-
Notifications
You must be signed in to change notification settings - Fork 2
/
Copy pathcreate-diff-object.c
2020 lines (1720 loc) · 53.5 KB
/
create-diff-object.c
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
/*
* Copyright (C) 2014 Seth Jennings <[email protected]>
* Copyright (C) 2013-2014 Josh Poimboeuf <[email protected]>
* Copyright (C) 2015 Ross Lagerwall <[email protected]>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
/* Large amounts of this code have been copied from kpatch.
* The insn directory is copied from kpatch, which was in turn copied
* from the Linux kernel's arch/x86/lib.
*/
/*
* This file contains the heart of the ELF object differencing engine.
*
* The tool takes two ELF objects from two versions of the same source
* file; a "base" object and a "patched" object. These object need to have
* been compiled with the -ffunction-sections and -fdata-sections GCC options.
*
* The tool compares the objects at a section level to determine what
* sections have changed. Once a list of changed sections has been generated,
* various rules are applied to determine any object local sections that
* are dependencies of the changed section and also need to be included in
* the output object.
*/
#define _GNU_SOURCE
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdlib.h>
#include <string.h>
#include <libgen.h>
#include <argp.h>
#include <error.h>
#include <unistd.h>
#include <time.h>
#include <gelf.h>
#include "list.h"
#include "lookup.h"
#include "asm/insn.h"
#include "common.h"
char *childobj;
enum loglevel loglevel = NORMAL;
static void kpatch_compare_elf_headers(Elf *elf1, Elf *elf2)
{
GElf_Ehdr eh1, eh2;
if (!gelf_getehdr(elf1, &eh1))
ERROR("gelf_getehdr");
if (!gelf_getehdr(elf2, &eh2))
ERROR("gelf_getehdr");
if (memcmp(eh1.e_ident, eh2.e_ident, EI_NIDENT) ||
eh1.e_type != eh2.e_type ||
eh1.e_machine != eh2.e_machine ||
eh1.e_version != eh2.e_version ||
eh1.e_entry != eh2.e_entry ||
eh1.e_phoff != eh2.e_phoff ||
eh1.e_flags != eh2.e_flags ||
eh1.e_ehsize != eh2.e_ehsize ||
eh1.e_phentsize != eh2.e_phentsize ||
eh1.e_shentsize != eh2.e_shentsize)
DIFF_FATAL("ELF headers differ");
}
static void kpatch_check_program_headers(Elf *elf)
{
size_t ph_nr;
if (elf_getphdrnum(elf, &ph_nr))
ERROR("elf_getphdrnum");
if (ph_nr != 0)
DIFF_FATAL("ELF contains program header");
}
static void kpatch_mark_grouped_sections(struct kpatch_elf *kelf)
{
struct section *groupsec, *sec;
unsigned int *data, *end;
list_for_each_entry(groupsec, &kelf->sections, list) {
if (groupsec->sh.sh_type != SHT_GROUP)
continue;
data = groupsec->data->d_buf;
end = groupsec->data->d_buf + groupsec->data->d_size;
data++; /* skip first flag word (e.g. GRP_COMDAT) */
while (data < end) {
sec = find_section_by_index(&kelf->sections, *data);
if (!sec)
ERROR("group section not found");
sec->grouped = 1;
log_debug("marking section %s (%d) as grouped\n",
sec->name, sec->index);
data++;
}
}
}
/*
* Mangle the relas a little. The compiler will sometimes use section symbols
* to reference local objects and functions rather than the object or function
* symbols themselves. We substitute the object/function symbols for the
* section symbol in this case so that the relas can be properly correlated and
* so that the existing object/function in vmlinux can be linked to.
*/
static void kpatch_replace_sections_syms(struct kpatch_elf *kelf)
{
struct section *sec;
struct rela *rela;
struct symbol *sym;
int add_off;
log_debug("\n");
list_for_each_entry(sec, &kelf->sections, list) {
if (!is_rela_section(sec) ||
is_debug_section(sec))
continue;
list_for_each_entry(rela, &sec->relas, list) {
if (rela->sym->type != STT_SECTION)
continue;
/*
* Replace references to bundled sections with their
* symbols.
