samples/bpf/sampleip_user.c

   1 /*
   2  * sampleip: sample instruction pointer and frequency count in a BPF map.
   3  *
   4  * Copyright 2016 Netflix, Inc.
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of version 2 of the GNU General Public
   8  * License as published by the Free Software Foundation.
   9  */
  10 #include <stdio.h>
  11 #include <stdlib.h>
  12 #include <stdio.h>
  13 #include <unistd.h>
  14 #include <errno.h>
  15 #include <signal.h>
  16 #include <string.h>
  17 #include <assert.h>
  18 #include <linux/perf_event.h>
  19 #include <linux/ptrace.h>
  20 #include <linux/bpf.h>
  21 #include <sys/ioctl.h>
  22 #include "libbpf.h"
  23 #include "bpf_load.h"
  24 #include "perf-sys.h"
  25 #include "trace_helpers.h"
  26
  27 #define DEFAULT_FREQ    99
  28 #define DEFAULT_SECS    5
  29 #define MAX_IPS         8192
  30 #define PAGE_OFFSET     0xffff880000000000
  31
  32 static int nr_cpus;
  33
  34 static void usage(void)
  35 {
  36         printf("USAGE: sampleip [-F freq] [duration]\n");
  37         printf("       -F freq    # sample frequency (Hertz), default 99\n");
  38         printf("       duration   # sampling duration (seconds), default 5\n");
  39 }
  40
  41 static int sampling_start(int *pmu_fd, int freq)
  42 {
  43         int i;
  44
  45         struct perf_event_attr pe_sample_attr = {
  46                 .type = PERF_TYPE_SOFTWARE,
  47                 .freq = 1,
  48                 .sample_period = freq,
  49                 .config = PERF_COUNT_SW_CPU_CLOCK,
  50                 .inherit = 1,
  51         };
  52
  53         for (i = 0; i < nr_cpus; i++) {
  54                 pmu_fd[i] = sys_perf_event_open(&pe_sample_attr, -1 /* pid */, i,
  55                                             -1 /* group_fd */, 0 /* flags */);
  56                 if (pmu_fd[i] < 0) {
  57                         fprintf(stderr, "ERROR: Initializing perf sampling\n");
  58                         return 1;
  59                 }
  60                 assert(ioctl(pmu_fd[i], PERF_EVENT_IOC_SET_BPF,
  61                              prog_fd[0]) == 0);
  62                 assert(ioctl(pmu_fd[i], PERF_EVENT_IOC_ENABLE, 0) == 0);
  63         }
  64
  65         return 0;
  66 }
  67
  68 static void sampling_end(int *pmu_fd)
  69 {
  70         int i;
  71
  72         for (i = 0; i < nr_cpus; i++)
  73                 close(pmu_fd[i]);
  74 }
  75
  76 struct ipcount {
  77         __u64 ip;
  78         __u32 count;
  79 };
  80
  81 /* used for sorting */
  82 struct ipcount counts[MAX_IPS];
  83
  84 static int count_cmp(const void *p1, const void *p2)
  85 {
  86         return ((struct ipcount *)p1)->count - ((struct ipcount *)p2)->count;
  87 }
  88
  89 static void print_ip_map(int fd)
  90 {
  91         struct ksym *sym;
  92         __u64 key, next_key;
  93         __u32 value;
  94         int i, max;
  95
  96         printf("%-19s %-32s %s\n", "ADDR", "KSYM", "COUNT");
  97
  98         /* fetch IPs and counts */
  99         key = 0, i = 0;
 100         while (bpf_map_get_next_key(fd, &key, &next_key) == 0) {
 101                 bpf_map_lookup_elem(fd, &next_key, &value);
 102                 counts[i].ip = next_key;
 103                 counts[i++].count = value;
 104                 key = next_key;
 105         }
 106         max = i;
 107
 108         /* sort and print */
 109         qsort(counts, max, sizeof(struct ipcount), count_cmp);
 110         for (i = 0; i < max; i++) {
 111                 if (counts[i].ip > PAGE_OFFSET) {
 112                         sym = ksym_search(counts[i].ip);
 113                         printf("0x%-17llx %-32s %u\n", counts[i].ip, sym->name,
 114                                counts[i].count);
 115                 } else {
 116                         printf("0x%-17llx %-32s %u\n", counts[i].ip, "(user)",
 117                                counts[i].count);
 118                 }
 119         }
 120
 121         if (max == MAX_IPS) {
 122                 printf("WARNING: IP hash was full (max %d entries); ", max);
 123                 printf("may have dropped samples\n");
 124         }
 125 }
 126
 127 static void int_exit(int sig)
 128 {
 129         printf("\n");
 130         print_ip_map(map_fd[0]);
 131         exit(0);
 132 }
 133
 134 int main(int argc, char **argv)
 135 {
 136         char filename[256];
 137         int *pmu_fd, opt, freq = DEFAULT_FREQ, secs = DEFAULT_SECS;
 138
 139         /* process arguments */
 140         while ((opt = getopt(argc, argv, "F:h")) != -1) {
 141                 switch (opt) {
 142                 case 'F':
 143                         freq = atoi(optarg);
 144                         break;
 145                 case 'h':
 146                 default:
 147                         usage();
 148                         return 0;
 149                 }
 150         }
 151         if (argc - optind == 1)
 152                 secs = atoi(argv[optind]);
 153         if (freq == 0 || secs == 0) {
 154                 usage();
 155                 return 1;
 156         }
 157
 158         /* initialize kernel symbol translation */
 159         if (load_kallsyms()) {
 160                 fprintf(stderr, "ERROR: loading /proc/kallsyms\n");
 161                 return 2;
 162         }
 163
 164         /* create perf FDs for each CPU */
 165         nr_cpus = sysconf(_SC_NPROCESSORS_CONF);
 166         pmu_fd = malloc(nr_cpus * sizeof(int));
 167         if (pmu_fd == NULL) {
 168                 fprintf(stderr, "ERROR: malloc of pmu_fd\n");
 169                 return 1;
 170         }
 171
 172         /* load BPF program */
 173         snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
 174         if (load_bpf_file(filename)) {
 175                 fprintf(stderr, "ERROR: loading BPF program (errno %d):\n",
 176                         errno);
 177                 if (strcmp(bpf_log_buf, "") == 0)
 178                         fprintf(stderr, "Try: ulimit -l unlimited\n");
 179                 else
 180                         fprintf(stderr, "%s", bpf_log_buf);
 181                 return 1;
 182         }
 183         signal(SIGINT, int_exit);
 184         signal(SIGTERM, int_exit);
 185
 186         /* do sampling */
 187         printf("Sampling at %d Hertz for %d seconds. Ctrl-C also ends.\n",
 188                freq, secs);
 189         if (sampling_start(pmu_fd, freq) != 0)
 190                 return 1;
 191         sleep(secs);
 192         sampling_end(pmu_fd);
 193         free(pmu_fd);
 194
 195         /* output sample counts */
 196         print_ip_map(map_fd[0]);
 197
 198         return 0;
 199 }