Commit-ID: f1e1c9e5e357c05253affb13be29285c5cb56bf0
Gitweb: http://git.kernel.org/tip/f1e1c9e5e357c05253affb13be29285c5cb56bf0
Author: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
AuthorDate: Tue, 20 Sep 2016 15:12:21 +0200
Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitDate: Tue, 20 Sep 2016 16:06:09 +0200
perf/x86/intel/bts: Make sure debug store is valid
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
This happens because the code introduced in this commit dereferences the
debug store pointer unconditionally. The debug store is not guaranteed to
be available, so a NULL pointer check as on other places is required.
Fixes: 4d4c47412464 ("perf/x86/intel/bts: Fix BTS PMI detection")
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
Reviewed-by: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: vince@xxxxxxxxxx
Cc: eranian@xxxxxxxxxx
Link: http://lkml.kernel.org/r/20160920131220.xg5pbdjtznszuyzb@xxxxxxxxxxxxx
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
---
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 bdcd651..6ff66ef 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;
/*
--
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