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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * genelf_debug.c
4 * Copyright (C) 2015, Google, Inc
5 *
6 * Contributed by:
7 * Stephane Eranian <eranian@google.com>
8 *
9 * based on GPLv2 source code from Oprofile
10 * @remark Copyright 2007 OProfile authors
11 * @author Philippe Elie
12 */
13#include <linux/compiler.h>
14#include <linux/zalloc.h>
15#include <sys/types.h>
16#include <stdio.h>
17#include <getopt.h>
18#include <stddef.h>
19#include <libelf.h>
20#include <string.h>
21#include <stdlib.h>
22#include <inttypes.h>
23#include <limits.h>
24#include <fcntl.h>
25#include <err.h>
26#include <dwarf.h>
27
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 void
92buffer_ext_exit(struct buffer_ext *be)
93{
94 zfree(&be->data);
95}
96
97static inline size_t
98buffer_ext_size(struct buffer_ext *be)
99{
100 return be->cur_pos;
101}
102
103static inline void *
104buffer_ext_addr(struct buffer_ext *be)
105{
106 return be->data;
107}
108
109struct debug_line_header {
110 // Not counting this field
111 uword total_length;
112 // version number (2 currently)
113 uhalf version;
114 // relative offset from next field to
115 // program statement
116 uword prolog_length;
117 ubyte minimum_instruction_length;
118 ubyte default_is_stmt;
119 // line_base - see DWARF 2 specs
120 sbyte line_base;
121 // line_range - see DWARF 2 specs
122 ubyte line_range;
123 // number of opcode + 1
124 ubyte opcode_base;
125 /* follow the array of opcode args nr: ubytes [nr_opcode_base] */
126 /* follow the search directories index, zero terminated string
127 * terminated by an empty string.
128 */
129 /* follow an array of { filename, LEB128, LEB128, LEB128 }, first is
130 * the directory index entry, 0 means current directory, then mtime
131 * and filesize, last entry is followed by en empty string.
132 */
133 /* follow the first program statement */
134} __packed;
135
136/* DWARF 2 spec talk only about one possible compilation unit header while
137 * binutils can handle two flavours of dwarf 2, 32 and 64 bits, this is not
138 * related to the used arch, an ELF 32 can hold more than 4 Go of debug
139 * information. For now we handle only DWARF 2 32 bits comp unit. It'll only
140 * become a problem if we generate more than 4GB of debug information.
141 */
142struct compilation_unit_header {
143 uword total_length;
144 uhalf version;
145 uword debug_abbrev_offset;
146 ubyte pointer_size;
147} __packed;
148
149#define DW_LNS_num_opcode (DW_LNS_set_isa + 1)
150
151/* field filled at run time are marked with -1 */
152static struct debug_line_header const default_debug_line_header = {
153 .total_length = -1,
154 .version = 2,
155 .prolog_length = -1,
156 .minimum_instruction_length = 1, /* could be better when min instruction size != 1 */
157 .default_is_stmt = 1, /* we don't take care about basic block */
158 .line_base = -5, /* sensible value for line base ... */
159 .line_range = -14, /* ... and line range are guessed statically */
160 .opcode_base = DW_LNS_num_opcode
161};
162
163static ubyte standard_opcode_length[] =
164{
165 0, 1, 1, 1, 1, 0, 0, 0, 1, 0, 0, 1
166};
167#if 0
168{
169 [DW_LNS_advance_pc] = 1,
170 [DW_LNS_advance_line] = 1,
171 [DW_LNS_set_file] = 1,
172 [DW_LNS_set_column] = 1,
173 [DW_LNS_fixed_advance_pc] = 1,
174 [DW_LNS_set_isa] = 1,
175};
176#endif
177
178/* field filled at run time are marked with -1 */
179static struct compilation_unit_header default_comp_unit_header = {
180 .total_length = -1,
181 .version = 2,
182 .debug_abbrev_offset = 0, /* we reuse the same abbrev entries for all comp unit */
183 .pointer_size = sizeof(void *)
184};
185
186static void emit_uword(struct buffer_ext *be, uword data)
187{
188 buffer_ext_add(be, &data, sizeof(uword));
189}
190
