samples/bpf/trace_event_user.c

   1 /* Copyright (c) 2016 Facebook
   2  *
   3  * This program is free software; you can redistribute it and/or
   4  * modify it under the terms of version 2 of the GNU General Public
   5  * License as published by the Free Software Foundation.
   6  */
   7 #include <stdio.h>
   8 #include <unistd.h>
   9 #include <stdlib.h>
  10 #include <stdbool.h>
  11 #include <string.h>
  12 #include <fcntl.h>
  13 #include <poll.h>
  14 #include <sys/ioctl.h>
  15 #include <linux/perf_event.h>
  16 #include <linux/bpf.h>
  17 #include <signal.h>
  18 #include <assert.h>
  19 #include <errno.h>
  20 #include <sys/resource.h>
  21 #include "libbpf.h"
  22 #include "bpf_load.h"
  23 #include "perf-sys.h"
  24
  25 #define SAMPLE_FREQ 50
  26
  27 static bool sys_read_seen, sys_write_seen;
  28
  29 static void print_ksym(__u64 addr)
  30 {
  31         struct ksym *sym;
  32
  33         if (!addr)
  34                 return;
  35         sym = ksym_search(addr);
  36         printf("%s;", sym->name);
  37         if (!strcmp(sym->name, "sys_read"))
  38                 sys_read_seen = true;
  39         else if (!strcmp(sym->name, "sys_write"))
  40                 sys_write_seen = true;
  41 }
  42
  43 static void print_addr(__u64 addr)
  44 {
  45         if (!addr)
  46                 return;
  47         printf("%llx;", addr);
  48 }
  49
  50 #define TASK_COMM_LEN 16
  51
  52 struct key_t {
  53         char comm[TASK_COMM_LEN];
  54         __u32 kernstack;
  55         __u32 userstack;
  56 };
  57
  58 static void print_stack(struct key_t *key, __u64 count)
  59 {
  60         __u64 ip[PERF_MAX_STACK_DEPTH] = {};
  61         static bool warned;
  62         int i;
  63
  64         printf("%3lld %s;", count, key->comm);
  65         if (bpf_map_lookup_elem(map_fd[1], &key->kernstack, ip) != 0) {
  66                 printf("---;");
  67         } else {
  68                 for (i = PERF_MAX_STACK_DEPTH - 1; i >= 0; i--)
  69                         print_ksym(ip[i]);
  70         }
  71         printf("-;");
  72         if (bpf_map_lookup_elem(map_fd[1], &key->userstack, ip) != 0) {
  73                 printf("---;");
  74         } else {
  75                 for (i = PERF_MAX_STACK_DEPTH - 1; i >= 0; i--)
  76                         print_addr(ip[i]);
  77         }
  78         printf("\n");
  79
  80         if (key->kernstack == -EEXIST && !warned) {
  81                 printf("stackmap collisions seen. Consider increasing size\n");
  82                 warned = true;
  83         } else if ((int)key->kernstack < 0 && (int)key->userstack < 0) {
  84                 printf("err stackid %d %d\n", key->kernstack, key->userstack);
  85         }
  86 }
  87
  88 static void int_exit(int sig)
  89 {
  90         kill(0, SIGKILL);
  91         exit(0);
  92 }
  93
  94 static void print_stacks(void)
  95 {
  96         struct key_t key = {}, next_key;
  97         __u64 value;
  98         __u32 stackid = 0, next_id;
  99         int fd = map_fd[0], stack_map = map_fd[1];
 100
 101         sys_read_seen = sys_write_seen = false;
 102         while (bpf_map_get_next_key(fd, &key, &next_key) == 0) {
 103                 bpf_map_lookup_elem(fd, &next_key, &value);
 104                 print_stack(&next_key, value);
 105                 bpf_map_delete_elem(fd, &next_key);
 106                 key = next_key;
 107         }
 108
 109         if (!sys_read_seen || !sys_write_seen) {
 110                 printf("BUG kernel stack doesn't contain sys_read() and sys_write()\n");
 111                 int_exit(0);
