1 // SPDX-License-Identifier: GPL-2.0
2 // Copyright (c) 2019 Facebook
3 #include <linux/sched.h>
4 #include <linux/ptrace.h>
5 #include <stdint.h>
6 #include <stddef.h>
7 #include <stdbool.h>
8 #include <linux/bpf.h>
9 #include <bpf/bpf_helpers.h>
10 #include "bpf_misc.h"
11 #include "bpf_compiler.h"
12
13 #define FUNCTION_NAME_LEN 64
14 #define FILE_NAME_LEN 128
15 #define TASK_COMM_LEN 16
16
17 typedef struct {
18 int PyThreadState_frame;
19 int PyThreadState_thread;
20 int PyFrameObject_back;
21 int PyFrameObject_code;
22 int PyFrameObject_lineno;
23 int PyCodeObject_filename;
24 int PyCodeObject_name;
25 int String_data;
26 int String_size;
27 } OffsetConfig;
28
29 typedef struct {
30 uintptr_t current_state_addr;
31 uintptr_t tls_key_addr;
32 OffsetConfig offsets;
33 bool use_tls;
34 } PidData;
35
36 typedef struct {
37 uint32_t success;
38 } Stats;
39
40 typedef struct {
41 char name[FUNCTION_NAME_LEN];
42 char file[FILE_NAME_LEN];
43 } Symbol;
44
45 typedef struct {
46 uint32_t pid;
47 uint32_t tid;
48 char comm[TASK_COMM_LEN];
49 int32_t kernel_stack_id;
50 int32_t user_stack_id;
51 bool thread_current;
52 bool pthread_match;
53 bool stack_complete;
54 int16_t stack_len;
55 int32_t stack[STACK_MAX_LEN];
56
57 int has_meta;
58 int metadata;
59 char dummy_safeguard;
60 } Event;
61
62
63 typedef int pid_t;
64
65 typedef struct {
66 void* f_back; // PyFrameObject.f_back, previous frame
67 void* f_code; // PyFrameObject.f_code, pointer to PyCodeObject
68 void* co_filename; // PyCodeObject.co_filename
69 void* co_name; // PyCodeObject.co_name
70 } FrameData;
71
72 #ifdef SUBPROGS
73 __noinline
74 #else
75 __always_inline
76 #endif
get_thread_state(void * tls_base,PidData * pidData)77 static void *get_thread_state(void *tls_base, PidData *pidData)
78 {
79 void* thread_state;
80 int key;
81
82 bpf_probe_read_user(&key, sizeof(key), (void*)(long)pidData->tls_key_addr);
83 bpf_probe_read_user(&thread_state, sizeof(thread_state),
84 tls_base + 0x310 + key * 0x10 + 0x08);
85 return thread_state;
86 }
87
get_frame_data(void * frame_ptr,PidData * pidData,FrameData * frame,Symbol * symbol)88 static __always_inline bool get_frame_data(void *frame_ptr, PidData *pidData,
89 FrameData *frame, Symbol *symbol)
90 {
91 // read data from PyFrameObject
92 bpf_probe_read_user(&frame->f_back,
93 sizeof(frame->f_back),
94 frame_ptr + pidData->offsets.PyFrameObject_back);
95 bpf_probe_read_user(&frame->f_code,
96 sizeof(frame->f_code),
97 frame_ptr + pidData->offsets.PyFrameObject_code);
98
99 // read data from PyCodeObject
100 if (!frame->f_code)
101 return false;
102 bpf_probe_read_user(&frame->co_filename,
103 sizeof(frame->co_filename),
104 frame->f_code + pidData->offsets.PyCodeObject_filename);
105 bpf_probe_read_user(&frame->co_name,
106 sizeof(frame->co_name),
107 frame->f_code + pidData->offsets.PyCodeObject_name);
108 // read actual names into symbol
109 if (frame->co_filename)
110 bpf_probe_read_user_str(&symbol->file,
111 sizeof(symbol->file),
112 frame->co_filename +
113 pidData->offsets.String_data);
114 if (frame->co_name)
115 bpf_probe_read_user_str(&symbol->name,
116 sizeof(symbol->name),
117 frame->co_name +
118 pidData->offsets.String_data);
119 return true;
120 }
121
122 struct {
