diff options
author | Kan Liang <kan.liang@linux.intel.com> | 2022-07-14 11:26:30 -0700 |
---|---|---|
committer | Peter Zijlstra <peterz@infradead.org> | 2022-07-20 19:24:55 +0200 |
commit | b0380e13502adf7dd8be4c47d622c3522aae6c63 (patch) | |
tree | 2fd5198579d400115220d5763424e8520fe00eb6 /arch/x86/events/intel/lbr.c | |
parent | ff6992735ade75aae3e35d16b17da1008d753d28 (diff) | |
download | linux-b0380e13502adf7dd8be4c47d622c3522aae6c63.tar.bz2 |
perf/x86/intel/lbr: Fix unchecked MSR access error on HSW
The fuzzer triggers the below trace.
[ 7763.384369] unchecked MSR access error: WRMSR to 0x689
(tried to write 0x1fffffff8101349e) at rIP: 0xffffffff810704a4
(native_write_msr+0x4/0x20)
[ 7763.397420] Call Trace:
[ 7763.399881] <TASK>
[ 7763.401994] intel_pmu_lbr_restore+0x9a/0x1f0
[ 7763.406363] intel_pmu_lbr_sched_task+0x91/0x1c0
[ 7763.410992] __perf_event_task_sched_in+0x1cd/0x240
On a machine with the LBR format LBR_FORMAT_EIP_FLAGS2, when the TSX is
disabled, a TSX quirk is required to access LBR from registers.
The lbr_from_signext_quirk_needed() is introduced to determine whether
the TSX quirk should be applied. However, the
lbr_from_signext_quirk_needed() is invoked before the
intel_pmu_lbr_init(), which parses the LBR format information. Without
the correct LBR format information, the TSX quirk never be applied.
Move the lbr_from_signext_quirk_needed() into the intel_pmu_lbr_init().
Checking x86_pmu.lbr_has_tsx in the lbr_from_signext_quirk_needed() is
not required anymore.
Both LBR_FORMAT_EIP_FLAGS2 and LBR_FORMAT_INFO have LBR_TSX flag, but
only the LBR_FORMAT_EIP_FLAGS2 requirs the quirk. Update the comments
accordingly.
Fixes: 1ac7fd8159a8 ("perf/x86/intel/lbr: Support LBR format V7")
Reported-by: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20220714182630.342107-1-kan.liang@linux.intel.com
Diffstat (limited to 'arch/x86/events/intel/lbr.c')
-rw-r--r-- | arch/x86/events/intel/lbr.c | 19 |
1 files changed, 10 insertions, 9 deletions
diff --git a/arch/x86/events/intel/lbr.c b/arch/x86/events/intel/lbr.c index 13179f31fe10..4f70fb6c2c1e 100644 --- a/arch/x86/events/intel/lbr.c +++ b/arch/x86/events/intel/lbr.c @@ -278,9 +278,9 @@ enum { }; /* - * For formats with LBR_TSX flags (e.g. LBR_FORMAT_EIP_FLAGS2), bits 61:62 in - * MSR_LAST_BRANCH_FROM_x are the TSX flags when TSX is supported, but when - * TSX is not supported they have no consistent behavior: + * For format LBR_FORMAT_EIP_FLAGS2, bits 61:62 in MSR_LAST_BRANCH_FROM_x + * are the TSX flags when TSX is supported, but when TSX is not supported + * they have no consistent behavior: * * - For wrmsr(), bits 61:62 are considered part of the sign extension. * - For HW updates (branch captures) bits 61:62 are always OFF and are not @@ -288,7 +288,7 @@ enum { * * Therefore, if: * - * 1) LBR has TSX format + * 1) LBR format LBR_FORMAT_EIP_FLAGS2 * 2) CPU has no TSX support enabled * * ... then any value passed to wrmsr() must be sign extended to 63 bits and any @@ -300,7 +300,7 @@ static inline bool lbr_from_signext_quirk_needed(void) bool tsx_support = boot_cpu_has(X86_FEATURE_HLE) || boot_cpu_has(X86_FEATURE_RTM); - return !tsx_support && x86_pmu.lbr_has_tsx; + return !tsx_support; } static DEFINE_STATIC_KEY_FALSE(lbr_from_quirk_key); @@ -1609,9 +1609,6 @@ void intel_pmu_lbr_init_hsw(void) x86_pmu.lbr_sel_map = hsw_lbr_sel_map; x86_get_pmu(smp_processor_id())->task_ctx_cache = create_lbr_kmem_cache(size, 0); - - if (lbr_from_signext_quirk_needed()) - static_branch_enable(&lbr_from_quirk_key); } /* skylake */ @@ -1702,7 +1699,11 @@ void intel_pmu_lbr_init(void) switch (x86_pmu.intel_cap.lbr_format) { case LBR_FORMAT_EIP_FLAGS2: x86_pmu.lbr_has_tsx = 1; - fallthrough; + x86_pmu.lbr_from_flags = 1; + if (lbr_from_signext_quirk_needed()) + static_branch_enable(&lbr_from_quirk_key); + break; + case LBR_FORMAT_EIP_FLAGS: x86_pmu.lbr_from_flags = 1; break; |