51 lines
1.1 KiB
C
51 lines
1.1 KiB
C
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// SPDX-License-Identifier: GPL-2.0
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// Copyright (c) 2019 Facebook
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#include <stddef.h>
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#include <linux/ptrace.h>
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#include <linux/bpf.h>
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#include <bpf/bpf_helpers.h>
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#include <bpf/bpf_tracing.h>
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int valid = 0;
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int required_size_out = 0;
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int written_stack_out = 0;
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int written_global_out = 0;
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struct {
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__u64 _a;
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__u64 _b;
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__u64 _c;
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} fpbe[30] = {0};
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SEC("perf_event")
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int perf_branches(void *ctx)
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{
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__u64 entries[4 * 3] = {0};
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int required_size, written_stack, written_global;
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/* write to stack */
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written_stack = bpf_read_branch_records(ctx, entries, sizeof(entries), 0);
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/* ignore spurious events */
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if (!written_stack)
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return 1;
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/* get required size */
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required_size = bpf_read_branch_records(ctx, NULL, 0,
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BPF_F_GET_BRANCH_RECORDS_SIZE);
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written_global = bpf_read_branch_records(ctx, fpbe, sizeof(fpbe), 0);
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/* ignore spurious events */
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if (!written_global)
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return 1;
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required_size_out = required_size;
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written_stack_out = written_stack;
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written_global_out = written_global;
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valid = 1;
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return 0;
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}
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char _license[] SEC("license") = "GPL";
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