path: root/arch/powerpc
diff options
authorAthira Rajeev <>2021-06-17 13:55:06 -0400
committerMichael Ellerman <>2021-06-18 16:30:36 +1000
commit60b7ed54a41b550d50caf7f2418db4a7e75b5bdc (patch)
treed018242f18c748c09a3371434cc72fd0b91f2686 /arch/powerpc
parent478036c4cd1a16e613a2f883d79c03cf187faacb (diff)
powerpc/perf: Fix crash in perf_instruction_pointer() when ppmu is not set
On systems without any specific PMU driver support registered, running perf record causes Oops. The relevant portion from call trace: BUG: Kernel NULL pointer dereference on read at 0x00000040 Faulting instruction address: 0xc0021f0c Oops: Kernel access of bad area, sig: 11 [#1] BE PAGE_SIZE=4K PREEMPT CMPCPRO SAF3000 DIE NOTIFICATION CPU: 0 PID: 442 Comm: null_syscall Not tainted 5.13.0-rc6-s3k-dev-01645-g7649ee3d2957 #5164 NIP: c0021f0c LR: c00e8ad8 CTR: c00d8a5c NIP perf_instruction_pointer+0x10/0x60 LR perf_prepare_sample+0x344/0x674 Call Trace: perf_prepare_sample+0x7c/0x674 (unreliable) perf_event_output_forward+0x3c/0x94 __perf_event_overflow+0x74/0x14c perf_swevent_hrtimer+0xf8/0x170 __hrtimer_run_queues.constprop.0+0x160/0x318 hrtimer_interrupt+0x148/0x3b0 timer_interrupt+0xc4/0x22c Decrementer_virt+0xb8/0xbc During perf record session, perf_instruction_pointer() is called to capture the sample IP. This function in core-book3s accesses ppmu->flags. If a platform specific PMU driver is not registered, ppmu is set to NULL and accessing its members results in a crash. Fix this crash by checking if ppmu is set. Fixes: 2ca13a4cc56c ("powerpc/perf: Use regs->nip when SIAR is zero") Cc: # v5.11+ Reported-by: Christophe Leroy <> Signed-off-by: Athira Rajeev <> Tested-by: Christophe Leroy <> Signed-off-by: Michael Ellerman <> Link:
Diffstat (limited to 'arch/powerpc')
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/powerpc/perf/core-book3s.c b/arch/powerpc/perf/core-book3s.c
index 16d4d1b6a1ff..51622411a7cc 100644
--- a/arch/powerpc/perf/core-book3s.c
+++ b/arch/powerpc/perf/core-book3s.c
@@ -2254,7 +2254,7 @@ unsigned long perf_instruction_pointer(struct pt_regs *regs)
bool use_siar = regs_use_siar(regs);
unsigned long siar = mfspr(SPRN_SIAR);
- if (ppmu->flags & PPMU_P10_DD1) {
+ if (ppmu && (ppmu->flags & PPMU_P10_DD1)) {
if (siar)
return siar;