191static void emit_string(struct buffer_ext *be, const char *s)
192{
193 buffer_ext_add(be, (void *)s, strlen(s) + 1);
194}
195
196static void emit_unsigned_LEB128(struct buffer_ext *be,
197 unsigned long data)
198{
199 do {
200 ubyte cur = data & 0x7F;
201 data >>= 7;
202 if (data)
203 cur |= 0x80;
204 buffer_ext_add(be, &cur, 1);
205 } while (data);
206}
207
208static void emit_signed_LEB128(struct buffer_ext *be, long data)
209{
210 int more = 1;
211 int negative = data < 0;
212 int size = sizeof(long) * CHAR_BIT;
213 while (more) {
214 ubyte cur = data & 0x7F;
215 data >>= 7;
216 if (negative)
217 data |= - (1 << (size - 7));
218 if ((data == 0 && !(cur & 0x40)) ||
219 (data == -1l && (cur & 0x40)))
220 more = 0;
221 else
222 cur |= 0x80;
223 buffer_ext_add(be, &cur, 1);
224 }
225}
226
227static void emit_extended_opcode(struct buffer_ext *be, ubyte opcode,
228 void *data, size_t data_len)
229{
230 buffer_ext_add(be, (char *)"", 1);
231
232 emit_unsigned_LEB128(be, data_len + 1);
233
234 buffer_ext_add(be, &opcode, 1);
235 buffer_ext_add(be, data, data_len);
236}
237
238static void emit_opcode(struct buffer_ext *be, ubyte opcode)
239{
240 buffer_ext_add(be, &opcode, 1);
241}
242
243static void emit_opcode_signed(struct buffer_ext *be,
244 ubyte opcode, long data)
245{
246 buffer_ext_add(be, &opcode, 1);
247 emit_signed_LEB128(be, data);
248}
249
250static void emit_opcode_unsigned(struct buffer_ext *be, ubyte opcode,
251 unsigned long data)
252{
253 buffer_ext_add(be, &opcode, 1);
254 emit_unsigned_LEB128(be, data);
255}
256
257static void emit_advance_pc(struct buffer_ext *be, unsigned long delta_pc)
258{
259 emit_opcode_unsigned(be, DW_LNS_advance_pc, delta_pc);
260}
261
262static void emit_advance_lineno(struct buffer_ext *be, long delta_lineno)
263{
264 emit_opcode_signed(be, DW_LNS_advance_line, delta_lineno);
265}
266
267static void emit_lne_end_of_sequence(struct buffer_ext *be)
268{
269 emit_extended_opcode(be, DW_LNE_end_sequence, NULL, 0);
270}
271
272static void emit_set_file(struct buffer_ext *be, unsigned long idx)
273{
274 emit_opcode_unsigned(be, DW_LNS_set_file, idx);
275}
276
277static void emit_lne_define_filename(struct buffer_ext *be,
278 const char *filename)
279{
280 buffer_ext_add(be, (void *)"", 1);
281
282 /* LNE field, strlen(filename) + zero termination, 3 bytes for: the dir entry, timestamp, filesize */
283 emit_unsigned_LEB128(be, strlen(filename) + 5);
284 emit_opcode(be, DW_LNE_define_file);
285 emit_string(be, filename);
286 /* directory index 0=do not know */
287 emit_unsigned_LEB128(be, 0);
288 /* last modification date on file 0=do not know */
289 emit_unsigned_LEB128(be, 0);
290 /* filesize 0=do not know */
291 emit_unsigned_LEB128(be, 0);
292}
293
294static void emit_lne_set_address(struct buffer_ext *be,
295 void *address)
296{
297 emit_extended_opcode(be, DW_LNE_set_address, &address, sizeof(unsigned long));
298}
299
300static ubyte get_special_opcode(struct debug_entry *ent,
301 unsigned int last_line,
302 unsigned long last_vma)
303{
304 unsigned int temp;
305 unsigned long delta_addr;
306
307 /*
308 * delta from line_base
309 */
310 temp = (ent->lineno - last_line) - default_debug_line_header.line_base;
311
312 if (temp >= default_debug_line_header.line_range)
313 return 0;
314
315 /*
316 * delta of addresses
317 */
318 delta_addr = (ent->addr - last_vma) / default_debug_line_header.minimum_instruction_length;
319
320 /* This is not sufficient to ensure opcode will be in [0-256] but
321 * sufficient to ensure when summing with the delta lineno we will
322 * not overflow the unsigned long opcode */
323
324 if (delta_addr <= 256 / default_debug_line_header.line_range) {
325 unsigned long opcode = temp +
326 (delta_addr * default_debug_line_header.line_range) +
327 default_debug_line_header.opcode_base;
328