 112         }
 113
 114         /* clear stack map */
 115         while (bpf_map_get_next_key(stack_map, &stackid, &next_id) == 0) {
 116                 bpf_map_delete_elem(stack_map, &next_id);
 117                 stackid = next_id;
 118         }
 119 }
 120
 121 static void test_perf_event_all_cpu(struct perf_event_attr *attr)
 122 {
 123         int nr_cpus = sysconf(_SC_NPROCESSORS_CONF);
 124         int *pmu_fd = malloc(nr_cpus * sizeof(int));
 125         int i;
 126
 127         /* open perf_event on all cpus */
 128         for (i = 0; i < nr_cpus; i++) {
 129                 pmu_fd[i] = sys_perf_event_open(attr, -1, i, -1, 0);
 130                 if (pmu_fd[i] < 0) {
 131                         printf("sys_perf_event_open failed\n");
 132                         goto all_cpu_err;
 133                 }
 134                 assert(ioctl(pmu_fd[i], PERF_EVENT_IOC_SET_BPF, prog_fd[0]) == 0);
 135                 assert(ioctl(pmu_fd[i], PERF_EVENT_IOC_ENABLE, 0) == 0);
 136         }
 137         system("dd if=/dev/zero of=/dev/null count=5000k");
 138         print_stacks();
 139 all_cpu_err:
 140         for (i--; i >= 0; i--)
 141                 close(pmu_fd[i]);
 142         free(pmu_fd);
 143 }
 144
 145 static void test_perf_event_task(struct perf_event_attr *attr)
 146 {
 147         int pmu_fd;
 148
 149         /* open task bound event */
 150         pmu_fd = sys_perf_event_open(attr, 0, -1, -1, 0);
 151         if (pmu_fd < 0) {
 152                 printf("sys_perf_event_open failed\n");
 153                 return;
 154         }
 155         assert(ioctl(pmu_fd, PERF_EVENT_IOC_SET_BPF, prog_fd[0]) == 0);
 156         assert(ioctl(pmu_fd, PERF_EVENT_IOC_ENABLE, 0) == 0);
 157         system("dd if=/dev/zero of=/dev/null count=5000k");
 158         print_stacks();
 159         close(pmu_fd);
 160 }
 161
 162 static void test_bpf_perf_event(void)
 163 {
 164         struct perf_event_attr attr_type_hw = {
 165                 .sample_freq = SAMPLE_FREQ,
 166                 .freq = 1,
 167                 .type = PERF_TYPE_HARDWARE,
 168                 .config = PERF_COUNT_HW_CPU_CYCLES,
 169                 .inherit = 1,
 170         };
 171         struct perf_event_attr attr_type_sw = {
 172                 .sample_freq = SAMPLE_FREQ,
 173                 .freq = 1,
 174                 .type = PERF_TYPE_SOFTWARE,
 175                 .config = PERF_COUNT_SW_CPU_CLOCK,
 176                 .inherit = 1,
 177         };
 178
 179         test_perf_event_all_cpu(&attr_type_hw);
 180         test_perf_event_task(&attr_type_hw);
 181         test_perf_event_all_cpu(&attr_type_sw);
 182         test_perf_event_task(&attr_type_sw);
 183 }
 184
 185
 186 int main(int argc, char **argv)
 187 {
 188         struct rlimit r = {RLIM_INFINITY, RLIM_INFINITY};
 189         char filename[256];
 190
 191         snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
 192         setrlimit(RLIMIT_MEMLOCK, &r);
 193
 194         signal(SIGINT, int_exit);
 195         signal(SIGTERM, int_exit);
 196
 197         if (load_kallsyms()) {
 198                 printf("failed to process /proc/kallsyms\n");
 199                 return 1;
 200         }
 201
 202         if (load_bpf_file(filename)) {
 203                 printf("%s", bpf_log_buf);
 204                 return 2;
 205         }
 206
 207         if (fork() == 0) {
 208                 read_trace_pipe();
 209                 return 0;
 210         }
 211         test_bpf_perf_event();
 212
 213         int_exit(0);
 214         return 0;
 215 }