tools/perf/util/bpf_ftrace.c

   1 #include <stdio.h>
   2 #include <fcntl.h>
   3 #include <stdint.h>
   4 #include <stdlib.h>
   5
   6 #include <linux/err.h>
   7
   8 #include "util/ftrace.h"
   9 #include "util/cpumap.h"
  10 #include "util/thread_map.h"
  11 #include "util/debug.h"
  12 #include "util/evlist.h"
  13 #include "util/bpf_counter.h"
  14
  15 #include "util/bpf_skel/func_latency.skel.h"
  16
  17 static struct func_latency_bpf *skel;
  18
  19 int perf_ftrace__latency_prepare_bpf(struct perf_ftrace *ftrace)
  20 {
  21         int fd, err;
  22         int i, ncpus = 1, ntasks = 1;
  23         struct filter_entry *func;
  24
  25         if (!list_is_singular(&ftrace->filters)) {
  26                 pr_err("ERROR: %s target function(s).\n",
  27                        list_empty(&ftrace->filters) ? "No" : "Too many");
  28                 return -1;
  29         }
  30
  31         func = list_first_entry(&ftrace->filters, struct filter_entry, list);
  32
  33         skel = func_latency_bpf__open();
  34         if (!skel) {
  35                 pr_err("Failed to open func latency skeleton\n");
  36                 return -1;
  37         }
  38
  39         /* don't need to set cpu filter for system-wide mode */
  40         if (ftrace->target.cpu_list) {
  41                 ncpus = perf_cpu_map__nr(ftrace->evlist->core.user_requested_cpus);
  42                 bpf_map__set_max_entries(skel->maps.cpu_filter, ncpus);
  43                 skel->rodata->has_cpu = 1;
  44         }
  45
  46         if (target__has_task(&ftrace->target) || target__none(&ftrace->target)) {
  47                 ntasks = perf_thread_map__nr(ftrace->evlist->core.threads);
  48                 bpf_map__set_max_entries(skel->maps.task_filter, ntasks);
  49                 skel->rodata->has_task = 1;
  50         }
  51
  52         skel->rodata->use_nsec = ftrace->use_nsec;
  53
  54         set_max_rlimit();
  55
  56         err = func_latency_bpf__load(skel);
  57         if (err) {
  58                 pr_err("Failed to load func latency skeleton\n");
  59                 goto out;
  60         }
  61
  62         if (ftrace->target.cpu_list) {
  63                 u32 cpu;
  64                 u8 val = 1;
  65
  66                 fd = bpf_map__fd(skel->maps.cpu_filter);
  67
  68                 for (i = 0; i < ncpus; i++) {
  69                         cpu = perf_cpu_map__cpu(ftrace->evlist->core.user_requested_cpus, i).cpu;
  70                         bpf_map_update_elem(fd, &cpu, &val, BPF_ANY);
  71                 }
  72         }
  73
  74         if (target__has_task(&ftrace->target) || target__none(&ftrace->target)) {
  75                 u32 pid;
  76                 u8 val = 1;
  77
  78                 fd = bpf_map__fd(skel->maps.task_filter);
  79
  80                 for (i = 0; i < ntasks; i++) {
  81                         pid = perf_thread_map__pid(ftrace->evlist->core.threads, i);
  82                         bpf_map_update_elem(fd, &pid, &val, BPF_ANY);
  83                 }
  84         }
  85
  86         skel->links.func_begin = bpf_program__attach_kprobe(skel->progs.func_begin,
  87                                                             false, func->name);
  88         if (IS_ERR(skel->links.func_begin)) {
  89                 pr_err("Failed to attach fentry program\n");
  90                 err = PTR_ERR(skel->links.func_begin);
  91                 goto out;
  92         }
  93
  94         skel->links.func_end = bpf_program__attach_kprobe(skel->progs.func_end,
  95                                                           true, func->name);
  96         if (IS_ERR(skel->links.func_end)) {
  97                 pr_err("Failed to attach fexit program\n");
  98                 err = PTR_ERR(skel->links.func_end);
  99                 goto out;
 100         }
 101
 102         /* XXX: we don't actually use this fd - just for poll() */
 103         return open("/dev/null", O_RDONLY);
 104
 105 out:
 106         return err;
 107 }
 108
 109 int perf_ftrace__latency_start_bpf(struct perf_ftrace *ftrace __maybe_unused)
 110 {
 111         skel->bss->enabled = 1;
 112         return 0;
 113 }
 114
 115 int perf_ftrace__latency_stop_bpf(struct perf_ftrace *ftrace __maybe_unused)
 116 {
 117         skel->bss->enabled = 0;
 118         return 0;
 119 }
 120
 121 int perf_ftrace__latency_read_bpf(struct perf_ftrace *ftrace __maybe_unused,
 122                                   int buckets[])
 123 {
 124         int i, fd, err;
 125         u32 idx;
 126         u64 *hist;
 127         int ncpus = cpu__max_cpu().cpu;
 128
 129         fd = bpf_map__fd(skel->maps.latency);
 130
 131         hist = calloc(ncpus, sizeof(*hist));
 132         if (hist == NULL)
 133                 return -ENOMEM;
 134
 135         for (idx = 0; idx < NUM_BUCKET; idx++) {
 136                 err = bpf_map_lookup_elem(fd, &idx, hist);
 137                 if (err) {
 138                         buckets[idx] = 0;
 139                         continue;
 140                 }
 141
 142                 for (i = 0; i < ncpus; i++)
 143                         buckets[idx] += hist[i];
 144         }
 145
 146         free(hist);
 147         return 0;
 148 }
 149
 150 int perf_ftrace__latency_cleanup_bpf(struct perf_ftrace *ftrace __maybe_unused)
 151 {
 152         func_latency_bpf__destroy(skel);
 153         return 0;
 154 }