Messages in this thread Patch in this message | | | From | Anshuman Khandual <> | Subject | [PATCH V3 01/10] perf: Add irq and exception return branch types | Date | Mon, 14 Mar 2022 11:28:48 +0530 |
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This expands generic branch type classification by adding two more entries there in i.e irq and exception return. Also updates the x86 implementation to process X86_BR_IRET and X86_BR_IRQ records as appropriate. This changes branch types reported to user space on x86 platform but it should not be a problem. The possible scenarios and impacts are enumerated here.
-------------------------------------------------------------------------- | kernel | perf tool | Impact | -------------------------------------------------------------------------- | old | old | Works as before | -------------------------------------------------------------------------- | old | new | PERF_BR_UNKNOWN is processed | -------------------------------------------------------------------------- | new | old | PERF_BR_ERET/IRQ are blocked via old PERF_BR_MAX | -------------------------------------------------------------------------- | new | new | PERF_BR_ERET/IRQ are recognized | --------------------------------------------------------------------------
When PERF_BR_ERET/IRQ are blocked via old PERF_BR_MAX (new kernel with old perf tool) the user space might throw up an warning complaining about some unrecognized branch types being reported, but it is expected. PERF_BR_ERET and PERF_BR_IRQ branch types will be used for BRBE implementation on arm64 platform.
Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Arnaldo Carvalho de Melo <acme@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Will Deacon <will@kernel.org> Cc: linux-arm-kernel@lists.infradead.org Cc: linux-perf-users@vger.kernel.org Cc: linux-kernel@vger.kernel.org Reviewed-by: James Clark <james.clark@arm.com> Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com> --- arch/x86/events/intel/lbr.c | 4 ++-- include/uapi/linux/perf_event.h | 2 ++ 2 files changed, 4 insertions(+), 2 deletions(-)
diff --git a/arch/x86/events/intel/lbr.c b/arch/x86/events/intel/lbr.c index 669c2be14784..fe1742c4ca49 100644 --- a/arch/x86/events/intel/lbr.c +++ b/arch/x86/events/intel/lbr.c @@ -1329,10 +1329,10 @@ static int branch_map[X86_BR_TYPE_MAP_MAX] = { PERF_BR_SYSCALL, /* X86_BR_SYSCALL */ PERF_BR_SYSRET, /* X86_BR_SYSRET */ PERF_BR_UNKNOWN, /* X86_BR_INT */ - PERF_BR_UNKNOWN, /* X86_BR_IRET */ + PERF_BR_ERET, /* X86_BR_IRET */ PERF_BR_COND, /* X86_BR_JCC */ PERF_BR_UNCOND, /* X86_BR_JMP */ - PERF_BR_UNKNOWN, /* X86_BR_IRQ */ + PERF_BR_IRQ, /* X86_BR_IRQ */ PERF_BR_IND_CALL, /* X86_BR_IND_CALL */ PERF_BR_UNKNOWN, /* X86_BR_ABORT */ PERF_BR_UNKNOWN, /* X86_BR_IN_TX */ diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h index 82858b697c05..d37629dbad72 100644 --- a/include/uapi/linux/perf_event.h +++ b/include/uapi/linux/perf_event.h @@ -251,6 +251,8 @@ enum { PERF_BR_SYSRET = 8, /* syscall return */ PERF_BR_COND_CALL = 9, /* conditional function call */ PERF_BR_COND_RET = 10, /* conditional function return */ + PERF_BR_ERET = 11, /* exception return */ + PERF_BR_IRQ = 12, /* irq */ PERF_BR_MAX, }; -- 2.25.1
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