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6l, 8l: support for linking ELF and Mach-O .o files

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More support for references to dynamic symbols,
including full GOT and PLT for ELF objects.

For Mach-O everything ends up in the GOT: dealing
with the real lazy PLT is too hard for now so we punt.

R=iant, iant2
CC=golang-dev
https://golang.org/cl/3491042
This commit is contained in:
Russ Cox 2010-12-08 13:56:43 -05:00
parent 9042c2ce68
commit f5690004c2
14 changed files with 1312 additions and 453 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
src/cmd/6l/Makefile
View File

@ -14,6 +14,8 @@ OFILES=\
elf.$O\
enam.$O\
go.$O\
ldelf.$O\
ldmacho.$O\
lib.$O\
list.$O\
macho.$O\

512
src/cmd/6l/asm.c
View File

@ -138,6 +138,8 @@ enum {
ElfStrShstrtab,
ElfStrSymtab,
ElfStrStrtab,
ElfStrRelaPlt,
ElfStrPlt,
NElfStr
};
@ -159,11 +161,391 @@ needlib(char *name)
return 0;
}
int nelfsym = 1;
static void adddynsym(Sym*);
static void addpltsym(Sym*);
static void addgotsym(Sym*);
void
adddynrel(Sym *s, Reloc *r)
{
Sym *targ, *rela, *got;
targ = r->sym;
cursym = s;
switch(r->type) {
default:
if(r->type >= 256) {
diag("unexpected relocation type %d", r->type);
return;
}
break;
// Handle relocations found in ELF object files.
case 256 + R_X86_64_PC32:
if(targ->dynimpname)
diag("unexpected R_X86_64_PC32 relocation for dynamic symbol %s", targ->name);
if(targ->type == 0 || targ->type == SXREF)
diag("unknown symbol %s in pcrel", targ->name);
r->type = D_PCREL;
r->add += 4;
return;
case 256 + R_X86_64_PLT32:
addpltsym(targ);
r->type = D_PCREL;
r->sym = lookup(".plt", 0);
r->add += 4;
r->add += targ->plt;
return;
case 256 + R_X86_64_GOTPCREL:
addgotsym(targ);
r->type = D_PCREL;
r->sym = lookup(".got", 0);
r->add += 4;
r->add += targ->got;
return;
case 256 + R_X86_64_64:
if(targ->dynimpname)
diag("unexpected R_X86_64_64 relocation for dynamic symbol %s", targ->name);
r->type = D_ADDR;
return;
// Handle relocations found in Mach-O object files.
case 512 + MACHO_X86_64_RELOC_UNSIGNED*2 + 0:
case 512 + MACHO_X86_64_RELOC_SIGNED*2 + 0:
case 512 + MACHO_X86_64_RELOC_BRANCH*2 + 0:
// TODO: What is the difference between all these?
r->type = D_ADDR;
if(targ->dynimpname)
diag("unexpected reloc for dynamic symbol %s", targ->name);
return;
case 512 + MACHO_X86_64_RELOC_BRANCH*2 + 1:
if(targ->dynimpname) {
addpltsym(targ);
r->sym = lookup(".plt", 0);
r->add = targ->plt;
r->type = D_PCREL;
return;
}
// fall through
case 512 + MACHO_X86_64_RELOC_UNSIGNED*2 + 1:
case 512 + MACHO_X86_64_RELOC_SIGNED*2 + 1:
case 512 + MACHO_X86_64_RELOC_SIGNED_1*2 + 1:
case 512 + MACHO_X86_64_RELOC_SIGNED_2*2 + 1:
case 512 + MACHO_X86_64_RELOC_SIGNED_4*2 + 1:
r->type = D_PCREL;
if(targ->dynimpname)
diag("unexpected pc-relative reloc for dynamic symbol %s", targ->name);
return;
case 512 + MACHO_X86_64_RELOC_GOT_LOAD*2 + 1:
case 512 + MACHO_X86_64_RELOC_GOT*2 + 1:
// TODO: What is the difference between these two?
addgotsym(targ);
r->type = D_PCREL;
r->sym = lookup(".got", 0);
r->add += targ->got;
return;
}
// Handle references to ELF symbols from our own object files.
if(targ->dynimpname == nil)
return;
switch(r->type) {
case D_PCREL:
addpltsym(targ);
r->sym = lookup(".plt", 0);
r->add = targ->plt;
return;
case D_ADDR:
if(s->type != SDATA)
break;
if(iself) {
adddynsym(targ);
rela = lookup(".rela", 0);
addaddrplus(rela, s, r->off);
if(r->siz == 8)
adduint64(rela, ELF64_R_INFO(targ->dynid, R_X86_64_64));
else
adduint64(rela, ELF64_R_INFO(targ->dynid, R_X86_64_32));
adduint64(rela, r->add);
r->type = 256; // ignore during relocsym
return;
}
if(HEADTYPE == 6 && s->size == PtrSize && r->off == 0) {
// Mach-O relocations are a royal pain to lay out.
// They use a compact stateful bytecode representation
// that is too much bother to deal with.
// Instead, interpret the C declaration
// void *_Cvar_stderr = &stderr;
// as making _Cvar_stderr the name of a GOT entry
// for stderr. This is separate from the usual GOT entry,
// just in case the C code assigns to the variable,
// and of course it only works for single pointers,
// but we only need to support cgo and that's all it needs.
adddynsym(targ);
got = lookup(".got", 0);
s->type = got->type | SSUB;
s->outer = got;
s->sub = got->sub;
got->sub = s;
s->value = got->size;
adduint64(got, 0);
adduint32(lookup(".linkedit.got", 0), targ->dynid);
r->type = 256; // ignore during relocsym
return;
}
break;
}
cursym = s;
diag("unsupported relocation for dynamic symbol %s (type=%d stype=%d)", targ->name, r->type, targ->type);
}
int
archreloc(Reloc *r, Sym *s, vlong *val)
{
return -1;
}
static void
elfsetupplt(void)
{
Sym *plt, *got;
plt = lookup(".plt", 0);
got = lookup(".got.plt", 0);
if(plt->size == 0) {
// pushq got+8(IP)
adduint8(plt, 0xff);
adduint8(plt, 0x35);
addpcrelplus(plt, got, 8);
// jmpq got+16(IP)
adduint8(plt, 0xff);
adduint8(plt, 0x25);
addpcrelplus(plt, got, 16);
// nopl 0(AX)
adduint32(plt, 0x00401f0f);
// assume got->size == 0 too
addaddrplus(got, lookup(".dynamic", 0), 0);
adduint64(got, 0);
adduint64(got, 0);
}
}
static void
addpltsym(Sym *s)
{
if(s->plt >= 0)
return;
adddynsym(s);
if(iself) {
Sym *plt, *got, *rela;
plt = lookup(".plt", 0);
got = lookup(".got.plt", 0);
rela = lookup(".rela.plt", 0);
if(plt->size == 0)
elfsetupplt();
// jmpq *got+size(IP)
adduint8(plt, 0xff);
adduint8(plt, 0x25);
addpcrelplus(plt, got, got->size);
// add to got: pointer to current pos in plt
addaddrplus(got, plt, plt->size);
// pushq $x
adduint8(plt, 0x68);
adduint32(plt, (got->size-24-8)/8);
// jmpq .plt
adduint8(plt, 0xe9);
adduint32(plt, -(plt->size+4));
// rela
addaddrplus(rela, got, got->size-8);
adduint64(rela, ELF64_R_INFO(s->dynid, R_X86_64_JMP_SLOT));
adduint64(rela, 0);
s->plt = plt->size - 16;
} else if(HEADTYPE == 6) { // Mach-O
// To do lazy symbol lookup right, we're supposed
// to tell the dynamic loader which library each
// symbol comes from and format the link info
// section just so. I'm too lazy (ha!) to do that
// so for now we'll just use non-lazy pointers,
// which don't need to be told which library to use.
//
// http://networkpx.blogspot.com/2009/09/about-lcdyldinfoonly-command.html
// has details about what we're avoiding.
Sym *plt;
addgotsym(s);
plt = lookup(".plt", 0);
adduint32(lookup(".linkedit.plt", 0), s->dynid);
// jmpq *got+size(IP)
s->plt = plt->size;
adduint8(plt, 0xff);
adduint8(plt, 0x25);
addpcrelplus(plt, lookup(".got", 0), s->got);
} else {
diag("addpltsym: unsupported binary format");
}
}
static void
addgotsym(Sym *s)
{
Sym *got, *rela, *indir;
if(s->got >= 0)
return;
adddynsym(s);
got = lookup(".got", 0);
s->got = got->size;
adduint64(got, 0);
if(iself) {
rela = lookup(".rela", 0);
addaddrplus(rela, got, s->got);
adduint64(rela, ELF64_R_INFO(s->dynid, R_X86_64_GLOB_DAT));
