/
macho.go
1152 lines (1010 loc) · 30 KB
/
macho.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
// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package ld
import (
"bytes"
"github.com/pgavlin/gc/objabi"
"github.com/pgavlin/gc/sys"
"github.com/pgavlin/gc/link/loader"
"github.com/pgavlin/gc/link/sym"
"debug/macho"
"encoding/binary"
"fmt"
"io"
"os"
"sort"
"strings"
)
type MachoHdr struct {
cpu uint32
subcpu uint32
}
type MachoSect struct {
name string
segname string
addr uint64
size uint64
off uint32
align uint32
reloc uint32
nreloc uint32
flag uint32
res1 uint32
res2 uint32
}
type MachoSeg struct {
name string
vsize uint64
vaddr uint64
fileoffset uint64
filesize uint64
prot1 uint32
prot2 uint32
nsect uint32
msect uint32
sect []MachoSect
flag uint32
}
// MachoPlatformLoad represents a LC_VERSION_MIN_* or
// LC_BUILD_VERSION load command.
type MachoPlatformLoad struct {
platform MachoPlatform // One of PLATFORM_* constants.
cmd MachoLoad
}
type MachoLoad struct {
type_ uint32
data []uint32
}
type MachoPlatform int
/*
* Total amount of space to reserve at the start of the file
* for Header, PHeaders, and SHeaders.
* May waste some.
*/
const (
INITIAL_MACHO_HEADR = 4 * 1024
)
const (
MACHO_CPU_AMD64 = 1<<24 | 7
MACHO_CPU_386 = 7
MACHO_SUBCPU_X86 = 3
MACHO_CPU_ARM = 12
MACHO_SUBCPU_ARM = 0
MACHO_SUBCPU_ARMV7 = 9
MACHO_CPU_ARM64 = 1<<24 | 12
MACHO_SUBCPU_ARM64_ALL = 0
MACHO32SYMSIZE = 12
MACHO64SYMSIZE = 16
MACHO_X86_64_RELOC_UNSIGNED = 0
MACHO_X86_64_RELOC_SIGNED = 1
MACHO_X86_64_RELOC_BRANCH = 2
MACHO_X86_64_RELOC_GOT_LOAD = 3
MACHO_X86_64_RELOC_GOT = 4
MACHO_X86_64_RELOC_SUBTRACTOR = 5
MACHO_X86_64_RELOC_SIGNED_1 = 6
MACHO_X86_64_RELOC_SIGNED_2 = 7
MACHO_X86_64_RELOC_SIGNED_4 = 8
MACHO_ARM_RELOC_VANILLA = 0
MACHO_ARM_RELOC_PAIR = 1
MACHO_ARM_RELOC_SECTDIFF = 2
MACHO_ARM_RELOC_BR24 = 5
MACHO_ARM64_RELOC_UNSIGNED = 0
MACHO_ARM64_RELOC_BRANCH26 = 2
MACHO_ARM64_RELOC_PAGE21 = 3
MACHO_ARM64_RELOC_PAGEOFF12 = 4
MACHO_ARM64_RELOC_ADDEND = 10
MACHO_GENERIC_RELOC_VANILLA = 0
MACHO_FAKE_GOTPCREL = 100
)
const (
MH_MAGIC = 0xfeedface
MH_MAGIC_64 = 0xfeedfacf
MH_OBJECT = 0x1
MH_EXECUTE = 0x2
MH_NOUNDEFS = 0x1
)
const (
LC_SEGMENT = 0x1
LC_SYMTAB = 0x2
LC_SYMSEG = 0x3
LC_THREAD = 0x4
LC_UNIXTHREAD = 0x5
LC_LOADFVMLIB = 0x6
LC_IDFVMLIB = 0x7
LC_IDENT = 0x8
LC_FVMFILE = 0x9
LC_PREPAGE = 0xa
LC_DYSYMTAB = 0xb
LC_LOAD_DYLIB = 0xc
LC_ID_DYLIB = 0xd
LC_LOAD_DYLINKER = 0xe
LC_ID_DYLINKER = 0xf
LC_PREBOUND_DYLIB = 0x10
LC_ROUTINES = 0x11
LC_SUB_FRAMEWORK = 0x12
LC_SUB_UMBRELLA = 0x13
LC_SUB_CLIENT = 0x14
LC_SUB_LIBRARY = 0x15
LC_TWOLEVEL_HINTS = 0x16
LC_PREBIND_CKSUM = 0x17
LC_LOAD_WEAK_DYLIB = 0x80000018