*/
if (rela->sym->sec && rela->sym->sec->sym) {
rela->sym = rela->sym->sec->sym;
continue;
}
if (rela->type == R_X86_64_PC32 ||
rela->type == R_X86_64_PLT32) {
struct insn insn;
rela_insn(sec, rela, &insn);
add_off = (long)insn.next_byte -
(long)sec->base->data->d_buf -
rela->offset;
} else if (rela->type == R_X86_64_64 ||
rela->type == R_X86_64_32S)
add_off = 0;
else
continue;
/*
* Attempt to replace references to unbundled sections
* with their symbols.
*/
list_for_each_entry(sym, &kelf->symbols, list) {
int start, end;
if (sym->type == STT_SECTION ||
sym->sec != rela->sym->sec)
continue;
start = sym->sym.st_value;
end = sym->sym.st_value + sym->sym.st_size;
if (!is_text_section(sym->sec) &&
(rela->type == R_X86_64_32S ||
rela->type == R_X86_64_PC32 ||
rela->type == R_X86_64_PLT32) &&
(rela->addend + add_off) == sym->sec->sh.sh_size &&
end == sym->sec->sh.sh_size) {
/*
* A special case where gcc needs a
* pointer to the address at the end of
* a data section.
*
* This is usually used with a compare
* instruction to determine when to end
* a loop. The code doesn't actually
* dereference the pointer so this is
* "normal" and we just replace the
* section reference with a reference
* to the last symbol in the section.
*
* Note that this only catches the
* issue when it happens at the end of
* a section. It can also happen in
* the middle of a section. In that
* case, the wrong symbol will be
* associated with the reference. But
* that's ok because:
*
* 1) This situation only occurs when
* gcc is trying to get the address
* of the symbol, not the contents
* of its data; and
*
* 2) Because kpatch doesn't allow data
* sections to change,
* &(var1+sizeof(var1)) will always
* be the same as &var2.
*/
} else if (rela->addend + add_off < start ||
rela->addend + add_off >= end)
continue;
log_debug("%s: replacing %s+%d reference with %s+%d\n",
sec->name,
rela->sym->name, rela->addend,
sym->name, rela->addend - start);
rela->sym = sym;
rela->addend -= start;
break;
}
}
}
log_debug("\n");
}
/*
* This is like strcmp, but for gcc-mangled symbols. It skips the comparison
* of any substring which consists of '.' followed by any number of digits.
*/
static int kpatch_mangled_strcmp(char *s1, char *s2)
{
while (*s1 == *s2) {
if (!*s1)
return 0;
if (*s1 == '.' && isdigit(s1[1])) {
if (!isdigit(s2[1]))
return 1;
while (isdigit(*++s1))
;
while (isdigit(*++s2))
;
} else {
s1++;
s2++;
}
}
return 1;
}
/*
* When gcc makes compiler optimizations which affect a function's calling
* interface, it mangles the function's name. For example, sysctl_print_dir is
* renamed to sysctl_print_dir.isra.2. The problem is that the trailing number
* is chosen arbitrarily, and the patched version of the function may end up
* with a different trailing number. Rename any mangled patched functions to
* match their base counterparts.
*/
static void kpatch_rename_mangled_functions(struct kpatch_elf *base,
struct kpatch_elf *patched)
{
struct symbol *sym, *basesym;
char name[256], *origname;
struct section *sec, *basesec;
int found;
list_for_each_entry(sym, &patched->symbols, list) {
if (sym->type != STT_FUNC)
continue;
if (!strstr(sym->name, ".isra.") &&
!strstr(sym->name, ".constprop.") &&
!strstr(sym->name, ".part."))
continue;
found = 0;
list_for_each_entry(basesym, &base->symbols, list) {
if (!kpatch_mangled_strcmp(basesym->name, sym->name)) {
found = 1;
break;
}
}
if (!found)
continue;
if (!strcmp(sym->name, basesym->name))
continue;
log_debug("renaming %s to %s\n", sym->name, basesym->name);
origname = sym->name;
sym->name = strdup(basesym->name);
if (sym != sym->sec->sym)
continue;
sym->sec->name = strdup(basesym->sec->name);
if (sym->sec->rela)
sym->sec->rela->name = strdup(basesym->sec->rela->name);
/*
* When function foo.isra.1 has a switch statement, it might
* have a corresponding bundled .rodata.foo.isra.1 section (in
* addition to .text.foo.isra.1 which we renamed above).