329 return opcode <= 255 ? opcode : 0;
330 }
331 return 0;
332}
333
334static void emit_lineno_info(struct buffer_ext *be,
335 struct debug_entry *ent, size_t nr_entry,
336 unsigned long code_addr)
337{
338 size_t i;
339
340 /* as described in the jitdump format */
341 const char repeated_name_marker[] = {'\xff', '\0'};
342
343 /*
344 * Machine state at start of a statement program
345 * address = 0
346 * file = 1
347 * line = 1
348 * column = 0
349 * is_stmt = default_is_stmt as given in the debug_line_header
350 * basic block = 0
351 * end sequence = 0
352 */
353
354 /* start state of the state machine we take care of */
355 unsigned long last_vma = 0;
356 char const *cur_filename = NULL;
357 unsigned long cur_file_idx = 0;
358 int last_line = 1;
359
360 emit_lne_set_address(be, (void *)code_addr);
361
362 for (i = 0; i < nr_entry; i++, ent = debug_entry_next(ent)) {
363 int need_copy = 0;
364 ubyte special_opcode;
365
366 /*
367 * check if filename changed, if so add it
368 */
369 if ((!cur_filename || strcmp(cur_filename, ent->name)) &&
370 strcmp(repeated_name_marker, ent->name)) {
371 emit_lne_define_filename(be, ent->name);
372 cur_filename = ent->name;
373 emit_set_file(be, ++cur_file_idx);
374 need_copy = 1;
375 }
376
377 special_opcode = get_special_opcode(ent, last_line, last_vma);
378 if (special_opcode != 0) {
379 last_line = ent->lineno;
380 last_vma = ent->addr;
381 emit_opcode(be, special_opcode);
382 } else {
383 /*
384 * lines differ, emit line delta
385 */
386 if (last_line != ent->lineno) {
387 emit_advance_lineno(be, ent->lineno - last_line);
388 last_line = ent->lineno;
389 need_copy = 1;
390 }
391 /*
392 * addresses differ, emit address delta
393 */
394 if (last_vma != ent->addr) {
395 emit_advance_pc(be, ent->addr - last_vma);
396 last_vma = ent->addr;
397 need_copy = 1;
398 }
399 /*
400 * add new row to matrix
401 */
402 if (need_copy)
403 emit_opcode(be, DW_LNS_copy);
404 }
405 }
406}
407
408static void add_debug_line(struct buffer_ext *be,
409 struct debug_entry *ent, size_t nr_entry,
410 unsigned long code_addr)
411{
412 struct debug_line_header * dbg_header;
413 size_t old_size;
414
415 old_size = buffer_ext_size(be);
416
417 buffer_ext_add(be, (void *)&default_debug_line_header,
418 sizeof(default_debug_line_header));
419
420 buffer_ext_add(be, &standard_opcode_length, sizeof(standard_opcode_length));
421
422 // empty directory entry
423 buffer_ext_add(be, (void *)"", 1);
424
425 // empty filename directory
426 buffer_ext_add(be, (void *)"", 1);
427
428 dbg_header = buffer_ext_addr(be) + old_size;
429 dbg_header->prolog_length = (buffer_ext_size(be) - old_size) -
430 offsetof(struct debug_line_header, minimum_instruction_length);
431
432 emit_lineno_info(be, ent, nr_entry, code_addr);
433
434 emit_lne_end_of_sequence(be);
435
436 dbg_header = buffer_ext_addr(be) + old_size;
437 dbg_header->total_length = (buffer_ext_size(be) - old_size) -
438 offsetof(struct debug_line_header, version);
439}
440
441static void
442add_debug_abbrev(struct buffer_ext *be)
443{
444 emit_unsigned_LEB128(be, 1);
445 emit_unsigned_LEB128(be, DW_TAG_compile_unit);
446 emit_unsigned_LEB128(be, DW_CHILDREN_yes);
447 emit_unsigned_LEB128(be, DW_AT_stmt_list);
448 emit_unsigned_LEB128(be, DW_FORM_data4);
449 emit_unsigned_LEB128(be, 0);
450 emit_unsigned_LEB128(be, 0);
451 emit_unsigned_LEB128(be, 0);
452}
453
454static void
455add_compilation_unit(struct buffer_ext *be,
456 size_t offset_debug_line)
457{
458 struct compilation_unit_header *comp_unit_header;
459 size_t old_size = buffer_ext_size(be);
460
461 buffer_ext_add(be, &default_comp_unit_header,
462 sizeof(default_comp_unit_header));
463
464 emit_unsigned_LEB128(be, 1);
465 emit_uword(be, offset_debug_line);
466
467 comp_unit_header = buffer_ext_addr(be) + old_size;