LC_SEGMENT_64 = 0x19
LC_ROUTINES_64 = 0x1a
LC_UUID = 0x1b
LC_RPATH = 0x8000001c
LC_CODE_SIGNATURE = 0x1d
LC_SEGMENT_SPLIT_INFO = 0x1e
LC_REEXPORT_DYLIB = 0x8000001f
LC_LAZY_LOAD_DYLIB = 0x20
LC_ENCRYPTION_INFO = 0x21
LC_DYLD_INFO = 0x22
LC_DYLD_INFO_ONLY = 0x80000022
LC_LOAD_UPWARD_DYLIB = 0x80000023
LC_VERSION_MIN_MACOSX = 0x24
LC_VERSION_MIN_IPHONEOS = 0x25
LC_FUNCTION_STARTS = 0x26
LC_DYLD_ENVIRONMENT = 0x27
LC_MAIN = 0x80000028
LC_DATA_IN_CODE = 0x29
LC_SOURCE_VERSION = 0x2A
LC_DYLIB_CODE_SIGN_DRS = 0x2B
LC_ENCRYPTION_INFO_64 = 0x2C
LC_LINKER_OPTION = 0x2D
LC_LINKER_OPTIMIZATION_HINT = 0x2E
LC_VERSION_MIN_TVOS = 0x2F
LC_VERSION_MIN_WATCHOS = 0x30
LC_VERSION_NOTE = 0x31
LC_BUILD_VERSION = 0x32
)
const (
S_REGULAR = 0x0
S_ZEROFILL = 0x1
S_NON_LAZY_SYMBOL_POINTERS = 0x6
S_SYMBOL_STUBS = 0x8
S_MOD_INIT_FUNC_POINTERS = 0x9
S_ATTR_PURE_INSTRUCTIONS = 0x80000000
S_ATTR_DEBUG = 0x02000000
S_ATTR_SOME_INSTRUCTIONS = 0x00000400
)
const (
PLATFORM_MACOS MachoPlatform = 1
PLATFORM_IOS MachoPlatform = 2
PLATFORM_TVOS MachoPlatform = 3
PLATFORM_WATCHOS MachoPlatform = 4
PLATFORM_BRIDGEOS MachoPlatform = 5
)
// Mach-O file writing
// https://developer.apple.com/mac/library/DOCUMENTATION/DeveloperTools/Conceptual/MachORuntime/Reference/reference.html
var machohdr MachoHdr
var load []MachoLoad
var machoPlatform MachoPlatform
var seg [16]MachoSeg
var nseg int
var ndebug int
var nsect int
const (
SymKindLocal = 0 + iota
SymKindExtdef
SymKindUndef
NumSymKind
)
var nkind [NumSymKind]int
var sortsym []loader.Sym
var nsortsym int
// Amount of space left for adding load commands
// that refer to dynamic libraries. Because these have
// to go in the Mach-O header, we can't just pick a
// "big enough" header size. The initial header is
// one page, the non-dynamic library stuff takes
// up about 1300 bytes; we overestimate that as 2k.
var loadBudget = INITIAL_MACHO_HEADR - 2*1024
func getMachoHdr() *MachoHdr {
return &machohdr
}
func newMachoLoad(arch *sys.Arch, type_ uint32, ndata uint32) *MachoLoad {
if arch.PtrSize == 8 && (ndata&1 != 0) {
ndata++
}
load = append(load, MachoLoad{})
l := &load[len(load)-1]
l.type_ = type_
l.data = make([]uint32, ndata)
return l
}
func newMachoSeg(name string, msect int) *MachoSeg {
if nseg >= len(seg) {
Exitf("too many segs")
}
s := &seg[nseg]
nseg++
s.name = name
s.msect = uint32(msect)
s.sect = make([]MachoSect, msect)
return s
}
func newMachoSect(seg *MachoSeg, name string, segname string) *MachoSect {
if seg.nsect >= seg.msect {
Exitf("too many sects in segment %s", seg.name)
}
s := &seg.sect[seg.nsect]
seg.nsect++
s.name = name
s.segname = segname
nsect++
return s
}
// Generic linking code.
