[PATCH 12/31] perf, x86: Disable LBR recording for unknown LBR_FMT

[Andi Kleen]

From: Andi Kleen <ak@xxxxxxxxxxxxxxx>

When the LBR format is unknown disable LBR recording. This prevents
crashes when the LBR address is misdecoded and mis-sign extended.

Signed-off-by: Andi Kleen <ak@xxxxxxxxxxxxxxx>
---
 arch/x86/kernel/cpu/perf_event_intel_lbr.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/arch/x86/kernel/cpu/perf_event_intel_lbr.c b/arch/x86/kernel/cpu/perf_event_intel_lbr.c
index 2af6695b..ad5af13 100644
--- a/arch/x86/kernel/cpu/perf_event_intel_lbr.c
+++ b/arch/x86/kernel/cpu/perf_event_intel_lbr.c
@@ -13,6 +13,7 @@ enum {
 	LBR_FORMAT_EIP		= 0x02,
 	LBR_FORMAT_EIP_FLAGS	= 0x03,
 	LBR_FORMAT_EIP_FLAGS2	= 0x04,
+	LBR_FORMAT_MAX_KNOWN	= LBR_FORMAT_EIP_FLAGS2,
 };
 
 /*
@@ -392,7 +393,7 @@ int intel_pmu_setup_lbr_filter(struct perf_event *event)
 	/*
 	 * no LBR on this PMU
 	 */
-	if (!x86_pmu.lbr_nr)
+	if (!x86_pmu.lbr_nr || x86_pmu.intel_cap.lbr_format > LBR_FORMAT_MAX_KNOWN)
 		return -EOPNOTSUPP;
 
 	/*
-- 
1.7.7.6

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