468 comp_unit_header->total_length = (buffer_ext_size(be) - old_size) -
469 offsetof(struct compilation_unit_header, version);
470}
471
472static int
473jit_process_debug_info(uint64_t code_addr,
474 void *debug, int nr_debug_entries,
475 struct buffer_ext *dl,
476 struct buffer_ext *da,
477 struct buffer_ext *di)
478{
479 struct debug_entry *ent = debug;
480 int i;
481
482 for (i = 0; i < nr_debug_entries; i++) {
483 ent->addr = ent->addr - code_addr;
484 ent = debug_entry_next(ent);
485 }
486 add_compilation_unit(di, buffer_ext_size(dl));
487 add_debug_line(dl, debug, nr_debug_entries, GEN_ELF_TEXT_OFFSET);
488 add_debug_abbrev(da);
489 if (0) buffer_ext_dump(da, "abbrev");
490
491 return 0;
492}
493
494int
495jit_add_debug_info(Elf *e, uint64_t code_addr, void *debug, int nr_debug_entries)
496{
497 Elf_Data *d;
498 Elf_Scn *scn;
499 Elf_Shdr *shdr;
500 struct buffer_ext dl, di, da;
501 int ret = -1;
502
503 buffer_ext_init(&dl);
504 buffer_ext_init(&di);
505 buffer_ext_init(&da);
506
507 if (jit_process_debug_info(code_addr, debug, nr_debug_entries, &dl, &da, &di))
508 goto out;
509
510 /*
511 * setup .debug_line section
512 */
513 scn = elf_newscn(e);
514 if (!scn) {
515 warnx("cannot create section");
516 goto out;
517 }
518
519 d = elf_newdata(scn);
520 if (!d) {
521 warnx("cannot get new data");
522 goto out;
523 }
524
525 d->d_align = 1;
526 d->d_off = 0LL;
527 d->d_buf = buffer_ext_addr(&dl);
528 d->d_type = ELF_T_BYTE;
529 d->d_size = buffer_ext_size(&dl);
530 d->d_version = EV_CURRENT;
531
532 shdr = elf_getshdr(scn);
533 if (!shdr) {
534 warnx("cannot get section header");
535 goto out;
536 }
537
538 shdr->sh_name = 52; /* .debug_line */
539 shdr->sh_type = SHT_PROGBITS;
540 shdr->sh_addr = 0; /* must be zero or == sh_offset -> dynamic object */
541 shdr->sh_flags = 0;
542 shdr->sh_entsize = 0;
543
544 /*
545 * setup .debug_info section
546 */
547 scn = elf_newscn(e);
548 if (!scn) {
549 warnx("cannot create section");
550 goto out;
551 }
552
553 d = elf_newdata(scn);
554 if (!d) {
555 warnx("cannot get new data");
556 goto out;
557 }
558
559 d->d_align = 1;
560 d->d_off = 0LL;
561 d->d_buf = buffer_ext_addr(&di);
562 d->d_type = ELF_T_BYTE;
563 d->d_size = buffer_ext_size(&di);
564 d->d_version = EV_CURRENT;
565
566 shdr = elf_getshdr(scn);
567 if (!shdr) {
568 warnx("cannot get section header");
569 goto out;
570 }
571
572 shdr->sh_name = 64; /* .debug_info */
573 shdr->sh_type = SHT_PROGBITS;
574 shdr->sh_addr = 0; /* must be zero or == sh_offset -> dynamic object */
575 shdr->sh_flags = 0;
576 shdr->sh_entsize = 0;
577
578 /*
579 * setup .debug_abbrev section
580 */
581 scn = elf_newscn(e);
582 if (!scn) {
583 warnx("cannot create section");
584 goto out;
585 }
586
587 d = elf_newdata(scn);
588 if (!d) {
589 warnx("cannot get new data");
590 goto out;
591 }
592
593 d->d_align = 1;
594 d->d_off = 0LL;
595 d->d_buf = buffer_ext_addr(&da);
596 d->d_type = ELF_T_BYTE;
597 d->d_size = buffer_ext_size(&da);
598 d->d_version = EV_CURRENT;
599
600 shdr = elf_getshdr(scn);
601 if (!shdr) {
602 warnx("cannot get section header");
603 goto out;
604 }
605
606 shdr->sh_name = 76; /* .debug_info */
607 shdr->sh_type = SHT_PROGBITS;
608 shdr->sh_addr = 0; /* must be zero or == sh_offset -> dynamic object */
609 shdr->sh_flags = 0;
610 shdr->sh_entsize = 0;
611
612 /*
613 * now we update the ELF image with all the sections
614 */
615 if (elf_update(e, ELF_C_WRITE) < 0)
616 warnx("elf_update debug failed");
617 else
618 ret = 0;
619
620out:
621 buffer_ext_exit(&dl);
622 buffer_ext_exit(&di);
623 buffer_ext_exit(&da);
624 return ret;
625}
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 <linux/compiler.h>
15#include <sys/types.h>
16#include <stdio.h>
17#include <getopt.h>
18#include <stddef.h>
19#include <libelf.h>
20#include <string.h>
21#include <stdlib.h>