adduint64(rela, 0);
} else if(HEADTYPE == 6) { // Mach-O
adduint32(lookup(".linkedit.got", 0), s->dynid);
} else {
diag("addgotsym: unsupported binary format");
}
}
static void
adddynsym(Sym *s)
{
Sym *d, *str;
int t;
char *name;
if(s->dynid >= 0)
return;
if(iself) {
s->dynid = nelfsym++;
d = lookup(".dynsym", 0);
name = s->dynimpname;
if(name == nil)
name = s->name;
adduint32(d, addstring(lookup(".dynstr", 0), name));
/* type */
t = STB_GLOBAL << 4;
if(s->dynexport && s->type == STEXT)
t |= STT_FUNC;
else
t |= STT_OBJECT;
adduint8(d, t);
/* reserved */
adduint8(d, 0);
/* section where symbol is defined */
if(!s->dynexport && s->dynimpname != nil)
adduint16(d, SHN_UNDEF);
else {
switch(s->type) {
default:
case STEXT:
t = 11;
break;
case SRODATA:
t = 12;
break;
case SDATA:
t = 13;
break;
case SBSS:
t = 14;
break;
}
adduint16(d, t);
}
/* value */
if(s->type == SDYNIMPORT)
adduint64(d, 0);
else
addaddr(d, s);
/* size of object */
adduint64(d, 0);
if(!s->dynexport && s->dynimplib && needlib(s->dynimplib)) {
elfwritedynent(lookup(".dynamic", 0), DT_NEEDED,
addstring(lookup(".dynstr", 0), s->dynimplib));
}
} else if(HEADTYPE == 6) {
// Mach-o symbol nlist64
d = lookup(".dynsym", 0);
name = s->dynimpname;
if(name == nil)
name = s->name;
s->dynid = d->size/16;
// darwin still puts _ prefixes on all C symbols
str = lookup(".dynstr", 0);
adduint32(d, str->size);
adduint8(str, '_');
addstring(str, name);
adduint8(d, 0x01); // type - N_EXT - external symbol
adduint8(d, 0); // section
adduint16(d, 0); // desc
adduint64(d, 0); // value
} else {
diag("adddynsym: unsupported binary format");
}
}
void
adddynlib(char *lib)
{
Sym *s;
if(!needlib(lib))
return;
if(iself) {
s = lookup(".dynstr", 0);
if(s->size == 0)
addstring(s, "");
elfwritedynent(lookup(".dynamic", 0), DT_NEEDED, addstring(s, lib));
} else if(HEADTYPE == 6) { // Mach-O
machoadddynlib(lib);
} else {
diag("adddynlib: unsupported binary format");
}
}
void
doelf(void)
{
Sym *s, *shstrtab, *dynamic, *dynstr, *d;
int h, nsym, t;
Sym *s, *shstrtab, *dynstr;
if(HEADTYPE != 7 && HEADTYPE != 9)
return;
@ -198,6 +580,8 @@ doelf(void)
elfstr[ElfStrDynsym] = addstring(shstrtab, ".dynsym");
elfstr[ElfStrDynstr] = addstring(shstrtab, ".dynstr");
elfstr[ElfStrRela] = addstring(shstrtab, ".rela");
elfstr[ElfStrRelaPlt] = addstring(shstrtab, ".rela.plt");
elfstr[ElfStrPlt] = addstring(shstrtab, ".plt");
/* dynamic symbol table - first entry all zeros */
s = lookup(".dynsym", 0);
@ -209,6 +593,7 @@ doelf(void)
s = lookup(".dynstr", 0);
s->type = SELFDATA;
s->reachable = 1;
if(s->size == 0)
addstring(s, "");
dynstr = s;
@ -220,94 +605,35 @@ doelf(void)
/* global offset table */
s = lookup(".got", 0);
s->reachable = 1;
s->type = SELFDATA;
/* got.plt - ??? */
s = lookup(".got.plt", 0);
s->reachable = 1;
s->type = SELFDATA;
s->type = SDATA; // writable, so not SELFDATA
/* hash */
s = lookup(".hash", 0);
s->reachable = 1;
s->type = SELFDATA;
s = lookup(".got.plt", 0);
s->reachable = 1;
s->type = SDATA; // writable, not SELFDATA
s = lookup(".plt", 0);
s->reachable = 1;
s->type = SELFDATA;
elfsetupplt();
s = lookup(".rela.plt", 0);
s->reachable = 1;
s->type = SELFDATA;
/* define dynamic elf table */
s = lookup(".dynamic", 0);
s->reachable = 1;
s->type = SELFDATA;
dynamic = s;
/*
* relocation entries for dynimport symbols
*/
nsym = 1; // sym 0 is reserved
for(h=0; h<NHASH; h++) {
for(s=hash[h]; s!=S; s=s->hash) {
if(!s->reachable || (s->type != STEXT && s->type != SDATA && s->type != SBSS) || s->dynimpname == nil)
continue;
if(!s->dynexport) {
d = lookup(".rela", 0);
addaddr(d, s);
adduint64(d, ELF64_R_INFO(nsym, R_X86_64_64));
adduint64(d, 0);
}
nsym++;
d = lookup(".dynsym", 0);
adduint32(d, addstring(lookup(".dynstr", 0), s->dynimpname));
/* type */
t = STB_GLOBAL << 4;
if(s->dynexport && s->type == STEXT)
t |= STT_FUNC;
else
t |= STT_OBJECT;
adduint8(d, t);
/* reserved */
adduint8(d, 0);
/* section where symbol is defined */
if(!s->dynexport)
adduint16(d, SHN_UNDEF);
else {
switch(s->type) {
default:
case STEXT:
t = 9;
break;
case SDATA:
t = 10;
break;
case SBSS:
t = 11;
break;
}
adduint16(d, t);
}
/* value */
if(!s->dynexport)
adduint64(d, 0);
else
addaddr(d, s);
/* size of object */
adduint64(d, 0);
if(!s->dynexport && needlib(s->dynimplib))
elfwritedynent(dynamic, DT_NEEDED, addstring(dynstr, s->dynimplib));
}
}
elfdynhash(nsym);
/*
* .dynamic table
*/
s = dynamic;
elfwritedynentsym(s, DT_HASH, lookup(".hash", 0));
elfwritedynentsym(s, DT_SYMTAB, lookup(".dynsym", 0));
elfwritedynent(s, DT_SYMENT, ELF64SYMSIZE);
@ -318,6 +644,11 @@ doelf(void)
elfwritedynent(s, DT_RELAENT, ELF64RELASIZE);
if(rpath)
elfwritedynent(s, DT_RUNPATH, addstring(dynstr, rpath));
elfwritedynentsym(s, DT_PLTGOT, lookup(".got.plt", 0));
elfwritedynent(s, DT_PLTREL, DT_RELA);
elfwritedynentsymsize(s, DT_PLTRELSZ, lookup(".rela.plt", 0));
elfwritedynentsym(s, DT_JMPREL, lookup(".rela.plt", 0));
elfwritedynent(s, DT_NULL, 0);
}
}
@ -398,10 +729,10 @@ asmb(void)
case 9:
debug['8'] = 1; /* 64-bit addresses */
/* index of elf text section; needed by asmelfsym, double-checked below */
/* !debug['d'] causes 8 extra sections before the .text section */
/* !debug['d'] causes extra sections before the .text section */
elftextsh = 1;
if(!debug['d'])
elftextsh += 8;
elftextsh += 10;
break;
}
@ -579,6 +910,22 @@ asmb(void)
sh->addralign = 1;
shsym(sh, lookup(".dynstr", 0));
sh = newElfShdr(elfstr[ElfStrRelaPlt]);
sh->type = SHT_RELA;
sh->flags = SHF_ALLOC;
sh->entsize = ELF64RELASIZE;
sh->addralign = 8;
sh->link = dynsym;
sh->info = eh->shnum; // .plt
shsym(sh, lookup(".rela.plt", 0));
sh = newElfShdr(elfstr[ElfStrPlt]);
sh->type = SHT_PROGBITS;
sh->flags = SHF_ALLOC+SHF_EXECINSTR;
sh->entsize = 16;
sh->addralign = 4;
shsym(sh, lookup(".plt", 0));
sh = newElfShdr(elfstr[ElfStrHash]);
sh->type = SHT_HASH;
sh->flags = SHF_ALLOC;
@ -744,12 +1091,12 @@ genasmsym(void (*put)(Sym*, char*, int, vlong, vlong, int, Sym*))
for(h=0; h<NHASH; h++) {
for(s=hash[h]; s!=S; s=s->hash) {
switch(s->type) {
switch(s->type&~SSUB) {
case SCONST:
case SRODATA:
case SDATA:
case SELFDATA:
case SMACHO:
case SMACHOGOT:
if(!s->reachable)
continue;
put(s, s->name, 'D', symaddr(s), s->size, s->version, s->gotype);
@ -769,6 +1116,9 @@ genasmsym(void (*put)(Sym*, char*, int, vlong, vlong, int, Sym*))
}
for(s = textp; s != nil; s = s->next) {
if(s->text == nil)
continue;
/* filenames first */
for(a=s->autom; a; a=a->link)
if(a->type == D_FILE)
@ -777,7 +1127,7 @@ genasmsym(void (*put)(Sym*, char*, int, vlong, vlong, int, Sym*))
if(a->type == D_FILE1)
put(nil, a->asym->name, 'Z', a->aoffset, 0, 0, 0);
put(s, s->name, 'T', 0, s->size, s->version, s->gotype);
put(s, s->name, 'T', s->value, s->size, s->version, s->gotype);
/* frame, auto and param after */
put(nil, ".frame", 'm', s->text->to.offset+8, 0, 0, 0);

