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 __must_check
  22 #include <linux/err.h>
  23
  24 #define DEFAULT_FREQ    99
  25 #define DEFAULT_SECS    5
  26 #define MAX_IPS         8192
  27 #define PAGE_OFFSET     0xffff880000000000
  28
  29 static int map_fd;
  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 freq, struct bpf_program *prog,
  40                           struct bpf_link *links[])
  41 {
  42         int i, pmu_fd;
  43
  44         struct perf_event_attr pe_sample_attr = {
  45                 .type = PERF_TYPE_SOFTWARE,
  46                 .freq = 1,
  47                 .sample_period = freq,
  48                 .config = PERF_COUNT_SW_CPU_CLOCK,
  49                 .inherit = 1,
  50         };
  51
  52         for (i = 0; i < nr_cpus; i++) {
  53                 pmu_fd = sys_perf_event_open(&pe_sample_attr, -1 /* pid */, i,
  54                                             -1 /* group_fd */, 0 /* flags */);
  55                 if (pmu_fd < 0) {
  56                         fprintf(stderr, "ERROR: Initializing perf sampling\n");
  57                         return 1;
  58                 }
  59                 links[i] = bpf_program__attach_perf_event(prog, pmu_fd);
  60                 if (IS_ERR(links[i])) {
  61                         fprintf(stderr, "ERROR: Attach perf event\n");
  62                         links[i] = NULL;
  63                         close(pmu_fd);
  64                         return 1;
  65                 }
  66         }
  67
  68         return 0;
  69 }
  70
  71 static void sampling_end(struct bpf_link *links[])
  72 {
  73         int i;
  74
  75         for (i = 0; i < nr_cpus; i++)
  76                 bpf_link__destroy(links[i]);
  77 }
  78
  79 struct ipcount {
  80         __u64 ip;
  81         __u32 count;
  82 };
  83
  84 /* used for sorting */
  85 struct ipcount counts[MAX_IPS];
  86
  87 static int count_cmp(const void *p1, const void *p2)
  88 {
  89         return ((struct ipcount *)p1)->count - ((struct ipcount *)p2)->count;
  90 }
  91
  92 static void print_ip_map(int fd)
  93 {
  94         struct ksym *sym;
  95         __u64 key, next_key;
  96         __u32 value;
  97         int i, max;
  98
  99         printf("%-19s %-32s %s\n", "ADDR", "KSYM", "COUNT");
 100
 101         /* fetch IPs and counts */
 102         key = 0, i = 0;
 103         while (bpf_map_get_next_key(fd, &key, &next_key) == 0) {
 104                 bpf_map_lookup_elem(fd, &next_key, &value);
 105                 counts[i].ip = next_key;
 106                 counts[i++].count = value;
 107                 key = next_key;
 108         }
 109         max = i;
 110
 111         /* sort and print */
 112         qsort(counts, max, sizeof(struct ipcount), count_cmp);
 113         for (i = 0; i < max; i++) {
 114                 if (counts[i].ip > PAGE_OFFSET) {
 115                         sym = ksym_search(counts[i].ip);
 116                         if (!sym) {
 117                                 printf("ksym not found. Is kallsyms loaded?\n");
 118                                 continue;
 119                         }
 120
 121                         printf("0x%-17llx %-32s %u\n", counts[i].ip, sym->name,
 122                                counts[i].count);
 123                 } else {
 124                         printf("0x%-17llx %-32s %u\n", counts[i].ip, "(user)",
 125                                counts[i].count);
 126                 }
 127         }
 128
 129         if (max == MAX_IPS) {
 130                 printf("WARNING: IP hash was full (max %d entries); ", max);
 131                 printf("may have dropped samples\n");
 132         }
 133 }
 134
 135 static void int_exit(int sig)
 136 {
 137         printf("\n");
 138         print_ip_map(map_fd);
 139         exit(0);
 140 }
 141
 142 int main(int argc, char **argv)
 143 {
 144         int opt, freq = DEFAULT_FREQ, secs = DEFAULT_SECS, error = 1;
 145         struct bpf_object *obj = NULL;
 146         struct bpf_program *prog;
 147         struct bpf_link **links;
 148         char filename[256];
 149
 150         /* process arguments */
 151         while ((opt = getopt(argc, argv, "F:h")) != -1) {
 152                 switch (opt) {
 153                 case 'F':
 154                         freq = atoi(optarg);
 155                         break;
 156                 case 'h':
 157                 default:
 158                         usage();
 159                         return 0;
 160                 }
 161         }
 162         if (argc - optind == 1)
 163                 secs = atoi(argv[optind]);
 164         if (freq == 0 || secs == 0) {
 165                 usage();
 166                 return 1;
 167         }
 168
 169         /* initialize kernel symbol translation */
 170         if (load_kallsyms()) {
 171                 fprintf(stderr, "ERROR: loading /proc/kallsyms\n");
 172                 return 2;
 173         }
 174
 175         /* create perf FDs for each CPU */
 176         nr_cpus = sysconf(_SC_NPROCESSORS_ONLN);
 177         links = calloc(nr_cpus, sizeof(struct bpf_link *));
 178         if (!links) {
 179                 fprintf(stderr, "ERROR: malloc of links\n");
 180                 goto cleanup;
 181         }
 182
 183         snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
 184         obj = bpf_object__open_file(filename, NULL);
 185         if (IS_ERR(obj)) {
 186                 fprintf(stderr, "ERROR: opening BPF object file failed\n");
 187                 obj = NULL;
 188                 goto cleanup;
 189         }
 190
 191         prog = bpf_object__find_program_by_name(obj, "do_sample");
 192         if (!prog) {
 193                 fprintf(stderr, "ERROR: finding a prog in obj file failed\n");
 194                 goto cleanup;
 195         }
 196
 197         /* load BPF program */
 198         if (bpf_object__load(obj)) {
 199                 fprintf(stderr, "ERROR: loading BPF object file failed\n");
 200                 goto cleanup;
 201         }
 202
 203         map_fd = bpf_object__find_map_fd_by_name(obj, "ip_map");
 204         if (map_fd < 0) {
 205                 fprintf(stderr, "ERROR: finding a map in obj file failed\n");
 206                 goto cleanup;
 207         }
 208
 209         signal(SIGINT, int_exit);
 210         signal(SIGTERM, int_exit);
 211
 212         /* do sampling */
 213         printf("Sampling at %d Hertz for %d seconds. Ctrl-C also ends.\n",
 214                freq, secs);
 215         if (sampling_start(freq, prog, links) != 0)
 216                 goto cleanup;
 217
 218         sleep(secs);
 219         error = 0;
 220
 221 cleanup:
 222         sampling_end(links);
 223         /* output sample counts */
 224         if (!error)
 225                 print_ip_map(map_fd);
 226
 227         free(links);
 228         bpf_object__close(obj);
 229         return error;
 230 }