perf: Add system error and not in transaction branch types

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: Anshuman Khandual <anshuman.khandual@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: James Clark <james.clark@arm.com>
Link: https://lkml.kernel.org/r/20220824044822.70230-2-anshuman.khandual@arm.com

diff --git a/arch/x86/events/utils.c b/arch/x86/events/utils.c
index e013243..5f5617a 100644 (file)
--- a/arch/x86/events/utils.c
+++ b/arch/x86/events/utils.c
@@ -225,7 +225,7 @@ static int branch_map[X86_BR_TYPE_MAP_MAX] = {
        PERF_BR_IND_CALL,       /* X86_BR_IND_CALL */
        PERF_BR_UNKNOWN,        /* X86_BR_ABORT */
        PERF_BR_UNKNOWN,        /* X86_BR_IN_TX */
-       PERF_BR_UNKNOWN,        /* X86_BR_NO_TX */
+       PERF_BR_NO_TX,          /* X86_BR_NO_TX */
        PERF_BR_CALL,           /* X86_BR_ZERO_CALL */
        PERF_BR_UNKNOWN,        /* X86_BR_CALL_STACK */
        PERF_BR_IND,            /* X86_BR_IND_JMP */

diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h
index 30a4723..a79cc0e 100644 (file)
--- a/include/uapi/linux/perf_event.h
+++ b/include/uapi/linux/perf_event.h
@@ -253,6 +253,8 @@ enum {
        PERF_BR_COND_RET        = 10,   /* conditional function return */
        PERF_BR_ERET            = 11,   /* exception return */
        PERF_BR_IRQ             = 12,   /* irq */
+       PERF_BR_SERROR          = 13,   /* system error */
+       PERF_BR_NO_TX           = 14,   /* not in transaction */
        PERF_BR_MAX,
 };