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linux-next/samples/bpf/trace_event_kern.c
Teng Qin 12fe12253c samples/bpf: add example to test reading address
This commit adds additional test in the trace_event example, by
attaching the bpf program to MEM_UOPS_RETIRED.LOCK_LOADS event with
PERF_SAMPLE_ADDR requested, and print the lock address value read from
the bpf program to trace_pipe.

Signed-off-by: Teng Qin <qinteng@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-03-08 02:22:34 +01:00

80 lines
2.3 KiB
C

/* Copyright (c) 2016 Facebook
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of version 2 of the GNU General Public
* License as published by the Free Software Foundation.
*/
#include <linux/ptrace.h>
#include <linux/version.h>
#include <uapi/linux/bpf.h>
#include <uapi/linux/bpf_perf_event.h>
#include <uapi/linux/perf_event.h>
#include "bpf_helpers.h"
struct key_t {
char comm[TASK_COMM_LEN];
u32 kernstack;
u32 userstack;
};
struct bpf_map_def SEC("maps") counts = {
.type = BPF_MAP_TYPE_HASH,
.key_size = sizeof(struct key_t),
.value_size = sizeof(u64),
.max_entries = 10000,
};
struct bpf_map_def SEC("maps") stackmap = {
.type = BPF_MAP_TYPE_STACK_TRACE,
.key_size = sizeof(u32),
.value_size = PERF_MAX_STACK_DEPTH * sizeof(u64),
.max_entries = 10000,
};
#define KERN_STACKID_FLAGS (0 | BPF_F_FAST_STACK_CMP)
#define USER_STACKID_FLAGS (0 | BPF_F_FAST_STACK_CMP | BPF_F_USER_STACK)
SEC("perf_event")
int bpf_prog1(struct bpf_perf_event_data *ctx)
{
char time_fmt1[] = "Time Enabled: %llu, Time Running: %llu";
char time_fmt2[] = "Get Time Failed, ErrCode: %d";
char addr_fmt[] = "Address recorded on event: %llx";
char fmt[] = "CPU-%d period %lld ip %llx";
u32 cpu = bpf_get_smp_processor_id();
struct bpf_perf_event_value value_buf;
struct key_t key;
u64 *val, one = 1;
int ret;
if (ctx->sample_period < 10000)
/* ignore warmup */
return 0;
bpf_get_current_comm(&key.comm, sizeof(key.comm));
key.kernstack = bpf_get_stackid(ctx, &stackmap, KERN_STACKID_FLAGS);
key.userstack = bpf_get_stackid(ctx, &stackmap, USER_STACKID_FLAGS);
if ((int)key.kernstack < 0 && (int)key.userstack < 0) {
bpf_trace_printk(fmt, sizeof(fmt), cpu, ctx->sample_period,
PT_REGS_IP(&ctx->regs));
return 0;
}
ret = bpf_perf_prog_read_value(ctx, (void *)&value_buf, sizeof(struct bpf_perf_event_value));
if (!ret)
bpf_trace_printk(time_fmt1, sizeof(time_fmt1), value_buf.enabled, value_buf.running);
else
bpf_trace_printk(time_fmt2, sizeof(time_fmt2), ret);
if (ctx->addr != 0)
bpf_trace_printk(addr_fmt, sizeof(addr_fmt), ctx->addr);
val = bpf_map_lookup_elem(&counts, &key);
if (val)
(*val)++;
else
bpf_map_update_elem(&counts, &key, &one, BPF_NOEXIST);
return 0;
}
char _license[] SEC("license") = "GPL";