/
ldelf.go
1204 lines (1067 loc) · 27.7 KB
/
ldelf.go
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
package ld
import (
"bytes"
"cmd/internal/obj"
"encoding/binary"
"fmt"
"io"
"log"
"sort"
"strings"
)
/*
Derived from Plan 9 from User Space's src/libmach/elf.h, elf.c
http://code.swtch.com/plan9port/src/tip/src/libmach/
Copyright © 2004 Russ Cox.
Portions Copyright © 2008-2010 Google Inc.
Portions Copyright © 2010 The Go Authors.
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
*/
const (
ElfClassNone = 0
ElfClass32 = 1
ElfClass64 = 2
)
const (
ElfDataNone = 0
ElfDataLsb = 1
ElfDataMsb = 2
)
const (
ElfTypeNone = 0
ElfTypeRelocatable = 1
ElfTypeExecutable = 2
ElfTypeSharedObject = 3
ElfTypeCore = 4
)
const (
ElfMachNone = 0
ElfMach32100 = 1
ElfMachSparc = 2
ElfMach386 = 3
ElfMach68000 = 4
ElfMach88000 = 5
ElfMach486 = 6
ElfMach860 = 7
ElfMachMips = 8
ElfMachS370 = 9
ElfMachMipsLe = 10
ElfMachParisc = 15
ElfMachVpp500 = 17
ElfMachSparc32Plus = 18
ElfMach960 = 19
ElfMachPower = 20
ElfMachPower64 = 21
ElfMachS390 = 22
ElfMachV800 = 36
ElfMachFr20 = 37
ElfMachRh32 = 38
ElfMachRce = 39
ElfMachArm = 40
ElfMachAlpha = 41
ElfMachSH = 42
ElfMachSparc9 = 43
ElfMachAmd64 = 62
ElfMachArm64 = 183
)
const (
ElfAbiNone = 0
ElfAbiSystemV = 0
ElfAbiHPUX = 1
ElfAbiNetBSD = 2
ElfAbiLinux = 3
ElfAbiSolaris = 6
ElfAbiAix = 7
ElfAbiIrix = 8
ElfAbiFreeBSD = 9
ElfAbiTru64 = 10
ElfAbiModesto = 11
ElfAbiOpenBSD = 12
ElfAbiARM = 97
ElfAbiEmbedded = 255
)
const (
ElfSectNone = 0
ElfSectProgbits = 1
ElfSectSymtab = 2
ElfSectStrtab = 3
ElfSectRela = 4
ElfSectHash = 5
ElfSectDynamic = 6
ElfSectNote = 7
ElfSectNobits = 8
ElfSectRel = 9
ElfSectShlib = 10
ElfSectDynsym = 11
ElfSectFlagWrite = 0x1
ElfSectFlagAlloc = 0x2
ElfSectFlagExec = 0x4
)
const (
ElfSymBindLocal = 0
ElfSymBindGlobal = 1
ElfSymBindWeak = 2
)
const (
ElfSymTypeNone = 0
ElfSymTypeObject = 1
ElfSymTypeFunc = 2
ElfSymTypeSection = 3
ElfSymTypeFile = 4
)
const (
ElfSymShnNone = 0
ElfSymShnAbs = 0xFFF1
ElfSymShnCommon = 0xFFF2
)
const (
ElfProgNone = 0
ElfProgLoad = 1
ElfProgDynamic = 2
ElfProgInterp = 3
ElfProgNote = 4
ElfProgShlib = 5
ElfProgPhdr = 6
ElfProgFlagExec = 0x1
ElfProgFlagWrite = 0x2
ElfProgFlagRead = 0x4
)
const (
ElfNotePrStatus = 1
ElfNotePrFpreg = 2
ElfNotePrPsinfo = 3
ElfNotePrTaskstruct = 4
ElfNotePrAuxv = 6
ElfNotePrXfpreg = 0x46e62b7f
)
type ElfHdrBytes struct {
Ident [16]uint8
Type [2]uint8
Machine [2]uint8
Version [4]uint8
Entry [4]uint8
Phoff [4]uint8
Shoff [4]uint8
Flags [4]uint8
Ehsize [2]uint8
Phentsize [2]uint8
Phnum [2]uint8
Shentsize [2]uint8
Shnum [2]uint8
Shstrndx [2]uint8
}
type ElfSectBytes struct {
Name [4]uint8
Type [4]uint8
Flags [4]uint8
Addr [4]uint8
Off [4]uint8
Size [4]uint8