22#include <inttypes.h>
23#include <limits.h>
24#include <fcntl.h>
25#include <err.h>
26#include <dwarf.h>
27
28#include "perf.h"
29#include "genelf.h"
30#include "../util/jitdump.h"
31
32#define BUFFER_EXT_DFL_SIZE (4 * 1024)
33
34typedef uint32_t uword;
35typedef uint16_t uhalf;
36typedef int32_t sword;
37typedef int16_t shalf;
38typedef uint8_t ubyte;
39typedef int8_t sbyte;
40
41struct buffer_ext {
42 size_t cur_pos;
43 size_t max_sz;
44 void *data;
45};
46
47static void
48buffer_ext_dump(struct buffer_ext *be, const char *msg)
49{
50 size_t i;
51 warnx("DUMP for %s", msg);
52 for (i = 0 ; i < be->cur_pos; i++)
53 warnx("%4zu 0x%02x", i, (((char *)be->data)[i]) & 0xff);
54}
55
56static inline int
57buffer_ext_add(struct buffer_ext *be, void *addr, size_t sz)
58{
59 void *tmp;
60 size_t be_sz = be->max_sz;
61
62retry:
63 if ((be->cur_pos + sz) < be_sz) {
64 memcpy(be->data + be->cur_pos, addr, sz);
65 be->cur_pos += sz;
66 return 0;
67 }
68
69 if (!be_sz)
70 be_sz = BUFFER_EXT_DFL_SIZE;
71 else
72 be_sz <<= 1;
73
74 tmp = realloc(be->data, be_sz);
75 if (!tmp)
76 return -1;
77
78 be->data = tmp;
79 be->max_sz = be_sz;
80
81 goto retry;
82}
83
84static void
85buffer_ext_init(struct buffer_ext *be)
86{
87 be->data = NULL;
88 be->cur_pos = 0;
89 be->max_sz = 0;
90}
91
92static inline size_t
93buffer_ext_size(struct buffer_ext *be)
94{
95 return be->cur_pos;
96}
97
98static inline void *
99buffer_ext_addr(struct buffer_ext *be)
100{
101 return be->data;
102}
103
104struct debug_line_header {
105 // Not counting this field
106 uword total_length;
107 // version number (2 currently)
108 uhalf version;
109 // relative offset from next field to
110 // program statement
111 uword prolog_length;
112 ubyte minimum_instruction_length;
113 ubyte default_is_stmt;
114 // line_base - see DWARF 2 specs
115 sbyte line_base;
116 // line_range - see DWARF 2 specs
117 ubyte line_range;
118 // number of opcode + 1
119 ubyte opcode_base;
120 /* follow the array of opcode args nr: ubytes [nr_opcode_base] */
121 /* follow the search directories index, zero terminated string
122 * terminated by an empty string.
123 */
124 /* follow an array of { filename, LEB128, LEB128, LEB128 }, first is
125 * the directory index entry, 0 means current directory, then mtime
126 * and filesize, last entry is followed by en empty string.
127 */
128 /* follow the first program statement */
129} __packed;
130
131/* DWARF 2 spec talk only about one possible compilation unit header while
132 * binutils can handle two flavours of dwarf 2, 32 and 64 bits, this is not
133 * related to the used arch, an ELF 32 can hold more than 4 Go of debug
134 * information. For now we handle only DWARF 2 32 bits comp unit. It'll only
135 * become a problem if we generate more than 4GB of debug information.
136 */
137struct compilation_unit_header {
138 uword total_length;
139 uhalf version;
140 uword debug_abbrev_offset;
141 ubyte pointer_size;
142} __packed;
143
144#define DW_LNS_num_opcode (DW_LNS_set_isa + 1)
145
146/* field filled at run time are marked with -1 */
147static struct debug_line_header const default_debug_line_header = {
148 .total_length = -1,
149 .version = 2,
150 .prolog_length = -1,
151 .minimum_instruction_length = 1, /* could be better when min instruction size != 1 */
152 .default_is_stmt = 1, /* we don't take care about basic block */
153 .line_base = -5, /* sensible value for line base ... */
154 .line_range = -14, /* ... and line range are guessed statically */
155 .opcode_base = DW_LNS_num_opcode
156};
157
158static ubyte standard_opcode_length[] =
159{
160 0, 1, 1, 1, 1, 0, 0, 0, 1, 0, 0, 1
161};
162#if 0
163{
164 [DW_LNS_advance_pc] = 1,
165 [DW_LNS_advance_line] = 1,
166 [DW_LNS_set_file] = 1,
167 [DW_LNS_set_column] = 1,
168 [DW_LNS_fixed_advance_pc] = 1,
169 [DW_LNS_set_isa] = 1,
