tools/testing/selftests/bpf/test_stacktrace_map.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 // Copyright (c) 2018 Facebook
   3
   4 #include <linux/bpf.h>
   5 #include "bpf_helpers.h"
   6
   7 #ifndef PERF_MAX_STACK_DEPTH
   8 #define PERF_MAX_STACK_DEPTH         127
   9 #endif
  10
  11 struct bpf_map_def SEC("maps") control_map = {
  12         .type = BPF_MAP_TYPE_ARRAY,
  13         .key_size = sizeof(__u32),
  14         .value_size = sizeof(__u32),
  15         .max_entries = 1,
  16 };
  17
  18 struct bpf_map_def SEC("maps") stackid_hmap = {
  19         .type = BPF_MAP_TYPE_HASH,
  20         .key_size = sizeof(__u32),
  21         .value_size = sizeof(__u32),
  22         .max_entries = 16384,
  23 };
  24
  25 struct bpf_map_def SEC("maps") stackmap = {
  26         .type = BPF_MAP_TYPE_STACK_TRACE,
  27         .key_size = sizeof(__u32),
  28         .value_size = sizeof(__u64) * PERF_MAX_STACK_DEPTH,
  29         .max_entries = 16384,
  30 };
  31
  32 struct bpf_map_def SEC("maps") stack_amap = {
  33         .type = BPF_MAP_TYPE_ARRAY,
  34         .key_size = sizeof(__u32),
  35         .value_size = sizeof(__u64) * PERF_MAX_STACK_DEPTH,
  36         .max_entries = 16384,
  37 };
  38
  39 /* taken from /sys/kernel/debug/tracing/events/sched/sched_switch/format */
  40 struct sched_switch_args {
  41         unsigned long long pad;
  42         char prev_comm[16];
  43         int prev_pid;
  44         int prev_prio;
  45         long long prev_state;
  46         char next_comm[16];
  47         int next_pid;
  48         int next_prio;
  49 };
  50
  51 SEC("tracepoint/sched/sched_switch")
  52 int oncpu(struct sched_switch_args *ctx)
  53 {
  54         __u32 max_len = PERF_MAX_STACK_DEPTH * sizeof(__u64);
  55         __u32 key = 0, val = 0, *value_p;
  56         void *stack_p;
  57
  58         value_p = bpf_map_lookup_elem(&control_map, &key);
  59         if (value_p && *value_p)
  60                 return 0; /* skip if non-zero *value_p */
  61
  62         /* The size of stackmap and stackid_hmap should be the same */
  63         key = bpf_get_stackid(ctx, &stackmap, 0);
  64         if ((int)key >= 0) {
  65                 bpf_map_update_elem(&stackid_hmap, &key, &val, 0);
  66                 stack_p = bpf_map_lookup_elem(&stack_amap, &key);
  67                 if (stack_p)
  68                         bpf_get_stack(ctx, stack_p, max_len, 0);
  69         }
  70
  71         return 0;
  72 }
  73
  74 char _license[] SEC("license") = "GPL";
  75 __u32 _version SEC("version") = 1; /* ignored by tracepoints, required by libbpf.a */