123 __uint(type, BPF_MAP_TYPE_HASH);
124 __uint(max_entries, 1);
125 __type(key, int);
126 __type(value, PidData);
127 } pidmap SEC(".maps");
128
129 struct {
130 __uint(type, BPF_MAP_TYPE_HASH);
131 __uint(max_entries, 1);
132 __type(key, int);
133 __type(value, Event);
134 } eventmap SEC(".maps");
135
136 struct {
137 __uint(type, BPF_MAP_TYPE_HASH);
138 __uint(max_entries, 1);
139 __type(key, Symbol);
140 __type(value, int);
141 } symbolmap SEC(".maps");
142
143 struct {
144 __uint(type, BPF_MAP_TYPE_ARRAY);
145 __uint(max_entries, 1);
146 __type(key, int);
147 __type(value, Stats);
148 } statsmap SEC(".maps");
149
150 struct {
151 __uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
152 __uint(max_entries, 32);
153 __uint(key_size, sizeof(int));
154 __uint(value_size, sizeof(int));
155 } perfmap SEC(".maps");
156
157 struct {
158 __uint(type, BPF_MAP_TYPE_STACK_TRACE);
159 __uint(max_entries, 1000);
160 __uint(key_size, sizeof(int));
161 __uint(value_size, sizeof(long long) * 127);
162 } stackmap SEC(".maps");
163
164 #ifdef USE_BPF_LOOP
165 struct process_frame_ctx {
166 int cur_cpu;
167 int32_t *symbol_counter;
168 void *frame_ptr;
169 FrameData *frame;
170 PidData *pidData;
171 Symbol *sym;
172 Event *event;
173 bool done;
174 };
175
process_frame_callback(__u32 i,struct process_frame_ctx * ctx)176 static int process_frame_callback(__u32 i, struct process_frame_ctx *ctx)
177 {
178 int zero = 0;
179 void *frame_ptr = ctx->frame_ptr;
180 PidData *pidData = ctx->pidData;
181 FrameData *frame = ctx->frame;
182 int32_t *symbol_counter = ctx->symbol_counter;
183 int cur_cpu = ctx->cur_cpu;
184 Event *event = ctx->event;
185 Symbol *sym = ctx->sym;
186
187 if (frame_ptr && get_frame_data(frame_ptr, pidData, frame, sym)) {
188 int32_t new_symbol_id = *symbol_counter * 64 + cur_cpu;
189 int32_t *symbol_id = bpf_map_lookup_elem(&symbolmap, sym);
190
191 if (!symbol_id) {
192 bpf_map_update_elem(&symbolmap, sym, &zero, 0);
193 symbol_id = bpf_map_lookup_elem(&symbolmap, sym);
194 if (!symbol_id) {
195 ctx->done = true;
196 return 1;
197 }
198 }
199 if (*symbol_id == new_symbol_id)
200 (*symbol_counter)++;
201
202 barrier_var(i);
203 if (i >= STACK_MAX_LEN)
204 return 1;
205
206 event->stack[i] = *symbol_id;
207
208 event->stack_len = i + 1;
209 frame_ptr = frame->f_back;
210 }
211 return 0;
212 }
213 #endif /* USE_BPF_LOOP */
214
215 #ifdef GLOBAL_FUNC
216 __noinline
217 #elif defined(SUBPROGS)
218 static __noinline
219 #else
220 static __always_inline
221 #endif
__on_event(struct bpf_raw_tracepoint_args * ctx)222 int __on_event(struct bpf_raw_tracepoint_args *ctx)
223 {
224 uint64_t pid_tgid = bpf_get_current_pid_tgid();
225 pid_t pid = (pid_t)(pid_tgid >> 32);
226 PidData* pidData = bpf_map_lookup_elem(&pidmap, &pid);
227 if (!pidData)
228 return 0;
229
230 int zero = 0;
231 Event* event = bpf_map_lookup_elem(&eventmap, &zero);
232 if (!event)
233 return 0;
234
235 event->pid = pid;
236
237 event->tid = (pid_t)pid_tgid;
238 bpf_get_current_comm(&event->comm, sizeof(event->comm));
239
240 event->user_stack_id = bpf_get_stackid(ctx, &stackmap, BPF_F_USER_STACK);
241 event->kernel_stack_id = bpf_get_stackid(ctx, &stackmap, 0);
242
243 void* thread_state_current = (void*)0;
