diff options
Diffstat (limited to 'arch/x86/kernel')
| -rw-r--r-- | arch/x86/kernel/cpu/perf_event_intel_ds.c | 21 |
1 files changed, 19 insertions, 2 deletions
diff --git a/arch/x86/kernel/cpu/perf_event_intel_ds.c b/arch/x86/kernel/cpu/perf_event_intel_ds.c index a67fff14475..e7ac51770d4 100644 --- a/arch/x86/kernel/cpu/perf_event_intel_ds.c +++ b/arch/x86/kernel/cpu/perf_event_intel_ds.c @@ -399,10 +399,23 @@ static int intel_pmu_pebs_fixup_ip(struct pt_regs *regs) if (!x86_pmu.intel_cap.pebs_trap) return 1; + /* + * No LBR entry, no basic block, no rewinding + */ if (!cpuc->lbr_stack.nr || !from || !to) return 0; - if (ip < to) + /* + * Basic blocks should never cross user/kernel boundaries + */ + if (kernel_ip(ip) != kernel_ip(to)) + return 0; + + /* + * unsigned math, either ip is before the start (impossible) or + * the basic block is larger than 1 page (sanity) + */ + if ((ip - to) > PAGE_SIZE) return 0; /* @@ -420,7 +433,7 @@ static int intel_pmu_pebs_fixup_ip(struct pt_regs *regs) old_to = to; if (!kernel_ip(ip)) { - int bytes, size = min_t(int, MAX_INSN_SIZE, ip - to); + int bytes, size = MAX_INSN_SIZE; bytes = copy_from_user_nmi(buf, (void __user *)to, size); if (bytes != size) @@ -440,6 +453,10 @@ static int intel_pmu_pebs_fixup_ip(struct pt_regs *regs) return 1; } + /* + * Even though we decoded the basic block, the instruction stream + * never matched the given IP, either the TO or the IP got corrupted. + */ return 0; } |