[PATCH v2] powerpc/bpf/32: Fix Oops on tail call tests

[Michael Ellerman]

On Thu, 24 Nov 2022 09:37:27 +0100, Christophe Leroy wrote:
> test_bpf tail call tests end up as:
> 
>   test_bpf: #0 Tail call leaf jited:1 85 PASS
>   test_bpf: #1 Tail call 2 jited:1 111 PASS
>   test_bpf: #2 Tail call 3 jited:1 145 PASS
>   test_bpf: #3 Tail call 4 jited:1 170 PASS
>   test_bpf: #4 Tail call load/store leaf jited:1 190 PASS
>   test_bpf: #5 Tail call load/store jited:1
>   BUG: Unable to handle kernel data access on write at 0xf1b4e000
>   Faulting instruction address: 0xbe86b710
>   Oops: Kernel access of bad area, sig: 11 [#1]
>   BE PAGE_SIZE=4K MMU=Hash PowerMac
>   Modules linked in: test_bpf(+)
>   CPU: 0 PID: 97 Comm: insmod Not tainted 6.1.0-rc4+ #195
>   Hardware name: PowerMac3,1 750CL 0x87210 PowerMac
>   NIP:  be86b710 LR: be857e88 CTR: be86b704
>   REGS: f1b4df20 TRAP: 0300   Not tainted  (6.1.0-rc4+)
>   MSR:  00009032 <EE,ME,IR,DR,RI>  CR: 28008242  XER: 00000000
>   DAR: f1b4e000 DSISR: 42000000
>   GPR00: 00000001 f1b4dfe0 c11d2280 00000000 00000000 00000000 00000002 00000000
>   GPR08: f1b4e000 be86b704 f1b4e000 00000000 00000000 100d816a f2440000 fe73baa8
>   GPR16: f2458000 00000000 c1941ae4 f1fe2248 00000045 c0de0000 f2458030 00000000
>   GPR24: 000003e8 0000000f f2458000 f1b4dc90 3e584b46 00000000 f24466a0 c1941a00
>   NIP [be86b710] 0xbe86b710
>   LR [be857e88] __run_one+0xec/0x264 [test_bpf]
>   Call Trace:
>   [f1b4dfe0] [00000002] 0x2 (unreliable)
>   Instruction dump:
>   XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX
>   XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX
>   ---[ end trace 0000000000000000 ]---
> 
> [...]

Applied to powerpc/fixes.

[1/1] powerpc/bpf/32: Fix Oops on tail call tests
      https://git.kernel.org/powerpc/c/89d21e259a94f7d5582ec675aa445f5a79f347e4

cheers