1 // SPDX-License-Identifier: GPL-2.0
2 /* Copyright (c) 2023 Meta Platforms, Inc. and affiliates. */
3 #include "vmlinux.h"
4 #include <bpf/bpf_helpers.h>
5 #include <bpf/bpf_tracing.h>
6 #include <bpf/bpf_core_read.h>
7 #include "bpf_misc.h"
8
9 char _license[] SEC("license") = "GPL";
10
11 static long stack[256];
12
13 /*
14 * KPROBE contexts
15 */
16
kprobe_typedef_ctx_subprog(bpf_user_pt_regs_t * ctx)17 __weak int kprobe_typedef_ctx_subprog(bpf_user_pt_regs_t *ctx)
18 {
19 return bpf_get_stack(ctx, &stack, sizeof(stack), 0);
20 }
21
22 SEC("?kprobe")
23 __success
kprobe_typedef_ctx(void * ctx)24 int kprobe_typedef_ctx(void *ctx)
25 {
26 return kprobe_typedef_ctx_subprog(ctx);
27 }
28
29 /* s390x defines:
30 *
31 * typedef user_pt_regs bpf_user_pt_regs_t;
32 * typedef struct { ... } user_pt_regs;
33 *
34 * And so "canonical" underlying struct type is anonymous.
35 * So on s390x only valid ways to have PTR_TO_CTX argument in global subprogs
36 * are:
37 * - bpf_user_pt_regs_t *ctx (typedef);
38 * - struct bpf_user_pt_regs_t *ctx (backwards compatible struct hack);
39 * - void *ctx __arg_ctx (arg:ctx tag)
40 *
41 * Other architectures also allow using underlying struct types (e.g.,
42 * `struct pt_regs *ctx` for x86-64)
43 */
44 #ifndef bpf_target_s390
45
46 #define pt_regs_struct_t typeof(*(__PT_REGS_CAST((struct pt_regs *)NULL)))
47
kprobe_struct_ctx_subprog(pt_regs_struct_t * ctx)48 __weak int kprobe_struct_ctx_subprog(pt_regs_struct_t *ctx)
49 {
50 return bpf_get_stack((void *)ctx, &stack, sizeof(stack), 0);
51 }
52
53 SEC("?kprobe")
54 __success
kprobe_resolved_ctx(void * ctx)55 int kprobe_resolved_ctx(void *ctx)
56 {
57 return kprobe_struct_ctx_subprog(ctx);
58 }
59
60 #endif
61
62 /* this is current hack to make this work on old kernels */
63 struct bpf_user_pt_regs_t {};
64
kprobe_workaround_ctx_subprog(struct bpf_user_pt_regs_t * ctx)65 __weak int kprobe_workaround_ctx_subprog(struct bpf_user_pt_regs_t *ctx)
66 {
67 return bpf_get_stack(ctx, &stack, sizeof(stack), 0);
68 }
69
70 SEC("?kprobe")
71 __success
kprobe_workaround_ctx(void * ctx)72 int kprobe_workaround_ctx(void *ctx)
73 {
74 return kprobe_workaround_ctx_subprog(ctx);
75 }
76
77 /*
78 * RAW_TRACEPOINT contexts
79 */
80
raw_tp_ctx_subprog(struct bpf_raw_tracepoint_args * ctx)81 __weak int raw_tp_ctx_subprog(struct bpf_raw_tracepoint_args *ctx)
82 {
83 return bpf_get_stack(ctx, &stack, sizeof(stack), 0);
84 }
85
86 SEC("?raw_tp")
87 __success
raw_tp_ctx(void * ctx)88 int raw_tp_ctx(void *ctx)
89 {
90 return raw_tp_ctx_subprog(ctx);
91 }
92
93 /*
94 * RAW_TRACEPOINT_WRITABLE contexts
95 */
96
raw_tp_writable_ctx_subprog(struct bpf_raw_tracepoint_args * ctx)97 __weak int raw_tp_writable_ctx_subprog(struct bpf_raw_tracepoint_args *ctx)
98 {
99 return bpf_get_stack(ctx, &stack, sizeof(stack), 0);
100 }
101
102 SEC("?raw_tp")
103 __success
raw_tp_writable_ctx(void * ctx)104 int raw_tp_writable_ctx(void *ctx)
105 {
106 return raw_tp_writable_ctx_subprog(ctx);
107 }
108
109 /*
110 * PERF_EVENT contexts
111 */
112
perf_event_ctx_subprog(struct bpf_perf_event_data * ctx)113 __weak int perf_event_ctx_subprog(struct bpf_perf_event_data *ctx)
114 {
115 return bpf_get_stack(ctx, &stack, sizeof(stack), 0);
116 }
117
118 SEC("?perf_event")
119 __success
perf_event_ctx(void * ctx)120 int perf_event_ctx(void *ctx)
121 {
122 return perf_event_ctx_subprog(ctx);
123 }
124
125 /* this global subprog can be now called from many types of entry progs, each
126 * with different context type
127 */
subprog_ctx_tag(void * ctx __arg_ctx)128 __weak int subprog_ctx_tag(void *ctx __arg_ctx)
129 {
130 return bpf_get_stack(ctx, stack, sizeof(stack), 0);
131 }
132
133 struct my_struct { int x; };
134
subprog_multi_ctx_tags(void * ctx1 __arg_ctx,struct my_struct * mem,void * ctx2 __arg_ctx)135 __weak int subprog_multi_ctx_tags(void *ctx1 __arg_ctx,
136 struct my_struct *mem,
137 void *ctx2 __arg_ctx)
138 {
139 if (!mem)
140 return 0;
141
142 return bpf_get_stack(ctx1, stack, sizeof(stack), 0) +
143 mem->x +
144 bpf_get_stack(ctx2, stack, sizeof(stack), 0);
145 }
146
147 SEC("?raw_tp")
148 __success __log_level(2)
arg_tag_ctx_raw_tp(void * ctx)149 int arg_tag_ctx_raw_tp(void *ctx)
150 {
151 struct my_struct x = { .x = 123 };
152
153 return subprog_ctx_tag(ctx) + subprog_multi_ctx_tags(ctx, &x, ctx);
154 }
155
156 SEC("?perf_event")
157 __success __log_level(2)
arg_tag_ctx_perf(void * ctx)158 int arg_tag_ctx_perf(void *ctx)
159 {
160 struct my_struct x = { .x = 123 };
161
162 return subprog_ctx_tag(ctx) + subprog_multi_ctx_tags(ctx, &x, ctx);
163 }
164
165 SEC("?kprobe")
166 __success __log_level(2)
arg_tag_ctx_kprobe(void * ctx)167 int arg_tag_ctx_kprobe(void *ctx)
168 {
169 struct my_struct x = { .x = 123 };
170
171 return subprog_ctx_tag(ctx) + subprog_multi_ctx_tags(ctx, &x, ctx);
172 }
173