• Anshuman Khandual's avatar
    perf: Add system error and not in transaction branch types · a724ec82
    Anshuman Khandual authored
    This expands generic branch type classification by adding two more entries
    there in i.e system error and not in transaction. This also updates the x86
    implementation to process X86_BR_NO_TX 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_NO_TX is blocked via old PERF_BR_MAX     |
     --------------------------------------------------------------------------
     |   new  |    new    |  PERF_BR_NO_TX is recognized                      |
     --------------------------------------------------------------------------
    
    When PERF_BR_NO_TX is blocked via old PERF_BR_MAX (new kernel with old perf
    tool) the user space might throw up an warning complaining about an
    unrecognized branch types being reported, but it's expected. PERF_BR_SERROR
    & PERF_BR_NO_TX branch types will be used for BRBE implementation on arm64
    platform.
    
    PERF_BR_NO_TX complements 'abort' and 'in_tx' elements in perf_branch_entry
    which represent other transaction states for a given branch record. Because
    this completes the transaction state classification.
    Signed-off-by: default avatarAnshuman Khandual <anshuman.khandual@arm.com>
    Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
    Reviewed-by: default avatarJames Clark <james.clark@arm.com>
    Link: https://lkml.kernel.org/r/20220824044822.70230-2-anshuman.khandual@arm.com
    a724ec82
utils.c 6.41 KB