cac2bc90 TRAP: 0300   Not tainted  (6.11.0-s3k-dev-09856-g3de3d71ae2e6-dirty)
> [  218.894308] MSR:  00009032 <EE,ME,IR,DR,RI>  CR: 55005555  XER: a0007100
> [  218.901290] DAR: cb000000 DSISR: c2000000
> [  218.901290] GPR00: 000185d1 cac2bd50 c21b9580 caf7c030 c3883fcc 00000008 cafffffc 00000000
> [  218.901290] GPR08: 00040000 18300000 20000000 00000004 99005555 100d815e ca669d08 00000369
> [  218.901290] GPR16: ca730000 00000000 ca2c004c 00000000 00000000 0000035d 00000311 00000369
> [  218.901290] GPR24: ca732240 00000001 00030ba3 c3800000 00000000 00185d48 caf7c000 ca2c004c
> [  218.941087] NIP [c0017a80] memcpy+0x88/0xec
> [  218.945277] LR [beab859c] test_bpf_init+0x22c/0x3c90 [test_bpf]
> [  218.951476] Call Trace:
> [  218.953916] [cac2bd50] [beab8570] test_bpf_init+0x200/0x3c90 [test_bpf] (unreliable)
> [  218.962034] [cac2bde0] [c0004c04] do_one_initcall+0x4c/0x1fc
> [  218.967706] [cac2be40] [c00a2ec4] do_init_module+0x68/0x360
> [  218.973292] [cac2be60] [c00a5194] init_module_from_file+0x8c/0xc0
> [  218.979401] [cac2bed0] [c00a5568] sys_finit_module+0x250/0x3f0
> [  218.985248] [cac2bf20] [c000e390] system_call_exception+0x8c/0x15c
> [  218.991444] [cac2bf30] [c00120a8] ret_from_syscall+0x0/0x28
> 
> [...]

Applied to powerpc/fixes.

[1/1] powerpc/8xx: Fix kernel DTLB miss on dcbz
      https://git.kernel.org/powerpc/c/8956c582ac6b1693a351230179f898979dd00bdf

cheers