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1/*
2 * genelf_debug.c
3 * Copyright (C) 2015, Google, Inc
4 *
5 * Contributed by:
6 * Stephane Eranian <eranian@google.com>
7 *
8 * Released under the GPL v2.
9 *
10 * based on GPLv2 source code from Oprofile
11 * @remark Copyright 2007 OProfile authors
12 * @author Philippe Elie
13 */
14#include <sys/types.h>
15#include <stdio.h>
16#include <getopt.h>
17#include <stddef.h>
18#include <libelf.h>
19#include <string.h>
20#include <stdlib.h>
21#include <inttypes.h>
22#include <limits.h>
23#include <fcntl.h>
24#include <err.h>
25#include <dwarf.h>
26
27#include "perf.h"
28#include "genelf.h"
29#include "../util/jitdump.h"
30
31#define BUFFER_EXT_DFL_SIZE (4 * 1024)
32
33typedef uint32_t uword;
34typedef uint16_t uhalf;
35typedef int32_t sword;
36typedef int16_t shalf;
37typedef uint8_t ubyte;
38typedef int8_t sbyte;
39
40struct buffer_ext {
41 size_t cur_pos;
42 size_t max_sz;
43 void *data;
44};
45
46static void
47buffer_ext_dump(struct buffer_ext *be, const char *msg)
48{
49 size_t i;
50 warnx("DUMP for %s", msg);
51 for (i = 0 ; i < be->cur_pos; i++)
52 warnx("%4zu 0x%02x", i, (((char *)be->data)[i]) & 0xff);
53}
54
55static inline int
56buffer_ext_add(struct buffer_ext *be, void *addr, size_t sz)
57{
58 void *tmp;
59 size_t be_sz = be->max_sz;
60
61retry:
62 if ((be->cur_pos + sz) < be_sz) {
63 memcpy(be->data + be->cur_pos, addr, sz);
64 be->cur_pos += sz;
65 return 0;
66 }
67
68 if (!be_sz)
69 be_sz = BUFFER_EXT_DFL_SIZE;
70 else
71 be_sz <<= 1;
72
73 tmp = realloc(be->data, be_sz);
74 if (!tmp)
75 return -1;
76
77 be->data = tmp;
78 be->max_sz = be_sz;
79
80 goto retry;
81}
82
83static void
84buffer_ext_init(struct buffer_ext *be)
85{
86 be->data = NULL;
87 be->cur_pos = 0;
88 be->max_sz = 0;
89}
90
91static inline size_t
92buffer_ext_size(struct buffer_ext *be)
93{
94 return be->cur_pos;
95}
96
97static inline void *
98buffer_ext_addr(struct buffer_ext *be)
99{
100 return be->data;
101}
102
103struct debug_line_header {
104 // Not counting this field
105 uword total_length;
106 // version number (2 currently)
107 uhalf version;
108 // relative offset from next field to
109 // program statement
110 uword prolog_length;
111 ubyte minimum_instruction_length;
112 ubyte default_is_stmt;
113 // line_base - see DWARF 2 specs
114 sbyte line_base;
115 // line_range - see DWARF 2 specs
116 ubyte line_range;
117 // number of opcode + 1
118 ubyte opcode_base;
119 /* follow the array of opcode args nr: ubytes [nr_opcode_base] */
120 /* follow the search directories index, zero terminated string
121 * terminated by an empty string.
122 */
123 /* follow an array of { filename, LEB128, LEB128, LEB128 }, first is
124 * the directory index entry, 0 means current directory, then mtime
125 * and filesize, last entry is followed by en empty string.
126 */
127 /* follow the first program statement */
128} __attribute__((packed));
129
130/* DWARF 2 spec talk only about one possible compilation unit header while
131 * binutils can handle two flavours of dwarf 2, 32 and 64 bits, this is not
132 * related to the used arch, an ELF 32 can hold more than 4 Go of debug
133 * information. For now we handle only DWARF 2 32 bits comp unit. It'll only
134 * become a problem if we generate more than 4GB of debug information.