14
src/cmd/6l/l.h
View File

@ -84,7 +84,7 @@ struct Reloc
{
int32 off;
uchar siz;
uchar type;
int32 type;
int64 add;
Sym* sym;
};
@ -128,10 +128,14 @@ struct Sym
uchar reachable;
uchar dynexport;
uchar special;
int32 dynid;
int32 sig;
int32 plt;
int32 got;
Sym* hash; // in hash table
Sym* next; // in text or data list
Sym* sub; // in SSUB list
Sym* outer; // container of sub
vlong value;
vlong size;
Sym* gotype;
@ -174,14 +178,20 @@ enum
/* order here is order in output file */
STEXT = 1,
SELFDATA,
SMACHOPLT,
SRODATA,
SDATA,
SMACHO,
SMACHOGOT,
SBSS,
SXREF,
SMACHODYNSTR,
SMACHODYNSYM,
SMACHOINDIRECTPLT,
SMACHOINDIRECTGOT,
SFILE,
SCONST,
SDYNIMPORT,
SSUB = 1<<8,
NHASH = 10007,

2
src/cmd/8l/8.out.h
View File

@ -500,6 +500,8 @@ enum
D_CONST2 = D_INDIR+D_INDIR,
D_SIZE, /* 8l internal */
D_PCREL,
D_GOTOFF,
D_GOTPCREL,
T_TYPE = 1<<0,
T_INDEX = 1<<1,

2
src/cmd/8l/Makefile
View File

@ -14,6 +14,8 @@ OFILES=\
elf.$O\
enam.$O\
go.$O\
ldelf.$O\
ldmacho.$O\
lib.$O\
list.$O\
macho.$O\

