1
2
3
4#include <linux/list.h>
5#include <stdlib.h>
6#include <string.h>
7
8#include "cfg.h"
9#include "main.h"
10#include "xlated_dumper.h"
11
12struct cfg {
13 struct list_head funcs;
14 int func_num;
15};
16
17struct func_node {
18 struct list_head l;
19 struct list_head bbs;
20 struct bpf_insn *start;
21 struct bpf_insn *end;
22 int idx;
23 int bb_num;
24};
25
26struct bb_node {
27 struct list_head l;
28 struct list_head e_prevs;
29 struct list_head e_succs;
30 struct bpf_insn *head;
31 struct bpf_insn *tail;
32 int idx;
33};
34
35#define EDGE_FLAG_EMPTY 0x0
36#define EDGE_FLAG_FALLTHROUGH 0x1
37#define EDGE_FLAG_JUMP 0x2
38struct edge_node {
39 struct list_head l;
40 struct bb_node *src;
41 struct bb_node *dst;
42 int flags;
43};
44
45#define ENTRY_BLOCK_INDEX 0
46#define EXIT_BLOCK_INDEX 1
47#define NUM_FIXED_BLOCKS 2
48#define func_prev(func) list_prev_entry(func, l)
49#define func_next(func) list_next_entry(func, l)
50#define bb_prev(bb) list_prev_entry(bb, l)
51#define bb_next(bb) list_next_entry(bb, l)
52#define entry_bb(func) func_first_bb(func)
53#define exit_bb(func) func_last_bb(func)
54#define cfg_first_func(cfg) \
55 list_first_entry(&cfg->funcs, struct func_node, l)
56#define cfg_last_func(cfg) \
57 list_last_entry(&cfg->funcs, struct func_node, l)
58#define func_first_bb(func) \
59 list_first_entry(&func->bbs, struct bb_node, l)
60#define func_last_bb(func) \
61 list_last_entry(&func->bbs, struct bb_node, l)
62
63static struct func_node *cfg_append_func(struct cfg *cfg, struct bpf_insn *insn)
64{
65 struct func_node *new_func, *func;
66
67 list_for_each_entry(func, &cfg->funcs, l) {
68 if (func->start == insn)
69 return func;
70 else if (func->start > insn)
71 break;
72 }
73
74 func = func_prev(func);
75 new_func = calloc(1, sizeof(*new_func));
76 if (!new_func) {
77 p_err("OOM when allocating FUNC node");
78 return NULL;
79 }
80 new_func->start = insn;
81 new_func->idx = cfg->func_num;
82 list_add(&new_func->l, &func->l);
83 cfg->func_num++;
84
85 return new_func;
86}
87
88static struct bb_node *func_append_bb(struct func_node *func,
89 struct bpf_insn *insn)
90{
91 struct bb_node *new_bb, *bb;
92
93 list_for_each_entry(bb, &func->bbs, l) {
94 if (bb->head == insn)
95 return bb;
96 else if (bb->head > insn)
97 break;
98 }
99
100 bb = bb_prev(bb);
101 new_bb = calloc(1, sizeof(*new_bb));
102 if (!new_bb) {
103 p_err("OOM when allocating BB node");
104 return NULL;
105 }
106 new_bb->head = insn;
107 INIT_LIST_HEAD(&new_bb->e_prevs);
108 INIT_LIST_HEAD(&new_bb->e_succs);
109 list_add(&new_bb->l, &bb->l);
110
111 return new_bb;
112}
113
114static struct bb_node *func_insert_dummy_bb(struct list_head *after)
115{
116 struct bb_node *bb;
117
118 bb = calloc(1, sizeof(*bb));
119 if (!bb) {
120 p_err("OOM when allocating BB node");
121 return NULL;
122 }
123
124 INIT_LIST_HEAD(&bb->e_prevs);
125 INIT_LIST_HEAD(&bb->e_succs);
126 list_add(&bb->l, after);
127
128 return bb;
129}
130
131static bool cfg_partition_funcs(struct cfg *cfg, struct bpf_insn *cur,
132 struct bpf_insn *end)
133{
134 struct func_node *func, *last_func;
135
136 func = cfg_append_func(cfg, cur);
137 if (!func)
138 return true;
139
140 for (; cur < end; cur++) {
141 if (cur->code != (BPF_JMP | BPF_CALL))
142 continue;
143 if (cur->src_reg != BPF_PSEUDO_CALL)
144 continue;
145 func = cfg_append_func(cfg, cur + cur->off + 1);
146 if (!func)
147 return true;
148 }
149
150 last_func = cfg_last_func(cfg);
151 last_func->end = end - 1;
152 func = cfg_first_func(cfg);
153 list_for_each_entry_from(func, &last_func->l, l) {
154 func->end = func_next(func)->start - 1;
155 }
156
157 return false;
158}
159
160static bool is_jmp_insn(__u8 code)
161{