135 */
136struct compilation_unit_header {
137 uword total_length;
138 uhalf version;
139 uword debug_abbrev_offset;
140 ubyte pointer_size;
141} __attribute__((packed));
142
143#define DW_LNS_num_opcode (DW_LNS_set_isa + 1)
144
145/* field filled at run time are marked with -1 */
146static struct debug_line_header const default_debug_line_header = {
147 .total_length = -1,
148 .version = 2,
149 .prolog_length = -1,
150 .minimum_instruction_length = 1, /* could be better when min instruction size != 1 */
151 .default_is_stmt = 1, /* we don't take care about basic block */
152 .line_base = -5, /* sensible value for line base ... */
153 .line_range = -14, /* ... and line range are guessed statically */
154 .opcode_base = DW_LNS_num_opcode
155};
156
157static ubyte standard_opcode_length[] =
158{
159 0, 1, 1, 1, 1, 0, 0, 0, 1, 0, 0, 1
160};
161#if 0
162{
163 [DW_LNS_advance_pc] = 1,
164 [DW_LNS_advance_line] = 1,
165 [DW_LNS_set_file] = 1,
166 [DW_LNS_set_column] = 1,
167 [DW_LNS_fixed_advance_pc] = 1,
168 [DW_LNS_set_isa] = 1,
169};
170#endif
171
172/* field filled at run time are marked with -1 */
173static struct compilation_unit_header default_comp_unit_header = {
174 .total_length = -1,
175 .version = 2,
176 .debug_abbrev_offset = 0, /* we reuse the same abbrev entries for all comp unit */
177 .pointer_size = sizeof(void *)
178};
179
180static void emit_uword(struct buffer_ext *be, uword data)
181{
182 buffer_ext_add(be, &data, sizeof(uword));
183}
184
185static void emit_string(struct buffer_ext *be, const char *s)
186{
187 buffer_ext_add(be, (void *)s, strlen(s) + 1);
188}
189
190static void emit_unsigned_LEB128(struct buffer_ext *be,
191 unsigned long data)
192{
193 do {
194 ubyte cur = data & 0x7F;
195 data >>= 7;
196 if (data)
197 cur |= 0x80;
198 buffer_ext_add(be, &cur, 1);
199 } while (data);
200}
201
202static void emit_signed_LEB128(struct buffer_ext *be, long data)
203{
204 int more = 1;
205 int negative = data < 0;
206 int size = sizeof(long) * CHAR_BIT;
207 while (more) {
208 ubyte cur = data & 0x7F;
209 data >>= 7;
210 if (negative)
211 data |= - (1 << (size - 7));
212 if ((data == 0 && !(cur & 0x40)) ||
213 (data == -1l && (cur & 0x40)))
214 more = 0;
215 else
216 cur |= 0x80;
217 buffer_ext_add(be, &cur, 1);
218 }
219}
220
221static void emit_extended_opcode(struct buffer_ext *be, ubyte opcode,
222 void *data, size_t data_len)
223{
224 buffer_ext_add(be, (char *)"", 1);
225
226 emit_unsigned_LEB128(be, data_len + 1);
227
228 buffer_ext_add(be, &opcode, 1);
229 buffer_ext_add(be, data, data_len);
230}
231
232static void emit_opcode(struct buffer_ext *be, ubyte opcode)
233{
234 buffer_ext_add(be, &opcode, 1);
235}
236
237static void emit_opcode_signed(struct buffer_ext *be,
238 ubyte opcode, long data)
239{
240 buffer_ext_add(be, &opcode, 1);
241 emit_signed_LEB128(be, data);
242}
243
244static void emit_opcode_unsigned(struct buffer_ext *be, ubyte opcode,
245 unsigned long data)
246{
247 buffer_ext_add(be, &opcode, 1);
248 emit_unsigned_LEB128(be, data);
249}
250
251static void emit_advance_pc(struct buffer_ext *be, unsigned long delta_pc)