504
src/cmd/8l/asm.c
View File

@ -126,6 +126,10 @@ enum {
ElfStrGosymtab,
ElfStrGopclntab,
ElfStrShstrtab,
ElfStrSymtab,
ElfStrStrtab,
ElfStrRelPlt,
ElfStrPlt,
NElfStr
};
@ -147,11 +151,380 @@ needlib(char *name)
return 0;
}
int nelfsym = 1;
static void adddynsym(Sym*);
static void addpltsym(Sym*);
static void addgotsym(Sym*);
void
adddynrel(Sym *s, Reloc *r)
{
Sym *targ, *rel, *got;
targ = r->sym;
cursym = s;
switch(r->type) {
default:
if(r->type >= 256) {
diag("unexpected relocation type %d", r->type);
return;
}
break;
// Handle relocations found in ELF object files.
case 256 + R_386_PC32:
if(targ->dynimpname)
diag("unexpected R_386_PC32 relocation for dynamic symbol %s", targ->name);
if(targ->type == 0 || targ->type == SXREF)
diag("unknown symbol %s in pcrel", targ->name);
r->type = D_PCREL;
r->add += 4;
return;
case 256 + R_386_PLT32:
addpltsym(targ);
r->type = D_PCREL;
r->sym = lookup(".plt", 0);
r->add += 4;
r->add += targ->plt;
return;
case 256 + R_386_GOT32:
addgotsym(targ);
r->type = D_CONST; // write r->add during relocsym
r->sym = S;
r->add += targ->got;
return;
case 256 + R_386_GOTOFF:
r->type = D_GOTOFF;
return;
case 256 + R_386_GOTPC:
r->type = D_PCREL;
r->sym = lookup(".got", 0);
r->add += 4;
return;
case 256 + R_386_32:
if(targ->dynimpname)
diag("unexpected R_386_32 relocation for dynamic symbol %s", targ->name);
r->type = D_ADDR;
return;
case 512 + MACHO_GENERIC_RELOC_VANILLA*2 + 0:
r->type = D_ADDR;
if(targ->dynimpname)
diag("unexpected reloc for dynamic symbol %s", targ->name);
return;
case 512 + MACHO_GENERIC_RELOC_VANILLA*2 + 1:
if(targ->dynimpname) {
addpltsym(targ);
r->sym = lookup(".plt", 0);
r->add = targ->plt;
r->type = D_PCREL;
return;
}
r->type = D_PCREL;
if(targ->dynimpname)
diag("unexpected pc-relative reloc for dynamic symbol %s", targ->name);
return;
case 512 + MACHO_FAKE_GOTPCREL:
addgotsym(targ);
r->sym = lookup(".got", 0);
r->add += targ->got;
r->type = D_PCREL;
return;
}
// Handle references to ELF symbols from our own object files.
if(targ->dynimpname == nil)
return;
switch(r->type) {
case D_PCREL:
addpltsym(targ);
r->sym = lookup(".plt", 0);
r->add = targ->plt;
return;
case D_ADDR:
if(s->type != SDATA)
break;
if(iself) {
adddynsym(targ);
rel = lookup(".rel", 0);
addaddrplus(rel, s, r->off);
adduint32(rel, ELF32_R_INFO(targ->dynid, R_386_32));
r->type = D_CONST; // write r->add during relocsym
r->sym = S;
return;
}
if(HEADTYPE == 6 && s->size == PtrSize && r->off == 0) {
// Mach-O relocations are a royal pain to lay out.
// They use a compact stateful bytecode representation
// that is too much bother to deal with.
// Instead, interpret the C declaration
// void *_Cvar_stderr = &stderr;
// as making _Cvar_stderr the name of a GOT entry
// for stderr. This is separate from the usual GOT entry,
// just in case the C code assigns to the variable,
// and of course it only works for single pointers,
// but we only need to support cgo and that's all it needs.
adddynsym(targ);
got = lookup(".got", 0);
s->type = got->type | SSUB;
s->outer = got;
s->sub = got->sub;
got->sub = s;
s->value = got->size;
adduint32(got, 0);
adduint32(lookup(".linkedit.got", 0), targ->dynid);
r->type = 256; // ignore during relocsym
return;
}
break;
}
cursym = s;
diag("unsupported relocation for dynamic symbol %s (type=%d stype=%d)", targ->name, r->type, targ->type);
}
static void
elfsetupplt(void)
{
Sym *plt, *got;
plt = lookup(".plt", 0);
got = lookup(".got.plt", 0);
if(plt->size == 0) {
// pushl got+4
adduint8(plt, 0xff);
adduint8(plt, 0x35);
addaddrplus(plt, got, 4);
// jmp *got+8
adduint8(plt, 0xff);
adduint8(plt, 0x25);
addaddrplus(plt, got, 8);
// zero pad
adduint32(plt, 0);
// assume got->size == 0 too
addaddrplus(got, lookup(".dynamic", 0), 0);
adduint32(got, 0);
adduint32(got, 0);
}
}
int
archreloc(Reloc *r, Sym *s, vlong *val)
{
switch(r->type) {
case D_CONST:
*val = r->add;
return 0;
case D_GOTOFF:
*val = symaddr(r->sym) + r->add - symaddr(lookup(".got", 0));
return 0;
}
return -1;
}
static void
addpltsym(Sym *s)
{
Sym *plt, *got, *rel;
if(s->plt >= 0)
return;
adddynsym(s);
if(iself) {
plt = lookup(".plt", 0);
got = lookup(".got.plt", 0);
rel = lookup(".rel.plt", 0);
if(plt->size == 0)
elfsetupplt();
// jmpq *got+size
adduint8(plt, 0xff);
adduint8(plt, 0x25);
addaddrplus(plt, got, got->size);
// add to got: pointer to current pos in plt
addaddrplus(got, plt, plt->size);
// pushl $x
adduint8(plt, 0x68);
adduint32(plt, rel->size);
// jmp .plt
adduint8(plt, 0xe9);
adduint32(plt, -(plt->size+4));
// rel
addaddrplus(rel, got, got->size-4);
adduint32(rel, ELF32_R_INFO(s->dynid, R_386_JMP_SLOT));
s->plt = plt->size - 16;
} else if(HEADTYPE == 6) { // Mach-O
// Same laziness as in 6l.
Sym *plt;
plt = lookup(".plt", 0);
addgotsym(s);
adduint32(lookup(".linkedit.plt", 0), s->dynid);
// jmpq *got+size(IP)
s->plt = plt->size;
adduint8(plt, 0xff);
adduint8(plt, 0x25);
addaddrplus(plt, lookup(".got", 0), s->got);
} else {
diag("addpltsym: unsupported binary format");
}
}
static void
addgotsym(Sym *s)
{
Sym *got, *rel;
if(s->got >= 0)
return;
adddynsym(s);
got = lookup(".got", 0);
s->got = got->size;
adduint32(got, 0);
if(iself) {
rel = lookup(".rel", 0);
addaddrplus(rel, got, s->got);
adduint32(rel, ELF32_R_INFO(s->dynid, R_386_GLOB_DAT));
} else if(HEADTYPE == 6) { // Mach-O
adduint32(lookup(".linkedit.got", 0), s->dynid);
} else {
diag("addgotsym: unsupported binary format");
}
}
static void
adddynsym(Sym *s)
{
Sym *d, *str;
int t;
char *name;
if(s->dynid >= 0)
return;
if(iself) {
s->dynid = nelfsym++;
d = lookup(".dynsym", 0);
/* name */
name = s->dynimpname;
if(name == nil)
name = s->name;
adduint32(d, addstring(lookup(".dynstr", 0), name));
/* value */
if(s->type == SDYNIMPORT)
adduint32(d, 0);
else
addaddr(d, s);
/* size */
adduint32(d, 0);
/* type */
t = STB_GLOBAL << 4;
if(s->dynexport && s->type == STEXT)
t |= STT_FUNC;
else
t |= STT_OBJECT;
adduint8(d, t);
adduint8(d, 0);
/* shndx */
if(!s->dynexport && s->dynimpname != nil)
adduint16(d, SHN_UNDEF);
else {
switch(s->type) {
default:
case STEXT:
t = 11;
break;
case SRODATA:
t = 12;
break;
case SDATA:
t = 13;
break;
case SBSS:
t = 14;
break;
}
adduint16(d, t);
}
} else if(HEADTYPE == 6) {
// Mach-O symbol nlist32
d = lookup(".dynsym", 0);
name = s->dynimpname;
if(name == nil)
name = s->name;
s->dynid = d->size/12;
// darwin still puts _ prefixes on all C symbols
str = lookup(".dynstr", 0);
adduint32(d, str->size);
adduint8(str, '_');
addstring(str, name);
adduint8(d, 0x01); // type - N_EXT - external symbol
adduint8(d, 0); // section
adduint16(d, 0); // desc
adduint32(d, 0); // value
} else {
diag("adddynsym: unsupported binary format");
}
}
void
adddynlib(char *lib)
{
Sym *s;
if(!needlib(lib))
return;
if(iself) {
s = lookup(".dynstr", 0);
if(s->size == 0)
addstring(s, "");
elfwritedynent(lookup(".dynamic", 0), DT_NEEDED, addstring(s, lib));
} else if(HEADTYPE == 6) { // Mach-O
machoadddynlib(lib);
} else {
diag("adddynlib: unsupported binary format");
}
}
void
doelf(void)
{
Sym *s, *shstrtab, *dynamic, *dynstr, *d;
int h, nsym, t;
Sym *s, *shstrtab, *dynstr;
if(!iself)
return;
@ -186,6 +559,8 @@ doelf(void)
elfstr[ElfStrDynsym] = addstring(shstrtab, ".dynsym");
elfstr[ElfStrDynstr] = addstring(shstrtab, ".dynstr");
elfstr[ElfStrRel] = addstring(shstrtab, ".rel");
elfstr[ElfStrRelPlt] = addstring(shstrtab, ".rel.plt");
elfstr[ElfStrPlt] = addstring(shstrtab, ".plt");
/* interpreter string */
s = lookup(".interp", 0);
@ -202,6 +577,7 @@ doelf(void)
s = lookup(".dynstr", 0);
s->reachable = 1;
s->type = SELFDATA;
if(s->size == 0)
addstring(s, "");
dynstr = s;
@ -213,88 +589,36 @@ doelf(void)
/* global offset table */
s = lookup(".got", 0);
s->reachable = 1;
s->type = SELFDATA;
s->type = SDATA; // writable, so not SELFDATA
/* got.plt - ??? */
s = lookup(".got.plt", 0);
/* hash */
s = lookup(".hash", 0);
s->reachable = 1;
s->type = SELFDATA;
/* got.plt */
s = lookup(".got.plt", 0);
s->reachable = 1;
s->type = SDATA; // writable, so not SELFDATA
s = lookup(".plt", 0);
s->reachable = 1;
s->type = SELFDATA;
s = lookup(".rel.plt", 0);
s->reachable = 1;
s->type = SELFDATA;
elfsetupplt();
/* define dynamic elf table */
s = lookup(".dynamic", 0);
s->reachable = 1;
s->type = SELFDATA;
dynamic = s;
/*
* relocation entries for dynimport symbols
*/
nsym = 1; // sym 0 is reserved
for(h=0; h<NHASH; h++) {
for(s=hash[h]; s!=S; s=s->hash) {
if(!s->reachable || (s->type != STEXT && s->type != SDATA && s->type != SBSS) || s->dynimpname == nil)
continue;
if(!s->dynexport) {
d = lookup(".rel", 0);
addaddr(d, s);
adduint32(d, ELF32_R_INFO(nsym, R_386_32));
}
nsym++;
d = lookup(".dynsym", 0);
adduint32(d, addstring(lookup(".dynstr", 0), s->dynimpname));
/* value */
if(!s->dynexport)
adduint32(d, 0);
else
addaddr(d, s);
/* size of object */
adduint32(d, 0);
/* type */
t = STB_GLOBAL << 4;
if(s->dynexport && s->type == STEXT)
t |= STT_FUNC;
else
t |= STT_OBJECT;
adduint8(d, t);
/* reserved */
adduint8(d, 0);
/* section where symbol is defined */
if(!s->dynexport)
adduint16(d, SHN_UNDEF);
else {
switch(s->type) {
default:
case STEXT:
t = 9;
break;
case SDATA:
t = 10;
break;
case SBSS:
t = 11;
break;
}
adduint16(d, t);
}
if(!s->dynexport && needlib(s->dynimplib))
elfwritedynent(dynamic, DT_NEEDED, addstring(dynstr, s->dynimplib));
}
}
elfdynhash(nsym);
/*
* .dynamic table
*/
s = dynamic;
elfwritedynentsym(s, DT_HASH, lookup(".hash", 0));
elfwritedynentsym(s, DT_SYMTAB, lookup(".dynsym", 0));
elfwritedynent(s, DT_SYMENT, ELF32SYMSIZE);
@ -305,6 +629,10 @@ doelf(void)
elfwritedynent(s, DT_RELENT, ELF32RELSIZE);
if(rpath)
elfwritedynent(s, DT_RUNPATH, addstring(dynstr, rpath));
elfwritedynentsym(s, DT_PLTGOT, lookup(".got.plt", 0));
elfwritedynent(s, DT_PLTREL, DT_REL);
elfwritedynentsymsize(s, DT_PLTRELSZ, lookup(".rel.plt", 0));
elfwritedynentsym(s, DT_JMPREL, lookup(".rel.plt", 0));
elfwritedynent(s, DT_NULL, 0);
}
}
@ -365,6 +693,14 @@ asmb(void)
if(HEADTYPE == 6)
machlink = domacholink();
if(iself) {
/* index of elf text section; needed by asmelfsym, double-checked below */
/* !debug['d'] causes extra sections before the .text section */
elftextsh = 1;
if(!debug['d'])
elftextsh += 10;
}
symsize = 0;
spsize = 0;
lcsize = 0;
@ -636,6 +972,22 @@ asmb(void)
sh->addralign = 1;
shsym(sh, lookup(".dynstr", 0));
sh = newElfShdr(elfstr[ElfStrRelPlt]);
sh->type = SHT_REL;
sh->flags = SHF_ALLOC;
sh->entsize = ELF32RELSIZE;
sh->addralign = 4;
sh->link = dynsym;
sh->info = eh->shnum; // .plt
shsym(sh, lookup(".rel.plt", 0));
sh = newElfShdr(elfstr[ElfStrPlt]);
sh->type = SHT_PROGBITS;
sh->flags = SHF_ALLOC+SHF_EXECINSTR;
sh->entsize = 4;
sh->addralign = 4;
shsym(sh, lookup(".plt", 0));
sh = newElfShdr(elfstr[ElfStrHash]);
sh->type = SHT_HASH;
sh->flags = SHF_ALLOC;
@ -682,6 +1034,8 @@ asmb(void)
ph->flags = PF_W+PF_R;
ph->align = 4;
if(elftextsh != eh->shnum)
diag("elftextsh = %d, want %d", elftextsh, eh->shnum);
for(sect=segtext.sect; sect!=nil; sect=sect->next)
elfshbits(sect);
for(sect=segrodata.sect; sect!=nil; sect=sect->next)
@ -814,12 +1168,13 @@ genasmsym(void (*put)(Sym*, char*, int, vlong, vlong, int, Sym*))
for(h=0; h<NHASH; h++) {
for(s=hash[h]; s!=S; s=s->hash) {
switch(s->type) {
switch(s->type&~SSUB) {
case SCONST:
case SRODATA:
case SDATA:
case SELFDATA:
case SMACHO:
case SMACHOGOT:
case SWINDOWS:
if(!s->reachable)
continue;
@ -840,6 +1195,9 @@ genasmsym(void (*put)(Sym*, char*, int, vlong, vlong, int, Sym*))
}
for(s = textp; s != nil; s = s->next) {
if(s->text == nil)
continue;
/* filenames first */
for(a=s->autom; a; a=a->link)
if(a->type == D_FILE)

