samples/bpf/sampleip_user.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * sampleip: sample instruction pointer and frequency count in a BPF map.
   4  *
   5  * Copyright 2016 Netflix, Inc.
   6  */
   7 #include <stdio.h>
   8 #include <stdlib.h>
   9 #include <unistd.h>
  10 #include <errno.h>
  11 #include <signal.h>
  12 #include <string.h>
  13 #include <linux/perf_event.h>
  14 #include <linux/ptrace.h>
  15 #include <linux/bpf.h>
  16 #include <bpf/bpf.h>
  17 #include <bpf/libbpf.h>
  18 #include "perf-sys.h"
  19 #include "trace_helpers.h"
  20
  21 #define DEFAULT_FREQ    99
  22 #define DEFAULT_SECS    5
  23 #define MAX_IPS         8192
  24 #define PAGE_OFFSET     0xffff880000000000
  25
  26 static int map_fd;
  27 static int nr_cpus;
  28
  29 static void usage(void)
  30 {
  31         printf("USAGE: sampleip [-F freq] [duration]\n");
  32         printf("       -F freq    # sample frequency (Hertz), default 99\n");
  33         printf("       duration   # sampling duration (seconds), default 5\n");
  34 }
  35
  36 static int sampling_start(int freq, struct bpf_program *prog,
  37                           struct bpf_link *links[])
  38 {
  39         int i, pmu_fd;
  40
  41         struct perf_event_attr pe_sample_attr = {
  42                 .type = PERF_TYPE_SOFTWARE,
  43                 .freq = 1,
  44                 .sample_period = freq,
  45                 .config = PERF_COUNT_SW_CPU_CLOCK,
  46                 .inherit = 1,
  47         };
  48
  49         for (i = 0; i < nr_cpus; i++) {
  50                 pmu_fd = sys_perf_event_open(&pe_sample_attr, -1 /* pid */, i,
  51                                             -1 /* group_fd */, 0 /* flags */);
  52                 if (pmu_fd < 0) {
  53                         fprintf(stderr, "ERROR: Initializing perf sampling\n");
  54                         return 1;
  55                 }
  56                 links[i] = bpf_program__attach_perf_event(prog, pmu_fd);
  57                 if (libbpf_get_error(links[i])) {
  58                         fprintf(stderr, "ERROR: Attach perf event\n");
  59                         links[i] = NULL;
  60                         close(pmu_fd);
  61                         return 1;
  62                 }
  63         }
  64
  65         return 0;
  66 }
  67
  68 static void sampling_end(struct bpf_link *links[])
  69 {
  70         int i;
  71
  72         for (i = 0; i < nr_cpus; i++)
  73                 bpf_link__destroy(links[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                         if (!sym) {
 114                                 printf("ksym not found. Is kallsyms loaded?\n");
 115                                 continue;
 116                         }
 117
 118                         printf("0x%-17llx %-32s %u\n", counts[i].ip, sym->name,
 119                                counts[i].count);
 120                 } else {
 121                         printf("0x%-17llx %-32s %u\n", counts[i].ip, "(user)",
 122                                counts[i].count);
 123                 }
 124         }
 125
 126         if (max == MAX_IPS) {
 127                 printf("WARNING: IP hash was full (max %d entries); ", max);
 128                 printf("may have dropped samples\n");
 129         }
 130 }
 131
 132 static void int_exit(int sig)
 133 {
 134         printf("\n");
 135         print_ip_map(map_fd);
 136         exit(0);
 137 }
 138
 139 int main(int argc, char **argv)
 140 {
 141         int opt, freq = DEFAULT_FREQ, secs = DEFAULT_SECS, error = 1;
 142         struct bpf_object *obj = NULL;
 143         struct bpf_program *prog;
 144         struct bpf_link **links;
 145         char filename[256];
 146
 147         /* process arguments */
 148         while ((opt = getopt(argc, argv, "F:h")) != -1) {
 149                 switch (opt) {
 150                 case 'F':
 151                         freq = atoi(optarg);
 152                         break;
 153                 case 'h':
 154                 default:
 155                         usage();
 156                         return 0;
 157                 }
 158         }
 159         if (argc - optind == 1)
 160                 secs = atoi(argv[optind]);
 161         if (freq == 0 || secs == 0) {
 162                 usage();
 163                 return 1;
 164         }
 165
 166         /* initialize kernel symbol translation */
 167         if (load_kallsyms()) {
 168                 fprintf(stderr, "ERROR: loading /proc/kallsyms\n");
 169                 return 2;
 170         }
 171
 172         /* create perf FDs for each CPU */
 173         nr_cpus = sysconf(_SC_NPROCESSORS_ONLN);
 174         links = calloc(nr_cpus, sizeof(struct bpf_link *));
 175         if (!links) {
 176                 fprintf(stderr, "ERROR: malloc of links\n");
 177                 goto cleanup;
 178         }
 179
 180         snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
 181         obj = bpf_object__open_file(filename, NULL);
 182         if (libbpf_get_error(obj)) {
 183                 fprintf(stderr, "ERROR: opening BPF object file failed\n");
 184                 obj = NULL;
 185                 goto cleanup;
 186         }
 187
 188         prog = bpf_object__find_program_by_name(obj, "do_sample");
 189         if (!prog) {
 190                 fprintf(stderr, "ERROR: finding a prog in obj file failed\n");
 191                 goto cleanup;
 192         }
 193
 194         /* load BPF program */
 195         if (bpf_object__load(obj)) {
 196                 fprintf(stderr, "ERROR: loading BPF object file failed\n");
 197                 goto cleanup;
 198         }
 199
 200         map_fd = bpf_object__find_map_fd_by_name(obj, "ip_map");
 201         if (map_fd < 0) {
 202                 fprintf(stderr, "ERROR: finding a map in obj file failed\n");
 203                 goto cleanup;
 204         }
 205
 206         signal(SIGINT, int_exit);
 207         signal(SIGTERM, int_exit);
 208
 209         /* do sampling */
 210         printf("Sampling at %d Hertz for %d seconds. Ctrl-C also ends.\n",
 211                freq, secs);
 212         if (sampling_start(freq, prog, links) != 0)
 213                 goto cleanup;
 214
 215         sleep(secs);
 216         error = 0;
 217
 218 cleanup:
 219         sampling_end(links);
 220         /* output sample counts */
 221         if (!error)
 222                 print_ip_map(map_fd);
 223
 224         free(links);
 225         bpf_object__close(obj);
 226         return error;
 227 }