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perf: Add system error and not in transaction branch types

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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
This commit is contained in:
Anshuman Khandual 2022-08-24 10:18:15 +05:30 committed by Peter Zijlstra
parent 0bc3be5b4b
commit a724ec8296
2 changed files with 3 additions and 1 deletions
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2
arch/x86/events/utils.c
View File

@ -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 */

2
include/uapi/linux/perf_event.h
View File

@ -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,
};