15
src/cmd/8l/l.h
View File

@ -84,7 +84,7 @@ struct Reloc
{
int32 off;
uchar siz;
uchar type;
int32 type;
int32 add;
Sym* sym;
};
@ -130,9 +130,13 @@ struct Sym
int32 value;
int32 size;
int32 sig;
int32 dynid;
int32 plt;
int32 got;
Sym* hash; // in hash table
Sym* next; // in text or data list
Sym* sub; // in sub list
Sym* outer; // container of sub
Sym* gotype;
char* file;
char* dynimpname;
@ -165,15 +169,22 @@ enum
/* order here is order in output file */
STEXT,
SELFDATA,
SMACHOPLT,
SRODATA,
SDATA,
SMACHO, /* Mach-O __nl_symbol_ptr */
SMACHOGOT,
SWINDOWS,
SBSS,
SXREF,
SMACHODYNSTR,
SMACHODYNSYM,
SMACHOINDIRECTPLT,
SMACHOINDIRECTGOT,
SFILE,
SCONST,
SDYNIMPORT,
SSUB = 1<<8, /* sub-symbol, linked from parent via ->sub list */
@ -317,7 +328,7 @@ EXTERN int dtype;
EXTERN int tlsoffset;
EXTERN Sym* adrgotype; // type symbol on last Adr read
EXTERN Sym* fromgotype; // type symbol on last p->from read
EXTERN int elftextsh;
extern Optab optab[];
extern char* anames[];

154
src/cmd/ld/data.c
View File

@ -35,6 +35,8 @@
#include "../ld/elf.h"
#include "../ld/pe.h"
void dynreloc(void);
/*
* divide-and-conquer list-link
* sort of Sym* structures.
@ -147,27 +149,49 @@ relocsym(Sym *s)
vlong o;
uchar *cast;
cursym = s;
memset(&p, 0, sizeof p);
for(r=s->r; r<s->r+s->nr; r++) {
off = r->off;
siz = r->siz;
if(off < 0 || off+(siz&~Rbig) > s->np) {
diag("%s: invalid relocation %d+%d not in [%d,%d)", s->name, off, siz&~Rbig, 0, s->np);
continue;
}
if(r->sym != S && (r->sym->type == 0 || r->sym->type == SXREF)) {
diag("%s: not defined", r->sym->name);
continue;
}
if(r->type >= 256)
continue;
if(r->sym != S && (r->sym->type == SDYNIMPORT || r->sym->dynimpname != nil))
diag("unhandled relocation for %s (rtype %d)", r->sym->name, r->type);
if(r->sym != S && !r->sym->reachable)
diag("unreachable sym in relocation: %s %s", s->name, r->sym->name);
switch(r->type) {
default:
o = 0;
if(archreloc(r, s, &o) < 0)
diag("unknown reloc %d", r->type);
break;
case D_ADDR:
o = symaddr(r->sym);
o = symaddr(r->sym) + r->add;
break;
case D_PCREL:
o = symaddr(r->sym) - (s->value + r->off + r->siz);
o = symaddr(r->sym) + r->add - (s->value + r->off + r->siz);
break;
case D_SIZE:
o = r->sym->size;
o = r->sym->size + r->add;
break;
}
o += r->add;
//print("relocate %s %p %s => %p %p %p %p [%p]\n", s->name, s->value+off, r->sym ? r->sym->name : "<nil>", (void*)symaddr(r->sym), (void*)s->value, (void*)r->off, (void*)r->siz, (void*)o);
switch(siz) {
default:
diag("bad reloc size %#ux", siz);
cursym = s;
diag("bad reloc size %#ux for %s", siz, r->sym->name);
case 4 + Rbig:
fl = o;
s->p[off] = fl>>24;
@ -212,6 +236,33 @@ reloc(void)
relocsym(s);
}
void
dynrelocsym(Sym *s)
{
Reloc *r;
for(r=s->r; r<s->r+s->nr; r++)
if(r->sym->type == SDYNIMPORT || r->type >= 256)
adddynrel(s, r);
}
void
dynreloc(void)
{
Sym *s;
if(debug['v'])
Bprint(&bso, "%5.2f reloc\n", cputime());
Bflush(&bso);
for(s=textp; s!=S; s=s->next)
dynrelocsym(s);
for(s=datap; s!=S; s=s->next)
dynrelocsym(s);
if(iself)
elfdynhash();
}
void
symgrow(Sym *s, int32 siz)
{
@ -324,11 +375,13 @@ blk(Sym *allsym, int32 addr, int32 size)
uchar *p, *ep;
for(sym = allsym; sym != nil; sym = sym->next)
if(sym->value >= addr)
if(!(sym->type&SSUB) && sym->value >= addr)
break;
eaddr = addr+size;
for(; sym != nil; sym = sym->next) {
if(sym->type&SSUB)
continue;
if(sym->value >= eaddr)
break;
if(sym->value < addr) {
@ -411,7 +464,7 @@ codeblk(int32 addr, int32 size)
continue;
}
Bprint(&bso, "%.6llux\t%-20s | %P\n", (vlong)addr, sym->name, p);
Bprint(&bso, "%.6llux\t%-20s | %P\n", sym->value, sym->name, p);
for(p = p->link; p != P; p = p->link) {
if(p->link != P)
epc = p->link->pc;
@ -522,6 +575,7 @@ adduintxx(Sym *s, uint64 v, int wid)
r = s->size;
s->size += wid;
symgrow(s, s->size);
assert(r+wid <= s->size);
fl = v;
cast = (uchar*)&fl;
switch(wid) {
@ -571,7 +625,7 @@ adduint64(Sym *s, uint64 v)
}
vlong
addaddr(Sym *s, Sym *t)
addaddrplus(Sym *s, Sym *t, int32 add)
{
vlong i;
Reloc *r;
@ -587,9 +641,37 @@ addaddr(Sym *s, Sym *t)
r->off = i;
r->siz = PtrSize;
r->type = D_ADDR;
r->add = add;
return i;
}
vlong
addpcrelplus(Sym *s, Sym *t, int32 add)
{
vlong i;
Reloc *r;
if(s->type == 0)
s->type = SDATA;
s->reachable = 1;
i = s->size;
s->size += 4;
symgrow(s, s->size);
r = addrel(s);
r->sym = t;
r->off = i;
r->add = add;
r->type = D_PCREL;
r->siz = 4;
return i;
}
vlong
addaddr(Sym *s, Sym *t)
{
return addaddrplus(s, t, 0);
}
vlong
addsize(Sym *s, Sym *t)
{
@ -615,7 +697,7 @@ dodata(void)
{
int32 h, t, datsize;
Section *sect;
Sym *s, *last;
Sym *s, *last, **l;
if(debug['v'])
Bprint(&bso, "%5.2f dodata\n", cputime());
@ -645,6 +727,24 @@ dodata(void)
diag("%s: initialize bounds (%lld < %d)",
s->name, s->size, s->np);
}
/*
* now that we have the datap list, but before we start
* to assign addresses, record all the necessary
* dynamic relocations. these will grow the relocation
* symbol, which is itself data.
*/
dynreloc();
/* some symbols may no longer belong in datap (Mach-O) */
for(l=&datap; (s=*l) != nil; ) {
if(s->type <= STEXT || SXREF <= s->type)
*l = s->next;
else
l = &s->next;
}
*l = nil;
datap = datsort(datap);
/*
@ -714,6 +814,40 @@ dodata(void)
sect->len = datsize - sect->vaddr;
}
// assign addresses to text
void
textaddress(void)
{
uvlong va;
Prog *p;
Section *sect;
Sym *sym, *sub;
addsection(&segtext, ".text", 05);
// Assign PCs in text segment.
// Could parallelize, by assigning to text
// and then letting threads copy down, but probably not worth it.
sect = segtext.sect;
va = INITTEXT;
sect->vaddr = va;
for(sym = textp; sym != nil; sym = sym->next) {
if(sym->type & SSUB)
continue;
sym->value = 0;
for(sub = sym; sub != S; sub = sub->sub) {
sub->value += va;
for(p = sub->text; p != P; p = p->link)
p->pc += sub->value;
}
if(sym->size == 0 && sym->sub != S) {
cursym = sym;
}
va += sym->size;
}
sect->len = va - sect->vaddr;
}
// assign addresses
void
address(void)
@ -723,7 +857,7 @@ address(void)
uvlong va;
va = INITTEXT;
segtext.rwx = 05;
segtext.rwx = 07;
segtext.vaddr = va;
segtext.fileoff = HEADR;
for(s=segtext.sect; s != nil; s=s->next) {