var dylib []string
var linkoff int64
func machowrite(arch *sys.Arch, out *OutBuf, linkmode LinkMode) int {
o1 := out.Offset()
loadsize := 4 * 4 * ndebug
for i := range load {
loadsize += 4 * (len(load[i].data) + 2)
}
if arch.PtrSize == 8 {
loadsize += 18 * 4 * nseg
loadsize += 20 * 4 * nsect
} else {
loadsize += 14 * 4 * nseg
loadsize += 17 * 4 * nsect
}
if arch.PtrSize == 8 {
out.Write32(MH_MAGIC_64)
} else {
out.Write32(MH_MAGIC)
}
out.Write32(machohdr.cpu)
out.Write32(machohdr.subcpu)
if linkmode == LinkExternal {
out.Write32(MH_OBJECT) /* file type - mach object */
} else {
out.Write32(MH_EXECUTE) /* file type - mach executable */
}
out.Write32(uint32(len(load)) + uint32(nseg) + uint32(ndebug))
out.Write32(uint32(loadsize))
if nkind[SymKindUndef] == 0 {
out.Write32(MH_NOUNDEFS) /* flags - no undefines */
} else {
out.Write32(0) /* flags */
}
if arch.PtrSize == 8 {
out.Write32(0) /* reserved */
}
for i := 0; i < nseg; i++ {
s := &seg[i]
if arch.PtrSize == 8 {
out.Write32(LC_SEGMENT_64)
out.Write32(72 + 80*s.nsect)
out.WriteStringN(s.name, 16)
out.Write64(s.vaddr)
out.Write64(s.vsize)
out.Write64(s.fileoffset)
out.Write64(s.filesize)
out.Write32(s.prot1)
out.Write32(s.prot2)
out.Write32(s.nsect)
out.Write32(s.flag)
} else {
out.Write32(LC_SEGMENT)
out.Write32(56 + 68*s.nsect)
out.WriteStringN(s.name, 16)
out.Write32(uint32(s.vaddr))
out.Write32(uint32(s.vsize))
out.Write32(uint32(s.fileoffset))
out.Write32(uint32(s.filesize))
out.Write32(s.prot1)
out.Write32(s.prot2)
out.Write32(s.nsect)
out.Write32(s.flag)
}
for j := uint32(0); j < s.nsect; j++ {
t := &s.sect[j]
if arch.PtrSize == 8 {
out.WriteStringN(t.name, 16)
out.WriteStringN(t.segname, 16)
out.Write64(t.addr)
out.Write64(t.size)
out.Write32(t.off)
out.Write32(t.align)
out.Write32(t.reloc)
out.Write32(t.nreloc)
out.Write32(t.flag)
out.Write32(t.res1) /* reserved */
out.Write32(t.res2) /* reserved */
out.Write32(0) /* reserved */
} else {
out.WriteStringN(t.name, 16)
out.WriteStringN(t.segname, 16)
out.Write32(uint32(t.addr))
out.Write32(uint32(t.size))
out.Write32(t.off)
out.Write32(t.align)
out.Write32(t.reloc)
out.Write32(t.nreloc)
out.Write32(t.flag)
out.Write32(t.res1) /* reserved */
out.Write32(t.res2) /* reserved */
}
}
}
for i := range load {
l := &load[i]
out.Write32(l.type_)
out.Write32(4 * (uint32(len(l.data)) + 2))
for j := 0; j < len(l.data); j++ {
out.Write32(l.data[j])
}
}
return int(out.Offset() - o1)
}
func (ctxt *Link) domacho() {
if *FlagD {
return
}
// Copy platform load command.
for _, h := range hostobj {
load, err := hostobjMachoPlatform(&h)
if err != nil {
Exitf("%v", err)
}
if load != nil {
machoPlatform = load.platform
ml := newMachoLoad(ctxt.Arch, load.cmd.type_, uint32(len(load.cmd.data)))
copy(ml.data, load.cmd.data)
break
}
}
if machoPlatform == 0 {
switch ctxt.Arch.Family {
default:
machoPlatform = PLATFORM_MACOS
if ctxt.LinkMode == LinkInternal {
// For lldb, must say LC_VERSION_MIN_MACOSX or else
// it won't know that this Mach-O binary is from OS X
// (could be iOS or WatchOS instead).
// Go on iOS uses linkmode=external, and linkmode=external
// adds this itself. So we only need this code for linkmode=internal
// and we can assume OS X.
//
// See golang.org/issues/12941.
