From 2369ce0f16b89e3d85c9683c06eb104545999378 Mon Sep 17 00:00:00 2001 From: Chun-Tse Shao Date: Tue, 2 Jun 2026 11:13:48 -0700 Subject: perf: Reveal PMU type in fdinfo It gives useful info on knowing which PMUs are reserved by this process. Also add config which would be useful. Testing cycles: $ ./perf stat -e cycles & $ cat /proc/`pidof perf`/fdinfo/3 pos: 0 flags: 02000002 mnt_id: 16 ino: 3081 perf_event_attr.type: 0 perf_event_attr.config: 0x0 perf_event_attr.config1: 0x0 perf_event_attr.config2: 0x0 perf_event_attr.config3: 0x0 perf_event_attr.config4: 0x0 Testing L1-dcache-load-misses: $ ./perf stat -e L1-dcache-load-misses & $ cat /proc/`pidof perf`/fdinfo/3 pos: 0 flags: 02000002 mnt_id: 16 ino: 1072 perf_event_attr.type: 3 perf_event_attr.config: 0x10000 perf_event_attr.config1: 0x0 perf_event_attr.config2: 0x0 perf_event_attr.config3: 0x0 perf_event_attr.config4: 0x0 Signed-off-by: Chun-Tse Shao Assisted-by: Gemini:gemini-3.1-pro-preview Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Ian Rogers Link: https://patch.msgid.link/20260602181349.3969429-1-ctshao@google.com --- kernel/events/core.c | 29 +++++++++++++++++++++++++++++ 1 file changed, 29 insertions(+) (limited to 'kernel') diff --git a/kernel/events/core.c b/kernel/events/core.c index 7935d5663944..95d806bba654 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -58,6 +58,7 @@ #include #include #include +#include #include "internal.h" @@ -7546,6 +7547,33 @@ static int perf_fasync(int fd, struct file *filp, int on) return 0; } +static void perf_show_fdinfo(struct seq_file *m, struct file *f) +{ + struct perf_event *event = f->private_data; + struct perf_event_context *ctx; + struct mutex *child_mutex; + + ctx = perf_event_ctx_lock(event); + child_mutex = event->parent ? &event->parent->child_mutex : &event->child_mutex; + mutex_lock(child_mutex); + + seq_printf(m, "perf_event_attr.type:\t%u\n", event->orig_type); + if (event->pmu) + seq_printf(m, "pmu_type:\t%u\n", event->pmu->type); + seq_printf(m, "perf_event_attr.config:\t0x%llx\n", (unsigned long long)event->attr.config); + seq_printf(m, "perf_event_attr.config1:\t0x%llx\n", + (unsigned long long)event->attr.config1); + seq_printf(m, "perf_event_attr.config2:\t0x%llx\n", + (unsigned long long)event->attr.config2); + seq_printf(m, "perf_event_attr.config3:\t0x%llx\n", + (unsigned long long)event->attr.config3); + seq_printf(m, "perf_event_attr.config4:\t0x%llx\n", + (unsigned long long)event->attr.config4); + + mutex_unlock(child_mutex); + perf_event_ctx_unlock(event, ctx); +} + static const struct file_operations perf_fops = { .release = perf_release, .read = perf_read, @@ -7554,6 +7582,7 @@ static const struct file_operations perf_fops = { .compat_ioctl = perf_compat_ioctl, .mmap = perf_mmap, .fasync = perf_fasync, + .show_fdinfo = perf_show_fdinfo, }; /* -- cgit v1.2.3