Link [4]uint8
Info [4]uint8
Align [4]uint8
Entsize [4]uint8
}
type ElfProgBytes struct {
}
type ElfSymBytes struct {
Name [4]uint8
Value [4]uint8
Size [4]uint8
Info uint8
Other uint8
Shndx [2]uint8
}
type ElfHdrBytes64 struct {
Ident [16]uint8
Type [2]uint8
Machine [2]uint8
Version [4]uint8
Entry [8]uint8
Phoff [8]uint8
Shoff [8]uint8
Flags [4]uint8
Ehsize [2]uint8
Phentsize [2]uint8
Phnum [2]uint8
Shentsize [2]uint8
Shnum [2]uint8
Shstrndx [2]uint8
}
type ElfSectBytes64 struct {
Name [4]uint8
Type [4]uint8
Flags [8]uint8
Addr [8]uint8
Off [8]uint8
Size [8]uint8
Link [4]uint8
Info [4]uint8
Align [8]uint8
Entsize [8]uint8
}
type ElfProgBytes64 struct {
}
type ElfSymBytes64 struct {
Name [4]uint8
Info uint8
Other uint8
Shndx [2]uint8
Value [8]uint8
Size [8]uint8
}
type ElfSect struct {
name string
nameoff uint32
type_ uint32
flags uint64
addr uint64
off uint64
size uint64
link uint32
info uint32
align uint64
entsize uint64
base []byte
sym *LSym
}
type ElfObj struct {
f *obj.Biobuf
base int64 // offset in f where ELF begins
length int64 // length of ELF
is64 int
name string
e binary.ByteOrder
sect []ElfSect
nsect uint
shstrtab string
nsymtab int
symtab *ElfSect
symstr *ElfSect
type_ uint32
machine uint32
version uint32
entry uint64
phoff uint64
shoff uint64
flags uint32
ehsize uint32
phentsize uint32
phnum uint32
shentsize uint32
shnum uint32
shstrndx uint32
}
type ElfSym struct {
name string
value uint64
size uint64
bind uint8
type_ uint8
other uint8
shndx uint16
sym *LSym
}
var ElfMagic = [4]uint8{0x7F, 'E', 'L', 'F'}
func valuecmp(a *LSym, b *LSym) int {
if a.Value < b.Value {
return -1
}
if a.Value > b.Value {
return +1
}
return 0
}
const (
Tag_file = 1
Tag_CPU_name = 4
Tag_CPU_raw_name = 5
Tag_compatibility = 32
Tag_nodefaults = 64
Tag_also_compatible_with = 65
Tag_ABI_VFP_args = 28
)
type elfAttribute struct {
tag uint64
sval string
ival uint64
}
type elfAttributeList struct {
data []byte
err error
}
func (a *elfAttributeList) string() string {
if a.err != nil {
return ""
}
nul := bytes.IndexByte(a.data, 0)
if nul < 0 {
a.err = io.EOF
return ""
}
s := string(a.data[:nul])
a.data = a.data[nul+1:]
return s
}
func (a *elfAttributeList) uleb128() uint64 {
if a.err != nil {
return 0
}
v, size := binary.Uvarint(a.data)
a.data = a.data[size:]
return v
}
// Read an elfAttribute from the list following the rules used on ARM systems.
func (a *elfAttributeList) armAttr() elfAttribute {
attr := elfAttribute{tag: a.uleb128()}
switch {
case attr.tag == Tag_compatibility:
attr.ival = a.uleb128()
attr.sval = a.string()
case attr.tag == 64: // Tag_nodefaults has no argument
case attr.tag == 65: // Tag_also_compatible_with
// Not really, but we don't actually care about this tag.