40
src/cmd/ld/elf.c
View File

@ -164,8 +164,7 @@ newElfPhdr(void)
{
ElfPhdr *e;
e = malloc(sizeof *e);
memset(e, 0, sizeof *e);
e = mal(sizeof *e);
if (hdr.phnum >= NSECT)
diag("too many phdrs");
else
@ -189,8 +188,7 @@ newElfShdr(vlong name)
{
ElfShdr *e;
e = malloc(sizeof *e);
memset(e, 0, sizeof *e);
e = mal(sizeof *e);
e->name = name;
if (hdr.shnum >= NSECT) {
diag("too many shdrs");
@ -332,17 +330,25 @@ elfinterp(ElfShdr *sh, uint64 startva, char *p)
sh->size = n;
}
extern int nelfsym;
void
elfdynhash(int nsym)
elfdynhash(void)
{
Sym *s, *sy;
int i, h, nbucket, b;
uchar *pc;
uint32 hc, g;
uint32 *chain, *buckets;
int nsym;
char *name;
if(!iself)
return;
nsym = nelfsym;
s = lookup(".hash", 0);
s->type = SELFDATA; // TODO: rodata
s->type = SELFDATA;
s->reachable = 1;
i = nsym;
@ -353,17 +359,24 @@ elfdynhash(int nsym)
}
chain = malloc(nsym * sizeof(uint32));
memset(chain, 0, nsym * sizeof(uint32));
buckets = malloc(nbucket * sizeof(uint32));
if(chain == nil || buckets == nil) {
cursym = nil;
diag("out of memory");
errorexit();
}
memset(chain, 0, nsym * sizeof(uint32));
memset(buckets, 0, nbucket * sizeof(uint32));
i = 1;
for(h = 0; h<NHASH; h++) {
for(sy=hash[h]; sy!=S; sy=sy->hash) {
if (!sy->reachable || (sy->type != STEXT && sy->type != SDATA && sy->type != SBSS) || sy->dynimpname == nil)
if (sy->dynid <= 0)
continue;
hc = 0;
for(pc = (uchar*)sy->dynimpname; *pc; pc++) {
name = sy->dynimpname;
if(name == nil)
name = sy->name;
for(pc = (uchar*)name; *pc; pc++) {
hc = (hc<<4) + *pc;
g = hc & 0xf0000000;
hc ^= g >> 24;
@ -371,9 +384,8 @@ elfdynhash(int nsym)
}
b = hc % nbucket;
chain[i] = buckets[b];
buckets[b] = i;
i++;
chain[sy->dynid] = buckets[b];
buckets[b] = sy->dynid;
}
}
@ -386,6 +398,8 @@ elfdynhash(int nsym)
free(chain);
free(buckets);
elfwritedynent(lookup(".dynamic", 0), DT_NULL, 0);
}
ElfPhdr*

19
src/cmd/ld/go.c
View File

@ -266,6 +266,10 @@ expandpkg(char *t0, char *pkg)
// use malloc, not mal, so that caller can free
w0 = malloc(strlen(t0) + strlen(pkg)*n);
if(w0 == nil) {
diag("out of memory");
errorexit();
}
w = w0;
for(p=t=t0; (p=strstr(p, "\"\".")) != nil; p=t) {
memmove(w, t, p - t);
@ -443,11 +447,20 @@ loaddynimport(char *file, char *pkg, char *p, int n)
*strchr(name, ' ') = 0;
*strchr(def, ' ') = 0;
name = expandpkg(name, pkg);
if(strcmp(name, "_") == 0 && strcmp(def, "_") == 0) {
// allow #pragma dynimport _ _ "foo.so"
// to force a link of foo.so.
adddynlib(lib);
continue;
}
name = expandpkg(name, pkg);
s = lookup(name, 0);
if(s->type == 0 || s->type == SXREF) {
s->dynimplib = lib;
s->dynimpname = def;
s->type = SDYNIMPORT;
}
}
return;
@ -547,6 +560,10 @@ mark(Sym *s)
mark(s->r[i].sym);
if(s->gotype)
mark(s->gotype);
if(s->sub)
mark(s->sub);
if(s->outer)
mark(s->outer);
}
static char*

94
src/cmd/ld/lib.c
View File

@ -374,32 +374,38 @@ out:
void
ldobj(Biobuf *f, char *pkg, int64 len, char *pn, int whence)
{
static int files;
static char **filen;
char **nfilen, *line;
int i, n, c1, c2, c3;
char *line;
int n, c1, c2, c3, c4;
uint32 magic;
vlong import0, import1, eof;
char src[1024];
eof = Boffset(f) + len;
src[0] = '\0';
// don't load individual object more than once.
// happens with import of .6 files because of loop in xresolv.
// doesn't happen with .a because SYMDEF is consulted
// first to decide whether each individual object file is needed.
for(i=0; i<files; i++)
if(strcmp(filen[i], pn) == 0)
return;
if((files&15) == 0){
nfilen = malloc((files+16)*sizeof(char*));
memmove(nfilen, filen, files*sizeof(char*));
free(filen);
filen = nfilen;
}
pn = strdup(pn);
filen[files++] = pn;
USED(c4);
USED(magic);
c1 = Bgetc(f);
c2 = Bgetc(f);
c3 = Bgetc(f);
c4 = Bgetc(f);
Bungetc(f);
Bungetc(f);
Bungetc(f);
Bungetc(f);
magic = c1<<24 | c2<<16 | c3<<8 | c4;
if(magic == 0x7f454c46) { // \x7F E L F
ldelf(f, pkg, len, pn);
return;
}
if((magic&~1) == 0xfeedface || (magic&~0x01000000) == 0xcefaedfe) {
ldmacho(f, pkg, len, pn);
return;
}
/* check the header */
line = Brdline(f, '\n');
@ -471,6 +477,9 @@ lookup(char *symb, int v)
if(debug['v'] > 1)
Bprint(&bso, "lookup %s\n", symb);
s->dynid = -1;
s->plt = -1;
s->got = -1;
s->name = mal(l + 1);
memmove(s->name, symb, l);
@ -766,11 +775,19 @@ mal(uint32 n)
n = (n+7)&~7;
if(n > NHUNK) {
v = malloc(n);
if(v == nil) {
diag("out of memory");
errorexit();
}
memset(v, 0, n);
return v;
}
if(n > nhunk) {
hunk = malloc(NHUNK);
if(hunk == nil) {
diag("out of memory");
errorexit();
}
nhunk = NHUNK;
}
@ -1013,3 +1030,42 @@ mkfwd(void)
}
}
}
uint16
le16(uchar *b)
{
return b[0] | b[1]<<8;
}
uint32
le32(uchar *b)
{
return b[0] | b[1]<<8 | b[2]<<16 | b[3]<<24;
}
uint64
le64(uchar *b)
{
return le32(b) | (uint64)le32(b+4)<<32;
}
uint16
be16(uchar *b)
{
return b[0]<<8 | b[1];
}
uint32
be32(uchar *b)
{
return b[0]<<24 | b[1]<<16 | b[2]<<8 | b[3];
}
uint64
be64(uchar *b)
{
return (uvlong)be32(b)<<32 | be32(b+4);
}
Endian be = { be16, be32, be64 };
Endian le = { le16, le32, le64 };

