forked from Minki/linux
bpf: add helper bpf_perf_prog_read_value
This patch adds helper bpf_perf_prog_read_cvalue for perf event based bpf programs, to read event counter and enabled/running time. The enabled/running time is accumulated since the perf event open. The typical use case for perf event based bpf program is to attach itself to a single event. In such cases, if it is desirable to get scaling factor between two bpf invocations, users can can save the time values in a map, and use the value from the map and the current value to calculate the scaling factor. Signed-off-by: Yonghong Song <yhs@fb.com> Acked-by: Alexei Starovoitov <ast@fb.com> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: David S. Miller <davem@davemloft.net>
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parent
020a32d958
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4bebdc7a85
@ -649,6 +649,13 @@ union bpf_attr {
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* @buf: buf to fill
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* @buf_size: size of the buf
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* Return: 0 on success or negative error code
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*
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* int bpf_perf_prog_read_value(ctx, buf, buf_size)
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* read perf prog attached perf event counter and enabled/running time
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* @ctx: pointer to ctx
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* @buf: buf to fill
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* @buf_size: size of the buf
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* Return : 0 on success or negative error code
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*/
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#define __BPF_FUNC_MAPPER(FN) \
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FN(unspec), \
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@ -706,7 +713,8 @@ union bpf_attr {
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FN(sk_redirect_map), \
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FN(sock_map_update), \
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FN(xdp_adjust_meta), \
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FN(perf_event_read_value),
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FN(perf_event_read_value), \
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FN(perf_prog_read_value),
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/* integer value in 'imm' field of BPF_CALL instruction selects which helper
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* function eBPF program intends to call
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@ -613,6 +613,32 @@ static const struct bpf_func_proto bpf_get_stackid_proto_tp = {
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.arg3_type = ARG_ANYTHING,
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};
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BPF_CALL_3(bpf_perf_prog_read_value_tp, struct bpf_perf_event_data_kern *, ctx,
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struct bpf_perf_event_value *, buf, u32, size)
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{
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int err = -EINVAL;
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if (unlikely(size != sizeof(struct bpf_perf_event_value)))
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goto clear;
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err = perf_event_read_local(ctx->event, &buf->counter, &buf->enabled,
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&buf->running);
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if (unlikely(err))
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goto clear;
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return 0;
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clear:
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memset(buf, 0, size);
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return err;
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}
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static const struct bpf_func_proto bpf_perf_prog_read_value_proto_tp = {
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.func = bpf_perf_prog_read_value_tp,
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.gpl_only = true,
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.ret_type = RET_INTEGER,
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.arg1_type = ARG_PTR_TO_CTX,
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.arg2_type = ARG_PTR_TO_UNINIT_MEM,
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.arg3_type = ARG_CONST_SIZE,
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};
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static const struct bpf_func_proto *tp_prog_func_proto(enum bpf_func_id func_id)
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{
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switch (func_id) {
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@ -620,6 +646,8 @@ static const struct bpf_func_proto *tp_prog_func_proto(enum bpf_func_id func_id)
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return &bpf_perf_event_output_proto_tp;
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case BPF_FUNC_get_stackid:
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return &bpf_get_stackid_proto_tp;
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case BPF_FUNC_perf_prog_read_value:
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return &bpf_perf_prog_read_value_proto_tp;
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default:
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return tracing_func_proto(func_id);
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}
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