252{
253 emit_opcode_unsigned(be, DW_LNS_advance_pc, delta_pc);
254}
255
256static void emit_advance_lineno(struct buffer_ext *be, long delta_lineno)
257{
258 emit_opcode_signed(be, DW_LNS_advance_line, delta_lineno);
259}
260
261static void emit_lne_end_of_sequence(struct buffer_ext *be)
262{
263 emit_extended_opcode(be, DW_LNE_end_sequence, NULL, 0);
264}
265
266static void emit_set_file(struct buffer_ext *be, unsigned long idx)
267{
268 emit_opcode_unsigned(be, DW_LNS_set_file, idx);
269}
270
271static void emit_lne_define_filename(struct buffer_ext *be,
272 const char *filename)
273{
274 buffer_ext_add(be, (void *)"", 1);
275
276 /* LNE field, strlen(filename) + zero termination, 3 bytes for: the dir entry, timestamp, filesize */
277 emit_unsigned_LEB128(be, strlen(filename) + 5);
278 emit_opcode(be, DW_LNE_define_file);
279 emit_string(be, filename);
280 /* directory index 0=do not know */
281 emit_unsigned_LEB128(be, 0);
282 /* last modification date on file 0=do not know */
283 emit_unsigned_LEB128(be, 0);
284 /* filesize 0=do not know */
285 emit_unsigned_LEB128(be, 0);
286}
287
288static void emit_lne_set_address(struct buffer_ext *be,
289 void *address)
290{
291 emit_extended_opcode(be, DW_LNE_set_address, &address, sizeof(unsigned long));
292}
293
294static ubyte get_special_opcode(struct debug_entry *ent,
295 unsigned int last_line,
296 unsigned long last_vma)
297{
298 unsigned int temp;
299 unsigned long delta_addr;
300
301 /*
302 * delta from line_base
303 */
304 temp = (ent->lineno - last_line) - default_debug_line_header.line_base;
305
306 if (temp >= default_debug_line_header.line_range)
307 return 0;
308
309 /*
310 * delta of addresses
311 */
312 delta_addr = (ent->addr - last_vma) / default_debug_line_header.minimum_instruction_length;
313
314 /* This is not sufficient to ensure opcode will be in [0-256] but
315 * sufficient to ensure when summing with the delta lineno we will
316 * not overflow the unsigned long opcode */
317
318 if (delta_addr <= 256 / default_debug_line_header.line_range) {
319 unsigned long opcode = temp +
320 (delta_addr * default_debug_line_header.line_range) +
321 default_debug_line_header.opcode_base;
322
323 return opcode <= 255 ? opcode : 0;
324 }
325 return 0;
326}
327
328static void emit_lineno_info(struct buffer_ext *be,
329 struct debug_entry *ent, size_t nr_entry,
330 unsigned long code_addr)
331{
332 size_t i;
333
334 /*
335 * Machine state at start of a statement program
336 * address = 0
337 * file = 1
338 * line = 1
339 * column = 0
340 * is_stmt = default_is_stmt as given in the debug_line_header
341 * basic block = 0
342 * end sequence = 0
343 */
344
345 /* start state of the state machine we take care of */
346 unsigned long last_vma = code_addr;
347 char const *cur_filename = NULL;
348 unsigned long cur_file_idx = 0;
349 int last_line = 1;
350
351 emit_lne_set_address(be, (void *)code_addr);
352
353 for (i = 0; i < nr_entry; i++, ent = debug_entry_next(ent)) {
354 int need_copy = 0;
355 ubyte special_opcode;
356
357 /*
358 * check if filename changed, if so add it
359 */
360 if (!cur_filename || strcmp(cur_filename, ent->name)) {
