Commit 0515e599 authored by Alexei Starovoitov's avatar Alexei Starovoitov Committed by David S. Miller

bpf: introduce BPF_PROG_TYPE_PERF_EVENT program type

Introduce BPF_PROG_TYPE_PERF_EVENT programs that can be attached to
HW and SW perf events (PERF_TYPE_HARDWARE and PERF_TYPE_SOFTWARE
correspondingly in uapi/linux/perf_event.h)

The program visible context meta structure is
struct bpf_perf_event_data {
    struct pt_regs regs;
     __u64 sample_period;
};
which is accessible directly from the program:
int bpf_prog(struct bpf_perf_event_data *ctx)
{
  ... ctx->sample_period ...
  ... ctx->regs.ip ...
}

The bpf verifier rewrites the accesses into kernel internal
struct bpf_perf_event_data_kern which allows changing
struct perf_sample_data without affecting bpf programs.
New fields can be added to the end of struct bpf_perf_event_data
in the future.
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Acked-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent ea2e7ce5
......@@ -788,6 +788,11 @@ struct perf_output_handle {
int page;
};
struct bpf_perf_event_data_kern {
struct pt_regs *regs;
struct perf_sample_data *data;
};
#ifdef CONFIG_CGROUP_PERF
/*
......
......@@ -71,6 +71,7 @@ header-y += binfmts.h
header-y += blkpg.h
header-y += blktrace_api.h
header-y += bpf_common.h
header-y += bpf_perf_event.h
header-y += bpf.h
header-y += bpqether.h
header-y += bsg.h
......
......@@ -95,6 +95,7 @@ enum bpf_prog_type {
BPF_PROG_TYPE_SCHED_ACT,
BPF_PROG_TYPE_TRACEPOINT,
BPF_PROG_TYPE_XDP,
BPF_PROG_TYPE_PERF_EVENT,
};
#define BPF_PSEUDO_MAP_FD 1
......
/* 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.
*/
#ifndef _UAPI__LINUX_BPF_PERF_EVENT_H__
#define _UAPI__LINUX_BPF_PERF_EVENT_H__
#include <linux/types.h>
#include <linux/ptrace.h>
struct bpf_perf_event_data {
struct pt_regs regs;
__u64 sample_period;
};
#endif /* _UAPI__LINUX_BPF_PERF_EVENT_H__ */
/* Copyright (c) 2011-2015 PLUMgrid, http://plumgrid.com
* 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
......@@ -8,6 +9,7 @@
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/bpf.h>
#include <linux/bpf_perf_event.h>
#include <linux/filter.h>
#include <linux/uaccess.h>
#include <linux/ctype.h>
......@@ -552,10 +554,69 @@ static struct bpf_prog_type_list tracepoint_tl = {
.type = BPF_PROG_TYPE_TRACEPOINT,
};
static bool pe_prog_is_valid_access(int off, int size, enum bpf_access_type type,
enum bpf_reg_type *reg_type)
{
if (off < 0 || off >= sizeof(struct bpf_perf_event_data))
return false;
if (type != BPF_READ)
return false;
if (off % size != 0)
return false;
if (off == offsetof(struct bpf_perf_event_data, sample_period)) {
if (size != sizeof(u64))
return false;
} else {
if (size != sizeof(long))
return false;
}
return true;
}
static u32 pe_prog_convert_ctx_access(enum bpf_access_type type, int dst_reg,
int src_reg, int ctx_off,
struct bpf_insn *insn_buf,
struct bpf_prog *prog)
{
struct bpf_insn *insn = insn_buf;
switch (ctx_off) {
case offsetof(struct bpf_perf_event_data, sample_period):
BUILD_BUG_ON(FIELD_SIZEOF(struct perf_sample_data, period) != sizeof(u64));
*insn++ = BPF_LDX_MEM(bytes_to_bpf_size(FIELD_SIZEOF(struct bpf_perf_event_data_kern, data)),
dst_reg, src_reg,
offsetof(struct bpf_perf_event_data_kern, data));
*insn++ = BPF_LDX_MEM(BPF_DW, dst_reg, dst_reg,
offsetof(struct perf_sample_data, period));
break;
default:
*insn++ = BPF_LDX_MEM(bytes_to_bpf_size(FIELD_SIZEOF(struct bpf_perf_event_data_kern, regs)),
dst_reg, src_reg,
offsetof(struct bpf_perf_event_data_kern, regs));
*insn++ = BPF_LDX_MEM(bytes_to_bpf_size(sizeof(long)),
dst_reg, dst_reg, ctx_off);
break;
}
return insn - insn_buf;
}
static const struct bpf_verifier_ops perf_event_prog_ops = {
.get_func_proto = tp_prog_func_proto,
.is_valid_access = pe_prog_is_valid_access,
.convert_ctx_access = pe_prog_convert_ctx_access,
};
static struct bpf_prog_type_list perf_event_tl = {
.ops = &perf_event_prog_ops,
.type = BPF_PROG_TYPE_PERF_EVENT,
};
static int __init register_kprobe_prog_ops(void)
{
bpf_register_prog_type(&kprobe_tl);
bpf_register_prog_type(&tracepoint_tl);
bpf_register_prog_type(&perf_event_tl);
return 0;
}
late_initcall(register_kprobe_prog_ops);
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