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1// SPDX-License-Identifier: GPL-2.02// Copyright (c) 2019 Facebook3 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 10int valid = 0;11int required_size_out = 0;12int written_stack_out = 0;13int written_global_out = 0;14 15struct {16 __u64 _a;17 __u64 _b;18 __u64 _c;19} fpbe[30] = {0};20 21SEC("perf_event")22int 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 50char _license[] SEC("license") = "GPL";51