[PATCH V2] powerpc/perf: Fix crash with is_sier_available when pmu is not set

[Michael Ellerman]

On Mon, 23 Nov 2020 21:40:40 -0500, Athira Rajeev wrote:
> On systems without any specific PMU driver support registered, running
> 'perf record' with —intr-regs  will crash ( perf record -I <workload> ).
> 
> The relevant portion from crash logs and Call Trace:
> 
> Unable to handle kernel paging request for data at address 0x00000068
> Faulting instruction address: 0xc00000000013eb18
> Oops: Kernel access of bad area, sig: 11 [#1]
> CPU: 2 PID: 13435 Comm: kill Kdump: loaded Not tainted 4.18.0-193.el8.ppc64le #1
> NIP:  c00000000013eb18 LR: c000000000139f2c CTR: c000000000393d80
> REGS: c0000004a07ab4f0 TRAP: 0300   Not tainted  (4.18.0-193.el8.ppc64le)
> NIP [c00000000013eb18] is_sier_available+0x18/0x30
> LR [c000000000139f2c] perf_reg_value+0x6c/0xb0
> Call Trace:
> [c0000004a07ab770] [c0000004a07ab7c8] 0xc0000004a07ab7c8 (unreliable)
> [c0000004a07ab7a0] [c0000000003aa77c] perf_output_sample+0x60c/0xac0
> [c0000004a07ab840] [c0000000003ab3f0] perf_event_output_forward+0x70/0xb0
> [c0000004a07ab8c0] [c00000000039e208] __perf_event_overflow+0x88/0x1a0
> [c0000004a07ab910] [c00000000039e42c] perf_swevent_hrtimer+0x10c/0x1d0
> [c0000004a07abc50] [c000000000228b9c] __hrtimer_run_queues+0x17c/0x480
> [c0000004a07abcf0] [c00000000022aaf4] hrtimer_interrupt+0x144/0x520
> [c0000004a07abdd0] [c00000000002a864] timer_interrupt+0x104/0x2f0
> [c0000004a07abe30] [c0000000000091c4] decrementer_common+0x114/0x120
> 
> [...]

Applied to powerpc/next.

[1/1] powerpc/perf: Fix crash with is_sier_available when pmu is not set
      https://git.kernel.org/powerpc/c/f75e7d73bdf73f07b0701a6d21c111ef5d9021dd

cheers