162 return BPF_CLASS(code) == BPF_JMP || BPF_CLASS(code) == BPF_JMP32;
163}
164
165static bool func_partition_bb_head(struct func_node *func)
166{
167 struct bpf_insn *cur, *end;
168 struct bb_node *bb;
169
170 cur = func->start;
171 end = func->end;
172 INIT_LIST_HEAD(&func->bbs);
173 bb = func_append_bb(func, cur);
174 if (!bb)
175 return true;
176
177 for (; cur <= end; cur++) {
178 if (is_jmp_insn(cur->code)) {
179 __u8 opcode = BPF_OP(cur->code);
180
181 if (opcode == BPF_EXIT || opcode == BPF_CALL)
182 continue;
183
184 bb = func_append_bb(func, cur + cur->off + 1);
185 if (!bb)
186 return true;
187
188 if (opcode != BPF_JA) {
189 bb = func_append_bb(func, cur + 1);
190 if (!bb)
191 return true;
192 }
193 }
194 }
195
196 return false;
197}
198
199static void func_partition_bb_tail(struct func_node *func)
200{
201 unsigned int bb_idx = NUM_FIXED_BLOCKS;
202 struct bb_node *bb, *last;
203
204 last = func_last_bb(func);
205 last->tail = func->end;
206 bb = func_first_bb(func);
207 list_for_each_entry_from(bb, &last->l, l) {
208 bb->tail = bb_next(bb)->head - 1;
209 bb->idx = bb_idx++;
210 }
211
212 last->idx = bb_idx++;
213 func->bb_num = bb_idx;
214}
215
216static bool func_add_special_bb(struct func_node *func)
217{
218 struct bb_node *bb;
219
220 bb = func_insert_dummy_bb(&func->bbs);
221 if (!bb)
222 return true;
223 bb->idx = ENTRY_BLOCK_INDEX;
224
225 bb = func_insert_dummy_bb(&func_last_bb(func)->l);
226 if (!bb)
227 return true;
228 bb->idx = EXIT_BLOCK_INDEX;
229
230 return false;
231}
232
233static bool func_partition_bb(struct func_node *func)
234{
235 if (func_partition_bb_head(func))
236 return true;
237
238 func_partition_bb_tail(func);
239
240 return false;
241}
242
243static struct bb_node *func_search_bb_with_head(struct func_node *func,
244 struct bpf_insn *insn)
245{
246 struct bb_node *bb;
247
248 list_for_each_entry(bb, &func->bbs, l) {
249 if (bb->head == insn)
250 return bb;
251 }
252
253 return NULL;
254}
255
256static struct edge_node *new_edge(struct bb_node *src, struct bb_node *dst,
257 int flags)
258{
259 struct edge_node *e;
260
261 e = calloc(1, sizeof(*e));
262 if (!e) {
263 p_err("OOM when allocating edge node");
264 return NULL;
265 }
266
267 if (src)
268 e->src = src;
269 if (dst)
270 e->dst = dst;
271
272 e->flags |= flags;
273
274 return e;
275}
276
277static bool func_add_bb_edges(struct func_node *func)
278{
279 struct bpf_insn *insn;
280 struct edge_node *e;
281 struct bb_node *bb;
282
283 bb = entry_bb(func);
284 e = new_edge(bb, bb_next(bb), EDGE_FLAG_FALLTHROUGH);
285 if (!e)
286 return true;
287 list_add_tail(&e->l, &bb->e_succs);
288
289 bb = exit_bb(func);
290 e = new_edge(bb_prev(bb), bb, EDGE_FLAG_FALLTHROUGH);
291 if (!e)
292 return true;
293 list_add_tail(&e->l, &bb->e_prevs);
294
295 bb = entry_bb(func);
296 bb = bb_next(bb);
297 list_for_each_entry_from(bb, &exit_bb(func)->l, l) {
298 e = new_edge(bb, NULL, EDGE_FLAG_EMPTY);
299 if (!e)
300 return true;
301 e->src = bb;
302
303 insn = bb->tail;
304 if (!is_jmp_insn(insn->code) ||
305 BPF_OP(insn->code) == BPF_EXIT) {
306 e->dst = bb_next(bb);
307 e->flags |= EDGE_FLAG_FALLTHROUGH;
308 list_add_tail(&e->l, &bb->e_succs);
309 continue;
310 } else if (BPF_OP(insn->code) == BPF_JA) {
311 e->dst = func_search_bb_with_head(func,
312 insn + insn->off + 1);
313 e->flags |= EDGE_FLAG_JUMP;
314 list_add_tail(&e->l, &bb->e_succs);
315 continue;
316 }
317
318 e->dst = bb_next(bb);
319 e->flags |= EDGE_FLAG_FALLTHROUGH;
320 list_add_tail(&e->l, &bb->e_succs);
321
322 e = new_edge(bb, NULL, EDGE_FLAG_JUMP);
323 if (!e)
324 return true;
325 e->src = bb;
326 e->dst = func_search_bb_with_head(func, insn + insn->off + 1);