*/
sprintf(name, ".rodata.%s", origname);
sec = find_section_by_name(&patched->sections, name);
if (!sec)
continue;
sprintf(name, ".rodata.%s", basesym->name);
basesec = find_section_by_name(&base->sections, name);
if (!basesec)
continue;
sec->name = strdup(basesec->name);
sec->secsym->name = sec->name;
if (sec->rela)
sec->rela->name = strdup(basesec->rela->name);
}
}
/*
* This function detects whether the given symbol is a "special" static local
* variable (for lack of a better term).
*
* Special static local variables should never be correlated and should always
* be included if they are referenced by an included function.
*/
static int is_special_static(struct symbol *sym)
{
static char *prefixes[] = {
"__key.",
"__warned.",
"descriptor.",
"__func__.",
"_rs.",
NULL,
};
char **prefix;
if (!sym)
return 0;
if (sym->type == STT_SECTION) {
/* __verbose section contains the descriptor variables */
if (!strcmp(sym->name, "__verbose"))
return 1;
/* otherwise make sure section is bundled */
if (!sym->sec->sym)
return 0;
/* use bundled object/function symbol for matching */
sym = sym->sec->sym;
}
if (sym->type != STT_OBJECT || sym->bind != STB_LOCAL)
return 0;
for (prefix = prefixes; *prefix; prefix++)
if (!strncmp(sym->name, *prefix, strlen(*prefix)))
return 1;
return 0;
}
static int is_constant_label(struct symbol *sym)
{
const char *str;
if (sym->bind != STB_LOCAL)
return 0;
if (strncmp(sym->name, ".LC", 3))
return 0;
str = sym->name + 3;
do {
if (!isdigit(*str))
return 0;
} while (*++str);
return 1;
}
static void kpatch_correlate_sections(struct list_head *seclist1,
struct list_head *seclist2)
{
struct section *sec1, *sec2;
list_for_each_entry(sec1, seclist1, list) {
list_for_each_entry(sec2, seclist2, list) {
if (strcmp(sec1->name, sec2->name))
continue;
if (is_special_static(is_rela_section(sec1) ?
sec1->base->secsym :
sec1->secsym))
continue;
/*
* Group sections must match exactly to be correlated.
* Changed group sections are currently not supported.
*/
if (sec1->sh.sh_type == SHT_GROUP) {
if (sec1->data->d_size != sec2->data->d_size)
continue;
if (memcmp(sec1->data->d_buf, sec2->data->d_buf,
sec1->data->d_size))
continue;
}
log_debug("Found section twins: %s\n", sec1->name);
sec1->twin = sec2;
sec2->twin = sec1;
/* set initial status, might change */
sec1->status = sec2->status = SAME;
break;
}
}
}
static void kpatch_correlate_symbols(struct list_head *symlist1,
struct list_head *symlist2)
{
struct symbol *sym1, *sym2;
list_for_each_entry(sym1, symlist1, list) {
list_for_each_entry(sym2, symlist2, list) {
if (strcmp(sym1->name, sym2->name) ||
sym1->type != sym2->type)
continue;
if (is_special_static(sym1))
continue;
if (is_constant_label(sym1))
continue;
/* group section symbols must have correlated sections */
if (sym1->sec &&
sym1->sec->sh.sh_type == SHT_GROUP &&
sym1->sec->twin != sym2->sec)
continue;
log_debug("Found symbol twins: %s\n", sym1->name);
sym1->twin = sym2;
sym2->twin = sym1;
/* set initial status, might change */
sym1->status = sym2->status = SAME;
break;
}
}
}
static void kpatch_correlate_elfs(struct kpatch_elf *kelf1,
struct kpatch_elf *kelf2)
{
kpatch_correlate_sections(&kelf1->sections, &kelf2->sections);
kpatch_correlate_symbols(&kelf1->symbols, &kelf2->symbols);
}
static char *kpatch_section_function_name(struct section *sec)
{
if (is_rela_section(sec))
sec = sec->base;
return sec->sym ? sec->sym->name : sec->name;
}
/*
* Given a static local variable symbol and a rela section which references it
* in the base object, find a corresponding usage of a similarly named symbol
* in the patched object.
