linux/samples/bpf/tracex6_kern.c
Teng Qin 41e9a8046c samples/bpf: add tests for more perf event types
$ trace_event

tests attaching BPF program to HW_CPU_CYCLES, SW_CPU_CLOCK, HW_CACHE_L1D and other events.
It runs 'dd' in the background while bpf program collects user and kernel
stack trace on counter overflow.
User space expects to see sys_read and sys_write in the kernel stack.

$ tracex6

tests reading of various perf counters from BPF program.

Both tests were refactored to increase coverage and be more accurate.

Signed-off-by: Teng Qin <qinteng@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-06-04 21:58:15 -04:00

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C

#include <linux/ptrace.h>
#include <linux/version.h>
#include <uapi/linux/bpf.h>
#include "bpf_helpers.h"
struct bpf_map_def SEC("maps") counters = {
.type = BPF_MAP_TYPE_PERF_EVENT_ARRAY,
.key_size = sizeof(int),
.value_size = sizeof(u32),
.max_entries = 64,
};
struct bpf_map_def SEC("maps") values = {
.type = BPF_MAP_TYPE_HASH,
.key_size = sizeof(int),
.value_size = sizeof(u64),
.max_entries = 64,
};
SEC("kprobe/htab_map_get_next_key")
int bpf_prog1(struct pt_regs *ctx)
{
u32 key = bpf_get_smp_processor_id();
u64 count, *val;
s64 error;
count = bpf_perf_event_read(&counters, key);
error = (s64)count;
if (error <= -2 && error >= -22)
return 0;
val = bpf_map_lookup_elem(&values, &key);
if (val)
*val = count;
else
bpf_map_update_elem(&values, &key, &count, BPF_NOEXIST);
return 0;
}
char _license[] SEC("license") = "GPL";
u32 _version SEC("version") = LINUX_VERSION_CODE;