361 emit_lne_define_filename(be, ent->name);
362 cur_filename = ent->name;
363 emit_set_file(be, ++cur_file_idx);
364 need_copy = 1;
365 }
366
367 special_opcode = get_special_opcode(ent, last_line, last_vma);
368 if (special_opcode != 0) {
369 last_line = ent->lineno;
370 last_vma = ent->addr;
371 emit_opcode(be, special_opcode);
372 } else {
373 /*
374 * lines differ, emit line delta
375 */
376 if (last_line != ent->lineno) {
377 emit_advance_lineno(be, ent->lineno - last_line);
378 last_line = ent->lineno;
379 need_copy = 1;
380 }
381 /*
382 * addresses differ, emit address delta
383 */
384 if (last_vma != ent->addr) {
385 emit_advance_pc(be, ent->addr - last_vma);
386 last_vma = ent->addr;
387 need_copy = 1;
388 }
389 /*
390 * add new row to matrix
391 */
392 if (need_copy)
393 emit_opcode(be, DW_LNS_copy);
394 }
395 }
396}
397
398static void add_debug_line(struct buffer_ext *be,
399 struct debug_entry *ent, size_t nr_entry,
400 unsigned long code_addr)
401{
402 struct debug_line_header * dbg_header;
403 size_t old_size;
404
405 old_size = buffer_ext_size(be);
406
407 buffer_ext_add(be, (void *)&default_debug_line_header,
408 sizeof(default_debug_line_header));
409
410 buffer_ext_add(be, &standard_opcode_length, sizeof(standard_opcode_length));
411
412 // empty directory entry
413 buffer_ext_add(be, (void *)"", 1);
414
415 // empty filename directory
416 buffer_ext_add(be, (void *)"", 1);
417
418 dbg_header = buffer_ext_addr(be) + old_size;
419 dbg_header->prolog_length = (buffer_ext_size(be) - old_size) -
420 offsetof(struct debug_line_header, minimum_instruction_length);
421
422 emit_lineno_info(be, ent, nr_entry, code_addr);
423
424 emit_lne_end_of_sequence(be);
425
426 dbg_header = buffer_ext_addr(be) + old_size;
427 dbg_header->total_length = (buffer_ext_size(be) - old_size) -
428 offsetof(struct debug_line_header, version);
429}
430
431static void
432add_debug_abbrev(struct buffer_ext *be)
433{
434 emit_unsigned_LEB128(be, 1);
435 emit_unsigned_LEB128(be, DW_TAG_compile_unit);
436 emit_unsigned_LEB128(be, DW_CHILDREN_yes);
437 emit_unsigned_LEB128(be, DW_AT_stmt_list);
438 emit_unsigned_LEB128(be, DW_FORM_data4);
439 emit_unsigned_LEB128(be, 0);
440 emit_unsigned_LEB128(be, 0);
441 emit_unsigned_LEB128(be, 0);
442}
443
444static void
445add_compilation_unit(struct buffer_ext *be,
446 size_t offset_debug_line)
447{
448 struct compilation_unit_header *comp_unit_header;
449 size_t old_size = buffer_ext_size(be);
450
451 buffer_ext_add(be, &default_comp_unit_header,
452 sizeof(default_comp_unit_header));
453
454 emit_unsigned_LEB128(be, 1);
455 emit_uword(be, offset_debug_line);
456
457 comp_unit_header = buffer_ext_addr(be) + old_size;
458 comp_unit_header->total_length = (buffer_ext_size(be) - old_size) -
459 offsetof(struct compilation_unit_header, version);
460}
461
462static int
463jit_process_debug_info(uint64_t code_addr,
464 void *debug, int nr_debug_entries,
465 struct buffer_ext *dl,
466 struct buffer_ext *da,
467 struct buffer_ext *di)
468{
469 struct debug_entry *ent = debug;
470 int i;
471