attr.sval = a.string()
// Tag with string argument
case attr.tag == Tag_CPU_name || attr.tag == Tag_CPU_raw_name || (attr.tag >= 32 && attr.tag&1 != 0):
attr.sval = a.string()
default: // Tag with integer argument
attr.ival = a.uleb128()
}
return attr
}
func (a *elfAttributeList) done() bool {
if a.err != nil || len(a.data) == 0 {
return true
}
return false
}
// Look for the attribute that indicates the object uses the hard-float ABI (a
// file-level attribute with tag Tag_VFP_arch and value 1). Unfortunately the
// format used means that we have to parse all of the file-level attributes to
// find the one we are looking for. This format is slightly documented in "ELF
// for the ARM Architecture" but mostly this is derived from reading the source
// to gold and readelf.
func parseArmAttributes(e binary.ByteOrder, data []byte) {
// We assume the soft-float ABI unless we see a tag indicating otherwise.
if ehdr.flags == 0x5000002 {
ehdr.flags = 0x5000202
}
if data[0] != 'A' {
fmt.Fprintf(&Bso, ".ARM.attributes has unexpected format %c\n", data[0])
return
}
data = data[1:]
for len(data) != 0 {
sectionlength := e.Uint32(data)
sectiondata := data[4:sectionlength]
data = data[sectionlength:]
nulIndex := bytes.IndexByte(sectiondata, 0)
if nulIndex < 0 {
fmt.Fprintf(&Bso, "corrupt .ARM.attributes (section name not NUL-terminated)\n")
return
}
name := string(sectiondata[:nulIndex])
sectiondata = sectiondata[nulIndex+1:]
if name != "aeabi" {
continue
}
for len(sectiondata) != 0 {
subsectiontag, sz := binary.Uvarint(sectiondata)
subsectionsize := e.Uint32(sectiondata[sz:])
subsectiondata := sectiondata[sz+4 : subsectionsize]
sectiondata = sectiondata[subsectionsize:]
if subsectiontag == Tag_file {
attrList := elfAttributeList{data: subsectiondata}
for !attrList.done() {
attr := attrList.armAttr()
if attr.tag == Tag_ABI_VFP_args && attr.ival == 1 {
ehdr.flags = 0x5000402 // has entry point, Version5 EABI, hard-float ABI
}
}
if attrList.err != nil {
fmt.Fprintf(&Bso, "could not parse .ARM.attributes\n")
}
}
}
}
}
func ldelf(f *obj.Biobuf, pkg string, length int64, pn string) {
if Debug['v'] != 0 {
fmt.Fprintf(&Bso, "%5.2f ldelf %s\n", obj.Cputime(), pn)
}
Ctxt.IncVersion()
base := int32(obj.Boffset(f))
var add uint64
var e binary.ByteOrder
var elfobj *ElfObj
var err error
var flag int
var hdr *ElfHdrBytes
var hdrbuf [64]uint8
var info uint64
var is64 int
var j int
var n int
var name string
var p []byte
var r []Reloc
var rela int
var rp *Reloc
var rsect *ElfSect
var s *LSym
var sect *ElfSect
var sym ElfSym
var symbols []*LSym
if obj.Bread(f, hdrbuf[:]) != len(hdrbuf) {
goto bad
}
hdr = new(ElfHdrBytes)
binary.Read(bytes.NewReader(hdrbuf[:]), binary.BigEndian, hdr) // only byte arrays; byte order doesn't matter
if string(hdr.Ident[:4]) != "\x7FELF" {
goto bad
}
switch hdr.Ident[5] {
case ElfDataLsb:
e = binary.LittleEndian
