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