From 93315e46b000fc80fff5d53c3f444417fb3df6de Mon Sep 17 00:00:00 2001 From: Sandipan Das Date: Thu, 11 Aug 2022 18:00:00 +0530 Subject: [PATCH] perf/core: Add speculation info to branch entries Add a new "spec" bitfield to branch entries for providing speculation information. This will be populated using hints provided by branch sampling features on supported hardware. The following cases are covered: * No branch speculation information is available * Branch is speculative but taken on the wrong path * Branch is non-speculative but taken on the correct path * Branch is speculative and taken on the correct path Suggested-by: Stephane Eranian Signed-off-by: Sandipan Das Signed-off-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/r/834088c302faf21c7b665031dd111f424e509a64.1660211399.git.sandipan.das@amd.com --- include/linux/perf_event.h | 1 + include/uapi/linux/perf_event.h | 15 ++++++++++++++- 2 files changed, 15 insertions(+), 1 deletion(-) diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index ee8b9ecdc03b..ae30c61957d2 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -1078,6 +1078,7 @@ static inline void perf_clear_branch_entry_bitfields(struct perf_branch_entry *b br->abort = 0; br->cycles = 0; br->type = 0; + br->spec = PERF_BR_SPEC_NA; br->reserved = 0; } diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h index 03b370062741..30a4723aefd4 100644 --- a/include/uapi/linux/perf_event.h +++ b/include/uapi/linux/perf_event.h @@ -256,6 +256,17 @@ enum { PERF_BR_MAX, }; +/* + * Common branch speculation outcome classification + */ +enum { + PERF_BR_SPEC_NA = 0, /* Not available */ + PERF_BR_SPEC_WRONG_PATH = 1, /* Speculative but on wrong path */ + PERF_BR_NON_SPEC_CORRECT_PATH = 2, /* Non-speculative but on correct path */ + PERF_BR_SPEC_CORRECT_PATH = 3, /* Speculative and on correct path */ + PERF_BR_SPEC_MAX, +}; + #define PERF_SAMPLE_BRANCH_PLM_ALL \ (PERF_SAMPLE_BRANCH_USER|\ PERF_SAMPLE_BRANCH_KERNEL|\ @@ -1363,6 +1374,7 @@ union perf_mem_data_src { * abort: aborting a hardware transaction * cycles: cycles from last branch (or 0 if not supported) * type: branch type + * spec: branch speculation info (or 0 if not supported) */ struct perf_branch_entry { __u64 from; @@ -1373,7 +1385,8 @@ struct perf_branch_entry { abort:1, /* transaction abort */ cycles:16, /* cycle count to last branch */ type:4, /* branch type */ - reserved:40; + spec:2, /* branch speculation info */ + reserved:38; }; union perf_sample_weight {