case ElfDataMsb:
e = binary.BigEndian
default:
goto bad
}
// read header
elfobj = new(ElfObj)
elfobj.e = e
elfobj.f = f
elfobj.base = int64(base)
elfobj.length = length
elfobj.name = pn
is64 = 0
if hdr.Ident[4] == ElfClass64 {
is64 = 1
hdr := new(ElfHdrBytes64)
binary.Read(bytes.NewReader(hdrbuf[:]), binary.BigEndian, hdr) // only byte arrays; byte order doesn't matter
elfobj.type_ = uint32(e.Uint16(hdr.Type[:]))
elfobj.machine = uint32(e.Uint16(hdr.Machine[:]))
elfobj.version = e.Uint32(hdr.Version[:])
elfobj.phoff = e.Uint64(hdr.Phoff[:])
elfobj.shoff = e.Uint64(hdr.Shoff[:])
elfobj.flags = e.Uint32(hdr.Flags[:])
elfobj.ehsize = uint32(e.Uint16(hdr.Ehsize[:]))
elfobj.phentsize = uint32(e.Uint16(hdr.Phentsize[:]))
elfobj.phnum = uint32(e.Uint16(hdr.Phnum[:]))
elfobj.shentsize = uint32(e.Uint16(hdr.Shentsize[:]))
elfobj.shnum = uint32(e.Uint16(hdr.Shnum[:]))
elfobj.shstrndx = uint32(e.Uint16(hdr.Shstrndx[:]))
} else {
elfobj.type_ = uint32(e.Uint16(hdr.Type[:]))
elfobj.machine = uint32(e.Uint16(hdr.Machine[:]))
elfobj.version = e.Uint32(hdr.Version[:])
elfobj.entry = uint64(e.Uint32(hdr.Entry[:]))
elfobj.phoff = uint64(e.Uint32(hdr.Phoff[:]))
elfobj.shoff = uint64(e.Uint32(hdr.Shoff[:]))
elfobj.flags = e.Uint32(hdr.Flags[:])
elfobj.ehsize = uint32(e.Uint16(hdr.Ehsize[:]))
elfobj.phentsize = uint32(e.Uint16(hdr.Phentsize[:]))
elfobj.phnum = uint32(e.Uint16(hdr.Phnum[:]))
elfobj.shentsize = uint32(e.Uint16(hdr.Shentsize[:]))
elfobj.shnum = uint32(e.Uint16(hdr.Shnum[:]))
elfobj.shstrndx = uint32(e.Uint16(hdr.Shstrndx[:]))
}
elfobj.is64 = is64
if uint32(hdr.Ident[6]) != elfobj.version {
goto bad
}
if e.Uint16(hdr.Type[:]) != ElfTypeRelocatable {
Diag("%s: elf but not elf relocatable object", pn)
return
}
switch Thearch.Thechar {
default:
Diag("%s: elf %s unimplemented", pn, Thestring)
return
case '0':
if elfobj.machine != ElfMachMips || hdr.Ident[4] != ElfClass64 {
Diag("%s: elf object but not mips64", pn)
return
}
case '5':
if e != binary.LittleEndian || elfobj.machine != ElfMachArm || hdr.Ident[4] != ElfClass32 {
Diag("%s: elf object but not arm", pn)
return
}
case '6':
if e != binary.LittleEndian || elfobj.machine != ElfMachAmd64 || hdr.Ident[4] != ElfClass64 {
Diag("%s: elf object but not amd64", pn)
return
}
case '7':
if e != binary.LittleEndian || elfobj.machine != ElfMachArm64 || hdr.Ident[4] != ElfClass64 {
Diag("%s: elf object but not arm64", pn)
return
}
case '8':
if e != binary.LittleEndian || elfobj.machine != ElfMach386 || hdr.Ident[4] != ElfClass32 {
Diag("%s: elf object but not 386", pn)
return
}
case '9':
if elfobj.machine != ElfMachPower64 || hdr.Ident[4] != ElfClass64 {
Diag("%s: elf object but not ppc64", pn)
return
}
case 'z':
if elfobj.machine != ElfMachS390 || hdr.Ident[4] != ElfClass64 {
Diag("%s: elf object but not s390x", pn)
return
}
}
// load section list into memory.
