Messages in this thread | ![/](/images/icornerl.gif) | | Subject | Re: [PATCH net-next 2/3] bpf: introduce bpf_perf_event_output() helper | From | He Kuang <> | Date | Wed, 21 Oct 2015 18:01:05 +0800 |
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hi, Alexei
I've tested the sample in next patch and it works well. I think more work on the perf side needs to be done for parsing PERF_COUNT_SW_BPF_OUTPUT event type, are you working on that?
Thank you.
On 2015/10/21 11:02, Alexei Starovoitov wrote: > This helper is used to send raw data from eBPF program into > special PERF_TYPE_SOFTWARE/PERF_COUNT_SW_BPF_OUTPUT perf_event. > User space needs to perf_event_open() it (either for one or all cpus) and > store FD into perf_event_array (similar to bpf_perf_event_read() helper) > before eBPF program can send data into it. > > Today the programs triggered by kprobe collect the data and either store > it into the maps or print it via bpf_trace_printk() where latter is the debug > facility and not suitable to stream the data. This new helper replaces > such bpf_trace_printk() usage and allows programs to have dedicated > channel into user space for post-processing of the raw data collected. > > Signed-off-by: Alexei Starovoitov <ast@kernel.org> > --- > include/uapi/linux/bpf.h | 11 ++++++++++ > include/uapi/linux/perf_event.h | 1 + > kernel/bpf/arraymap.c | 2 ++ > kernel/bpf/verifier.c | 3 ++- > kernel/trace/bpf_trace.c | 46 +++++++++++++++++++++++++++++++++++++++ > 5 files changed, 62 insertions(+), 1 deletion(-) > > diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h > index 564f1f091991..2e032426cfb7 100644 > --- a/include/uapi/linux/bpf.h > +++ b/include/uapi/linux/bpf.h > @@ -287,6 +287,17 @@ enum bpf_func_id { > * Return: realm if != 0 > */ > BPF_FUNC_get_route_realm, > + > + /** > + * bpf_perf_event_output(ctx, map, index, data, size) - output perf raw sample > + * @ctx: struct pt_regs* > + * @map: pointer to perf_event_array map > + * @index: index of event in the map > + * @data: data on stack to be output as raw data > + * @size: size of data > + * Return: 0 on success > + */ > + BPF_FUNC_perf_event_output, > __BPF_FUNC_MAX_ID, > }; > > diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h > index 2881145cda86..d3c417615361 100644 > --- a/include/uapi/linux/perf_event.h > +++ b/include/uapi/linux/perf_event.h > @@ -110,6 +110,7 @@ enum perf_sw_ids { > PERF_COUNT_SW_ALIGNMENT_FAULTS = 7, > PERF_COUNT_SW_EMULATION_FAULTS = 8, > PERF_COUNT_SW_DUMMY = 9, > + PERF_COUNT_SW_BPF_OUTPUT = 10, > > PERF_COUNT_SW_MAX, /* non-ABI */ > }; > diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c > index f2d9e698c753..e3cfe46b074f 100644 > --- a/kernel/bpf/arraymap.c > +++ b/kernel/bpf/arraymap.c > @@ -295,6 +295,8 @@ static void *perf_event_fd_array_get_ptr(struct bpf_map *map, int fd) > return (void *)attr; > > if (attr->type != PERF_TYPE_RAW && > + !(attr->type == PERF_TYPE_SOFTWARE && > + attr->config == PERF_COUNT_SW_BPF_OUTPUT) && > attr->type != PERF_TYPE_HARDWARE) { > perf_event_release_kernel(event); > return ERR_PTR(-EINVAL); > diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c > index 1d6b97be79e1..b56cf51f8d42 100644 > --- a/kernel/bpf/verifier.c > +++ b/kernel/bpf/verifier.c > @@ -245,6 +245,7 @@ static const struct { > } func_limit[] = { > {BPF_MAP_TYPE_PROG_ARRAY, BPF_FUNC_tail_call}, > {BPF_MAP_TYPE_PERF_EVENT_ARRAY, BPF_FUNC_perf_event_read}, > + {BPF_MAP_TYPE_PERF_EVENT_ARRAY, BPF_FUNC_perf_event_output}, > }; > > static void print_verifier_state(struct verifier_env *env) > @@ -910,7 +911,7 @@ static int check_map_func_compatibility(struct bpf_map *map, int func_id) > * don't allow any other map type to be passed into > * the special func; > */ > - if (bool_map != bool_func) > + if (bool_func && bool_map != bool_func) > return -EINVAL; > } > > diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c > index 0fe96c7c8803..47febbe7998e 100644 > --- a/kernel/trace/bpf_trace.c > +++ b/kernel/trace/bpf_trace.c > @@ -215,6 +215,50 @@ const struct bpf_func_proto bpf_perf_event_read_proto = { > .arg2_type = ARG_ANYTHING, > }; > > +static u64 bpf_perf_event_output(u64 r1, u64 r2, u64 index, u64 r4, u64 size) > +{ > + struct pt_regs *regs = (struct pt_regs *) (long) r1; > + struct bpf_map *map = (struct bpf_map *) (long) r2; > + struct bpf_array *array = container_of(map, struct bpf_array, map); > + void *data = (void *) (long) r4; > + struct perf_sample_data sample_data; > + struct perf_event *event; > + struct perf_raw_record raw = { > + .size = size, > + .data = data, > + }; > + > + if (unlikely(index >= array->map.max_entries)) > + return -E2BIG; > + > + event = (struct perf_event *)array->ptrs[index]; > + if (unlikely(!event)) > + return -ENOENT; > + > + if (unlikely(event->attr.type != PERF_TYPE_SOFTWARE || > + event->attr.config != PERF_COUNT_SW_BPF_OUTPUT)) > + return -EINVAL; > + > + if (unlikely(event->oncpu != smp_processor_id())) > + return -EOPNOTSUPP; > + > + perf_sample_data_init(&sample_data, 0, 0); > + sample_data.raw = &raw; > + perf_event_output(event, &sample_data, regs); > + return 0; > +} > + > +static const struct bpf_func_proto bpf_perf_event_output_proto = { > + .func = bpf_perf_event_output, > + .gpl_only = false, > + .ret_type = RET_INTEGER, > + .arg1_type = ARG_PTR_TO_CTX, > + .arg2_type = ARG_CONST_MAP_PTR, > + .arg3_type = ARG_ANYTHING, > + .arg4_type = ARG_PTR_TO_STACK, > + .arg5_type = ARG_CONST_STACK_SIZE, > +}; > + > static const struct bpf_func_proto *kprobe_prog_func_proto(enum bpf_func_id func_id) > { > switch (func_id) { > @@ -242,6 +286,8 @@ static const struct bpf_func_proto *kprobe_prog_func_proto(enum bpf_func_id func > return &bpf_get_smp_processor_id_proto; > case BPF_FUNC_perf_event_read: > return &bpf_perf_event_read_proto; > + case BPF_FUNC_perf_event_output: > + return &bpf_perf_event_output_proto; > default: > return NULL; > } >
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