root/samples/bpf/sampleip_user.c

DEFINITIONS

1. usage
2. sampling_start
3. sampling_end
4. count_cmp
5. print_ip_map
6. int_exit
7. main

   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 <assert.h>
  14 #include <linux/perf_event.h>
  15 #include <linux/ptrace.h>
  16 #include <linux/bpf.h>
  17 #include <sys/ioctl.h>
  18 #include "libbpf.h"
  19 #include "bpf_load.h"
  20 #include "perf-sys.h"
  21 #include "trace_helpers.h"
  22 
  23 #define DEFAULT_FREQ    99
  24 #define DEFAULT_SECS    5
  25 #define MAX_IPS         8192
  26 #define PAGE_OFFSET     0xffff880000000000
  27 
  28 static int nr_cpus;
  29 
  30 static void usage(void)
  31 {
  32         printf("USAGE: sampleip [-F freq] [duration]\n");
  33         printf("       -F freq    # sample frequency (Hertz), default 99\n");
  34         printf("       duration   # sampling duration (seconds), default 5\n");
  35 }
  36 
  37 static int sampling_start(int *pmu_fd, int freq)
  38 {
  39         int i;
  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[i] = sys_perf_event_open(&pe_sample_attr, -1 /* pid */, i,
  51                                             -1 /* group_fd */, 0 /* flags */);
  52                 if (pmu_fd[i] < 0) {
  53                         fprintf(stderr, "ERROR: Initializing perf sampling\n");
  54                         return 1;
  55                 }
  56                 assert(ioctl(pmu_fd[i], PERF_EVENT_IOC_SET_BPF,
  57                              prog_fd[0]) == 0);
  58                 assert(ioctl(pmu_fd[i], PERF_EVENT_IOC_ENABLE, 0) == 0);
  59         }
  60 
  61         return 0;
  62 }
  63 
  64 static void sampling_end(int *pmu_fd)
  65 {
  66         int i;
  67 
  68         for (i = 0; i < nr_cpus; i++)
  69                 close(pmu_fd[i]);
  70 }
  71 
  72 struct ipcount {
  73         __u64 ip;
  74         __u32 count;
  75 };
  76 
  77 /* used for sorting */
  78 struct ipcount counts[MAX_IPS];
  79 
  80 static int count_cmp(const void *p1, const void *p2)
  81 {
  82         return ((struct ipcount *)p1)->count - ((struct ipcount *)p2)->count;
  83 }
  84 
  85 static void print_ip_map(int fd)
  86 {
  87         struct ksym *sym;
  88         __u64 key, next_key;
  89         __u32 value;
  90         int i, max;
  91 
  92         printf("%-19s %-32s %s\n", "ADDR", "KSYM", "COUNT");
  93 
  94         /* fetch IPs and counts */
  95         key = 0, i = 0;
  96         while (bpf_map_get_next_key(fd, &key, &next_key) == 0) {
  97                 bpf_map_lookup_elem(fd, &next_key, &value);
  98                 counts[i].ip = next_key;
  99                 counts[i++].count = value;
 100                 key = next_key;
 101         }
 102         max = i;
 103 
 104         /* sort and print */
 105         qsort(counts, max, sizeof(struct ipcount), count_cmp);
 106         for (i = 0; i < max; i++) {
 107                 if (counts[i].ip > PAGE_OFFSET) {
 108                         sym = ksym_search(counts[i].ip);
 109                         if (!sym) {
 110                                 printf("ksym not found. Is kallsyms loaded?\n");
 111                                 continue;
 112                         }
 113 
 114                         printf("0x%-17llx %-32s %u\n", counts[i].ip, sym->name,
 115                                counts[i].count);
 116                 } else {
 117                         printf("0x%-17llx %-32s %u\n", counts[i].ip, "(user)",
 118                                counts[i].count);
 119                 }
 120         }
 121 
 122         if (max == MAX_IPS) {
 123                 printf("WARNING: IP hash was full (max %d entries); ", max);
 124                 printf("may have dropped samples\n");
 125         }
 126 }
 127 
 128 static void int_exit(int sig)
 129 {
 130         printf("\n");
 131         print_ip_map(map_fd[0]);
 132         exit(0);
 133 }
 134 
 135 int main(int argc, char **argv)
 136 {
 137         char filename[256];
 138         int *pmu_fd, opt, freq = DEFAULT_FREQ, secs = DEFAULT_SECS;
 139 
 140         /* process arguments */
 141         while ((opt = getopt(argc, argv, "F:h")) != -1) {
 142                 switch (opt) {
 143                 case 'F':
 144                         freq = atoi(optarg);
 145                         break;
 146                 case 'h':
 147                 default:
 148                         usage();
 149                         return 0;
 150                 }
 151         }
 152         if (argc - optind == 1)
 153                 secs = atoi(argv[optind]);
 154         if (freq == 0 || secs == 0) {
 155                 usage();
 156                 return 1;
 157         }
 158 
 159         /* initialize kernel symbol translation */
 160         if (load_kallsyms()) {
 161                 fprintf(stderr, "ERROR: loading /proc/kallsyms\n");
 162                 return 2;
 163         }
 164 
 165         /* create perf FDs for each CPU */
 166         nr_cpus = sysconf(_SC_NPROCESSORS_CONF);
 167         pmu_fd = malloc(nr_cpus * sizeof(int));
 168         if (pmu_fd == NULL) {
 169                 fprintf(stderr, "ERROR: malloc of pmu_fd\n");
 170                 return 1;
 171         }
 172 
 173         /* load BPF program */
 174         snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
 175         if (load_bpf_file(filename)) {
 176                 fprintf(stderr, "ERROR: loading BPF program (errno %d):\n",
 177                         errno);
 178                 if (strcmp(bpf_log_buf, "") == 0)
 179                         fprintf(stderr, "Try: ulimit -l unlimited\n");
 180                 else
 181                         fprintf(stderr, "%s", bpf_log_buf);
 182                 return 1;
 183         }
 184         signal(SIGINT, int_exit);
 185         signal(SIGTERM, int_exit);
 186 
 187         /* do sampling */
 188         printf("Sampling at %d Hertz for %d seconds. Ctrl-C also ends.\n",
 189                freq, secs);
 190         if (sampling_start(pmu_fd, freq) != 0)
 191                 return 1;
 192         sleep(secs);
 193         sampling_end(pmu_fd);
 194         free(pmu_fd);
 195 
 196         /* output sample counts */
 197         print_ip_map(map_fd[0]);
 198 
 199         return 0;
 200 }