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cmd/9l: support internal linking

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This implements the ELF relocations and dynamic linking tables
necessary to support internal linking on ppc64.  It also marks ppc64le
ELF files as ABI v2; failing to do this doesn't seem to confuse the
loader, but it does confuse libbfd (and hence gdb, objdump, etc).

Change-Id: I559dddf89b39052e1b6288a4dd5e72693b5355e4
Reviewed-on: https://go-review.googlesource.com/2006
Reviewed-by: Russ Cox <rsc@golang.org>
This commit is contained in:
Austin Clements 2014-12-16 14:59:59 -05:00
parent ac5a1ac318
commit db923390a0
7 changed files with 651 additions and 37 deletions
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9
include/link.h
View File

@ -212,6 +212,7 @@ enum
SMACHO, /* Mach-O __nl_symbol_ptr */
SMACHOGOT,
SWINDOWS,
SELFGOT, /* also .toc in ppc64 ABI */
SNOPTRDATA,
SINITARR,
SDATA,
@ -256,12 +257,20 @@ enum
R_PLT1,
R_PLT2,
R_USEFIELD,
R_POWER_TOC, // ELF R_PPC64_TOC16*
};
// Reloc.variant
enum
{
RV_NONE, // identity variant
RV_POWER_LO, // x & 0xFFFF
RV_POWER_HI, // x >> 16
RV_POWER_HA, // (x + 0x8000) >> 16
RV_POWER_DS, // x & 0xFFFC, check x&0x3 == 0
RV_CHECK_OVERFLOW = 1<<8, // check overflow flag
RV_TYPE_MASK = (RV_CHECK_OVERFLOW - 1),
};
// Auto.type