*/
static struct symbol *kpatch_find_static_twin(struct section *sec,
struct symbol *sym)
{
struct rela *rela;
if (!sec->twin)
return NULL;
/* find the patched object's corresponding variable */
list_for_each_entry(rela, &sec->twin->relas, list) {
if (rela->sym->twin)
continue;
if (kpatch_mangled_strcmp(rela->sym->name, sym->name))
continue;
return rela->sym;
}
return NULL;
}
/*
* gcc renames static local variables by appending a period and a number. For
* example, __foo could be renamed to __foo.31452. Unfortunately this number
* can arbitrarily change. Correlate them by comparing which functions
* reference them, and rename the patched symbols to match the base symbol
* names.
*/
void kpatch_correlate_static_local_variables(struct kpatch_elf *base,
struct kpatch_elf *patched)
{
struct symbol *sym, *patched_sym, *tmpsym;
struct section *sec;
struct rela *rela;
int bundled, patched_bundled;
list_for_each_entry(sym, &base->symbols, list) {
if (sym->type != STT_OBJECT || sym->bind != STB_LOCAL)
continue;
if (!strchr(sym->name, '.'))
continue;
if (is_special_static(sym))
continue;
/*
* Undo any previous correlation. Two static locals can have
* the same numbered suffix in the base and patched objects by
* coincidence.
*/
if (sym->twin) {
sym->twin->twin = NULL;
sym->twin = NULL;
}
bundled = sym == sym->sec->sym;
if (bundled && sym->sec->twin) {
sym->sec->twin->twin = NULL;
sym->sec->twin = NULL;
}
/*
*
* Some surprising facts about static local variable symbols:
*
* - It's possible for multiple functions to use the same
* static local variable if the variable is defined in an
* inlined function.
*
* - It's also possible for multiple static local variables
* with the same name to be used in the same function if they
* have different scopes. (We have to assume that in such
* cases, the order in which they're referenced remains the
* same between the base and patched objects, as there's no
* other way to distinguish them.)
*
* - Static locals are usually referenced by functions, but
* they can occasionally be referenced by data sections as
* well.
*
* For each section which references the variable in the base
* object, look for a corresponding reference in the section's
* twin in the patched object.
*/
patched_sym = NULL;
list_for_each_entry(sec, &base->sections, list) {
if (!is_rela_section(sec) ||
is_debug_section(sec))
continue;
list_for_each_entry(rela, &sec->relas, list) {
if (rela->sym != sym)
continue;
if (bundled && sym->sec == sec->base) {
/*
* A rare case where a static local
* data structure references itself.
* There's no reliable way to correlate
* this. Hopefully there's another
* reference to the symbol somewhere
* that can be used.
*/
log_debug("can't correlate static local %s's reference to itself\n",
sym->name);
break;
}
tmpsym = kpatch_find_static_twin(sec, sym);
if (!tmpsym)
DIFF_FATAL("reference to static local variable %s in %s was removed",
sym->name,
kpatch_section_function_name(sec));
if (patched_sym && patched_sym != tmpsym)
DIFF_FATAL("found two twins for static local variable %s: %s and %s",
sym->name, patched_sym->name,
tmpsym->name);
patched_sym = tmpsym;
break;
}
}
/*
* Check if the symbol is unused. This is possible if multiple
* static locals in the file refer to the same read-only data,
* and their symbols point to the same bundled section. In
* such a case we can ignore the extra symbol.