//
// The version must be at least 10.9; see golang.org/issues/30488.
ml := newMachoLoad(ctxt.Arch, LC_VERSION_MIN_MACOSX, 2)
ml.data[0] = 10<<16 | 9<<8 | 0<<0 // OS X version 10.9.0
ml.data[1] = 10<<16 | 9<<8 | 0<<0 // SDK 10.9.0
}
case sys.ARM, sys.ARM64:
machoPlatform = PLATFORM_IOS
}
}
// empirically, string table must begin with " \x00".
s := ctxt.loader.LookupOrCreateSym(".machosymstr", 0)
sb := ctxt.loader.MakeSymbolUpdater(s)
sb.SetType(sym.SMACHOSYMSTR)
sb.SetReachable(true)
sb.AddUint8(' ')
sb.AddUint8('\x00')
s = ctxt.loader.LookupOrCreateSym(".machosymtab", 0)
sb = ctxt.loader.MakeSymbolUpdater(s)
sb.SetType(sym.SMACHOSYMTAB)
sb.SetReachable(true)
if ctxt.IsInternal() {
s = ctxt.loader.LookupOrCreateSym(".plt", 0) // will be __symbol_stub
sb = ctxt.loader.MakeSymbolUpdater(s)
sb.SetType(sym.SMACHOPLT)
sb.SetReachable(true)
s = ctxt.loader.LookupOrCreateSym(".got", 0) // will be __nl_symbol_ptr
sb = ctxt.loader.MakeSymbolUpdater(s)
sb.SetType(sym.SMACHOGOT)
sb.SetReachable(true)
sb.SetAlign(4)
s = ctxt.loader.LookupOrCreateSym(".linkedit.plt", 0) // indirect table for .plt
sb = ctxt.loader.MakeSymbolUpdater(s)
sb.SetType(sym.SMACHOINDIRECTPLT)
sb.SetReachable(true)
s = ctxt.loader.LookupOrCreateSym(".linkedit.got", 0) // indirect table for .got
sb = ctxt.loader.MakeSymbolUpdater(s)
sb.SetType(sym.SMACHOINDIRECTGOT)
sb.SetReachable(true)
}
// Add a dummy symbol that will become the __asm marker section.
if ctxt.IsExternal() {
s = ctxt.loader.LookupOrCreateSym(".llvmasm", 0)
sb = ctxt.loader.MakeSymbolUpdater(s)
sb.SetType(sym.SMACHO)
sb.SetReachable(true)
sb.AddUint8(0)
}
}
func machoadddynlib(lib string, linkmode LinkMode) {
if seenlib[lib] || linkmode == LinkExternal {
return
}
seenlib[lib] = true
// Will need to store the library name rounded up
// and 24 bytes of header metadata. If not enough
// space, grab another page of initial space at the
// beginning of the output file.
loadBudget -= (len(lib)+7)/8*8 + 24
if loadBudget < 0 {
HEADR += 4096
*FlagTextAddr += 4096
loadBudget += 4096
}
dylib = append(dylib, lib)
}
func machoshbits(ctxt *Link, mseg *MachoSeg, sect *sym.Section, segname string) {
buf := "__" + strings.Replace(sect.Name[1:], ".", "_", -1)
var msect *MachoSect
if sect.Rwx&1 == 0 && segname != "__DWARF" && (ctxt.Arch.Family == sys.ARM64 ||
ctxt.Arch.Family == sys.ARM ||
(ctxt.Arch.Family == sys.AMD64 && ctxt.BuildMode != BuildModeExe)) {
// Darwin external linker on arm and arm64, and on amd64 in c-shared/c-archive buildmode
// complains about absolute relocs in __TEXT, so if the section is not
// executable, put it in __DATA segment.
