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![Song Liu](/assets/img/avatar_default.png)
Introduce 'perf stat -b' option, which counts events for BPF programs, like: [root@localhost ~]# ~/perf stat -e ref-cycles,cycles -b 254 -I 1000 1.487903822 115,200 ref-cycles 1.487903822 86,012 cycles 2.489147029 80,560 ref-cycles 2.489147029 73,784 cycles 3.490341825 60,720 ref-cycles 3.490341825 37,797 cycles 4.491540887 37,120 ref-cycles 4.491540887 31,963 cycles The example above counts 'cycles' and 'ref-cycles' of BPF program of id 254. This is similar to bpftool-prog-profile command, but more flexible. 'perf stat -b' creates per-cpu perf_event and loads fentry/fexit BPF programs (monitor-progs) to the target BPF program (target-prog). The monitor-progs read perf_event before and after the target-prog, and aggregate the difference in a BPF map. Then the user space reads data from these maps. A new 'struct bpf_counter' is introduced to provide a common interface that uses BPF programs/maps to count perf events. Committer notes: Removed all but bpf_counter.h includes from evsel.h, not needed at all. Also BPF map lookups for PERCPU_ARRAYs need to have as its value receive buffer passed to the kernel libbpf_num_possible_cpus() entries, not evsel__nr_cpus(evsel), as the former uses /sys/devices/system/cpu/possible while the later uses /sys/devices/system/cpu/online, which may be less than the 'possible' number making the bpf map lookup overwrite memory and cause hard to debug memory corruption. We need to continue using evsel__nr_cpus(evsel) when accessing the perf_counts array tho, not to overwrite another are of memory :-) Signed-off-by: Song Liu <songliubraving@fb.com> Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com> Link: https://lore.kernel.org/lkml/20210120163031.GU12699@kernel.org/ Acked-by: Namhyung Kim <namhyung@kernel.org> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: kernel-team@fb.com Link: http://lore.kernel.org/lkml/20201229214214.3413833-4-songliubraving@fb.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
184 lines
4.3 KiB
C
184 lines
4.3 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Helper functions for handling target threads/cpus
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*
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* Copyright (C) 2012, LG Electronics, Namhyung Kim <namhyung.kim@lge.com>
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*/
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#include "target.h"
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#include <pwd.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <linux/kernel.h>
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#include <linux/string.h>
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enum target_errno target__validate(struct target *target)
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{
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enum target_errno ret = TARGET_ERRNO__SUCCESS;
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if (target->pid)
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target->tid = target->pid;
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/* CPU and PID are mutually exclusive */
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if (target->tid && target->cpu_list) {
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target->cpu_list = NULL;
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if (ret == TARGET_ERRNO__SUCCESS)
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ret = TARGET_ERRNO__PID_OVERRIDE_CPU;
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}
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/* UID and PID are mutually exclusive */
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if (target->tid && target->uid_str) {
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target->uid_str = NULL;
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if (ret == TARGET_ERRNO__SUCCESS)
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ret = TARGET_ERRNO__PID_OVERRIDE_UID;
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}
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/* UID and CPU are mutually exclusive */
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if (target->uid_str && target->cpu_list) {
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target->cpu_list = NULL;
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if (ret == TARGET_ERRNO__SUCCESS)
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ret = TARGET_ERRNO__UID_OVERRIDE_CPU;
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}
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/* PID and SYSTEM are mutually exclusive */
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if (target->tid && target->system_wide) {
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target->system_wide = false;
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if (ret == TARGET_ERRNO__SUCCESS)
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ret = TARGET_ERRNO__PID_OVERRIDE_SYSTEM;
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}
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/* UID and SYSTEM are mutually exclusive */
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if (target->uid_str && target->system_wide) {
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target->system_wide = false;
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if (ret == TARGET_ERRNO__SUCCESS)
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ret = TARGET_ERRNO__UID_OVERRIDE_SYSTEM;
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}
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/* BPF and CPU are mutually exclusive */
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if (target->bpf_str && target->cpu_list) {
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target->cpu_list = NULL;
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if (ret == TARGET_ERRNO__SUCCESS)
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ret = TARGET_ERRNO__BPF_OVERRIDE_CPU;
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}
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/* BPF and PID/TID are mutually exclusive */
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if (target->bpf_str && target->tid) {
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target->tid = NULL;
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if (ret == TARGET_ERRNO__SUCCESS)
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ret = TARGET_ERRNO__BPF_OVERRIDE_PID;
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}
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/* BPF and UID are mutually exclusive */
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if (target->bpf_str && target->uid_str) {
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target->uid_str = NULL;
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if (ret == TARGET_ERRNO__SUCCESS)