26
src/cmd/ld/lib.h
View File

@ -125,8 +125,11 @@ void pclntab(void);
void symtab(void);
void Lflag(char *arg);
void usage(void);
void adddynrel(Sym*, Reloc*);
void ldobj1(Biobuf *f, char*, int64 len, char *pn);
void ldobj(Biobuf*, char*, int64, char*, int);
void ldelf(Biobuf*, char*, int64, char*);
void ldmacho(Biobuf*, char*, int64, char*);
void ldpkg(Biobuf*, char*, int64, char*, int);
void mark(Sym *s);
void mkfwd(void);
@ -144,6 +147,8 @@ vlong addstring(Sym*, char*);
vlong adduint32(Sym*, uint32);
vlong adduint64(Sym*, uint64);
vlong addaddr(Sym*, Sym*);
vlong addaddrplus(Sym*, Sym*, int32);
vlong addpcrelplus(Sym*, Sym*, int32);
vlong addsize(Sym*, Sym*);
vlong adduint8(Sym*, uint8);
vlong adduint16(Sym*, uint16);
@ -152,13 +157,34 @@ void asmelfsym64(void);
void strnput(char*, int);
void dodata(void);
void address(void);
void textaddress(void);
void genasmsym(void (*put)(Sym*, char*, int, vlong, vlong, int, Sym*));
vlong datoff(vlong);
void adddynlib(char*);
int archreloc(Reloc*, Sym*, vlong*);
int pathchar(void);
void* mal(uint32);
void unmal(void*, uint32);
void mywhatsys(void);
int rbyoff(const void*, const void*);
uint16 le16(uchar*);
uint32 le32(uchar*);
uint64 le64(uchar*);
uint16 be16(uchar*);
uint32 be32(uchar*);
uint64 be64(uchar*);
typedef struct Endian Endian;
struct Endian
{
uint16 (*e16)(uchar*);
uint32 (*e32)(uchar*);
uint64 (*e64)(uchar*);
};
extern Endian be, le;
// relocation size bits
enum {