511
src/cmd/9l/asm.c
View File

@ -36,6 +36,7 @@
#include "../ld/dwarf.h"
// TODO(austin): ABI v1 uses /usr/lib/ld.so.1
char linuxdynld[] = "/lib64/ld64.so.1";
char freebsddynld[] = "XXX";
char openbsddynld[] = "XXX";
@ -65,27 +66,264 @@ needlib(char *name)
int nelfsym = 1;
static void gencallstub(int abicase, LSym *stub, LSym *targ);
static void addpltsym(Link*, LSym*);
static LSym* ensureglinkresolver(void);
void
gentext(void)
{
LSym *s, *stub, **pprevtextp;
Reloc *r;
char *n;
uint32 o1;
uchar *cast;
int i;
// The ppc64 ABI PLT has similar concepts to other
// architectures, but is laid out quite differently. When we
// see an R_PPC64_REL24 relocation to a dynamic symbol
// (indicating that the call needs to go through the PLT), we
// generate up to three stubs and reserve a PLT slot.
//
// 1) The call site will be bl x; nop (where the relocation
// applies to the bl). We rewrite this to bl x_stub; ld
// r2,24(r1). The ld is necessary because x_stub will save
// r2 (the TOC pointer) at 24(r1) (the "TOC save slot").
//
// 2) We reserve space for a pointer in the .plt section (once
// per referenced dynamic function). .plt is a data
// section filled solely by the dynamic linker (more like
// .plt.got on other architectures). Initially, the
// dynamic linker will fill each slot with a pointer to the
// corresponding x@plt entry point.
//
// 3) We generate the "call stub" x_stub (once per dynamic
// function/object file pair). This saves the TOC in the
// TOC save slot, reads the function pointer from x's .plt
// slot and calls it like any other global entry point
// (including setting r12 to the function address).
//
// 4) We generate the "symbol resolver stub" x@plt (once per
// dynamic function). This is solely a branch to the glink
// resolver stub.
//
// 5) We generate the glink resolver stub (only once). This
// computes which symbol resolver stub we came through and
// invokes the dynamic resolver via a pointer provided by
// the dynamic linker. This will patch up the .plt slot to
// point directly at the function so future calls go
// straight from the call stub to the real function, and
// then call the function.
// NOTE: It's possible we could make ppc64 closer to other
// architectures: ppc64's .plt is like .plt.got on other
// platforms and ppc64's .glink is like .plt on other
// platforms.
// Find all R_PPC64_REL24 relocations that reference dynamic
// imports. Reserve PLT entries for these symbols and
// generate call stubs. The call stubs need to live in .text,
// which is why we need to do this pass this early.
//
// This assumes "case 1" from the ABI, where the caller needs
// us to save and restore the TOC pointer.
pprevtextp = &ctxt->textp;
for(s=*pprevtextp; s!=S; pprevtextp=&s->next, s=*pprevtextp) {
for(r=s->r; r<s->r+s->nr; r++) {
if(!(r->type == 256 + R_PPC64_REL24 &&
r->sym->type == SDYNIMPORT))
continue;
// Reserve PLT entry and generate symbol
// resolver
addpltsym(ctxt, r->sym);
// Generate call stub
n = smprint("%s.%s", s->name, r->sym->name);
stub = linklookup(ctxt, n, 0);
free(n);
stub->reachable |= s->reachable;
if(stub->size == 0) {
// Need outer to resolve .TOC.
stub->outer = s;
// Link in to textp before s (we could
// do it after, but would have to skip
// the subsymbols)
*pprevtextp = stub;
stub->next = s;
pprevtextp = &stub->next;
gencallstub(1, stub, r->sym);
}
// Update the relocation to use the call stub
r->sym = stub;
// Restore TOC after bl. The compiler put a
// nop here for us to overwrite.
o1 = 0xe8410018; // ld r2,24(r1)
