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