/* This program is free software; you can redistribute it and/or * modify it under the terms of version 2 of the GNU General Public * License as published by the Free Software Foundation. */ #include <stdio.h> #include <unistd.h> #include <stdlib.h> #include <stdbool.h> #include <string.h> #include <fcntl.h> #include <poll.h> #include <linux/perf_event.h> #include <linux/bpf.h> #include <errno.h> #include <assert.h> #include <sys/syscall.h> #include <sys/ioctl.h> #include <sys/mman.h> #include <time.h> #include <signal.h> #include "libbpf.h" #include "bpf_load.h" #include "perf-sys.h" static int pmu_fd; int page_size; int page_cnt = 8; volatile struct perf_event_mmap_page *header; typedef void (*print_fn)(void *data, int size); static int perf_event_mmap(int fd) { void *base; int mmap_size; page_size = getpagesize(); mmap_size = page_size * (page_cnt + 1); base = mmap(NULL, mmap_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0); if (base == MAP_FAILED) { printf("mmap err\n"); return -1; } header = base; return 0; } static int perf_event_poll(int fd) { struct pollfd pfd = { .fd = fd, .events = POLLIN }; return poll(&pfd, 1, 1000); } struct perf_event_sample { struct perf_event_header header; __u32 size; char data[]; }; static void perf_event_read(print_fn fn) { __u64 data_tail = header->data_tail; __u64 data_head = header->data_head; __u64 buffer_size = page_cnt * page_size; void *base, *begin, *end; char buf[256]; asm volatile("" ::: "memory"); /* in real code it should be smp_rmb() */ if (data_head == data_tail) return; base = ((char *)header) + page_size; begin = base + data_tail % buffer_size; end = base + data_head % buffer_size; while (begin != end) { struct perf_event_sample *e; e = begin; if (begin + e->header.size > base + buffer_size) { long len = base + buffer_size - begin; assert(len < e->header.size); memcpy(buf, begin, len); memcpy(buf + len, base, e->header.size - len); e = (void *) buf; begin = base + e->header.size - len; } else if (begin + e->header.size == base + buffer_size) { begin = base; } else { begin += e->header.size; } if (e->header.type == PERF_RECORD_SAMPLE) { fn(e->data, e->size); } else if (e->header.type == PERF_RECORD_LOST) { struct { struct perf_event_header header; __u64 id; __u64 lost; } *lost = (void *) e; printf("lost %lld events\n", lost->lost); } else { printf("unknown event type=%d size=%d\n", e->header.type, e->header.size); } } __sync_synchronize(); /* smp_mb() */ header->data_tail = data_head; } static __u64 time_get_ns(void) { struct timespec ts; clock_gettime(CLOCK_MONOTONIC, &ts); return ts.tv_sec * 1000000000ull + ts.tv_nsec; } static __u64 start_time; #define MAX_CNT 100000ll static void print_bpf_output(void *data, int size) { static __u64 cnt; struct { __u64 pid; __u64 cookie; } *e = data; if (e->cookie != 0x12345678) { printf("BUG pid %llx cookie %llx sized %d\n", e->pid, e->cookie, size); kill(0, SIGINT); } cnt++; if (cnt == MAX_CNT) { printf("recv %lld events per sec\n", MAX_CNT * 1000000000ll / (time_get_ns() - start_time)); kill(0, SIGINT); } } static void test_bpf_perf_event(void) { struct perf_event_attr attr = { .sample_type = PERF_SAMPLE_RAW, .type = PERF_TYPE_SOFTWARE, .config = PERF_COUNT_SW_BPF_OUTPUT, }; int key = 0; pmu_fd = sys_perf_event_open(&attr, -1/*pid*/, 0/*cpu*/, -1/*group_fd*/, 0); assert(pmu_fd >= 0); assert(bpf_map_update_elem(map_fd[0], &key, &pmu_fd, BPF_ANY) == 0); ioctl(pmu_fd, PERF_EVENT_IOC_ENABLE, 0); } int main(int argc, char **argv) { char filename[256]; FILE *f; snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]); if (load_bpf_file(filename)) { printf("%s", bpf_log_buf); return 1; } test_bpf_perf_event(); if (perf_event_mmap(pmu_fd) < 0) return 1; f = popen("taskset 1 dd if=/dev/zero of=/dev/null", "r"); (void) f; start_time = time_get_ns(); for (;;) { perf_event_poll(pmu_fd); perf_event_read(print_bpf_output); } return 0; }