[PATCH v3 1/3] perf pmu: Move pmu__find_core_pmu() to pmus.c
From: James Clark
Date: Wed Sep 13 2023 - 11:34:34 EST
pmu__find_core_pmu() more logically belongs in pmus.c because it
iterates over all PMUs, so move it to pmus.c
At the same time rename it to perf_pmus__find_core_pmu() to match the
naming convention in this file.
list_prepare_entry() can't be used in perf_pmus__scan_core() anymore now
that it's called from the same compilation unit. This is with -O2
(specifically -O1 -ftree-vrp -finline-functions
-finline-small-functions) which allow the bounds of the array
access to be determined at compile time. list_prepare_entry() subtracts
the offset of the 'list' member in struct perf_pmu from &core_pmus,
which isn't a struct perf_pmu. The compiler sees that pmu results in
&core_pmus - 8 and refuses to compile. At runtime this works because
list_for_each_entry_continue() always adds the offset back again before
dereferencing ->next, but it's technically undefined behavior. With
-fsanitize=undefined an additional warning is generated.
Using list_first_entry_or_null() to get the first entry here avoids
doing &core_pmus - 8 but has the same result and fixes both the compile
warning and the undefined behavior warning. There are other uses of
list_prepare_entry() in pmus.c, but the compiler doesn't seem to be
able to see that they can also be called with &core_pmus, so I won't
change any at this time.
Signed-off-by: James Clark <james.clark@xxxxxxx>
---
tools/perf/arch/arm64/util/pmu.c | 6 +++---
tools/perf/tests/expr.c | 2 +-
tools/perf/util/expr.c | 2 +-
tools/perf/util/pmu.c | 17 -----------------
tools/perf/util/pmu.h | 2 +-
tools/perf/util/pmus.c | 20 +++++++++++++++++++-
6 files changed, 25 insertions(+), 24 deletions(-)
diff --git a/tools/perf/arch/arm64/util/pmu.c b/tools/perf/arch/arm64/util/pmu.c
index 615084eb88d8..3d9330feebd2 100644
--- a/tools/perf/arch/arm64/util/pmu.c
+++ b/tools/perf/arch/arm64/util/pmu.c
@@ -10,7 +10,7 @@
const struct pmu_metrics_table *pmu_metrics_table__find(void)
{
- struct perf_pmu *pmu = pmu__find_core_pmu();
+ struct perf_pmu *pmu = perf_pmus__find_core_pmu();
if (pmu)
return perf_pmu__find_metrics_table(pmu);
@@ -20,7 +20,7 @@ const struct pmu_metrics_table *pmu_metrics_table__find(void)
const struct pmu_events_table *pmu_events_table__find(void)
{
- struct perf_pmu *pmu = pmu__find_core_pmu();
+ struct perf_pmu *pmu = perf_pmus__find_core_pmu();
if (pmu)
return perf_pmu__find_events_table(pmu);
@@ -32,7 +32,7 @@ double perf_pmu__cpu_slots_per_cycle(void)
{
char path[PATH_MAX];
unsigned long long slots = 0;
- struct perf_pmu *pmu = pmu__find_core_pmu();
+ struct perf_pmu *pmu = perf_pmus__find_core_pmu();
if (pmu) {
perf_pmu__pathname_scnprintf(path, sizeof(path),
diff --git a/tools/perf/tests/expr.c b/tools/perf/tests/expr.c
index 78544092ef0c..e3aa9d4fcf3a 100644
--- a/tools/perf/tests/expr.c
+++ b/tools/perf/tests/expr.c
@@ -76,7 +76,7 @@ static int test__expr(struct test_suite *t __maybe_unused, int subtest __maybe_u
struct expr_parse_ctx *ctx;
bool is_intel = false;
char strcmp_cpuid_buf[256];
- struct perf_pmu *pmu = pmu__find_core_pmu();
+ struct perf_pmu *pmu = perf_pmus__find_core_pmu();
char *cpuid = perf_pmu__getcpuid(pmu);
char *escaped_cpuid1, *escaped_cpuid2;
diff --git a/tools/perf/util/expr.c b/tools/perf/util/expr.c
index 4488f306de78..7be23b3ac082 100644
--- a/tools/perf/util/expr.c
+++ b/tools/perf/util/expr.c
@@ -509,7 +509,7 @@ 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();
+ struct perf_pmu *pmu = perf_pmus__find_core_pmu();
char *cpuid = perf_pmu__getcpuid(pmu);
if (!cpuid)
diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
index e2159854ab26..f50a5636633f 100644
--- a/tools/perf/util/pmu.c
+++ b/tools/perf/util/pmu.c
@@ -2050,20 +2050,3 @@ void perf_pmu__delete(struct perf_pmu *pmu)
zfree(&pmu->id);
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 bd5d804a6736..d7b46085642d 100644
--- a/tools/perf/util/pmu.h
+++ b/tools/perf/util/pmu.h
@@ -264,6 +264,6 @@ 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);
+struct perf_pmu *perf_pmus__find_core_pmu(void);
#endif /* __PMU_H */
diff --git a/tools/perf/util/pmus.c b/tools/perf/util/pmus.c
index 6631367c756f..cec869cbe163 100644
--- a/tools/perf/util/pmus.c
+++ b/tools/perf/util/pmus.c
@@ -10,6 +10,7 @@
#include <pthread.h>
#include <string.h>
#include <unistd.h>
+#include "cpumap.h"
#include "debug.h"
#include "evsel.h"
#include "pmus.h"
@@ -268,7 +269,7 @@ struct perf_pmu *perf_pmus__scan_core(struct perf_pmu *pmu)
{
if (!pmu) {
pmu_read_sysfs(/*core_only=*/true);
- pmu = list_prepare_entry(pmu, &core_pmus, list);
+ return list_first_entry_or_null(&core_pmus, typeof(*pmu), list);
}
list_for_each_entry_continue(pmu, &core_pmus, list)
return pmu;
@@ -592,3 +593,20 @@ struct perf_pmu *evsel__find_pmu(const struct evsel *evsel)
}
return pmu;
}
+
+struct perf_pmu *perf_pmus__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;
+}
--
2.34.1