Messages in this thread Patch in this message | | | Date | Tue, 20 Sep 2016 07:13:47 -0700 | From | tip-bot for Sebastian Andrzej Siewior <> | Subject | [tip:perf/urgent] perf/x86/intel/bts: Make sure debug store is valid |
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Commit-ID: f1e1c9e5e357c05253affb13be29285c5cb56bf0 Gitweb: http://git.kernel.org/tip/f1e1c9e5e357c05253affb13be29285c5cb56bf0 Author: Sebastian Andrzej Siewior <bigeasy@linutronix.de> AuthorDate: Tue, 20 Sep 2016 15:12:21 +0200 Committer: Thomas Gleixner <tglx@linutronix.de> 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@linutronix.de> Reviewed-by: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Arnaldo Carvalho de Melo <acme@infradead.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: vince@deater.net Cc: eranian@google.com Link: http://lkml.kernel.org/r/20160920131220.xg5pbdjtznszuyzb@breakpoint.cc Signed-off-by: Thomas Gleixner <tglx@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 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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