244 bpf_probe_read_user(&thread_state_current,
245 sizeof(thread_state_current),
246 (void*)(long)pidData->current_state_addr);
247
248 struct task_struct* task = (struct task_struct*)bpf_get_current_task();
249 void* tls_base = (void*)task;
250
251 void* thread_state = pidData->use_tls ? get_thread_state(tls_base, pidData)
252 : thread_state_current;
253 event->thread_current = thread_state == thread_state_current;
254
255 if (pidData->use_tls) {
256 uint64_t pthread_created;
257 uint64_t pthread_self;
258 bpf_probe_read_user(&pthread_self, sizeof(pthread_self),
259 tls_base + 0x10);
260
261 bpf_probe_read_user(&pthread_created,
262 sizeof(pthread_created),
263 thread_state +
264 pidData->offsets.PyThreadState_thread);
265 event->pthread_match = pthread_created == pthread_self;
266 } else {
267 event->pthread_match = 1;
268 }
269
270 if (event->pthread_match || !pidData->use_tls) {
271 void* frame_ptr;
272 FrameData frame;
273 Symbol sym = {};
274 int cur_cpu = bpf_get_smp_processor_id();
275
276 bpf_probe_read_user(&frame_ptr,
277 sizeof(frame_ptr),
278 thread_state +
279 pidData->offsets.PyThreadState_frame);
280
281 int32_t* symbol_counter = bpf_map_lookup_elem(&symbolmap, &sym);
282 if (symbol_counter == NULL)
283 return 0;
284 #ifdef USE_BPF_LOOP
285 struct process_frame_ctx ctx = {
286 .cur_cpu = cur_cpu,
287 .symbol_counter = symbol_counter,
288 .frame_ptr = frame_ptr,
289 .frame = &frame,
290 .pidData = pidData,
291 .sym = &sym,
292 .event = event,
293 };
294
295 bpf_loop(STACK_MAX_LEN, process_frame_callback, &ctx, 0);
296 if (ctx.done)
297 return 0;
298 #else
299 #if defined(USE_ITER)
300 /* no for loop, no unrolling */
301 #elif defined(NO_UNROLL)
302 __pragma_loop_no_unroll
303 #elif defined(UNROLL_COUNT)
304 __pragma_loop_unroll_count(UNROLL_COUNT)
305 #else
306 __pragma_loop_unroll_full
307 #endif /* NO_UNROLL */
308 /* Unwind python stack */
309 #ifdef USE_ITER
310 int i;
311 bpf_for(i, 0, STACK_MAX_LEN) {
312 #else /* !USE_ITER */
313 for (int i = 0; i < STACK_MAX_LEN; ++i) {
314 #endif
315 if (frame_ptr && get_frame_data(frame_ptr, pidData, &frame, &sym)) {
316 int32_t new_symbol_id = *symbol_counter * 64 + cur_cpu;
317 int32_t *symbol_id = bpf_map_lookup_elem(&symbolmap, &sym);
318 if (!symbol_id) {
319 bpf_map_update_elem(&symbolmap, &sym, &zero, 0);
320 symbol_id = bpf_map_lookup_elem(&symbolmap, &sym);
321 if (!symbol_id)
322 return 0;
323 }
324 if (*symbol_id == new_symbol_id)
325 (*symbol_counter)++;
326 event->stack[i] = *symbol_id;
327 event->stack_len = i + 1;
328 frame_ptr = frame.f_back;
329 }
330 }
331 #endif /* USE_BPF_LOOP */
332 event->stack_complete = frame_ptr == NULL;
333 } else {
334 event->stack_complete = 1;
335 }
336
337 Stats* stats = bpf_map_lookup_elem(&statsmap, &zero);
338 if (stats)
339 stats->success++;
340
341 event->has_meta = 0;
342 bpf_perf_event_output(ctx, &perfmap, 0, event, offsetof(Event, metadata));
343 return 0;
344 }
345
346 SEC("raw_tracepoint/kfree_skb")
347 int on_event(struct bpf_raw_tracepoint_args* ctx)
348 {
349 int ret = 0;
350 ret |= __on_event(ctx);
351 ret |= __on_event(ctx);
352 ret |= __on_event(ctx);
353 ret |= __on_event(ctx);
354 ret |= __on_event(ctx);
355 return ret;
356 }
357
358 char _license[] SEC("license") = "GPL";
359