From: Sebastian Andrzej Siewior <bige...@linutronix.de>
Since commit 4d4c47412464 ("perf/x86/intel/bts: Fix BTS PMI detection")
my box goes boom on boot:
| .... node #0, CPUs: #1 #2 #3 #4 #5 #6 #7
| BUG: unable to handle kernel NULL pointer dereference at 0000000000000018
| IP: [<ffffffff8100c463>] intel_bts_interrupt+0x43/0x130
| Call Trace:
| <NMI> d [<ffffffff8100b341>] intel_pmu_handle_irq+0x51/0x4b0
| [<ffffffff81004d47>] perf_event_nmi_handler+0x27/0x40
I don't know what is going on here but ds is not always dereferenced
unconditionally hence here the `ds' check to avoid the crash.
Fixes: 4d4c47412464 ("perf/x86/intel/bts: Fix BTS PMI detection")
Signed-off-by: Sebastian Andrzej Siewior <bige...@linutronix.de>
---
arch/x86/events/intel/bts.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/events/intel/bts.c b/arch/x86/events/intel/bts.c
index bdcd6510992c..6ff66efa0feb 100644
--- a/arch/x86/events/intel/bts.c
+++ b/arch/x86/events/intel/bts.c
@@ -455,7 +455,7 @@ int intel_bts_interrupt(void)
* The only surefire way of knowing if this NMI is ours is by checking
* the write ptr against the PMI threshold.
*/
- if (ds->bts_index >= ds->bts_interrupt_threshold)
+ if (ds && (ds->bts_index >= ds->bts_interrupt_threshold))
handled = 1;
/*
--
2.9.3