elfobj.sect = make([]ElfSect, elfobj.shnum)
elfobj.nsect = uint(elfobj.shnum)
for i := 0; uint(i) < elfobj.nsect; i++ {
if obj.Bseek(f, int64(uint64(base)+elfobj.shoff+uint64(int64(i)*int64(elfobj.shentsize))), 0) < 0 {
goto bad
}
sect = &elfobj.sect[i]
if is64 != 0 {
var b ElfSectBytes64
if err = binary.Read(f, e, &b); err != nil {
goto bad
}
sect.nameoff = uint32(e.Uint32(b.Name[:]))
sect.type_ = e.Uint32(b.Type[:])
sect.flags = e.Uint64(b.Flags[:])
sect.addr = e.Uint64(b.Addr[:])
sect.off = e.Uint64(b.Off[:])
sect.size = e.Uint64(b.Size[:])
sect.link = e.Uint32(b.Link[:])
sect.info = e.Uint32(b.Info[:])
sect.align = e.Uint64(b.Align[:])
sect.entsize = e.Uint64(b.Entsize[:])
} else {
var b ElfSectBytes
if err = binary.Read(f, e, &b); err != nil {
goto bad
}
sect.nameoff = uint32(e.Uint32(b.Name[:]))
sect.type_ = e.Uint32(b.Type[:])
sect.flags = uint64(e.Uint32(b.Flags[:]))
sect.addr = uint64(e.Uint32(b.Addr[:]))
sect.off = uint64(e.Uint32(b.Off[:]))
sect.size = uint64(e.Uint32(b.Size[:]))
sect.link = e.Uint32(b.Link[:])
sect.info = e.Uint32(b.Info[:])
sect.align = uint64(e.Uint32(b.Align[:]))
sect.entsize = uint64(e.Uint32(b.Entsize[:]))
}
}
// read section string table and translate names
if elfobj.shstrndx >= uint32(elfobj.nsect) {
err = fmt.Errorf("shstrndx out of range %d >= %d", elfobj.shstrndx, elfobj.nsect)
goto bad
}
sect = &elfobj.sect[elfobj.shstrndx]
if err = elfmap(elfobj, sect); err != nil {
goto bad
}
for i := 0; uint(i) < elfobj.nsect; i++ {
if elfobj.sect[i].nameoff != 0 {
elfobj.sect[i].name = cstring(sect.base[elfobj.sect[i].nameoff:])
}
}
// load string table for symbols into memory.
elfobj.symtab = section(elfobj, ".symtab")
if elfobj.symtab == nil {
// our work is done here - no symbols means nothing can refer to this file
return
}
if elfobj.symtab.link <= 0 || elfobj.symtab.link >= uint32(elfobj.nsect) {
Diag("%s: elf object has symbol table with invalid string table link", pn)
return
}
elfobj.symstr = &elfobj.sect[elfobj.symtab.link]
if is64 != 0 {
elfobj.nsymtab = int(elfobj.symtab.size / ELF64SYMSIZE)
} else {
elfobj.nsymtab = int(elfobj.symtab.size / ELF32SYMSIZE)
}
if err = elfmap(elfobj, elfobj.symtab); err != nil {
goto bad
}
if err = elfmap(elfobj, elfobj.symstr); err != nil {
goto bad
}
// load text and data segments into memory.
// they are not as small as the section lists, but we'll need
// the memory anyway for the symbol images, so we might
// as well use one large chunk.
// create symbols for elfmapped sections
for i := 0; uint(i) < elfobj.nsect; i++ {
sect = &elfobj.sect[i]
if sect.type_ == SHT_ARM_ATTRIBUTES && sect.name == ".ARM.attributes" {
if err = elfmap(elfobj, sect); err != nil {
goto bad
}
parseArmAttributes(e, sect.base[:sect.size])
}
if (sect.type_ != ElfSectProgbits && sect.type_ != ElfSectNobits) || sect.flags&ElfSectFlagAlloc == 0 {
continue
}
if sect.type_ != ElfSectNobits {
if err = elfmap(elfobj, sect); err != nil {
goto bad
}
}
name = fmt.Sprintf("%s(%s)", pkg, sect.name)
s = Linklookup(Ctxt, name, Ctxt.Version)
switch int(sect.flags) & (ElfSectFlagAlloc | ElfSectFlagWrite | ElfSectFlagExec) {
default:
err = fmt.Errorf("unexpected flags for ELF section %s", sect.name)
goto bad
case ElfSectFlagAlloc:
s.Type = obj.SRODATA
case ElfSectFlagAlloc + ElfSectFlagWrite:
if sect.type_ == ElfSectNobits {
s.Type = obj.SNOPTRBSS
} else {
s.Type = obj.SNOPTRDATA
}
case ElfSectFlagAlloc + ElfSectFlagExec:
s.Type = obj.STEXT
}
if sect.name == ".got" || sect.name == ".toc" {
s.Type = obj.SELFGOT
}
if sect.type_ == ElfSectProgbits {
s.P = sect.base
s.P = s.P[:sect.size]
}
s.Size = int64(sect.size)
s.Align = int32(sect.align)
sect.sym = s
}
// enter sub-symbols into symbol table.
