bpf/progs/freplace_attach_probe.c

0001 // SPDX-License-Identifier: GPL-2.0
0002 // Copyright (c) 2020 Facebook
0003
0004 #include <linux/ptrace.h>
0005 #include <linux/bpf.h>
0006 #include <bpf/bpf_helpers.h>
0007 #include <bpf/bpf_tracing.h>
0008
0009 #define VAR_NUM 2
0010
0011 struct hmap_elem {
0012     struct bpf_spin_lock lock;
0013     int var[VAR_NUM];
0014 };
0015
0016 struct {
0017     __uint(type, BPF_MAP_TYPE_HASH);
0018     __uint(max_entries, 1);
0019     __type(key, __u32);
0020     __type(value, struct hmap_elem);
0021 } hash_map SEC(".maps");
0022
0023 SEC("freplace/handle_kprobe")
0024 int new_handle_kprobe(struct pt_regs *ctx)
0025 {
0026     struct hmap_elem zero = {}, *val;
0027     int key = 0;
0028
0029     val = bpf_map_lookup_elem(&hash_map, &key);
0030     if (!val)
0031         return 1;
0032     /* spin_lock in hash map */
0033     bpf_spin_lock(&val->lock);
0034     val->var[0] = 99;
0035     bpf_spin_unlock(&val->lock);
0036
0037     return 0;
0038 }
0039
0040 char _license[] SEC("license") = "GPL";