tools/testing/selftests/bpf/progs/test_perf_branches.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 // Copyright (c) 2019 Facebook
   3
   4 #include <stddef.h>
   5 #include <linux/ptrace.h>
   6 #include <linux/bpf.h>
   7 #include <bpf/bpf_helpers.h>
   8 #include <bpf/bpf_tracing.h>
   9
  10 int valid = 0;
  11 int required_size_out = 0;
  12 int written_stack_out = 0;
  13 int written_global_out = 0;
  14
  15 struct {
  16         __u64 _a;
  17         __u64 _b;
  18         __u64 _c;
  19 } fpbe[30] = {0};
  20
  21 SEC("perf_event")
  22 int perf_branches(void *ctx)
  23 {
  24         __u64 entries[4 * 3] = {0};
  25         int required_size, written_stack, written_global;
  26
  27         /* write to stack */
  28         written_stack = bpf_read_branch_records(ctx, entries, sizeof(entries), 0);
  29         /* ignore spurious events */
  30         if (!written_stack)
  31                 return 1;
  32
  33         /* get required size */
  34         required_size = bpf_read_branch_records(ctx, NULL, 0,
  35                                                 BPF_F_GET_BRANCH_RECORDS_SIZE);
  36
  37         written_global = bpf_read_branch_records(ctx, fpbe, sizeof(fpbe), 0);
  38         /* ignore spurious events */
  39         if (!written_global)
  40                 return 1;
  41
  42         required_size_out = required_size;
  43         written_stack_out = written_stack;
  44         written_global_out = written_global;
  45         valid = 1;
  46
  47         return 0;
  48 }
  49
  50 char _license[] SEC("license") = "GPL";