cast = (uchar*)&o1;
for(i=0; i<4; i++)
s->p[r->off+4+i] = cast[inuxi4[i]];
}
}
}
// Construct a call stub in stub that calls symbol targ via its PLT
// entry.
static void
gencallstub(int abicase, LSym *stub, LSym *targ)
{
LSym *plt;
Reloc *r;
if(abicase != 1)
// If we see R_PPC64_TOCSAVE or R_PPC64_REL24_NOTOC
// relocations, we'll need to implement cases 2 and 3.
sysfatal("gencallstub only implements case 1 calls");
plt = linklookup(ctxt, ".plt", 0);
stub->type = STEXT;
// Save TOC pointer in TOC save slot
adduint32(ctxt, stub, 0xf8410018); // std r2,24(r1)
// Load the function pointer from the PLT.
r = addrel(stub);
r->off = stub->size;
r->sym = plt;
r->add = targ->plt;
r->siz = 2;
if(ctxt->arch->endian == BigEndian)
r->off += r->siz;
r->type = R_POWER_TOC;
r->variant = RV_POWER_HA;
adduint32(ctxt, stub, 0x3d820000); // addis r12,r2,targ@plt@toc@ha
r = addrel(stub);
r->off = stub->size;
r->sym = plt;
r->add = targ->plt;
r->siz = 2;
if(ctxt->arch->endian == BigEndian)
r->off += r->siz;
r->type = R_POWER_TOC;
r->variant = RV_POWER_LO;
adduint32(ctxt, stub, 0xe98c0000); // ld r12,targ@plt@toc@l(r12)
// Jump to the loaded pointer
adduint32(ctxt, stub, 0x7d8903a6); // mtctr r12
adduint32(ctxt, stub, 0x4e800420); // bctr
}
void
adddynrela(LSym *rel, LSym *s, Reloc *r)
{
// TODO(minux)
USED(rel); USED(s); USED(r);
sysfatal("adddynrela not implemented");
}
void
adddynrel(LSym *s, Reloc *r)
{
LSym *targ;
// TODO(minux)
LSym *targ, *rela;
targ = r->sym;
ctxt->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_PPC64_REL24:
r->type = R_CALLPOWER;
// This is a local call, so the caller isn't setting
// up r12 and r2 is the same for the caller and
// callee. Hence, we need to go to the local entry
// point. (If we don't do this, the callee will try
// to use r12 to compute r2.)
r->add += r->sym->localentry * 4;
if(targ->type == SDYNIMPORT)
// Should have been handled in elfsetupplt
diag("unexpected R_PPC64_REL24 for dyn import");
return;
case 256 + R_PPC64_ADDR64:
r->type = R_ADDR;
if(targ->type == SDYNIMPORT) {
// These happen in .toc sections
adddynsym(ctxt, targ);
rela = linklookup(ctxt, ".rela", 0);
addaddrplus(ctxt, rela, s, r->off);
adduint64(ctxt, rela, ELF64_R_INFO(targ->dynid, R_PPC64_ADDR64));
adduint64(ctxt, rela, r->add);
r->type = 256; // ignore during relocsym
}
return;
case 256 + R_PPC64_TOC16:
r->type = R_POWER_TOC;
r->variant = RV_POWER_LO | RV_CHECK_OVERFLOW;
return;
case 256 + R_PPC64_TOC16_LO:
r->type = R_POWER_TOC;
r->variant = RV_POWER_LO;
return;
case 256 + R_PPC64_TOC16_HA:
r->type = R_POWER_TOC;
r->variant = RV_POWER_HA | RV_CHECK_OVERFLOW;
return;
case 256 + R_PPC64_TOC16_HI:
r->type = R_POWER_TOC;
r->variant = RV_POWER_HI | RV_CHECK_OVERFLOW;
return;
case 256 + R_PPC64_TOC16_DS:
r->type = R_POWER_TOC;
r->variant = RV_POWER_DS | RV_CHECK_OVERFLOW;
return;
case 256 + R_PPC64_TOC16_LO_DS:
r->type = R_POWER_TOC;
r->variant = RV_POWER_DS;
return;
case 256 + R_PPC64_REL16_LO:
r->type = R_PCREL;
r->variant = RV_POWER_LO;
r->add += 2; // Compensate for relocation size of 2
return;
case 256 + R_PPC64_REL16_HI:
r->type = R_PCREL;
r->variant = RV_POWER_HI | RV_CHECK_OVERFLOW;
r->add += 2;
return;
case 256 + R_PPC64_REL16_HA:
r->type = R_PCREL;
r->variant = RV_POWER_HA | RV_CHECK_OVERFLOW;
r->add += 2;
return;
}
// Handle references to ELF symbols from our own object files.
if(targ->type != SDYNIMPORT)
return;
// TODO(austin): Translate our relocations to ELF
diag("unsupported relocation for dynamic symbol %s (type=%d stype=%d)", targ->name, r->type, targ->type);
