perf_clear_branch_entry_bitfields() clears the bitfields of struct perf_branch_entry one by one and leaves from/to alone, since callers overwrite those straight away. The list has to be kept in sync with the struct by hand and has already fallen behind: new_type and priv were added to perf_branch_entry and never added here. Only BRBE writes those two, and neither is written for every record. brbe_set_perf_entry_type() leaves new_type alone for a branch type it does not recognise, and priv is not set for source-only records. arm_pmuv3.c allocates the per-CPU branch stack with kmalloc(), so such a record carries whatever the slot held: uninitialised kmalloc() data on the first pass over the buffer, the previous record's values after that. Both reach userspace through the branch stack. Nothing under arch/x86/events/ writes either field, so x86 is unaffected. Clear the entry with a single struct assignment instead: *br = (struct perf_branch_entry){ }; The bitfields add up to exactly 64 bits, so there is no padding, and every caller assigns from/to immediately afterwards, so zeroing those as well changes nothing. PERF_BR_SPEC_NA is 0, so dropping the explicit spec assignment leaves the behaviour unchanged. Nothing needs keeping in sync when a field is added. The helper no longer touches only bitfields, so rename it to perf_clear_branch_entry(). Fixes: b190bc4ac9e6 ("perf: Extend branch type classification") Fixes: 5402d25aa571 ("perf: Capture branch privilege information") Suggested-by: James Clark Reviewed-by: James Clark Acked-by: Usama Arif Signed-off-by: Puranjay Mohan --- arch/x86/events/amd/brs.c | 2 +- arch/x86/events/amd/lbr.c | 2 +- arch/x86/events/intel/lbr.c | 6 +++--- drivers/perf/arm_brbe.c | 2 +- include/linux/perf_event.h | 16 ++-------------- 5 files changed, 8 insertions(+), 20 deletions(-) diff --git a/arch/x86/events/amd/brs.c b/arch/x86/events/amd/brs.c index 06f35a6b58a5b..68c5f42965e91 100644 --- a/arch/x86/events/amd/brs.c +++ b/arch/x86/events/amd/brs.c @@ -343,7 +343,7 @@ void amd_brs_drain(void) rdmsrq(brs_from(brs_idx), from); - perf_clear_branch_entry_bitfields(br+nr); + perf_clear_branch_entry(br + nr); br[nr].from = from; br[nr].to = to; diff --git a/arch/x86/events/amd/lbr.c b/arch/x86/events/amd/lbr.c index 5b437dc8e4ce2..3639817456119 100644 --- a/arch/x86/events/amd/lbr.c +++ b/arch/x86/events/amd/lbr.c @@ -183,7 +183,7 @@ void amd_pmu_lbr_read(void) entry.to.split.reserved) continue; - perf_clear_branch_entry_bitfields(br + out); + perf_clear_branch_entry(br + out); br[out].from = sign_ext_branch_ip(entry.from.split.ip); br[out].to = sign_ext_branch_ip(entry.to.split.ip); diff --git a/arch/x86/events/intel/lbr.c b/arch/x86/events/intel/lbr.c index f8fadb0b16a45..6541c7046c2b3 100644 --- a/arch/x86/events/intel/lbr.c +++ b/arch/x86/events/intel/lbr.c @@ -756,7 +756,7 @@ void intel_pmu_lbr_read_32(struct cpu_hw_events *cpuc) rdmsrq(x86_pmu.lbr_from + lbr_idx, msr_lastbranch.lbr); - perf_clear_branch_entry_bitfields(br); + perf_clear_branch_entry(br); br->from = msr_lastbranch.from; br->to = msr_lastbranch.to; @@ -847,7 +847,7 @@ void intel_pmu_lbr_read_64(struct cpu_hw_events *cpuc) if (abort && x86_pmu.lbr_double_abort && out > 0) out--; - perf_clear_branch_entry_bitfields(br+out); + perf_clear_branch_entry(br + out); br[out].from = from; br[out].to = to; br[out].mispred = mis; @@ -921,7 +921,7 @@ static void intel_pmu_store_lbr(struct cpu_hw_events *cpuc, to = rdlbr_to(i, lbr); info = rdlbr_info(i, lbr); - perf_clear_branch_entry_bitfields(e); + perf_clear_branch_entry(e); e->from = from; e->to = to; diff --git a/drivers/perf/arm_brbe.c b/drivers/perf/arm_brbe.c index ba554e0c846c4..effbdeacfcbb3 100644 --- a/drivers/perf/arm_brbe.c +++ b/drivers/perf/arm_brbe.c @@ -604,7 +604,7 @@ static bool perf_entry_from_brbe_regset(int index, struct perf_branch_entry *ent return false; brbinf = bregs.brbinf; - perf_clear_branch_entry_bitfields(entry); + perf_clear_branch_entry(entry); if (brbe_record_is_complete(brbinf)) { entry->from = bregs.brbsrc; entry->to = bregs.brbtgt; diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index 48d851fbd8ea5..e034be4a473a8 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -1467,21 +1467,9 @@ static inline u32 perf_sample_data_size(struct perf_sample_data *data, return size; } -/* - * Clear all bitfields in the perf_branch_entry. - * The to and from fields are not cleared because they are - * systematically modified by caller. - */ -static inline void perf_clear_branch_entry_bitfields(struct perf_branch_entry *br) +static inline void perf_clear_branch_entry(struct perf_branch_entry *br) { - br->mispred = 0; - br->predicted = 0; - br->in_tx = 0; - br->abort = 0; - br->cycles = 0; - br->type = 0; - br->spec = PERF_BR_SPEC_NA; - br->reserved = 0; + *br = (struct perf_branch_entry){ }; } extern void perf_output_sample(struct perf_output_handle *handle, -- 2.53.0-Meta