170};
171#endif
172
173/* field filled at run time are marked with -1 */
174static struct compilation_unit_header default_comp_unit_header = {
175 .total_length = -1,
176 .version = 2,
177 .debug_abbrev_offset = 0, /* we reuse the same abbrev entries for all comp unit */
178 .pointer_size = sizeof(void *)
179};
180
181static void emit_uword(struct buffer_ext *be, uword data)
182{
183 buffer_ext_add(be, &data, sizeof(uword));
184}
185
186static void emit_string(struct buffer_ext *be, const char *s)
187{
188 buffer_ext_add(be, (void *)s, strlen(s) + 1);
189}
190
191static void emit_unsigned_LEB128(struct buffer_ext *be,
192 unsigned long data)
193{
194 do {
195 ubyte cur = data & 0x7F;
196 data >>= 7;
197 if (data)
198 cur |= 0x80;
199 buffer_ext_add(be, &cur, 1);
200 } while (data);
201}
202
203static void emit_signed_LEB128(struct buffer_ext *be, long data)
204{
205 int more = 1;
206 int negative = data < 0;
207 int size = sizeof(long) * CHAR_BIT;
208 while (more) {
209 ubyte cur = data & 0x7F;
210 data >>= 7;
211 if (negative)
212 data |= - (1 << (size - 7));
213 if ((data == 0 && !(cur & 0x40)) ||
214 (data == -1l && (cur & 0x40)))
215 more = 0;
216 else
217 cur |= 0x80;
218 buffer_ext_add(be, &cur, 1);
219 }
220}
221
222static void emit_extended_opcode(struct buffer_ext *be, ubyte opcode,
223 void *data, size_t data_len)
224{
225 buffer_ext_add(be, (char *)"", 1);
226
227 emit_unsigned_LEB128(be, data_len + 1);
228
229 buffer_ext_add(be, &opcode, 1);
230 buffer_ext_add(be, data, data_len);
231}
232
233static void emit_opcode(struct buffer_ext *be, ubyte opcode)
234{
235 buffer_ext_add(be, &opcode, 1);
236}
237
238static void emit_opcode_signed(struct buffer_ext *be,
239 ubyte opcode, long data)
240{
241 buffer_ext_add(be, &opcode, 1);
242 emit_signed_LEB128(be, data);
243}
244
245static void emit_opcode_unsigned(struct buffer_ext *be, ubyte opcode,
246 unsigned long data)
247{
248 buffer_ext_add(be, &opcode, 1);
249 emit_unsigned_LEB128(be, data);
250}
251
252static void emit_advance_pc(struct buffer_ext *be, unsigned long delta_pc)
253{
254 emit_opcode_unsigned(be, DW_LNS_advance_pc, delta_pc);
255}
256
257static void emit_advance_lineno(struct buffer_ext *be, long delta_lineno)
258{
259 emit_opcode_signed(be, DW_LNS_advance_line, delta_lineno);
260}
261
262static void emit_lne_end_of_sequence(struct buffer_ext *be)
263{
264 emit_extended_opcode(be, DW_LNE_end_sequence, NULL, 0);
265}
266
267static void emit_set_file(struct buffer_ext *be, unsigned long idx)
268{
269 emit_opcode_unsigned(be, DW_LNS_set_file, idx);
270}
271
272static void emit_lne_define_filename(struct buffer_ext *be,
273 const char *filename)
274{
275 buffer_ext_add(be, (void *)"", 1);
276
277 /* LNE field, strlen(filename) + zero termination, 3 bytes for: the dir entry, timestamp, filesize */
278 emit_unsigned_LEB128(be, strlen(filename) + 5);
279 emit_opcode(be, DW_LNE_define_file);
280 emit_string(be, filename);
281 /* directory index 0=do not know */
282 emit_unsigned_LEB128(be, 0);
283 /* last modification date on file 0=do not know */
284 emit_unsigned_LEB128(be, 0);
285 /* filesize 0=do not know */
286 emit_unsigned_LEB128(be, 0);
287}
288
289static void emit_lne_set_address(struct buffer_ext *be,
290 void *address)
291{
292 emit_extended_opcode(be, DW_LNE_set_address, &address, sizeof(unsigned long));
293}
294
295static ubyte get_special_opcode(struct debug_entry *ent,
296 unsigned int last_line,
297 unsigned long last_vma)
298{
299 unsigned int temp;
300 unsigned long delta_addr;
301
302 /*
303 * delta from line_base
304 */
305 temp = (ent->lineno - last_line) - default_debug_line_header.line_base;
306
307 if (temp >= default_debug_line_header.line_range)
308 return 0;
309
310 /*
311 * delta of addresses
312 */