}
@ -100,8 +338,16 @@ elfreloc1(Reloc *r, vlong sectoff)
void
elfsetupplt(void)
{
// TODO(minux)
return;
LSym *plt;
plt = linklookup(ctxt, ".plt", 0);
if(plt->size == 0) {
// The dynamic linker stores the address of the
// dynamic resolver and the DSO identifier in the two
// doublewords at the beginning of the .plt section
// before the PLT array. Reserve space for these.
plt->size = 16;
}
}
int
@ -113,12 +359,29 @@ machoreloc1(Reloc *r, vlong sectoff)
return -1;
}
// Return the value of .TOC. for symbol s
static vlong
symtoc(LSym *s)
{
LSym *toc;
if(s->outer != nil)
toc = linkrlookup(ctxt, ".TOC.", s->outer->version);
else
toc = linkrlookup(ctxt, ".TOC.", s->version);
if(toc == nil) {
diag("TOC-relative relocation in object without .TOC.");
return 0;
}
return toc->value;
}
int
archreloc(Reloc *r, LSym *s, vlong *val)
{
uint32 o1, o2;
int32 t;
vlong t;
if(linkmode == LinkExternal) {
// TODO(minux): translate R_ADDRPOWER and R_CALLPOWER into standard ELF relocations.
@ -166,13 +429,16 @@ archreloc(Reloc *r, LSym *s, vlong *val)
t = symaddr(r->sym) + r->add - (s->value + r->off);
if(t & 3)
ctxt->diag("relocation for %s+%d is not aligned: %lld", r->sym->name, r->off, t);
if(t << 6 >> 6 != t)
if((int32)(t << 6) >> 6 != t)
// TODO(austin) This can happen if text > 32M.
// Add a call trampoline to .text in that case.
ctxt->diag("relocation for %s+%d is too big: %lld", r->sym->name, r->off, t);
*val = (o1 & 0xfc000003U) | (t & ~0xfc000003U);
return 0;
case R_POWER_TOC: // S + A - .TOC.
*val = symaddr(r->sym) + r->add - symtoc(s);
return 0;
}
return -1;
}
@ -180,18 +446,235 @@ archreloc(Reloc *r, LSym *s, vlong *val)
vlong
archrelocvariant(Reloc *r, LSym *s, vlong t)
{
USED(r);
USED(s);
sysfatal("unexpected relocation variant");
uint32 o1;
switch(r->variant & RV_TYPE_MASK) {
default:
diag("unexpected relocation variant %d", r->variant);
case RV_NONE:
return t;
case RV_POWER_LO:
if(r->variant & RV_CHECK_OVERFLOW) {
// Whether to check for signed or unsigned
// overflow depends on the instruction
if(ctxt->arch->endian == BigEndian)
o1 = be32(s->p + r->off - 2);
else
o1 = le32(s->p + r->off);
switch(o1 >> 26) {
case 24: // ori
case 26: // xori
case 28: // andi
if((t >> 16) != 0)
goto overflow;
break;
default:
if((int16)t != t)
goto overflow;
break;
}
}
return (int16)t;
case RV_POWER_HA:
t += 0x8000;
// Fallthrough
case RV_POWER_HI:
t >>= 16;
if(r->variant & RV_CHECK_OVERFLOW) {
// Whether to check for signed or unsigned
// overflow depends on the instruction
if(ctxt->arch->endian == BigEndian)
o1 = be32(s->p + r->off - 2);
else
o1 = le32(s->p + r->off);
switch(o1 >> 26) {
case 25: // oris
case 27: // xoris
case 29: // andis
if((t >> 16) != 0)
goto overflow;
break;
default:
if((int16)t != t)
goto overflow;
break;
}
}
return (int16)t;
case RV_POWER_DS:
if(ctxt->arch->endian == BigEndian)
o1 = be16(s->p + r->off);
else
o1 = le16(s->p + r->off);
if(t & 3)
diag("relocation for %s+%d is not aligned: %lld", r->sym->name, r->off, t);
if((r->variant & RV_CHECK_OVERFLOW) && (int16)t != t)
goto overflow;
return (o1 & 0x3) | (vlong)(int16)t;
}
overflow:
diag("relocation for %s+%d is too big: %lld", r->sym->name, r->off, t);
return t;
}
static void
addpltsym(Link *ctxt, LSym *s)
{
if(s->plt >= 0)
return;
adddynsym(ctxt, s);
if(iself) {
LSym *plt, *rela, *glink;
Reloc *r;
plt = linklookup(ctxt, ".plt", 0);
rela = linklookup(ctxt, ".rela.plt", 0);
if(plt->size == 0)
elfsetupplt();
// Create the glink resolver if necessary
glink = ensureglinkresolver();