msect = newMachoSect(mseg, buf, "__DATA")
} else {
msect = newMachoSect(mseg, buf, segname)
}
if sect.Rellen > 0 {
msect.reloc = uint32(sect.Reloff)
msect.nreloc = uint32(sect.Rellen / 8)
}
for 1<<msect.align < sect.Align {
msect.align++
}
msect.addr = sect.Vaddr
msect.size = sect.Length
if sect.Vaddr < sect.Seg.Vaddr+sect.Seg.Filelen {
// data in file
if sect.Length > sect.Seg.Vaddr+sect.Seg.Filelen-sect.Vaddr {
Errorf(nil, "macho cannot represent section %s crossing data and bss", sect.Name)
}
msect.off = uint32(sect.Seg.Fileoff + sect.Vaddr - sect.Seg.Vaddr)
} else {
msect.off = 0
msect.flag |= S_ZEROFILL
}
if sect.Rwx&1 != 0 {
msect.flag |= S_ATTR_SOME_INSTRUCTIONS
}
if sect.Name == ".text" {
msect.flag |= S_ATTR_PURE_INSTRUCTIONS
}
if sect.Name == ".plt" {
msect.name = "__symbol_stub1"
msect.flag = S_ATTR_PURE_INSTRUCTIONS | S_ATTR_SOME_INSTRUCTIONS | S_SYMBOL_STUBS
msect.res1 = 0 //nkind[SymKindLocal];
msect.res2 = 6
}
if sect.Name == ".got" {
msect.name = "__nl_symbol_ptr"
msect.flag = S_NON_LAZY_SYMBOL_POINTERS
msect.res1 = uint32(ctxt.Syms.Lookup(".linkedit.plt", 0).Size / 4) /* offset into indirect symbol table */
}
if sect.Name == ".init_array" {
msect.name = "__mod_init_func"
msect.flag = S_MOD_INIT_FUNC_POINTERS
}
// Some platforms such as watchOS and tvOS require binaries with
// bitcode enabled. The Go toolchain can't output bitcode, so use
// a marker section in the __LLVM segment, "__asm", to tell the Apple
// toolchain that the Go text came from assembler and thus has no
// bitcode. This is not true, but Kotlin/Native, Rust and Flutter
// are also using this trick.
if sect.Name == ".llvmasm" {
msect.name = "__asm"
msect.segname = "__LLVM"
}
if segname == "__DWARF" {
msect.flag |= S_ATTR_DEBUG
}
}
func Asmbmacho(ctxt *Link) {
/* apple MACH */
va := *FlagTextAddr - int64(HEADR)
mh := getMachoHdr()
switch ctxt.Arch.Family {
default:
Exitf("unknown macho architecture: %v", ctxt.Arch.Family)
case sys.ARM:
mh.cpu = MACHO_CPU_ARM
mh.subcpu = MACHO_SUBCPU_ARMV7
case sys.AMD64:
mh.cpu = MACHO_CPU_AMD64
mh.subcpu = MACHO_SUBCPU_X86
case sys.ARM64:
mh.cpu = MACHO_CPU_ARM64
mh.subcpu = MACHO_SUBCPU_ARM64_ALL
case sys.I386:
mh.cpu = MACHO_CPU_386
mh.subcpu = MACHO_SUBCPU_X86
}
var ms *MachoSeg
if ctxt.LinkMode == LinkExternal {
/* segment for entire file */
ms = newMachoSeg("", 40)
ms.fileoffset = Segtext.Fileoff
ms.filesize = Segdwarf.Fileoff + Segdwarf.Filelen - Segtext.Fileoff
ms.vsize = Segdwarf.Vaddr + Segdwarf.Length - Segtext.Vaddr
}
/* segment for zero page */
if ctxt.LinkMode != LinkExternal {
ms = newMachoSeg("__PAGEZERO", 0)
ms.vsize = uint64(va)
}
/* text */
v := Rnd(int64(uint64(HEADR)+Segtext.Length), int64(*FlagRound))
if ctxt.LinkMode != LinkExternal {
ms = newMachoSeg("__TEXT", 20)
ms.vaddr = uint64(va)
ms.vsize = uint64(v)
ms.fileoffset = 0
ms.filesize = uint64(v)
ms.prot1 = 7
ms.prot2 = 5
}
for _, sect := range Segtext.Sections {
machoshbits(ctxt, ms, sect, "__TEXT")
}
/* data */
if ctxt.LinkMode != LinkExternal {
w := int64(Segdata.Length)
ms = newMachoSeg("__DATA", 20)
ms.vaddr = uint64(va) + uint64(v)
ms.vsize = uint64(w)
ms.fileoffset = uint64(v)
ms.filesize = Segdata.Filelen
