1// SPDX-License-Identifier: GPL-2.0
 2#ifndef _PERF_BPF_H
 3#define _PERF_BPF_H
 4
 5#include <uapi/linux/bpf.h>
 6
 7/*
 8 * A helper structure used by eBPF C program to describe map attributes to
 9 * elf_bpf loader, taken from tools/testing/selftests/bpf/bpf_helpers.h:
10 */
11struct bpf_map {
12        unsigned int type;
13        unsigned int key_size;
14        unsigned int value_size;
15        unsigned int max_entries;
16        unsigned int map_flags;
17        unsigned int inner_map_idx;
18        unsigned int numa_node;
19};
20
21#define bpf_map(name, _type, type_key, type_val, _max_entries)	\
22struct bpf_map SEC("maps") name = {				\
23	.type	     = BPF_MAP_TYPE_##_type,			\
24	.key_size    = sizeof(type_key),			\
25	.value_size  = sizeof(type_val),			\
26	.max_entries = _max_entries,				\
27};								\
28struct ____btf_map_##name {					\
29	type_key key;						\
30	type_val value;                                 	\
31};								\
32struct ____btf_map_##name __attribute__((section(".maps." #name), used)) \
33	____btf_map_##name = { }
34
35/*
36 * FIXME: this should receive .max_entries as a parameter, as careful
37 *	  tuning of these limits is needed to avoid hitting limits that
38 *	  prevents other BPF constructs, such as tracepoint handlers,
39 *	  to get installed, with cryptic messages from libbpf, etc.
40 *	  For the current need, 'perf trace --filter-pids', 64 should
41 *	  be good enough, but this surely needs to be revisited.
42 */
43#define pid_map(name, value_type) bpf_map(name, HASH, pid_t, value_type, 64)
44
45static int (*bpf_map_update_elem)(struct bpf_map *map, void *key, void *value, u64 flags) = (void *)BPF_FUNC_map_update_elem;
46static void *(*bpf_map_lookup_elem)(struct bpf_map *map, void *key) = (void *)BPF_FUNC_map_lookup_elem;
47
48static void (*bpf_tail_call)(void *ctx, void *map, int index) = (void *)BPF_FUNC_tail_call;
49
50#define SEC(NAME) __attribute__((section(NAME),  used))
51
52#define probe(function, vars) \
53	SEC(#function "=" #function " " #vars) function
54
55#define syscall_enter(name) \
56	SEC("syscalls:sys_enter_" #name) syscall_enter_ ## name
57
58#define syscall_exit(name) \
59	SEC("syscalls:sys_exit_" #name) syscall_exit_ ## name
60
61#define license(name) \
62char _license[] SEC("license") = #name; \
63int _version SEC("version") = LINUX_VERSION_CODE;
64
65static int (*probe_read)(void *dst, int size, const void *unsafe_addr) = (void *)BPF_FUNC_probe_read;
66static int (*probe_read_str)(void *dst, int size, const void *unsafe_addr) = (void *)BPF_FUNC_probe_read_str;
67
68static int (*perf_event_output)(void *, struct bpf_map *, int, void *, unsigned long) = (void *)BPF_FUNC_perf_event_output;
69
70#endif /* _PERF_BPF_H */