// symbol 0 is the null symbol.
symbols = make([]*LSym, elfobj.nsymtab)
for i := 1; i < elfobj.nsymtab; i++ {
if err = readelfsym(elfobj, i, &sym, 1); err != nil {
goto bad
}
symbols[i] = sym.sym
if sym.type_ != ElfSymTypeFunc && sym.type_ != ElfSymTypeObject && sym.type_ != ElfSymTypeNone {
continue
}
if sym.shndx == ElfSymShnCommon {
s = sym.sym
if uint64(s.Size) < sym.size {
s.Size = int64(sym.size)
}
if s.Type == 0 || s.Type == obj.SXREF {
s.Type = obj.SNOPTRBSS
}
continue
}
if uint(sym.shndx) >= elfobj.nsect || sym.shndx == 0 {
continue
}
// even when we pass needSym == 1 to readelfsym, it might still return nil to skip some unwanted symbols
if sym.sym == nil {
continue
}
sect = &elfobj.sect[sym.shndx:][0]
if sect.sym == nil {
if strings.HasPrefix(sym.name, ".Linfo_string") { // clang does this
continue
}
if sym.name == "" && sym.type_ == 0 && sect.name == ".debug_str" {
// This reportedly happens with clang 3.7 on ARM.
// See issue 13139.
continue
}
if strings.HasPrefix(sym.name, ".LASF") { // gcc on s390x does this
continue
}
Diag("%s: sym#%d: ignoring %s in section %d (type %d)", pn, i, sym.name, sym.shndx, sym.type_)
continue
}
s = sym.sym
if s.Outer != nil {
if s.Attr.DuplicateOK() {
continue
}
Exitf("%s: duplicate symbol reference: %s in both %s and %s", pn, s.Name, s.Outer.Name, sect.sym.Name)
}
s.Sub = sect.sym.Sub
sect.sym.Sub = s
s.Type = sect.sym.Type | s.Type&^obj.SMASK | obj.SSUB
if !s.Attr.CgoExportDynamic() {
s.Dynimplib = "" // satisfy dynimport
}
s.Value = int64(sym.value)
s.Size = int64(sym.size)
s.Outer = sect.sym
if sect.sym.Type == obj.STEXT {
if s.Attr.External() && !s.Attr.DuplicateOK() {
Diag("%s: duplicate definition of %s", pn, s.Name)
}
s.Attr |= AttrExternal
}
if elfobj.machine == ElfMachPower64 {
flag = int(sym.other) >> 5
if 2 <= flag && flag <= 6 {
s.Localentry = 1 << uint(flag-2)
} else if flag == 7 {
Diag("%s: invalid sym.other 0x%x for %s", pn, sym.other, s.Name)
}
}
}
// Sort outer lists by address, adding to textp.
// This keeps textp in increasing address order.