*/
if (!patched_sym) {
log_debug("ignoring base unused static local %s\n",
sym->name);
continue;
}
patched_bundled = patched_sym == patched_sym->sec->sym;
if (bundled != patched_bundled)
ERROR("bundle mismatch for symbol %s", sym->name);
if (!bundled && sym->sec->twin != patched_sym->sec)
ERROR("sections %s and %s aren't correlated",
sym->sec->name, patched_sym->sec->name);
log_debug("renaming and correlating static local %s to %s\n",
patched_sym->name, sym->name);
patched_sym->name = strdup(sym->name);
sym->twin = patched_sym;
patched_sym->twin = sym;
if (bundled) {
sym->sec->twin = patched_sym->sec;
patched_sym->sec->twin = sym->sec;
if (sym->sec->rela && patched_sym->sec->rela) {
sym->sec->rela->twin = patched_sym->sec->rela;
patched_sym->sec->rela->twin = sym->sec->rela;
}
}
}
/*
* All the base object's static local variables have been correlated.
* Now go through the patched object and look for any uncorrelated
* static locals to see if we need to print some warnings.
*/
list_for_each_entry(sym, &patched->symbols, list) {
if (sym->type != STT_OBJECT || sym->bind != STB_LOCAL ||
sym->twin)
continue;
if (!strchr(sym->name, '.'))
continue;
if (is_special_static(sym))
continue;
list_for_each_entry(sec, &patched->sections, list) {
if (!is_rela_section(sec) ||
is_debug_section(sec))
continue;
list_for_each_entry(rela, &sec->relas, list) {
if (rela->sym != sym)
continue;
log_normal("WARNING: unable to correlate static local variable %s used by %s, assuming variable is new\n",
sym->name,
kpatch_section_function_name(sec));
return;
}
}
/*
* This symbol is unused by any functions. This is possible if
* multiple static locals in the file refer to the same
* read-only data, and their symbols point to the same bundled
* section. In such a case we can ignore the extra symbol.
*/
log_debug("ignoring patched unused static local %s\n",
sym->name);
}
}
static int rela_equal(struct rela *rela1, struct rela *rela2)
{
log_debug("Comparing rela %s with %s\n", rela1->sym->name, rela2->sym->name);
if (rela1->type != rela2->type ||
rela1->offset != rela2->offset)
return 0;
if (rela1->string)
return rela2->string && !strcmp(rela1->string, rela2->string);
if (rela1->addend != rela2->addend)
return 0;
if (is_constant_label(rela1->sym) && is_constant_label(rela2->sym))
return 1;
if (is_special_static(rela1->sym))
return !kpatch_mangled_strcmp(rela1->sym->name,
rela2->sym->name);
return !strcmp(rela1->sym->name, rela2->sym->name);
}
static void kpatch_compare_correlated_rela_section(struct section *sec)
{
struct rela *rela1, *rela2 = NULL;
rela2 = list_entry(sec->twin->relas.next, struct rela, list);
list_for_each_entry(rela1, &sec->relas, list) {
if (rela_equal(rela1, rela2)) {
rela2 = list_entry(rela2->list.next, struct rela, list);
continue;
}
sec->status = CHANGED;
return;
}
sec->status = SAME;
}
static void kpatch_compare_correlated_nonrela_section(struct section *sec)
{
struct section *sec1 = sec, *sec2 = sec->twin;
if (sec1->sh.sh_type != SHT_NOBITS &&
memcmp(sec1->data->d_buf, sec2->data->d_buf, sec1->data->d_size))
sec->status = CHANGED;
else
sec->status = SAME;
}
static void kpatch_compare_correlated_section(struct section *sec)
{
struct section *sec1 = sec, *sec2 = sec->twin;
log_debug("Compare correlated section: %s\n", sec->name);
/* Compare section headers (must match or fatal) */
if (sec1->sh.sh_type != sec2->sh.sh_type ||
sec1->sh.sh_flags != sec2->sh.sh_flags ||
sec1->sh.sh_addr != sec2->sh.sh_addr ||
sec1->sh.sh_addralign != sec2->sh.sh_addralign ||
sec1->sh.sh_entsize != sec2->sh.sh_entsize)
DIFF_FATAL("%s section header details differ", sec1->name);
if (sec1->sh.sh_size != sec2->sh.sh_size ||
sec1->data->d_size != sec2->data->d_size) {
sec->status = CHANGED;
goto out;
}
if (is_rela_section(sec))
kpatch_compare_correlated_rela_section(sec);
else
kpatch_compare_correlated_nonrela_section(sec);
out:
if (sec->status == CHANGED)
