diff options
| author | Athira Rajeev <atrajeev@linux.vnet.ibm.com> | 2021-06-17 13:55:06 -0400 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2021-06-18 16:30:36 +1000 |
| commit | 60b7ed54a41b550d50caf7f2418db4a7e75b5bdc (patch) | |
| tree | d018242f18c748c09a3371434cc72fd0b91f2686 | |
| parent | 478036c4cd1a16e613a2f883d79c03cf187faacb (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: stable@vger.kernel.org # v5.11+
Reported-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Tested-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/1623952506-1431-1-git-send-email-atrajeev@linux.vnet.ibm.com
| -rw-r--r-- | arch/powerpc/perf/core-book3s.c | 2 |
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; else |