337
src/cmd/ld/macho.c
View File

@ -102,21 +102,12 @@ newMachoDebug(void)
// Generic linking code.
static uchar *linkdata;
static uint32 nlinkdata;
static uint32 mlinkdata;
static uchar *strtab;
static uint32 nstrtab;
static uint32 mstrtab;
struct Expsym
{
int off;
Sym* s;
} *expsym;
static int nexpsym;
static int nimpsym;
static char **dylib;
static int ndylib;
@ -199,8 +190,8 @@ machowrite(void)
LPUT(t->reloc);
LPUT(t->nreloc);
LPUT(t->flag);
LPUT(0); /* reserved */
LPUT(0); /* reserved */
LPUT(t->res1); /* reserved */
LPUT(t->res2); /* reserved */
LPUT(0); /* reserved */
} else {
strnput(t->name, 16);
@ -212,8 +203,8 @@ machowrite(void)
LPUT(t->reloc);
LPUT(t->nreloc);
LPUT(t->flag);
LPUT(0); /* reserved */
LPUT(0); /* reserved */
LPUT(t->res1); /* reserved */
LPUT(t->res2); /* reserved */
}
}
}
@ -237,147 +228,45 @@ machowrite(void)
return cpos() - o1;
}
static void*
grow(uchar **dat, uint32 *ndat, uint32 *mdat, uint32 n)
{
uchar *p;
uint32 old;
if(*ndat+n > *mdat) {
old = *mdat;
*mdat = (*ndat+n)*2 + 128;
*dat = realloc(*dat, *mdat);
if(*dat == 0) {
diag("out of memory");
errorexit();
}
memset(*dat+old, 0, *mdat-old);
}
p = *dat + *ndat;
*ndat += n;
return p;
}
static int
needlib(char *name)
{
char *p;
Sym *s;
/* reuse hash code in symbol table */
p = smprint(".machoload.%s", name);
s = lookup(p, 0);
if(s->type == 0) {
s->type = 100; // avoid SDATA, etc.
return 1;
}
return 0;
}
void
domacho(void)
{
int h, ptrsize, t;
char *p;
uchar *dat;
uint32 x;
Sym *s, *smacho;
Sym **impsym;
Sym *s;
ptrsize = 4;
if(macho64)
ptrsize = 8;
if(debug['d'])
return;
// empirically, string table must begin with " \x00".
if(!debug['d'])
*(char*)grow(&strtab, &nstrtab, &mstrtab, 2) = ' ';
s = lookup(".dynstr", 0);
s->type = SMACHODYNSTR;
s->reachable = 1;
adduint8(s, ' ');
adduint8(s, '\0');
impsym = nil;
for(h=0; h<NHASH; h++) {
for(s=hash[h]; s!=S; s=s->hash) {
if(!s->reachable || (s->type != STEXT && s->type != SDATA && s->type != SBSS) || s->dynimpname == nil)
continue;
if(debug['d']) {
diag("cannot use dynamic loading and -d");
errorexit();
}
if(!s->dynexport) {
if(nimpsym%32 == 0) {
impsym = realloc(impsym, (nimpsym+32)*sizeof impsym[0]);
if(impsym == nil) {
diag("out of memory");
errorexit();
}
}
impsym[nimpsym++] = s;
continue;
}
/* symbol table entry - darwin still puts _ prefixes on all C symbols */
x = nstrtab;
p = grow(&strtab, &nstrtab, &mstrtab, 1+strlen(s->dynimpname)+1);
*p++ = '_';
strcpy(p, s->dynimpname);
dat = grow(&linkdata, &nlinkdata, &mlinkdata, 8+ptrsize);
dat[0] = x;
dat[1] = x>>8;
dat[2] = x>>16;
dat[3] = x>>24;
dat[4] = 0x0f; // type: N_SECT | N_EXT - external, defined in sect
switch(s->type) {
default:
case STEXT:
t = 1;
break;
case SDATA:
t = 2;
break;
case SBSS:
t = 4;
break;
}
dat[5] = t; // sect: section number
if (nexpsym%32 == 0) {
expsym = realloc(expsym, (nexpsym+32)*sizeof expsym[0]);
if (expsym == nil) {
diag("out of memory");
errorexit();
}
}
expsym[nexpsym].off = nlinkdata - ptrsize;
expsym[nexpsym++].s = s;
}
}
smacho = lookup("__nl_symbol_ptr", 0);
smacho->type = SMACHO;
smacho->reachable = 1;
for(h=0; h<nimpsym; h++) {
s = impsym[h];
s->type = SMACHO | SSUB;
s->sub = smacho->sub;
smacho->sub = s;
s->value = (nexpsym+h) * ptrsize;
s = lookup(".dynsym", 0);
s->type = SMACHODYNSYM;
s->reachable = 1;
/* symbol table entry - darwin still puts _ prefixes on all C symbols */
x = nstrtab;
p = grow(&strtab, &nstrtab, &mstrtab, 1+strlen(s->dynimpname)+1);
*p++ = '_';
strcpy(p, s->dynimpname);
s = lookup(".plt", 0); // will be __symbol_stub
s->type = SMACHOPLT;
s->reachable = 1;
dat = grow(&linkdata, &nlinkdata, &mlinkdata, 8+ptrsize);
dat[0] = x;
dat[1] = x>>8;
dat[2] = x>>16;
dat[3] = x>>24;
s = lookup(".got", 0); // will be __nl_symbol_ptr
s->type = SMACHOGOT;
s->reachable = 1;
dat[4] = 0x01; // type: N_EXT - external symbol
s = lookup(".linkedit.plt", 0); // indirect table for .plt
s->type = SMACHOINDIRECTPLT;
s->reachable = 1;
if(needlib(s->dynimplib)) {
s = lookup(".linkedit.got", 0); // indirect table for .got
s->type = SMACHOINDIRECTGOT;
s->reachable = 1;
}
void
machoadddynlib(char *lib)
{
if(ndylib%32 == 0) {
dylib = realloc(dylib, (ndylib+32)*sizeof dylib[0]);
if(dylib == nil) {
@ -385,70 +274,7 @@ domacho(void)
errorexit();
}
}
dylib[ndylib++] = s->dynimplib;
}
}
free(impsym);
/*
* list of symbol table indexes.
* we don't take advantage of the opportunity
* to order the symbol table differently from
* this list, so it is boring: 0 1 2 3 4 ...
*/
for(x=0; x<nexpsym+nimpsym; x++) {
dat = grow(&linkdata, &nlinkdata, &mlinkdata, 4);
dat[0] = x;
dat[1] = x>>8;
dat[2] = x>>16;
dat[3] = x>>24;
}
smacho->size = (nexpsym+nimpsym) * ptrsize;
if(smacho->size == 0)
smacho->reachable = 0;
}
vlong
domacholink(void)
{
int i;
uchar *p;
Sym *s;
uint64 val;
Sym *smacho;
smacho = lookup("__nl_symbol_ptr", 0);
linkoff = 0;
if(nlinkdata > 0 || nstrtab > 0) {
linkoff = rnd(HEADR+segtext.len, INITRND) + rnd(segdata.filelen - smacho->size, INITRND);
seek(cout, linkoff, 0);
for(i = 0; i<nexpsym; ++i) {
s = expsym[i].s;
val = s->value;
if(s->type == SXREF)
diag("export of undefined symbol %s", s->name);
if (s->type != STEXT)
val += segdata.vaddr;
p = linkdata+expsym[i].off;
p[0] = val;
p[1] = val >> 8;
p[2] = val >> 16;
p[3] = val >> 24;
if (macho64) {
p[4] = val >> 32;
p[5] = val >> 40;
p[6] = val >> 48;
p[7] = val >> 56;
}
}
ewrite(cout, linkdata, nlinkdata);
ewrite(cout, strtab, nstrtab);
}
return rnd(nlinkdata+nstrtab, INITRND);
dylib[ndylib++] = lib;
}
void
@ -456,14 +282,14 @@ asmbmacho(void)
{
vlong v, w;
vlong va;
int a, i, ptrsize;
int a, i;
char *pkgroot;
MachoHdr *mh;
MachoSect *msect;
MachoSeg *ms;
MachoDebug *md;
MachoLoad *ml;
Sym *smacho;
Sym *s;
/* apple MACH */
va = INITTEXT - HEADR;
@ -475,12 +301,10 @@ asmbmacho(void)
case '6':
mh->cpu = MACHO_CPU_AMD64;
mh->subcpu = MACHO_SUBCPU_X86;
ptrsize = 8;
break;
case '8':
mh->cpu = MACHO_CPU_386;
mh->subcpu = MACHO_SUBCPU_X86;
ptrsize = 4;
break;
}
@ -490,7 +314,7 @@ asmbmacho(void)
/* text */
v = rnd(HEADR+segtext.len, INITRND);
ms = newMachoSeg("__TEXT", 1);
ms = newMachoSeg("__TEXT", 2);
ms->vaddr = va;
ms->vsize = v;
ms->filesize = v;
@ -503,10 +327,20 @@ asmbmacho(void)
msect->off = INITTEXT - va;
msect->flag = 0x400; /* flag - some instructions */
s = lookup(".plt", 0);
if(s->size > 0) {
msect = newMachoSect(ms, "__symbol_stub1");
msect->addr = symaddr(s);
msect->size = s->size;
msect->off = ms->fileoffset + msect->addr - ms->vaddr;
msect->flag = 0x80000408; /* flag */
msect->res1 = 0; /* index into indirect symbol table */
msect->res2 = 6; /* size of stubs */
}
/* data */
smacho = lookup("__nl_symbol_ptr", 0);
w = segdata.len;
ms = newMachoSeg("__DATA", 2+(smacho->size > 0));
ms = newMachoSeg("__DATA", 3);
ms->vaddr = va+v;
ms->vsize = w;
ms->fileoffset = v;
@ -516,25 +350,18 @@ asmbmacho(void)
msect = newMachoSect(ms, "__data");
msect->addr = va+v;
msect->size = segdata.filelen - smacho->size;
msect->size = symaddr(lookup(".got", 0)) - msect->addr;
msect->off = v;
if(smacho->size > 0) {
s = lookup(".got", 0);
if(s->size > 0) {
msect = newMachoSect(ms, "__nl_symbol_ptr");
msect->addr = smacho->value;
msect->size = smacho->size;
msect->addr = symaddr(s);
msect->size = s->size;
msect->off = datoff(msect->addr);
msect->align = 2;
msect->flag = 6; /* section with nonlazy symbol pointers */
/*
* The reserved1 field is supposed to be the index of
* the first entry in the list of symbol table indexes
* in isymtab for the symbols we need. We only use
* pointers, so we need the entire list, so the index
* here should be 0, which luckily is what the Mach-O
* writing code emits by default for this not really reserved field.
msect->reserved1 = 0; - first indirect symbol table entry we need
*/
msect->res1 = lookup(".linkedit.plt", 0)->size / 4; /* offset into indirect symbol table */
}
msect = newMachoSect(ms, "__bss");
@ -562,39 +389,43 @@ asmbmacho(void)
}
if(!debug['d']) {
int nsym;
Sym *s1, *s2, *s3, *s4;
nsym = smacho->size/ptrsize;
// must match domacholink below
s1 = lookup(".dynsym", 0);
s2 = lookup(".dynstr", 0);
s3 = lookup(".linkedit.plt", 0);
s4 = lookup(".linkedit.got", 0);
ms = newMachoSeg("__LINKEDIT", 0);
ms->vaddr = va+v+rnd(segdata.len, INITRND);
ms->vsize = nlinkdata+nstrtab;
ms->vsize = s1->size + s2->size + s3->size + s4->size;
ms->fileoffset = linkoff;
ms->filesize = nlinkdata+nstrtab;
ms->filesize = ms->vsize;
ms->prot1 = 7;
ms->prot2 = 3;
ml = newMachoLoad(2, 4); /* LC_SYMTAB */
ml->data[0] = linkoff; /* symoff */
ml->data[1] = nsym; /* nsyms */
ml->data[2] = linkoff + nlinkdata; /* stroff */
ml->data[3] = nstrtab; /* strsize */
ml->data[1] = s1->size / (macho64 ? 16 : 12); /* nsyms */
ml->data[2] = linkoff + s1->size; /* stroff */
ml->data[3] = s2->size; /* strsize */
ml = newMachoLoad(11, 18); /* LC_DYSYMTAB */
ml->data[0] = 0; /* ilocalsym */
ml->data[1] = 0; /* nlocalsym */
ml->data[2] = 0; /* iextdefsym */
ml->data[3] = nexpsym; /* nextdefsym */
ml->data[4] = nexpsym; /* iundefsym */
ml->data[5] = nimpsym; /* nundefsym */
ml->data[3] = 0; /* nextdefsym */ // TODO nexpsym
ml->data[4] = 0; /* iundefsym */ // TODO nexpsym
ml->data[5] = s1->size / (macho64 ? 16 : 12); /* 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 */
ml->data[12] = linkoff + nlinkdata - nsym*4; /* indirectsymoff */
ml->data[13] = nsym; /* nindirectsyms */
ml->data[12] = linkoff + s1->size + s2->size; /* indirectsymoff */
ml->data[13] = (s3->size + s4->size) / 4; /* nindirectsyms */
ml->data[14] = 0; /* extreloff */
ml->data[15] = 0; /* nextrel */
ml->data[16] = 0; /* locreloff */
@ -640,3 +471,33 @@ asmbmacho(void)
if(a > MACHORESERVE)
diag("MACHORESERVE too small: %d > %d", a, MACHORESERVE);
}
vlong
domacholink(void)
{
int size;
Sym *s1, *s2, *s3, *s4;
// write data that will be linkedit section
s1 = lookup(".dynsym", 0);
s2 = lookup(".dynstr", 0);
s3 = lookup(".linkedit.plt", 0);
s4 = lookup(".linkedit.got", 0);
while(s2->size%4)
adduint8(s2, 0);
size = s1->size + s2->size + s3->size + s4->size;
if(size > 0) {
linkoff = rnd(HEADR+segtext.len, INITRND) + rnd(segdata.filelen, INITRND);
seek(cout, linkoff, 0);
ewrite(cout, s1->p, s1->size);
ewrite(cout, s2->p, s2->size);
ewrite(cout, s3->p, s3->size);
ewrite(cout, s4->p, s4->size);
}
return rnd(size, INITRND);
}

16
src/cmd/ld/macho.h
View File

@ -18,6 +18,8 @@ struct MachoSect {
uint32 reloc;
uint32 nreloc;
uint32 flag;
uint32 res1;
uint32 res2;
};
typedef struct MachoSeg MachoSeg;
@ -70,6 +72,20 @@ enum {
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_GENERIC_RELOC_VANILLA = 0,
MACHO_FAKE_GOTPCREL = 100,
};
void domacho(void);