// Write symbol resolver stub (just a branch to the
// glink resolver stub)
r = addrel(glink);
r->sym = glink;
r->off = glink->size;
r->siz = 4;
r->type = R_CALLPOWER;
adduint32(ctxt, glink, 0x48000000); // b .glink
// In the ppc64 ABI, the dynamic linker is responsible
// for writing the entire PLT. We just need to
// reserve 8 bytes for each PLT entry and generate a
// JMP_SLOT dynamic relocation for it.
//
// TODO(austin): ABI v1 is different
s->plt = plt->size;
plt->size += 8;
addaddrplus(ctxt, rela, plt, s->plt);
adduint64(ctxt, rela, ELF64_R_INFO(s->dynid, R_PPC64_JMP_SLOT));
adduint64(ctxt, rela, 0);
} else {
diag("addpltsym: unsupported binary format");
}
}
// Generate the glink resolver stub if necessary and return the .glink section
static LSym*
ensureglinkresolver(void)
{
LSym *glink, *s;
Reloc *r;
glink = linklookup(ctxt, ".glink", 0);
if(glink->size != 0)
return glink;
// This is essentially the resolver from the ppc64 ELF ABI.
// At entry, r12 holds the address of the symbol resolver stub
// for the target routine and the argument registers hold the
// arguments for the target routine.
//
// This stub is PIC, so first get the PC of label 1 into r11.
// Other things will be relative to this.
adduint32(ctxt, glink, 0x7c0802a6); // mflr r0
adduint32(ctxt, glink, 0x429f0005); // bcl 20,31,1f
adduint32(ctxt, glink, 0x7d6802a6); // 1: mflr r11
adduint32(ctxt, glink, 0x7c0803a6); // mtlf r0
// Compute the .plt array index from the entry point address.
// Because this is PIC, everything is relative to label 1b (in
// r11):
// r0 = ((r12 - r11) - (res_0 - r11)) / 4 = (r12 - res_0) / 4
adduint32(ctxt, glink, 0x3800ffd0); // li r0,-(res_0-1b)=-48
adduint32(ctxt, glink, 0x7c006214); // add r0,r0,r12
adduint32(ctxt, glink, 0x7c0b0050); // sub r0,r0,r11
adduint32(ctxt, glink, 0x7800f082); // srdi r0,r0,2
// r11 = address of the first byte of the PLT
r = addrel(glink);
r->off = glink->size;
r->sym = linklookup(ctxt, ".plt", 0);
r->siz = 8;
r->type = R_ADDRPOWER;
// addis r11,0,.plt@ha; addi r11,r11,.plt@l
r->add = (0x3d600000ull << 32) | 0x396b0000;
glink->size += 8;
// Load r12 = dynamic resolver address and r11 = DSO
// identifier from the first two doublewords of the PLT.
adduint32(ctxt, glink, 0xe98b0000); // ld r12,0(r11)
adduint32(ctxt, glink, 0xe96b0008); // ld r11,8(r11)
// Jump to the dynamic resolver
adduint32(ctxt, glink, 0x7d8903a6); // mtctr r12
adduint32(ctxt, glink, 0x4e800420); // bctr
// The symbol resolvers must immediately follow.
// res_0:
// Add DT_PPC64_GLINK .dynamic entry, which points to 32 bytes
// before the first symbol resolver stub.
s = linklookup(ctxt, ".dynamic", 0);
elfwritedynentsymplus(s, DT_PPC64_GLINK, glink, glink->size - 32);
return glink;
}
void
adddynsym(Link *ctxt, LSym *s)
{
USED(ctxt); USED(s);
// TODO(minux)
return;
LSym *d;
int t;
char *name;
if(s->dynid >= 0)
return;
if(iself) {
s->dynid = nelfsym++;
d = linklookup(ctxt, ".dynsym", 0);
name = s->extname;
adduint32(ctxt, d, addstring(linklookup(ctxt, ".dynstr", 0), name));
/* type */
t = STB_GLOBAL << 4;
if(s->cgoexport && (s->type&SMASK) == STEXT)
t |= STT_FUNC;
else
t |= STT_OBJECT;
adduint8(ctxt, d, t);
/* reserved */
adduint8(ctxt, d, 0);
/* section where symbol is defined */
if(s->type == SDYNIMPORT)
adduint16(ctxt, d, SHN_UNDEF);
else
adduint16(ctxt, d, 1);
/* value */
if(s->type == SDYNIMPORT)
adduint64(ctxt, d, 0);
else
addaddr(ctxt, d, s);
/* size of object */
adduint64(ctxt, d, s->size);
} else {
diag("adddynsym: unsupported binary format");
}
}
void