log_debug("section %s has changed\n", sec->name);
}
static void kpatch_compare_sections(struct list_head *seclist)
{
struct section *sec;
/* compare all sections */
list_for_each_entry(sec, seclist, list) {
if (sec->twin)
kpatch_compare_correlated_section(sec);
else
sec->status = NEW;
}
/* sync symbol status */
list_for_each_entry(sec, seclist, list) {
if (is_rela_section(sec)) {
if (sec->base->sym && sec->base->sym->status != CHANGED)
sec->base->sym->status = sec->status;
} else {
if (sec->sym && sec->sym->status != CHANGED)
sec->sym->status = sec->status;
}
}
}
static void kpatch_compare_correlated_symbol(struct symbol *sym)
{
struct symbol *sym1 = sym, *sym2 = sym->twin;
if (sym1->sym.st_info != sym2->sym.st_info ||
sym1->sym.st_other != sym2->sym.st_other ||
(sym1->sec && !sym2->sec) ||
(sym2->sec && !sym1->sec))
DIFF_FATAL("symbol info mismatch: %s", sym1->name);
/*
* If two symbols are correlated but their sections are not, then the
* symbol has changed sections. This is only allowed if the symbol is
* moving out of an ignored section.
*/
if (sym1->sec && sym2->sec && sym1->sec->twin != sym2->sec) {
if (sym2->sec->twin && sym2->sec->twin->ignore)
sym->status = CHANGED;
else
DIFF_FATAL("symbol changed sections: %s, %s, %s, %s", sym1->name, sym2->name, sym1->sec->name, sym2->sec->name);
}
if (sym1->type == STT_OBJECT &&
sym1->sym.st_size != sym2->sym.st_size)
DIFF_FATAL("object size mismatch: %s", sym1->name);
if (sym1->sym.st_shndx == SHN_UNDEF ||
sym1->sym.st_shndx == SHN_ABS)
sym1->status = SAME;
/*
* The status of LOCAL symbols is dependent on the status of their
* matching section and is set during section comparison.
*/
}
static void kpatch_compare_symbols(struct list_head *symlist)
{
struct symbol *sym;
list_for_each_entry(sym, symlist, list) {
if (sym->twin)
kpatch_compare_correlated_symbol(sym);
else
sym->status = NEW;
log_debug("symbol %s is %s\n", sym->name, status_str(sym->status));
}
}
static void kpatch_compare_correlated_elements(struct kpatch_elf *kelf)
{
/* lists are already correlated at this point */
log_debug("Compare sections\n");
kpatch_compare_sections(&kelf->sections);
log_debug("Compare symbols\n");
kpatch_compare_symbols(&kelf->symbols);
}
static void kpatch_mark_ignored_functions_same(struct kpatch_elf *kelf)
{
struct section *sec;
struct rela *rela;
sec = find_section_by_name(&kelf->sections, ".livepatch.ignore.functions");
if (!sec)
return;
list_for_each_entry(rela, &sec->rela->relas, list) {
if (!rela->sym->sec)
ERROR("expected bundled symbol");
if (rela->sym->type != STT_FUNC)
ERROR("expected function symbol");
log_normal("ignoring function: %s\n", rela->sym->name);
if (rela->sym->status != CHANGED)
log_normal("NOTICE: no change detected in function %s, unnecessary KPATCH_IGNORE_FUNCTION()?\n", rela->sym->name);
rela->sym->status = SAME;
rela->sym->sec->status = SAME;
if (rela->sym->sec->secsym)
rela->sym->sec->secsym->status = SAME;
if (rela->sym->sec->rela)
rela->sym->sec->rela->status = SAME;
}
}
static void kpatch_mark_ignored_sections(struct kpatch_elf *kelf)
{
struct section *sec, *strsec, *ignoresec;
struct rela *rela;
char *name;
sec = find_section_by_name(&kelf->sections, ".livepatch.ignore.sections");
if (!sec)
return;
list_for_each_entry(rela, &sec->rela->relas, list) {
strsec = rela->sym->sec;
strsec->status = CHANGED;
/*
* Include the string section here. This is because the
* KPATCH_IGNORE_SECTION() macro is passed a literal string
* by the patch author, resulting in a change to the string
* section. If we don't include it, then we will potentially
* get a "changed section not included" error in
* kpatch_verify_patchability() if no other function based change
* also changes the string section. We could try to exclude each
* literal string added to the section by KPATCH_IGNORE_SECTION()
* from the section data comparison, but this is a simpler way.
