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bpf, trace: add BPF_F_CURRENT_CPU flag for bpf_perf_event_output

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Add a BPF_F_CURRENT_CPU flag to optimize the use-case where user space has
per-CPU ring buffers and the eBPF program pushes the data into the current
CPU's ring buffer which saves us an extra helper function call in eBPF.
Also, make sure to properly reserve the remaining flags which are not used.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Daniel Borkmann
2016-04-18 21:01:23 +02:00
committed by David S. Miller
parent 553bc087ca
commit 1e33759c78
2 changed files with 10 additions and 1 deletions
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7
kernel/trace/bpf_trace.c
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@@ -225,11 +225,12 @@ static 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)
static u64 bpf_perf_event_output(u64 r1, u64 r2, u64 flags, 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);
u64 index = flags & BPF_F_INDEX_MASK;
void *data = (void *) (long) r4;
struct perf_sample_data sample_data;
struct perf_event *event;
@@ -239,6 +240,10 @@ static u64 bpf_perf_event_output(u64 r1, u64 r2, u64 index, u64 r4, u64 size)
.data = data,
};
if (unlikely(flags & ~(BPF_F_INDEX_MASK)))
return -EINVAL;
if (index == BPF_F_CURRENT_CPU)
index = raw_smp_processor_id();
if (unlikely(index >= array->map.max_entries))
return -E2BIG;