3
src/cmd/9l/obj.c
View File

@ -80,7 +80,8 @@ archinit(void)
INITRND = 4096;
break;
case Hlinux: /* ppc64 elf */
debug['d'] = 1; // TODO(minux): dynamic linking is not supported yet.
if(strcmp(thestring, "ppc64") == 0)
debug['d'] = 1; // TODO(austin): ELF ABI v1 not supported yet
elfinit();
HEADR = ELFRESERVE;
if(INITTEXT == -1)

37
src/cmd/ld/data.c
View File

@ -49,7 +49,11 @@ datcmp(LSym *s1, LSym *s2)
{
if(s1->type != s2->type)
return (int)s1->type - (int)s2->type;
if(s1->size != s2->size) {
// For ppc64, we want to interleave the .got and .toc sections
// from input files. Both are type SELFGOT, so in that case
// fall through to the name comparison (conveniently, .got
// sorts before .toc).
if(s1->type != SELFGOT && s1->size != s2->size) {
if(s1->size < s2->size)
return -1;
return +1;
@ -920,7 +924,7 @@ dodata(void)
vlong datsize;
Section *sect;
Segment *segro;
LSym *s, *last, **l;
LSym *s, *last, **l, *toc;
LSym *gcdata, *gcbss;
ProgGen gen;
@ -994,7 +998,7 @@ dodata(void)
/* writable ELF sections */
datsize = 0;
for(; s != nil && s->type < SNOPTRDATA; s = s->next) {
for(; s != nil && s->type < SELFGOT; s = s->next) {
sect = addsection(&segdata, s->name, 06);
sect->align = symalign(s);
datsize = rnd(datsize, sect->align);
@ -1006,6 +1010,33 @@ dodata(void)
sect->len = datsize - sect->vaddr;
}
/* .got (and .toc on ppc64) */
if(s->type == SELFGOT) {
sect = addsection(&segdata, ".got", 06);
sect->align = maxalign(s, SELFGOT);
datsize = rnd(datsize, sect->align);
sect->vaddr = datsize;
for(; s != nil && s->type == SELFGOT; s = s->next) {
datsize = aligndatsize(datsize, s);
s->sect = sect;
s->type = SDATA;
s->value = datsize - sect->vaddr;
// Resolve .TOC. symbol for this object file (ppc64)
toc = linkrlookup(ctxt, ".TOC.", s->version);
if(toc != nil) {
toc->sect = sect;
toc->outer = s;
toc->sub = s->sub;
s->sub = toc;
toc->value = 0x8000;
}
growdatsize(&datsize, s);
}
sect->len = datsize - sect->vaddr;
}
/* pointer-free data */
sect = addsection(&segdata, ".noptrdata", 06);
sect->align = maxalign(s, SINITARR-1);