*/
strsec->include = 1;
name = strsec->data->d_buf + rela->addend;
ignoresec = find_section_by_name(&kelf->sections, name);
if (!ignoresec)
ERROR("KPATCH_IGNORE_SECTION: can't find %s", name);
log_normal("ignoring section: %s\n", name);
if (is_rela_section(ignoresec))
ignoresec = ignoresec->base;
ignoresec->ignore = 1;
if (ignoresec->twin)
ignoresec->twin->ignore = 1;
}
}
static void kpatch_mark_ignored_sections_same(struct kpatch_elf *kelf)
{
struct section *sec;
struct symbol *sym;
list_for_each_entry(sec, &kelf->sections, list) {
if (!sec->ignore)
continue;
sec->status = SAME;
if (sec->secsym)
sec->secsym->status = SAME;
if (sec->rela)
sec->rela->status = SAME;
list_for_each_entry(sym, &kelf->symbols, list) {
if (sym->sec != sec)
continue;
sym->status = SAME;
}
}
}
static void kpatch_mark_constant_labels_same(struct kpatch_elf *kelf)
{
struct symbol *sym;
list_for_each_entry(sym, &kelf->symbols, list) {
if (is_constant_label(sym))
sym->status = SAME;
}
}
static int bug_frames_0_group_size(struct kpatch_elf *kelf, int offset) { return 8; }
static int bug_frames_1_group_size(struct kpatch_elf *kelf, int offset) { return 8; }
static int bug_frames_2_group_size(struct kpatch_elf *kelf, int offset) { return 8; }
static int bug_frames_3_group_size(struct kpatch_elf *kelf, int offset) { return 16; }
static int ex_table_group_size(struct kpatch_elf *kelf, int offset) { return 8; }
static int altinstructions_group_size(struct kpatch_elf *kelf, int offset) { return 12; }
/*
* The rela groups in the .fixup section vary in size. The beginning of each
* .fixup rela group is referenced by the .ex_table section. To find the size
* of a .fixup rela group, we have to traverse the .ex_table relas.
*/
static int fixup_group_size(struct kpatch_elf *kelf, int offset)
{
struct section *sec;
struct rela *rela;
int found;
sec = find_section_by_name(&kelf->sections, ".rela.ex_table");
if (!sec)
ERROR("missing .rela.ex_table section");
/* find beginning of this group */
found = 0;
list_for_each_entry(rela, &sec->relas, list) {
if (!strcmp(rela->sym->name, ".fixup") &&
rela->addend == offset) {
found = 1;
break;
}
}
if (!found)
ERROR("can't find .fixup rela group at offset %d\n", offset);
/* find beginning of next group */
found = 0;
list_for_each_entry_continue(rela, &sec->relas, list) {
if (!strcmp(rela->sym->name, ".fixup") &&
rela->addend > offset) {
found = 1;
break;
}
}
if (!found) {
/* last group */
struct section *fixupsec;