From 66ec11919a0f96e936bb731fdbc2851316077d26 Mon Sep 17 00:00:00 2001 From: Mark Rutland Date: Fri, 6 Oct 2017 19:38:22 +0100 Subject: perf pmu: Unbreak perf record for arm/arm64 with events with explicit PMU Currently, perf record is broken on arm/arm64 systems when the PMU is specified explicitly as part of the event, e.g. $ ./perf record -e armv8_cortex_a53/cpu_cycles/u true In such cases, perf record fails to open events unless perf_event_paranoid is set to -1, even if the PMU in question supports mode exclusion. Further, even when perf_event_paranoid is toggled, no samples are recorded. This is an unintended side effect of commit: e3ba76deef23064f ("perf tools: Force uncore events to system wide monitoring) ... which assumes that if a PMU has an associated cpu_map, it is an uncore PMU, and forces events for such PMUs to be system-wide. This is not true for arm/arm64 systems, which can have heterogeneous CPUs. To account for this, multiple CPU PMUs are exposed, each with a "cpus" field under sysfs, which the perf tool parses into a cpu_map. ARM PMUs do not have a "cpumask" file, and only have a "cpus" file. For the gory details as to why, see commit: 7e3fcffe95544010 ("perf pmu: Support alternative sysfs cpumask") Given all of this, we can instead identify uncore PMUs by explicitly checking for a "cpumask" file, and restore arm/arm64 PMU support back to a working state. This patch does so, adding a new perf_pmu::is_uncore field, and splitting the existing cpumask parsing so that it can be reused. Signed-off-by: Mark Rutland Tested-by Will Deacon Acked-by: Jiri Olsa Cc: Adrian Hunter Cc: Borislav Petkov Cc: David Ahern Cc: Namhyung Kim Cc: Peter Zijlstra Cc: 4.12+ Fixes: e3ba76deef23064f ("perf tools: Force uncore events to system wide monitoring) Link: http://lkml.kernel.org/r/1507315102-5942-1-git-send-email-mark.rutland@arm.com Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/pmu.c | 56 +++++++++++++++++++++++++++++++++++++-------------- 1 file changed, 41 insertions(+), 15 deletions(-) (limited to 'tools/perf/util/pmu.c') diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c index ac16a9db1fb5..1c4d7b4e4fb5 100644 --- a/tools/perf/util/pmu.c +++ b/tools/perf/util/pmu.c @@ -470,17 +470,36 @@ static void pmu_read_sysfs(void) closedir(dir); } +static struct cpu_map *__pmu_cpumask(const char *path) +{ + FILE *file; + struct cpu_map *cpus; + + file = fopen(path, "r"); + if (!file) + return NULL; + + cpus = cpu_map__read(file); + fclose(file); + return cpus; +} + +/* + * Uncore PMUs have a "cpumask" file under sysfs. CPU PMUs (e.g. on arm/arm64) + * may have a "cpus" file. + */ +#define CPUS_TEMPLATE_UNCORE "%s/bus/event_source/devices/%s/cpumask" +#define CPUS_TEMPLATE_CPU "%s/bus/event_source/devices/%s/cpus" + static struct cpu_map *pmu_cpumask(const char *name) { - struct stat st; char path[PATH_MAX]; - FILE *file; struct cpu_map *cpus; const char *sysfs = sysfs__mountpoint(); const char *templates[] = { - "%s/bus/event_source/devices/%s/cpumask", - "%s/bus/event_source/devices/%s/cpus", - NULL + CPUS_TEMPLATE_UNCORE, + CPUS_TEMPLATE_CPU, + NULL }; const char **template; @@ -489,20 +508,25 @@ static struct cpu_map *pmu_cpumask(const char *name) for (template = templates; *template; template++) { snprintf(path, PATH_MAX, *template, sysfs, name); - if (stat(path, &st) == 0) - break; + cpus = __pmu_cpumask(path); + if (cpus) + return cpus; } - if (!*template) - return NULL; + return NULL; +} - file = fopen(path, "r"); - if (!file) - return NULL; +static bool pmu_is_uncore(const char *name) +{ + char path[PATH_MAX]; + struct cpu_map *cpus; + const char *sysfs = sysfs__mountpoint(); - cpus = cpu_map__read(file); - fclose(file); - return cpus; + snprintf(path, PATH_MAX, CPUS_TEMPLATE_UNCORE, sysfs, name); + cpus = __pmu_cpumask(path); + cpu_map__put(cpus); + + return !!cpus; } /* @@ -617,6 +641,8 @@ static struct perf_pmu *pmu_lookup(const char *name) pmu->cpus = pmu_cpumask(name); + pmu->is_uncore = pmu_is_uncore(name); + INIT_LIST_HEAD(&pmu->format); INIT_LIST_HEAD(&pmu->aliases); list_splice(&format, &pmu->format); -- cgit v1.2.3