313 delta_addr = (ent->addr - last_vma) / default_debug_line_header.minimum_instruction_length;
314
315 /* This is not sufficient to ensure opcode will be in [0-256] but
316 * sufficient to ensure when summing with the delta lineno we will
317 * not overflow the unsigned long opcode */
318
319 if (delta_addr <= 256 / default_debug_line_header.line_range) {
320 unsigned long opcode = temp +
321 (delta_addr * default_debug_line_header.line_range) +
322 default_debug_line_header.opcode_base;
323
324 return opcode <= 255 ? opcode : 0;
325 }
326 return 0;
327}
328
329static void emit_lineno_info(struct buffer_ext *be,
330 struct debug_entry *ent, size_t nr_entry,
331 unsigned long code_addr)
332{
333 size_t i;
334
335 /*
336 * Machine state at start of a statement program
337 * address = 0
338 * file = 1
339 * line = 1
340 * column = 0
341 * is_stmt = default_is_stmt as given in the debug_line_header
342 * basic block = 0
343 * end sequence = 0
344 */
345
346 /* start state of the state machine we take care of */
347 unsigned long last_vma = code_addr;
348 char const *cur_filename = NULL;
349 unsigned long cur_file_idx = 0;
350 int last_line = 1;
351
352 emit_lne_set_address(be, (void *)code_addr);
353
354 for (i = 0; i < nr_entry; i++, ent = debug_entry_next(ent)) {
355 int need_copy = 0;
356 ubyte special_opcode;
357
358 /*
359 * check if filename changed, if so add it
360 */
361 if (!cur_filename || strcmp(cur_filename, ent->name)) {
362 emit_lne_define_filename(be, ent->name);
363 cur_filename = ent->name;
364 emit_set_file(be, ++cur_file_idx);
365 need_copy = 1;
366 }
367
368 special_opcode = get_special_opcode(ent, last_line, last_vma);
369 if (special_opcode != 0) {
370 last_line = ent->lineno;
371 last_vma = ent->addr;
372 emit_opcode(be, special_opcode);
373 } else {
374 /*
375 * lines differ, emit line delta
376 */
377 if (last_line != ent->lineno) {
378 emit_advance_lineno(be, ent->lineno - last_line);
379 last_line = ent->lineno;
380 need_copy = 1;
381 }
382 /*
383 * addresses differ, emit address delta
384 */
385 if (last_vma != ent->addr) {
386 emit_advance_pc(be, ent->addr - last_vma);
387 last_vma = ent->addr;
388 need_copy = 1;
389 }
390 /*
391 * add new row to matrix
392 */
393 if (need_copy)
394 emit_opcode(be, DW_LNS_copy);
395 }
396 }
397}
398
399static void add_debug_line(struct buffer_ext *be,
400 struct debug_entry *ent, size_t nr_entry,
401 unsigned long code_addr)
402{
403 struct debug_line_header * dbg_header;
404 size_t old_size;
405
406 old_size = buffer_ext_size(be);
407
408 buffer_ext_add(be, (void *)&default_debug_line_header,
409 sizeof(default_debug_line_header));
410
411 buffer_ext_add(be, &standard_opcode_length, sizeof(standard_opcode_length));
412
413 // empty directory entry
414 buffer_ext_add(be, (void *)"", 1);
415
416 // empty filename directory
417 buffer_ext_add(be, (void *)"", 1);
418
419 dbg_header = buffer_ext_addr(be) + old_size;
420 dbg_header->prolog_length = (buffer_ext_size(be) - old_size) -
421 offsetof(struct debug_line_header, minimum_instruction_length);
422
423 emit_lineno_info(be, ent, nr_entry, code_addr);
424
425 emit_lne_end_of_sequence(be);
426
427 dbg_header = buffer_ext_addr(be) + old_size;
428 dbg_header->total_length = (buffer_ext_size(be) - old_size) -
429 offsetof(struct debug_line_header, version);
430}
431
432static void
433add_debug_abbrev(struct buffer_ext *be)
434{
435 emit_unsigned_LEB128(be, 1);
436 emit_unsigned_LEB128(be, DW_TAG_compile_unit);
437 emit_unsigned_LEB128(be, DW_CHILDREN_yes);
438 emit_unsigned_LEB128(be, DW_AT_stmt_list);
439 emit_unsigned_LEB128(be, DW_FORM_data4);
440 emit_unsigned_LEB128(be, 0);
441 emit_unsigned_LEB128(be, 0);
442 emit_unsigned_LEB128(be, 0);
443}
444
445static void
446add_compilation_unit(struct buffer_ext *be,
447 size_t offset_debug_line)
448{