472 for (i = 0; i < nr_debug_entries; i++) {
473 ent->addr = ent->addr - code_addr;
474 ent = debug_entry_next(ent);
475 }
476 add_compilation_unit(di, buffer_ext_size(dl));
477 add_debug_line(dl, debug, nr_debug_entries, 0);
478 add_debug_abbrev(da);
479 if (0) buffer_ext_dump(da, "abbrev");
480
481 return 0;
482}
483
484int
485jit_add_debug_info(Elf *e, uint64_t code_addr, void *debug, int nr_debug_entries)
486{
487 Elf_Data *d;
488 Elf_Scn *scn;
489 Elf_Shdr *shdr;
490 struct buffer_ext dl, di, da;
491 int ret;
492
493 buffer_ext_init(&dl);
494 buffer_ext_init(&di);
495 buffer_ext_init(&da);
496
497 ret = jit_process_debug_info(code_addr, debug, nr_debug_entries, &dl, &da, &di);
498 if (ret)
499 return -1;
500 /*
501 * setup .debug_line section
502 */
503 scn = elf_newscn(e);
504 if (!scn) {
505 warnx("cannot create section");
506 return -1;
507 }
508
509 d = elf_newdata(scn);
510 if (!d) {
511 warnx("cannot get new data");
512 return -1;
513 }
514
515 d->d_align = 1;
516 d->d_off = 0LL;
517 d->d_buf = buffer_ext_addr(&dl);
518 d->d_type = ELF_T_BYTE;
519 d->d_size = buffer_ext_size(&dl);
520 d->d_version = EV_CURRENT;
521
522 shdr = elf_getshdr(scn);
523 if (!shdr) {
524 warnx("cannot get section header");
525 return -1;
526 }
527
528 shdr->sh_name = 52; /* .debug_line */
529 shdr->sh_type = SHT_PROGBITS;
530 shdr->sh_addr = 0; /* must be zero or == sh_offset -> dynamic object */
531 shdr->sh_flags = 0;
532 shdr->sh_entsize = 0;
533
534 /*
535 * setup .debug_info section
536 */
537 scn = elf_newscn(e);
538 if (!scn) {
539 warnx("cannot create section");
540 return -1;
541 }
542
543 d = elf_newdata(scn);
544 if (!d) {
545 warnx("cannot get new data");
546 return -1;
547 }
548
549 d->d_align = 1;
550 d->d_off = 0LL;
551 d->d_buf = buffer_ext_addr(&di);
552 d->d_type = ELF_T_BYTE;
553 d->d_size = buffer_ext_size(&di);
554 d->d_version = EV_CURRENT;
555
556 shdr = elf_getshdr(scn);
557 if (!shdr) {
558 warnx("cannot get section header");
559 return -1;
560 }
561
562 shdr->sh_name = 64; /* .debug_info */
563 shdr->sh_type = SHT_PROGBITS;
564 shdr->sh_addr = 0; /* must be zero or == sh_offset -> dynamic object */
565 shdr->sh_flags = 0;
566 shdr->sh_entsize = 0;
567
568 /*
569 * setup .debug_abbrev section
570 */
571 scn = elf_newscn(e);
572 if (!scn) {
573 warnx("cannot create section");
574 return -1;
575 }
576
577 d = elf_newdata(scn);
578 if (!d) {
579 warnx("cannot get new data");
580 return -1;
581 }
582
583 d->d_align = 1;
584 d->d_off = 0LL;
585 d->d_buf = buffer_ext_addr(&da);
586 d->d_type = ELF_T_BYTE;
587 d->d_size = buffer_ext_size(&da);
588 d->d_version = EV_CURRENT;
589
590 shdr = elf_getshdr(scn);
591 if (!shdr) {
592 warnx("cannot get section header");
593 return -1;
594 }
595
596 shdr->sh_name = 76; /* .debug_info */
597 shdr->sh_type = SHT_PROGBITS;
598 shdr->sh_addr = 0; /* must be zero or == sh_offset -> dynamic object */
599 shdr->sh_flags = 0;
600 shdr->sh_entsize = 0;
601
602 /*
603 * now we update the ELF image with all the sections
604 */
605 if (elf_update(e, ELF_C_WRITE) < 0) {
606 warnx("elf_update debug failed");
607 return -1;
608 }
609 return 0;
610}