ms.prot1 = 3
ms.prot2 = 3
}
for _, sect := range Segdata.Sections {
machoshbits(ctxt, ms, sect, "__DATA")
}
/* dwarf */
if !*FlagW {
if ctxt.LinkMode != LinkExternal {
ms = newMachoSeg("__DWARF", 20)
ms.vaddr = Segdwarf.Vaddr
ms.vsize = 0
ms.fileoffset = Segdwarf.Fileoff
ms.filesize = Segdwarf.Filelen
}
for _, sect := range Segdwarf.Sections {
machoshbits(ctxt, ms, sect, "__DWARF")
}
}
if ctxt.LinkMode != LinkExternal {
switch ctxt.Arch.Family {
default:
Exitf("unknown macho architecture: %v", ctxt.Arch.Family)
case sys.ARM:
ml := newMachoLoad(ctxt.Arch, LC_UNIXTHREAD, 17+2)
ml.data[0] = 1 /* thread type */
ml.data[1] = 17 /* word count */
ml.data[2+15] = uint32(Entryvalue(ctxt)) /* start pc */
case sys.AMD64:
ml := newMachoLoad(ctxt.Arch, LC_UNIXTHREAD, 42+2)
ml.data[0] = 4 /* thread type */
ml.data[1] = 42 /* word count */
ml.data[2+32] = uint32(Entryvalue(ctxt)) /* start pc */
ml.data[2+32+1] = uint32(Entryvalue(ctxt) >> 32)
case sys.ARM64:
ml := newMachoLoad(ctxt.Arch, LC_UNIXTHREAD, 68+2)
ml.data[0] = 6 /* thread type */
ml.data[1] = 68 /* word count */
ml.data[2+64] = uint32(Entryvalue(ctxt)) /* start pc */
ml.data[2+64+1] = uint32(Entryvalue(ctxt) >> 32)
case sys.I386:
ml := newMachoLoad(ctxt.Arch, LC_UNIXTHREAD, 16+2)
ml.data[0] = 1 /* thread type */
ml.data[1] = 16 /* word count */
ml.data[2+10] = uint32(Entryvalue(ctxt)) /* start pc */
}
}
if !*FlagD {
// must match domacholink below
s1 := ctxt.Syms.Lookup(".machosymtab", 0)
s2 := ctxt.Syms.Lookup(".linkedit.plt", 0)
s3 := ctxt.Syms.Lookup(".linkedit.got", 0)
s4 := ctxt.Syms.Lookup(".machosymstr", 0)
if ctxt.LinkMode != LinkExternal {
ms := newMachoSeg("__LINKEDIT", 0)
ms.vaddr = uint64(va) + uint64(v) + uint64(Rnd(int64(Segdata.Length), int64(*FlagRound)))
ms.vsize = uint64(s1.Size) + uint64(s2.Size) + uint64(s3.Size) + uint64(s4.Size)
ms.fileoffset = uint64(linkoff)
ms.filesize = ms.vsize
ms.prot1 = 7
ms.prot2 = 3
}
ml := newMachoLoad(ctxt.Arch, LC_SYMTAB, 4)
ml.data[0] = uint32(linkoff) /* symoff */
ml.data[1] = uint32(nsortsym) /* nsyms */
ml.data[2] = uint32(linkoff + s1.Size + s2.Size + s3.Size) /* stroff */
ml.data[3] = uint32(s4.Size) /* strsize */
machodysymtab(ctxt)
if ctxt.LinkMode != LinkExternal {
ml := newMachoLoad(ctxt.Arch, LC_LOAD_DYLINKER, 6)
ml.data[0] = 12 /* offset to string */
stringtouint32(ml.data[1:], "/usr/lib/dyld")
for _, lib := range dylib {
ml = newMachoLoad(ctxt.Arch, LC_LOAD_DYLIB, 4+(uint32(len(lib))+1+7)/8*2)
ml.data[0] = 24 /* offset of string from beginning of load */
ml.data[1] = 0 /* time stamp */
ml.data[2] = 0 /* version */
ml.data[3] = 0 /* compatibility version */
stringtouint32(ml.data[4:], lib)
}
}
}
a := machowrite(ctxt.Arch, ctxt.Out, ctxt.LinkMode)
if int32(a) > HEADR {
Exitf("HEADR too small: %d > %d", a, HEADR)
}
}
func symkind(ldr *loader.Loader, s loader.Sym) int {
if ldr.SymType(s) == sym.SDYNIMPORT {
return SymKindUndef
}
if ldr.AttrCgoExport(s) {
return SymKindExtdef
}
return SymKindLocal
}
func collectmachosyms(ctxt *Link) {
ldr := ctxt.loader
addsym := func(s loader.Sym) {
sortsym = append(sortsym, s)
nkind[symkind(ldr, s)]++
}
// Add special runtime.text and runtime.etext symbols.
