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Subject[PATCH 09/12] perf, x86: Disable LBR recording for unknown LBR_FMT
Date
From: Andi Kleen <ak@linux.intel.com>

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@linux.intel.com>
---
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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