83
src/cmd/ld/elf.c
View File

@ -306,12 +306,18 @@ elfwritedynent(LSym *s, int tag, uint64 val)
void
elfwritedynentsym(LSym *s, int tag, LSym *t)
{
elfwritedynentsymplus(s, tag, t, 0);
}
void
elfwritedynentsymplus(LSym *s, int tag, LSym *t, vlong add)
{
if(elf64)
adduint64(ctxt, s, tag);
else
adduint32(ctxt, s, tag);
addaddr(ctxt, s, t);
addaddrplus(ctxt, s, t, add);
}
void
@ -977,6 +983,8 @@ doelf(void)
addstring(shstrtab, ".interp");
addstring(shstrtab, ".hash");
addstring(shstrtab, ".got");
if(thechar == '9')
addstring(shstrtab, ".glink");
addstring(shstrtab, ".got.plt");
addstring(shstrtab, ".dynamic");
addstring(shstrtab, ".dynsym");
@ -1020,7 +1028,14 @@ doelf(void)
/* global offset table */
s = linklookup(ctxt, ".got", 0);
s->reachable = 1;
s->type = SELFSECT; // writable
s->type = SELFGOT; // writable
/* ppc64 glink resolver */
if(thechar == '9') {
s = linklookup(ctxt, ".glink", 0);
s->reachable = 1;
s->type = SELFRXSECT;
}
/* hash */
s = linklookup(ctxt, ".hash", 0);
@ -1033,7 +1048,12 @@ doelf(void)
s = linklookup(ctxt, ".plt", 0);
s->reachable = 1;
s->type = SELFRXSECT;
if(thechar == '9')
// In the ppc64 ABI, .plt is a data section
// written by the dynamic linker.
s->type = SELFSECT;
else
s->type = SELFRXSECT;
elfsetupplt();
@ -1079,8 +1099,14 @@ doelf(void)
}
if(rpath)
elfwritedynent(s, DT_RUNPATH, addstring(dynstr, rpath));
elfwritedynentsym(s, DT_PLTGOT, linklookup(ctxt, ".got.plt", 0));
if(thechar == '9')
elfwritedynentsym(s, DT_PLTGOT, linklookup(ctxt, ".plt", 0));
else
elfwritedynentsym(s, DT_PLTGOT, linklookup(ctxt, ".got.plt", 0));
if(thechar == '9')
elfwritedynent(s, DT_PPC64_OPT, 0);
// Solaris dynamic linker can't handle an empty .rela.plt if
// DT_JMPREL is emitted so we have to defer generation of DT_PLTREL,
@ -1309,6 +1335,7 @@ asmbelf(vlong symo)
switch(eh->machine) {
case EM_X86_64:
case EM_PPC64:
sh = elfshname(".rela.plt");
sh->type = SHT_RELA;
sh->flags = SHF_ALLOC;
@ -1345,29 +1372,47 @@ asmbelf(vlong symo)
break;
}
if(eh->machine == EM_PPC64) {
sh = elfshname(".glink");
sh->type = SHT_PROGBITS;
sh->flags = SHF_ALLOC+SHF_EXECINSTR;
sh->addralign = 4;
shsym(sh, linklookup(ctxt, ".glink", 0));
}
sh = elfshname(".plt");
sh->type = SHT_PROGBITS;
sh->flags = SHF_ALLOC+SHF_EXECINSTR;
if(eh->machine == EM_X86_64)
sh->entsize = 16;
else
else if(eh->machine == EM_PPC64) {
// On ppc64, this is just a table of addresses
// filled by the dynamic linker
sh->type = SHT_NOBITS;
sh->flags = SHF_ALLOC+SHF_WRITE;
sh->entsize = 8;
} else
sh->entsize = 4;
sh->addralign = 4;
sh->addralign = sh->entsize;
shsym(sh, linklookup(ctxt, ".plt", 0));
sh = elfshname(".got");
sh->type = SHT_PROGBITS;
sh->flags = SHF_ALLOC+SHF_WRITE;
sh->entsize = RegSize;
sh->addralign = RegSize;
shsym(sh, linklookup(ctxt, ".got", 0));
// On ppc64, .got comes from the input files, so don't
// create it here, and .got.plt is not used.
if(eh->machine != EM_PPC64) {
sh = elfshname(".got");
sh->type = SHT_PROGBITS;
sh->flags = SHF_ALLOC+SHF_WRITE;
sh->entsize = RegSize;
sh->addralign = RegSize;
shsym(sh, linklookup(ctxt, ".got", 0));
sh = elfshname(".got.plt");
sh->type = SHT_PROGBITS;
sh->flags = SHF_ALLOC+SHF_WRITE;
sh->entsize = RegSize;
sh->addralign = RegSize;
shsym(sh, linklookup(ctxt, ".got.plt", 0));
sh = elfshname(".got.plt");
sh->type = SHT_PROGBITS;
sh->flags = SHF_ALLOC+SHF_WRITE;
sh->entsize = RegSize;
sh->addralign = RegSize;
shsym(sh, linklookup(ctxt, ".got.plt", 0));
}
sh = elfshname(".hash");
sh->type = SHT_HASH;

