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// SPDX-License-Identifier: GPL-2.0
// Copyright (c) 2020 Facebook
#include "profiler.h"
#include <linux/bpf.h>
#include <bpf/bpf_helpers.h>
#include <bpf/bpf_tracing.h>
/* map of perf event fds, num_cpu * num_metric entries */
struct {
__uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
__uint(key_size, sizeof(u32));
__uint(value_size, sizeof(int));
} events SEC(".maps");
/* readings at fentry */
struct {
__uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
__uint(key_size, sizeof(u32));
__uint(value_size, sizeof(struct bpf_perf_event_value));
} fentry_readings SEC(".maps");
/* accumulated readings */
struct {
__uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
__uint(key_size, sizeof(u32));
__uint(value_size, sizeof(struct bpf_perf_event_value));
} accum_readings SEC(".maps");
/* sample counts, one per cpu */
struct {
__uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
__uint(key_size, sizeof(u32));
__uint(value_size, sizeof(u64));
} counts SEC(".maps");
const volatile __u32 num_cpu = 1;
const volatile __u32 num_metric = 1;
#define MAX_NUM_MATRICS 4
SEC("fentry/XXX")
int BPF_PROG(fentry_XXX)
{
struct bpf_perf_event_value *ptrs[MAX_NUM_MATRICS];
u32 key = bpf_get_smp_processor_id();
u32 i;
/* look up before reading, to reduce error */
for (i = 0; i < num_metric && i < MAX_NUM_MATRICS; i++) {
u32 flag = i;
ptrs[i] = bpf_map_lookup_elem(&fentry_readings, &flag);
if (!ptrs[i])
return 0;
}
for (i = 0; i < num_metric && i < MAX_NUM_MATRICS; i++) {
struct bpf_perf_event_value reading;
int err;
err = bpf_perf_event_read_value(&events, key, &reading,
sizeof(reading));
if (err)
return 0;
*(ptrs[i]) = reading;
key += num_cpu;
}
return 0;
}
static inline void
fexit_update_maps(u32 id, struct bpf_perf_event_value *after)
{
struct bpf_perf_event_value *before, diff, *accum;
before = bpf_map_lookup_elem(&fentry_readings, &id);
/* only account samples with a valid fentry_reading */
if (before && before->counter) {
struct bpf_perf_event_value *accum;
diff.counter = after->counter - before->counter;
diff.enabled = after->enabled - before->enabled;
diff.running = after->running - before->running;
accum = bpf_map_lookup_elem(&accum_readings, &id);
if (accum) {
accum->counter += diff.counter;
accum->enabled += diff.enabled;
accum->running += diff.running;
}
}
}
SEC("fexit/XXX")
int BPF_PROG(fexit_XXX)
{
struct bpf_perf_event_value readings[MAX_NUM_MATRICS];
u32 cpu = bpf_get_smp_processor_id();
u32 i, one = 1, zero = 0;
int err;
u64 *count;
/* read all events before updating the maps, to reduce error */
for (i = 0; i < num_metric && i < MAX_NUM_MATRICS; i++) {
err = bpf_perf_event_read_value(&events, cpu + i * num_cpu,
readings + i, sizeof(*readings));
if (err)
return 0;
}
count = bpf_map_lookup_elem(&counts, &zero);
if (count) {
*count += 1;
for (i = 0; i < num_metric && i < MAX_NUM_MATRICS; i++)
fexit_update_maps(i, &readings[i]);
}
return 0;
}
char LICENSE[] SEC("license") = "GPL";
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