// We've already included this symbol in Textp on darwin if ctxt.DynlinkingGo().
// See data.go:/textaddress
if !ctxt.DynlinkingGo() {
s := ldr.Lookup("runtime.text", 0)
if ldr.SymType(s) == sym.STEXT {
addsym(s)
}
s = ldr.Lookup("runtime.etext", 0)
if ldr.SymType(s) == sym.STEXT {
addsym(s)
}
}
// Add text symbols.
for _, s := range ctxt.Textp2 {
addsym(s)
}
shouldBeInSymbolTable := func(s loader.Sym) bool {
if ldr.AttrNotInSymbolTable(s) {
return false
}
name := ldr.RawSymName(s) // TODO: try not to read the name
if name == "" || name[0] == '.' {
return false
}
return true
}
// Add data symbols and external references.
for s := loader.Sym(1); s < loader.Sym(ldr.NSym()); s++ {
if !ldr.AttrReachable(s) {
continue
}
t := ldr.SymType(s)
if t >= sym.SELFRXSECT && t < sym.SXREF || t == sym.SCONST { // data sections handled in dodata
if t == sym.STLSBSS {
// TLSBSS is not used on darwin. See data.go:allocateDataSections
continue
}
if !shouldBeInSymbolTable(s) {
continue
}
addsym(s)
}
switch t {
case sym.SDYNIMPORT, sym.SHOSTOBJ, sym.SUNDEFEXT:
addsym(s)
}
// Some 64-bit functions have a "$INODE64" or "$INODE64$UNIX2003" suffix.
if t == sym.SDYNIMPORT && ldr.SymDynimplib(s) == "/usr/lib/libSystem.B.dylib" {
// But only on macOS.
if machoPlatform == PLATFORM_MACOS {
switch n := ldr.SymExtname(s); n {
case "fdopendir":
switch objabi.GOARCH {
case "amd64":
ldr.SetSymExtname(s, n+"$INODE64")
case "386":
ldr.SetSymExtname(s, n+"$INODE64$UNIX2003")
}
case "readdir_r", "getfsstat":
switch objabi.GOARCH {
case "amd64", "386":
ldr.SetSymExtname(s, n+"$INODE64")
}
}
}
}
}
nsortsym = len(sortsym)
}
func machosymorder(ctxt *Link) {
ldr := ctxt.loader
// On Mac OS X Mountain Lion, we must sort exported symbols
// So we sort them here and pre-allocate dynid for them
// See https://golang.org/issue/4029
for _, s := range ctxt.dynexp2 {
if !ldr.AttrReachable(s) {
panic("dynexp symbol is not reachable")
}
}
collectmachosyms(ctxt)
sort.Slice(sortsym[:nsortsym], func(i, j int) bool {
s1 := sortsym[i]
s2 := sortsym[j]
k1 := symkind(ldr, s1)
k2 := symkind(ldr, s2)
if k1 != k2 {
return k1 < k2
}
return ldr.SymExtname(s1) < ldr.SymExtname(s2) // Note: unnamed symbols are not added in collectmachosyms
})
for i, s := range sortsym {
ldr.SetSymDynid(s, int32(i))
}
}
// machoShouldExport reports whether a symbol needs to be exported.
//
// When dynamically linking, all non-local variables and plugin-exported
// symbols need to be exported.
func machoShouldExport(ctxt *Link, s *sym.Symbol) bool {
if !ctxt.DynlinkingGo() || s.Attr.Local() {
return false
}
if ctxt.BuildMode == BuildModePlugin && strings.HasPrefix(s.Extname(), objabi.PathToPrefix(*flagPluginPath)) {
return true
}
if strings.HasPrefix(s.Name, "go.itab.") {
return true
}
if strings.HasPrefix(s.Name, "type.") && !strings.HasPrefix(s.Name, "type..") {
// reduce runtime typemap pressure, but do not
// export alg functions (type..*), as these
// appear in pclntable.
return true
}
if strings.HasPrefix(s.Name, "go.link.pkghash") {
return true
}
return s.Type >= sym.SFirstWritable // only writable sections
}
func machosymtab(ctxt *Link) {
symtab := ctxt.Syms.Lookup(".machosymtab", 0)
symstr := ctxt.Syms.Lookup(".machosymstr", 0)
for i := 0; i < nsortsym; i++ {
s := ctxt.loader.Syms[sortsym[i]]
symtab.AddUint32(ctxt.Arch, uint32(symstr.Size))
export := machoShouldExport(ctxt, s)
isGoSymbol := strings.Contains(s.Extname(), ".")
