LXR linux/tools/testing/selftests/bpf/progs/test_stacktrace_build

   1// SPDX-License-Identifier: GPL-2.0
   2// Copyright (c) 2018 Facebook
   3
   4#include <linux/bpf.h>
   5#include <bpf/bpf_helpers.h>
   6
   7#ifndef PERF_MAX_STACK_DEPTH
   8#define PERF_MAX_STACK_DEPTH         127
   9#endif
  10
  11struct {
  12        __uint(type, BPF_MAP_TYPE_ARRAY);
  13        __uint(max_entries, 1);
  14        __type(key, __u32);
  15        __type(value, __u32);
  16} control_map SEC(".maps");
  17
  18struct {
  19        __uint(type, BPF_MAP_TYPE_HASH);
  20        __uint(max_entries, 16384);
  21        __type(key, __u32);
  22        __type(value, __u32);
  23} stackid_hmap SEC(".maps");
  24
  25typedef struct bpf_stack_build_id stack_trace_t[PERF_MAX_STACK_DEPTH];
  26
  27struct {
  28        __uint(type, BPF_MAP_TYPE_STACK_TRACE);
  29        __uint(max_entries, 128);
  30        __uint(map_flags, BPF_F_STACK_BUILD_ID);
  31        __uint(key_size, sizeof(__u32));
  32        __uint(value_size, sizeof(stack_trace_t));
  33} stackmap SEC(".maps");
  34
  35struct {
  36        __uint(type, BPF_MAP_TYPE_ARRAY);
  37        __uint(max_entries, 128);
  38        __type(key, __u32);
  39        __type(value, stack_trace_t);
  40} stack_amap SEC(".maps");
  41
  42/* taken from /sys/kernel/debug/tracing/events/random/urandom_read/format */
  43struct random_urandom_args {
  44        unsigned long long pad;
  45        int got_bits;
  46        int pool_left;
  47        int input_left;
  48};
  49
  50SEC("tracepoint/random/urandom_read")
  51int oncpu(struct random_urandom_args *args)
  52{
  53        __u32 max_len = sizeof(struct bpf_stack_build_id)
  54                        * PERF_MAX_STACK_DEPTH;
  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(args, &stackmap, BPF_F_USER_STACK);
  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(args, stack_p, max_len,
  69                                      BPF_F_USER_STACK | BPF_F_USER_BUILD_ID);
  70        }
  71
  72        return 0;
  73}
  74
  75char _license[] SEC("license") = "GPL";
  76__u32 _version SEC("version") = 1; /* ignored by tracepoints, required by libbpf.a */
  77