449 struct compilation_unit_header *comp_unit_header;
450 size_t old_size = buffer_ext_size(be);
451
452 buffer_ext_add(be, &default_comp_unit_header,
453 sizeof(default_comp_unit_header));
454
455 emit_unsigned_LEB128(be, 1);
456 emit_uword(be, offset_debug_line);
457
458 comp_unit_header = buffer_ext_addr(be) + old_size;
459 comp_unit_header->total_length = (buffer_ext_size(be) - old_size) -
460 offsetof(struct compilation_unit_header, version);
461}
462
463static int
464jit_process_debug_info(uint64_t code_addr,
465 void *debug, int nr_debug_entries,
466 struct buffer_ext *dl,
467 struct buffer_ext *da,
468 struct buffer_ext *di)
469{
470 struct debug_entry *ent = debug;
471 int i;
472
473 for (i = 0; i < nr_debug_entries; i++) {
474 ent->addr = ent->addr - code_addr;
475 ent = debug_entry_next(ent);
476 }
477 add_compilation_unit(di, buffer_ext_size(dl));
478 add_debug_line(dl, debug, nr_debug_entries, 0);
479 add_debug_abbrev(da);
480 if (0) buffer_ext_dump(da, "abbrev");
481
482 return 0;
483}
484
485int
486jit_add_debug_info(Elf *e, uint64_t code_addr, void *debug, int nr_debug_entries)
487{
488 Elf_Data *d;
489 Elf_Scn *scn;
490 Elf_Shdr *shdr;
491 struct buffer_ext dl, di, da;
492 int ret;
493
494 buffer_ext_init(&dl);
495 buffer_ext_init(&di);
496 buffer_ext_init(&da);
497
498 ret = jit_process_debug_info(code_addr, debug, nr_debug_entries, &dl, &da, &di);
499 if (ret)
500 return -1;
501 /*
502 * setup .debug_line section
503 */
504 scn = elf_newscn(e);
505 if (!scn) {
506 warnx("cannot create section");
507 return -1;
508 }
509
510 d = elf_newdata(scn);
511 if (!d) {
512 warnx("cannot get new data");
513 return -1;
514 }
515
516 d->d_align = 1;
517 d->d_off = 0LL;
518 d->d_buf = buffer_ext_addr(&dl);
519 d->d_type = ELF_T_BYTE;
520 d->d_size = buffer_ext_size(&dl);
521 d->d_version = EV_CURRENT;
522
523 shdr = elf_getshdr(scn);
524 if (!shdr) {
525 warnx("cannot get section header");
526 return -1;
527 }
528
529 shdr->sh_name = 52; /* .debug_line */
530 shdr->sh_type = SHT_PROGBITS;
531 shdr->sh_addr = 0; /* must be zero or == sh_offset -> dynamic object */
532 shdr->sh_flags = 0;
533 shdr->sh_entsize = 0;
534
535 /*
536 * setup .debug_info section
537 */
538 scn = elf_newscn(e);
539 if (!scn) {
540 warnx("cannot create section");
541 return -1;
542 }
543
544 d = elf_newdata(scn);
545 if (!d) {
546 warnx("cannot get new data");
547 return -1;
548 }
549
550 d->d_align = 1;
551 d->d_off = 0LL;
552 d->d_buf = buffer_ext_addr(&di);
553 d->d_type = ELF_T_BYTE;
554 d->d_size = buffer_ext_size(&di);
555 d->d_version = EV_CURRENT;
556
557 shdr = elf_getshdr(scn);
558 if (!shdr) {
559 warnx("cannot get section header");
560 return -1;
561 }
562
563 shdr->sh_name = 64; /* .debug_info */
564 shdr->sh_type = SHT_PROGBITS;
565 shdr->sh_addr = 0; /* must be zero or == sh_offset -> dynamic object */
566 shdr->sh_flags = 0;
567 shdr->sh_entsize = 0;
568
569 /*
570 * setup .debug_abbrev section
571 */
572 scn = elf_newscn(e);
573 if (!scn) {
574 warnx("cannot create section");
575 return -1;
576 }
577
578 d = elf_newdata(scn);
579 if (!d) {
580 warnx("cannot get new data");
581 return -1;
582 }
583
584 d->d_align = 1;
585 d->d_off = 0LL;
586 d->d_buf = buffer_ext_addr(&da);
587 d->d_type = ELF_T_BYTE;
588 d->d_size = buffer_ext_size(&da);
589 d->d_version = EV_CURRENT;
590
591 shdr = elf_getshdr(scn);
592 if (!shdr) {
593 warnx("cannot get section header");
594 return -1;
595 }
596
597 shdr->sh_name = 76; /* .debug_info */
598 shdr->sh_type = SHT_PROGBITS;
599 shdr->sh_addr = 0; /* must be zero or == sh_offset -> dynamic object */
600 shdr->sh_flags = 0;
601 shdr->sh_entsize = 0;
602
603 /*
604 * now we update the ELF image with all the sections
605 */
606 if (elf_update(e, ELF_C_WRITE) < 0) {
607 warnx("elf_update debug failed");
608 return -1;
609 }
610 return 0;
611}