// In normal buildmodes, only add _ to C symbols, as
// Go symbols have dot in the name.
//
// Do not export C symbols in plugins, as runtime C
// symbols like crosscall2 are in pclntab and end up
// pointing at the host binary, breaking unwinding.
// See Issue #18190.
cexport := !isGoSymbol && (ctxt.BuildMode != BuildModePlugin || onlycsymbol(s.Name))
if cexport || export || isGoSymbol {
symstr.AddUint8('_')
}
// replace "·" as ".", because DTrace cannot handle it.
Addstring(symstr, strings.Replace(s.Extname(), "·", ".", -1))
if s.Type == sym.SDYNIMPORT || s.Type == sym.SHOSTOBJ || s.Type == sym.SUNDEFEXT {
symtab.AddUint8(0x01) // type N_EXT, external symbol
symtab.AddUint8(0) // no section
symtab.AddUint16(ctxt.Arch, 0) // desc
symtab.AddUintXX(ctxt.Arch, 0, ctxt.Arch.PtrSize) // no value
} else {
if s.Attr.CgoExport() || export {
symtab.AddUint8(0x0f)
} else {
symtab.AddUint8(0x0e)
}
o := s
for o.Outer != nil {
o = o.Outer
}
if o.Sect == nil {
Errorf(s, "missing section for symbol")
symtab.AddUint8(0)
} else {
symtab.AddUint8(uint8(o.Sect.Extnum))
}
symtab.AddUint16(ctxt.Arch, 0) // desc
symtab.AddUintXX(ctxt.Arch, uint64(Symaddr(s)), ctxt.Arch.PtrSize)
}
}
}
func machodysymtab(ctxt *Link) {
ml := newMachoLoad(ctxt.Arch, LC_DYSYMTAB, 18)
n := 0
ml.data[0] = uint32(n) /* ilocalsym */
ml.data[1] = uint32(nkind[SymKindLocal]) /* nlocalsym */
n += nkind[SymKindLocal]
ml.data[2] = uint32(n) /* iextdefsym */
ml.data[3] = uint32(nkind[SymKindExtdef]) /* nextdefsym */
n += nkind[SymKindExtdef]
ml.data[4] = uint32(n) /* iundefsym */
ml.data[5] = uint32(nkind[SymKindUndef]) /* nundefsym */
ml.data[6] = 0 /* tocoffset */
ml.data[7] = 0 /* ntoc */
ml.data[8] = 0 /* modtaboff */
ml.data[9] = 0 /* nmodtab */
ml.data[10] = 0 /* extrefsymoff */
ml.data[11] = 0 /* nextrefsyms */
// must match domacholink below
s1 := ctxt.Syms.Lookup(".machosymtab", 0)
s2 := ctxt.Syms.Lookup(".linkedit.plt", 0)
s3 := ctxt.Syms.Lookup(".linkedit.got", 0)
ml.data[12] = uint32(linkoff + s1.Size) /* indirectsymoff */
ml.data[13] = uint32((s2.Size + s3.Size) / 4) /* nindirectsyms */
ml.data[14] = 0 /* extreloff */
ml.data[15] = 0 /* nextrel */
ml.data[16] = 0 /* locreloff */
ml.data[17] = 0 /* nlocrel */
}
func Domacholink(ctxt *Link) int64 {
machosymtab(ctxt)
// write data that will be linkedit section
s1 := ctxt.Syms.Lookup(".machosymtab", 0)
s2 := ctxt.Syms.Lookup(".linkedit.plt", 0)
s3 := ctxt.Syms.Lookup(".linkedit.got", 0)
s4 := ctxt.Syms.Lookup(".machosymstr", 0)
// Force the linkedit section to end on a 16-byte
// boundary. This allows pure (non-cgo) Go binaries
// to be code signed correctly.
//
// Apple's codesign_allocate (a helper utility for
// the codesign utility) can do this fine itself if
// it is run on a dynamic Mach-O binary. However,