[PATCH v6 4/6] perf jevents: Add a new expression builtin strcmp_cpuid_str()

From: James Clark
Date: Wed Aug 16 2023 - 07:53:47 EST

This will allow writing formulas that are conditional on a specific
CPU type or CPU version. It calls through to the existing
strcmp_cpuid_str() function in Perf which has a default weak version,
and an arch specific version for x86 and arm64.

The function takes an 'ID' type value, which is a string. But in this
case Arm CPU IDs are hex numbers prefixed with '0x'. metric.py
assumes strings are only used by event names, and that they can't start
with a number ('0'), so an additional change has to be made to the
regex to convert hex numbers back to 'ID' types.

Signed-off-by: James Clark <james.clark@xxxxxxx>
---
tools/perf/arch/arm64/util/pmu.c | 18 +-----------------
tools/perf/pmu-events/metric.py | 17 +++++++++++++++--
tools/perf/util/expr.c | 18 ++++++++++++++++++
tools/perf/util/expr.h | 1 +
tools/perf/util/expr.l | 1 +
tools/perf/util/expr.y | 8 +++++++-
tools/perf/util/pmu.c | 17 +++++++++++++++++
tools/perf/util/pmu.h | 1 +
8 files changed, 61 insertions(+), 20 deletions(-)

diff --git a/tools/perf/arch/arm64/util/pmu.c b/tools/perf/arch/arm64/util/pmu.c
index 512a8f13c4de..615084eb88d8 100644
--- a/tools/perf/arch/arm64/util/pmu.c
+++ b/tools/perf/arch/arm64/util/pmu.c
@@ -2,28 +2,12 @@

#include <internal/cpumap.h>
#include "../../../util/cpumap.h"
+#include "../../../util/header.h"
#include "../../../util/pmu.h"
#include "../../../util/pmus.h"
#include <api/fs/fs.h>
#include <math.h>

-static struct perf_pmu *pmu__find_core_pmu(void)
-{
- struct perf_pmu *pmu = NULL;
-
- while ((pmu = perf_pmus__scan_core(pmu))) {
- /*
- * The cpumap should cover all CPUs. Otherwise, some CPUs may
- * not support some events or have different event IDs.
- */
- if (RC_CHK_ACCESS(pmu->cpus)->nr != cpu__max_cpu().cpu)
- return NULL;
-
- return pmu;
- }
- return NULL;
-}
-
const struct pmu_metrics_table *pmu_metrics_table__find(void)
{
struct perf_pmu *pmu = pmu__find_core_pmu();
diff --git a/tools/perf/pmu-events/metric.py b/tools/perf/pmu-events/metric.py
index 85a3545f5b6a..0e9ec65d92ae 100644
--- a/tools/perf/pmu-events/metric.py
+++ b/tools/perf/pmu-events/metric.py
@@ -413,6 +413,10 @@ def has_event(event: Event) -> Function:
# pylint: disable=invalid-name
return Function('has_event', event)

+def strcmp_cpuid_str(event: str) -> Function:
+ # pylint: disable=redefined-builtin
+ # pylint: disable=invalid-name
+ return Function('strcmp_cpuid_str', event)

class Metric:
"""An individual metric that will specifiable on the perf command line."""
@@ -541,14 +545,23 @@ def ParsePerfJson(orig: str) -> Expression:
"""
# pylint: disable=eval-used
py = orig.strip()
+ # First try to convert everything that looks like a string (event name) into Event(r"EVENT_NAME").
+ # This isn't very selective so is followed up by converting some unwanted conversions back again
py = re.sub(r'([a-zA-Z][^-+/\* \\\(\),]*(?:\\.[^-+/\* \\\(\),]*)*)',
r'Event(r"\1")', py)
+ # If it started with a # it should have been a literal, rather than an event name
py = re.sub(r'#Event\(r"([^"]*)"\)', r'Literal("#\1")', py)
+ # Convert accidentally converted hex constants ("0Event(r"xDEADBEEF)"") back to a constant,
+ # but keep it wrapped in Event(), otherwise Python drops the 0x prefix and it gets interpreted as
+ # a double by the Bison parser
+ py = re.sub(r'0Event\(r"[xX]([0-9a-fA-F]*)"\)', r'Event("0x\1")', py)
+ # Convert accidentally converted scientific notation constants back
py = re.sub(r'([0-9]+)Event\(r"(e[0-9]+)"\)', r'\1\2', py)
- keywords = ['if', 'else', 'min', 'max', 'd_ratio', 'source_count', 'has_event']
+ # Convert all the known keywords back from events to just the keyword
+ keywords = ['if', 'else', 'min', 'max', 'd_ratio', 'source_count', 'has_event', 'strcmp_cpuid_str',
+ 'cpuid_not_more_than']
for kw in keywords:
py = re.sub(rf'Event\(r"{kw}"\)', kw, py)
-
try:
parsed = ast.parse(py, mode='eval')
except SyntaxError as e:
diff --git a/tools/perf/util/expr.c b/tools/perf/util/expr.c
index 7410a165f68b..0985a3cbc6f9 100644
--- a/tools/perf/util/expr.c
+++ b/tools/perf/util/expr.c
@@ -13,6 +13,8 @@
#include <util/expr-bison.h>
#include <util/expr-flex.h>
#include "util/hashmap.h"
+#include "util/header.h"
+#include "util/pmu.h"
#include "smt.h"
#include "tsc.h"
#include <api/fs/fs.h>
@@ -495,3 +497,19 @@ double expr__has_event(const struct expr_parse_ctx *ctx, bool compute_ids, const
evlist__delete(tmp);
return ret;
}
+
+double expr__strcmp_cpuid_str(const struct expr_parse_ctx *ctx __maybe_unused,
+ bool compute_ids __maybe_unused, const char *test_id)
+{
+ double ret;
+ struct perf_pmu *pmu = pmu__find_core_pmu();
+ char *cpuid = perf_pmu__getcpuid(pmu);
+
+ if (!cpuid)
+ return NAN;
+
+ ret = !strcmp_cpuid_str(test_id, cpuid);
+
+ free(cpuid);
+ return ret;
+}
diff --git a/tools/perf/util/expr.h b/tools/perf/util/expr.h
index 3c1e49b3e35d..c0cec29ddc29 100644
--- a/tools/perf/util/expr.h
+++ b/tools/perf/util/expr.h
@@ -55,5 +55,6 @@ double expr_id_data__value(const struct expr_id_data *data);
double expr_id_data__source_count(const struct expr_id_data *data);
double expr__get_literal(const char *literal, const struct expr_scanner_ctx *ctx);
double expr__has_event(const struct expr_parse_ctx *ctx, bool compute_ids, const char *id);
+double expr__strcmp_cpuid_str(const struct expr_parse_ctx *ctx, bool compute_ids, const char *id);

