1 // SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
2 /* Copyright (c) 2020 Facebook */
3 #include <vmlinux.h>
4 #include <bpf/bpf_helpers.h>
5 #include <bpf/bpf_core_read.h>
6 #include <bpf/bpf_tracing.h>
7 #include "pid_iter.h"
8
9 /* keep in sync with the definition in main.h */
10 enum bpf_obj_type {
11 BPF_OBJ_UNKNOWN,
12 BPF_OBJ_PROG,
13 BPF_OBJ_MAP,
14 BPF_OBJ_LINK,
15 BPF_OBJ_BTF,
16 };
17
18 struct bpf_perf_link___local {
19 struct bpf_link link;
20 struct file *perf_file;
21 } __attribute__((preserve_access_index));
22
23 struct perf_event___local {
24 u64 bpf_cookie;
25 } __attribute__((preserve_access_index));
26
27 enum bpf_link_type___local {
28 BPF_LINK_TYPE_PERF_EVENT___local = 7,
29 };
30
31 extern const void bpf_link_fops __ksym;
32 extern const void bpf_map_fops __ksym;
33 extern const void bpf_prog_fops __ksym;
34 extern const void btf_fops __ksym;
35
36 const volatile enum bpf_obj_type obj_type = BPF_OBJ_UNKNOWN;
37
get_obj_id(void * ent,enum bpf_obj_type type)38 static __always_inline __u32 get_obj_id(void *ent, enum bpf_obj_type type)
39 {
40 switch (type) {
41 case BPF_OBJ_PROG:
42 return BPF_CORE_READ((struct bpf_prog *)ent, aux, id);
43 case BPF_OBJ_MAP:
44 return BPF_CORE_READ((struct bpf_map *)ent, id);
45 case BPF_OBJ_BTF:
46 return BPF_CORE_READ((struct btf *)ent, id);
47 case BPF_OBJ_LINK:
48 return BPF_CORE_READ((struct bpf_link *)ent, id);
49 default:
50 return 0;
51 }
52 }
53
54 /* could be used only with BPF_LINK_TYPE_PERF_EVENT links */
get_bpf_cookie(struct bpf_link * link)55 static __u64 get_bpf_cookie(struct bpf_link *link)
56 {
57 struct bpf_perf_link___local *perf_link;
58 struct perf_event___local *event;
59
60 perf_link = container_of(link, struct bpf_perf_link___local, link);
61 event = BPF_CORE_READ(perf_link, perf_file, private_data);
62 return BPF_CORE_READ(event, bpf_cookie);
63 }
64
65 SEC("iter/task_file")
iter(struct bpf_iter__task_file * ctx)66 int iter(struct bpf_iter__task_file *ctx)
67 {
68 struct file *file = ctx->file;
69 struct task_struct *task = ctx->task;
70 struct pid_iter_entry e;
71 const void *fops;
72
73 if (!file || !task)
74 return 0;
75
76 switch (obj_type) {
77 case BPF_OBJ_PROG:
78 fops = &bpf_prog_fops;
79 break;
80 case BPF_OBJ_MAP:
81 fops = &bpf_map_fops;
82 break;
83 case BPF_OBJ_BTF:
84 fops = &btf_fops;
85 break;
86 case BPF_OBJ_LINK:
87 fops = &bpf_link_fops;
88 break;
89 default:
90 return 0;
91 }
92
93 if (file->f_op != fops)
94 return 0;
95
96 __builtin_memset(&e, 0, sizeof(e));
97 e.pid = task->tgid;
98 e.id = get_obj_id(file->private_data, obj_type);
99
100 if (obj_type == BPF_OBJ_LINK &&
101 bpf_core_enum_value_exists(enum bpf_link_type___local,
102 BPF_LINK_TYPE_PERF_EVENT___local)) {
103 struct bpf_link *link = (struct bpf_link *) file->private_data;
104
105 if (BPF_CORE_READ(link, type) == bpf_core_enum_value(enum bpf_link_type___local,
106 BPF_LINK_TYPE_PERF_EVENT___local)) {
107 e.has_bpf_cookie = true;
108 e.bpf_cookie = get_bpf_cookie(link);
109 }
110 }
111
112 bpf_probe_read_kernel_str(&e.comm, sizeof(e.comm),
113 task->group_leader->comm);
114 bpf_seq_write(ctx->meta->seq, &e, sizeof(e));
115
116 return 0;
117 }
118
119 char LICENSE[] SEC("license") = "Dual BSD/GPL";
120