327 list_add_tail(&e->l, &bb->e_succs);
328 }
329
330 return false;
331}
332
333static bool cfg_build(struct cfg *cfg, struct bpf_insn *insn, unsigned int len)
334{
335 int cnt = len / sizeof(*insn);
336 struct func_node *func;
337
338 INIT_LIST_HEAD(&cfg->funcs);
339
340 if (cfg_partition_funcs(cfg, insn, insn + cnt))
341 return true;
342
343 list_for_each_entry(func, &cfg->funcs, l) {
344 if (func_partition_bb(func) || func_add_special_bb(func))
345 return true;
346
347 if (func_add_bb_edges(func))
348 return true;
349 }
350
351 return false;
352}
353
354static void cfg_destroy(struct cfg *cfg)
355{
356 struct func_node *func, *func2;
357
358 list_for_each_entry_safe(func, func2, &cfg->funcs, l) {
359 struct bb_node *bb, *bb2;
360
361 list_for_each_entry_safe(bb, bb2, &func->bbs, l) {
362 struct edge_node *e, *e2;
363
364 list_for_each_entry_safe(e, e2, &bb->e_prevs, l) {
365 list_del(&e->l);
366 free(e);
367 }
368
369 list_for_each_entry_safe(e, e2, &bb->e_succs, l) {
370 list_del(&e->l);
371 free(e);
372 }
373
374 list_del(&bb->l);
375 free(bb);
376 }
377
378 list_del(&func->l);
379 free(func);
380 }
381}
382
383static void draw_bb_node(struct func_node *func, struct bb_node *bb)
384{
385 const char *shape;
386
387 if (bb->idx == ENTRY_BLOCK_INDEX || bb->idx == EXIT_BLOCK_INDEX)
388 shape = "Mdiamond";
389 else
390 shape = "record";
391
392 printf("\tfn_%d_bb_%d [shape=%s,style=filled,label=\"",
393 func->idx, bb->idx, shape);
394
395 if (bb->idx == ENTRY_BLOCK_INDEX) {
396 printf("ENTRY");
397 } else if (bb->idx == EXIT_BLOCK_INDEX) {
398 printf("EXIT");
399 } else {
400 unsigned int start_idx;
401 struct dump_data dd = {};
402
403 printf("{");
404 kernel_syms_load(&dd);
405 start_idx = bb->head - func->start;
406 dump_xlated_for_graph(&dd, bb->head, bb->tail, start_idx);
407 kernel_syms_destroy(&dd);
408 printf("}");
409 }
410
411 printf("\"];\n\n");
412}
413
414static void draw_bb_succ_edges(struct func_node *func, struct bb_node *bb)
415{
416 const char *style = "\"solid,bold\"";
417 const char *color = "black";
418 int func_idx = func->idx;
419 struct edge_node *e;
420 int weight = 10;
421
422 if (list_empty(&bb->e_succs))
423 return;
424
425 list_for_each_entry(e, &bb->e_succs, l) {
426 printf("\tfn_%d_bb_%d:s -> fn_%d_bb_%d:n [style=%s, color=%s, weight=%d, constraint=true",
427 func_idx, e->src->idx, func_idx, e->dst->idx,
428 style, color, weight);
429 printf("];\n");
430 }
431}
432
433static void func_output_bb_def(struct func_node *func)
434{
435 struct bb_node *bb;
436
437 list_for_each_entry(bb, &func->bbs, l) {
438 draw_bb_node(func, bb);
439 }
440}
441
442static void func_output_edges(struct func_node *func)
443{
444 int func_idx = func->idx;
445 struct bb_node *bb;
446
447 list_for_each_entry(bb, &func->bbs, l) {
448 draw_bb_succ_edges(func, bb);
449 }
450
451
452
453
454 printf("\tfn_%d_bb_%d:s -> fn_%d_bb_%d:n [style=\"invis\", constraint=true];\n",
455 func_idx, ENTRY_BLOCK_INDEX, func_idx, EXIT_BLOCK_INDEX);
456}
457
458static void cfg_dump(struct cfg *cfg)
459{
460 struct func_node *func;
461
462 printf("digraph \"DOT graph for eBPF program\" {\n");
463 list_for_each_entry(func, &cfg->funcs, l) {
464 printf("subgraph \"cluster_%d\" {\n\tstyle=\"dashed\";\n\tcolor=\"black\";\n\tlabel=\"func_%d ()\";\n",
465 func->idx, func->idx);
466 func_output_bb_def(func);
467 func_output_edges(func);
468 printf("}\n");
469 }
470 printf("}\n");
471}
472
473void dump_xlated_cfg(void *buf, unsigned int len)
474{
475 struct bpf_insn *insn = buf;
476 struct cfg cfg;
477
478 memset(&cfg, 0, sizeof(cfg));
479 if (cfg_build(&cfg, insn, len))
480 return;
481
482 cfg_dump(&cfg);
483
484 cfg_destroy(&cfg);
485}
486