for i := 0; uint(i) < elfobj.nsect; i++ {
s = elfobj.sect[i].sym
if s == nil {
continue
}
if s.Sub != nil {
s.Sub = listsort(s.Sub, valuecmp, listsubp)
}
if s.Type == obj.STEXT {
if s.Attr.OnList() {
log.Fatalf("symbol %s listed multiple times", s.Name)
}
s.Attr |= AttrOnList
if Ctxt.Etextp != nil {
Ctxt.Etextp.Next = s
} else {
Ctxt.Textp = s
}
Ctxt.Etextp = s
for s = s.Sub; s != nil; s = s.Sub {
if s.Attr.OnList() {
log.Fatalf("symbol %s listed multiple times", s.Name)
}
s.Attr |= AttrOnList
Ctxt.Etextp.Next = s
Ctxt.Etextp = s
}
}
}
// load relocations
for i := 0; uint(i) < elfobj.nsect; i++ {
rsect = &elfobj.sect[i]
if rsect.type_ != ElfSectRela && rsect.type_ != ElfSectRel {
continue
}
if rsect.info >= uint32(elfobj.nsect) || elfobj.sect[rsect.info].base == nil {
continue
}
sect = &elfobj.sect[rsect.info]
if err = elfmap(elfobj, rsect); err != nil {
goto bad
}
rela = 0
if rsect.type_ == ElfSectRela {
rela = 1
}
n = int(rsect.size / uint64(4+4*is64) / uint64(2+rela))
r = make([]Reloc, n)
p = rsect.base
for j = 0; j < n; j++ {
add = 0
rp = &r[j]
if is64 != 0 {
// 64-bit rel/rela
rp.Off = int32(e.Uint64(p))
p = p[8:]
info = e.Uint64(p)
p = p[8:]
if rela != 0 {
add = e.Uint64(p)
p = p[8:]
}
} else {
// 32-bit rel/rela
rp.Off = int32(e.Uint32(p))
p = p[4:]
info = uint64(e.Uint32(p))
info = info>>8<<32 | info&0xff // convert to 64-bit info
p = p[4:]
if rela != 0 {
add = uint64(e.Uint32(p))
p = p[4:]
}
}
if info&0xffffffff == 0 { // skip R_*_NONE relocation
j--
n--
continue
}
if info>>32 == 0 { // absolute relocation, don't bother reading the null symbol
rp.Sym = nil
} else {
if err = readelfsym(elfobj, int(info>>32), &sym, 0); err != nil {
goto bad
}
sym.sym = symbols[info>>32]
if sym.sym == nil {
err = fmt.Errorf("%s#%d: reloc of invalid sym #%d %s shndx=%d type=%d", sect.sym.Name, j, int(info>>32), sym.name, sym.shndx, sym.type_)
goto bad
}
rp.Sym = sym.sym
}
rp.Type = int32(reltype(pn, int(uint32(info)), &rp.Siz))
if rela != 0 {
rp.Add = int64(add)
} else {
// load addend from image
if rp.Siz == 4 {
rp.Add = int64(e.Uint32(sect.base[rp.Off:]))
} else if rp.Siz == 8 {
rp.Add = int64(e.Uint64(sect.base[rp.Off:]))
} else {
Diag("invalid rela size %d", rp.Siz)
}
}
if rp.Siz == 2 {
rp.Add = int64(int16(rp.Add))
}
if rp.Siz == 4 {
rp.Add = int64(int32(rp.Add))
}
}
//print("rel %s %d %d %s %#llx\n", sect->sym->name, rp->type, rp->siz, rp->sym->name, rp->add);
sort.Sort(rbyoff(r[:n]))
// just in case
s = sect.sym
s.R = r
s.R = s.R[:n]
}
return
bad:
Diag("%s: malformed elf file: %v", pn, err)
}
func section(elfobj *ElfObj, name string) *ElfSect {
for i := 0; uint(i) < elfobj.nsect; i++ {
if elfobj.sect[i].name != "" && name != "" && elfobj.sect[i].name == name {
return &elfobj.sect[i]
}
}
return nil
}
func elfmap(elfobj *ElfObj, sect *ElfSect) (err error) {
if sect.base != nil {
return nil
}
if sect.off+sect.size > uint64(elfobj.length) {
err = fmt.Errorf("elf section past end of file")
return err
}
sect.base = make([]byte, sect.size)
err = fmt.Errorf("short read")
if obj.Bseek(elfobj.f, int64(uint64(elfobj.base)+sect.off), 0) < 0 || obj.Bread(elfobj.f, sect.base) != len(sect.base) {
return err
}
return nil
}
func readelfsym(elfobj *ElfObj, i int, sym *ElfSym, needSym int) (err error) {
if i >= elfobj.nsymtab || i < 0 {
err = fmt.Errorf("invalid elf symbol index")
return err
}
if i == 0 {
Diag("readym: read null symbol!")