#endif
diff --git a/tools/perf/util/expr.l b/tools/perf/util/expr.l
index dbb117414710..0feef0726c48 100644
--- a/tools/perf/util/expr.l
+++ b/tools/perf/util/expr.l
@@ -114,6 +114,7 @@ if { return IF; }
else { return ELSE; }
source_count { return SOURCE_COUNT; }
has_event { return HAS_EVENT; }
+strcmp_cpuid_str { return STRCMP_CPUID_STR; }
{literal} { return literal(yyscanner, sctx); }
{number} { return value(yyscanner); }
{symbol} { return str(yyscanner, ID, sctx->runtime); }
diff --git a/tools/perf/util/expr.y b/tools/perf/util/expr.y
index 65d54a6f29ad..6c93b358cc2d 100644
--- a/tools/perf/util/expr.y
+++ b/tools/perf/util/expr.y
@@ -39,7 +39,7 @@ int expr_lex(YYSTYPE * yylval_param , void *yyscanner);
} ids;
}

-%token ID NUMBER MIN MAX IF ELSE LITERAL D_RATIO SOURCE_COUNT HAS_EVENT EXPR_ERROR
+%token ID NUMBER MIN MAX IF ELSE LITERAL D_RATIO SOURCE_COUNT HAS_EVENT STRCMP_CPUID_STR EXPR_ERROR
%left MIN MAX IF
%left '|'
%left '^'
@@ -207,6 +207,12 @@ expr: NUMBER
$$.ids = NULL;
free($3);
}
+| STRCMP_CPUID_STR '(' ID ')'
+{
+ $$.val = expr__strcmp_cpuid_str(ctx, compute_ids, $3);
+ $$.ids = NULL;
+ free($3);
+}
| expr '|' expr
{
if (is_const($1.val) && is_const($3.val)) {
diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
index d5406effc169..a7f05e4dda97 100644
--- a/tools/perf/util/pmu.c
+++ b/tools/perf/util/pmu.c
@@ -1790,3 +1790,20 @@ void perf_pmu__delete(struct perf_pmu *pmu)
zfree(&pmu->alias_name);
free(pmu);
}
+
+struct perf_pmu *pmu__find_core_pmu(void)
+{
+ struct perf_pmu *pmu = NULL;
+
+ while ((pmu = perf_pmus__scan_core(pmu))) {
+ /*
+ * The cpumap should cover all CPUs. Otherwise, some CPUs may
+ * not support some events or have different event IDs.
+ */
+ if (RC_CHK_ACCESS(pmu->cpus)->nr != cpu__max_cpu().cpu)
+ return NULL;
+
+ return pmu;
+ }
+ return NULL;
+}
diff --git a/tools/perf/util/pmu.h b/tools/perf/util/pmu.h
index 6b414cecbad2..7ff925224165 100644
--- a/tools/perf/util/pmu.h
+++ b/tools/perf/util/pmu.h
@@ -289,5 +289,6 @@ int perf_pmu__pathname_fd(int dirfd, const char *pmu_name, const char *filename,
struct perf_pmu *perf_pmu__lookup(struct list_head *pmus, int dirfd, const char *lookup_name);
struct perf_pmu *perf_pmu__create_placeholder_core_pmu(struct list_head *core_pmus);
void perf_pmu__delete(struct perf_pmu *pmu);
+struct perf_pmu *pmu__find_core_pmu(void);

#endif /* __PMU_H */
--
2.34.1