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

@ -317,6 +317,9 @@ typedef struct {
#define DT_VERNEEDNUM 0x6fffffff
#define DT_VERSYM 0x6ffffff0
#define DT_PPC64_GLINK (DT_LOPROC + 0)
#define DT_PPC64_OPT (DT_LOPROC + 3)
/* Values for DT_FLAGS */
/* Indicates that the object being loaded may make reference to
the $ORIGIN substitution string */
@ -700,6 +703,18 @@ typedef struct {
/* Count of defined relocation types. */
#define R_PPC_EMB_COUNT (R_PPC_EMB_RELSDA - R_PPC_EMB_NADDR32 + 1)
#define R_PPC64_REL24 R_PPC_REL24
#define R_PPC64_JMP_SLOT R_PPC_JMP_SLOT
#define R_PPC64_ADDR64 38
#define R_PPC64_TOC16 47
#define R_PPC64_TOC16_LO 48
#define R_PPC64_TOC16_HI 49
#define R_PPC64_TOC16_HA 50
#define R_PPC64_TOC16_DS 63
#define R_PPC64_TOC16_LO_DS 64
#define R_PPC64_REL16_LO 250
#define R_PPC64_REL16_HI 251
#define R_PPC64_REL16_HA 252
#define R_SPARC_NONE 0
#define R_SPARC_8 1
@ -970,6 +985,7 @@ uint32 elfwritephdrs(void);
uint32 elfwriteshdrs(void);
void elfwritedynent(LSym*, int, uint64);
void elfwritedynentsym(LSym*, int, LSym*);
void elfwritedynentsymplus(LSym*, int, LSym*, vlong);
void elfwritedynentsymsize(LSym*, int, LSym*);
uint32 elfhash(uchar*);
uint64 startelf(void);

29
src/cmd/ld/ldelf.c
View File

@ -554,6 +554,9 @@ ldelf(Biobuf *f, char *pkg, int64 len, char *pn)
s->type = STEXT;
break;
}
if(strcmp(sect->name, ".got") == 0 ||
strcmp(sect->name, ".toc") == 0)
s->type = SELFGOT;
if(sect->type == ElfSectProgbits) {
s->p = sect->base;
s->np = sect->size;
@ -812,6 +815,10 @@ readsym(ElfObj *obj, int i, ElfSym *sym, int needSym)
s = nil;
if(strcmp(sym->name, "_GLOBAL_OFFSET_TABLE_") == 0)
sym->name = ".got";
if(strcmp(sym->name, ".TOC.") == 0)
// Magic symbol on ppc64. Will be set to this object
// file's .got+0x8000.
sym->bind = ElfSymBindLocal;
switch(sym->type) {
case ElfSymTypeSection:
s = obj->sect[sym->shndx].sym;
@ -842,6 +849,15 @@ readsym(ElfObj *obj, int i, ElfSym *sym, int needSym)
// symbols, ignore these
break;
}
if(strcmp(sym->name, ".TOC.") == 0) {
// We need to be able to look this up,
// so put it in the hash table.
if(needSym) {
s = linklookup(ctxt, sym->name, ctxt->version);
s->type |= SHIDDEN;
}
break;
}
if(needSym) {
// local names and hidden visiblity global names are unique
// and should only reference by its index, not name, so we
@ -892,6 +908,17 @@ reltype(char *pn, int elftype, uchar *siz)
switch(R(thechar, elftype)) {
default:
diag("%s: unknown relocation type %d; compiled without -fpic?", pn, elftype);
case R('9', R_PPC64_TOC16):
case R('9', R_PPC64_TOC16_LO):
case R('9', R_PPC64_TOC16_HI):
case R('9', R_PPC64_TOC16_HA):
case R('9', R_PPC64_TOC16_DS):
case R('9', R_PPC64_TOC16_LO_DS):
case R('9', R_PPC64_REL16_LO):
case R('9', R_PPC64_REL16_HI):
case R('9', R_PPC64_REL16_HA):
*siz = 2;
break;
case R('5', R_ARM_ABS32):
case R('5', R_ARM_GOT32):
case R('5', R_ARM_PLT32):
@ -913,9 +940,11 @@ reltype(char *pn, int elftype, uchar *siz)
case R('8', R_386_PLT32):
case R('8', R_386_GOTOFF):
case R('8', R_386_GOTPC):
case R('9', R_PPC64_REL24):
*siz = 4;
break;
case R('6', R_X86_64_64):
case R('9', R_PPC64_ADDR64):
*siz = 8;
break;
}