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ret = TARGET_ERRNO__BPF_OVERRIDE_UID;
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}
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/* BPF and THREADS are mutually exclusive */
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if (target->bpf_str && target->per_thread) {
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target->per_thread = false;
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if (ret == TARGET_ERRNO__SUCCESS)
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ret = TARGET_ERRNO__BPF_OVERRIDE_THREAD;
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}
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/* THREAD and SYSTEM/CPU are mutually exclusive */
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if (target->per_thread && (target->system_wide || target->cpu_list)) {
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target->per_thread = false;
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if (ret == TARGET_ERRNO__SUCCESS)
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ret = TARGET_ERRNO__SYSTEM_OVERRIDE_THREAD;
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}
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return ret;
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}
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enum target_errno target__parse_uid(struct target *target)
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{
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struct passwd pwd, *result;
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char buf[1024];
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const char *str = target->uid_str;
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target->uid = UINT_MAX;
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if (str == NULL)
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return TARGET_ERRNO__SUCCESS;
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/* Try user name first */
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getpwnam_r(str, &pwd, buf, sizeof(buf), &result);
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if (result == NULL) {
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/*
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* The user name not found. Maybe it's a UID number.
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*/
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char *endptr;
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int uid = strtol(str, &endptr, 10);
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if (*endptr != '\0')
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return TARGET_ERRNO__INVALID_UID;
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getpwuid_r(uid, &pwd, buf, sizeof(buf), &result);
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if (result == NULL)
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return TARGET_ERRNO__USER_NOT_FOUND;
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}
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target->uid = result->pw_uid;
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return TARGET_ERRNO__SUCCESS;
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}
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/*
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* This must have a same ordering as the enum target_errno.
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*/
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static const char *target__error_str[] = {
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"PID/TID switch overriding CPU",
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"PID/TID switch overriding UID",
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"UID switch overriding CPU",
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"PID/TID switch overriding SYSTEM",
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"UID switch overriding SYSTEM",
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"SYSTEM/CPU switch overriding PER-THREAD",
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"BPF switch overriding CPU",
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"BPF switch overriding PID/TID",
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"BPF switch overriding UID",
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"BPF switch overriding THREAD",
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"Invalid User: %s",
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"Problems obtaining information for user %s",
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};
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int target__strerror(struct target *target, int errnum,
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char *buf, size_t buflen)
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{
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int idx;
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const char *msg;
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BUG_ON(buflen == 0);
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if (errnum >= 0) {
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str_error_r(errnum, buf, buflen);
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return 0;
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}
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if (errnum < __TARGET_ERRNO__START || errnum >= __TARGET_ERRNO__END)
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return -1;
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idx = errnum - __TARGET_ERRNO__START;
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msg = target__error_str[idx];
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switch (errnum) {
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case TARGET_ERRNO__PID_OVERRIDE_CPU ...
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TARGET_ERRNO__BPF_OVERRIDE_THREAD:
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snprintf(buf, buflen, "%s", msg);
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break;
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case TARGET_ERRNO__INVALID_UID:
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case TARGET_ERRNO__USER_NOT_FOUND:
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snprintf(buf, buflen, msg, target->uid_str);
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break;
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default:
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/* cannot reach here */
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break;
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}
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return 0;
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}
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