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rtld support for PowerPC. Mostly obtained from NetBSD, with mods

Browse Source 
for binutils 2.13

Reviewed by:  benno

Approved by:  re (blanket)
This commit is contained in:
Peter Grehan 2002-12-04 07:32:20 +00:00
parent 8238b87b55
commit b9dea67fa8
5 changed files with 926 additions and 0 deletions
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1
libexec/rtld-elf/powerpc/Makefile.inc Normal file
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# $FreeBSD$

169
libexec/rtld-elf/powerpc/lockdflt.c Normal file
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/*-
* Copyright 1999, 2000 John D. Polstra.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* from: FreeBSD: src/libexec/rtld-elf/alpha/lockdflt.c,v 1.6 2000/07/17
* $FreeBSD$
*/
/*
* Thread locking implementation for the dynamic linker.
*
* We use the "simple, non-scalable reader-preference lock" from:
*
* J. M. Mellor-Crummey and M. L. Scott. "Scalable Reader-Writer
* Synchronization for Shared-Memory Multiprocessors." 3rd ACM Symp. on
* Principles and Practice of Parallel Programming, April 1991.
*
* In this algorithm the lock is a single word. Its low-order bit is
* set when a writer holds the lock. The remaining high-order bits
* contain a count of readers desiring the lock. The algorithm requires
* atomic "compare_and_store" and "add" operations, which we implement
* using assembly language sequences in "rtld_start.S".
*/
#include <signal.h>
#include <stdlib.h>
#include <time.h>
#include <machine/atomic.h>
#include "debug.h"
#include "rtld.h"
#include "rtld_machdep.h"
#define WAFLAG 0x1 /* A writer holds the lock */
#define RC_INCR 0x2 /* Adjusts count of readers desiring lock */
typedef struct Struct_Lock {
volatile int lock;
void *base;
} Lock;
static sigset_t fullsigmask, oldsigmask;
static void *
lock_create(void *context)
{
void *base;
char *p;
uintptr_t r;
Lock *l;
/*
* Arrange for the lock to occupy its own cache line. First, we
* optimistically allocate just a cache line, hoping that malloc
* will give us a well-aligned block of memory. If that doesn't
* work, we allocate a larger block and take a well-aligned cache
* line from it.
*/
base = xmalloc(CACHE_LINE_SIZE);
p = (char *)base;
if ((uintptr_t)p % CACHE_LINE_SIZE != 0) {
free(base);
base = xmalloc(2 * CACHE_LINE_SIZE);
p = (char *)base;
if ((r = (uintptr_t)p % CACHE_LINE_SIZE) != 0)
p += CACHE_LINE_SIZE - r;
}
l = (Lock *)p;
l->base = base;
l->lock = 0;
return l;
}
static void
lock_destroy(void *lock)
{
Lock *l = (Lock *)lock;
free(l->base);
}
static void
rlock_acquire(void *lock)
{
Lock *l = (Lock *)lock;
atomic_add_acq_int(&l->lock, RC_INCR);
while (l->lock & WAFLAG)
; /* Spin */
}
static void
wlock_acquire(void *lock)
{
Lock *l = (Lock *)lock;
sigset_t tmp_oldsigmask;
for ( ; ; ) {
sigprocmask(SIG_BLOCK, &fullsigmask, &tmp_oldsigmask);
if (atomic_cmpset_acq_int(&l->lock, 0, WAFLAG))
break;
sigprocmask(SIG_SETMASK, &tmp_oldsigmask, NULL);
}
oldsigmask = tmp_oldsigmask;
}
static void
rlock_release(void *lock)
{
Lock *l = (Lock *)lock;
atomic_add_rel_int(&l->lock, -RC_INCR);
}
static void
wlock_release(void *lock)
{
Lock *l = (Lock *)lock;
atomic_add_rel_int(&l->lock, -WAFLAG);
sigprocmask(SIG_SETMASK, &oldsigmask, NULL);
}
void
lockdflt_init(LockInfo *li)
{
li->context = NULL;
li->lock_create = lock_create;
li->rlock_acquire = rlock_acquire;
li->wlock_acquire = wlock_acquire;
li->rlock_release = rlock_release;
li->wlock_release = wlock_release;
li->lock_destroy = lock_destroy;
li->context_destroy = NULL;
/*
* Construct a mask to block all signals except traps which might
* conceivably be generated within the dynamic linker itself.
*/
sigfillset(&fullsigmask);
sigdelset(&fullsigmask, SIGILL);
sigdelset(&fullsigmask, SIGTRAP);
sigdelset(&fullsigmask, SIGABRT);
sigdelset(&fullsigmask, SIGEMT);
sigdelset(&fullsigmask, SIGFPE);
sigdelset(&fullsigmask, SIGBUS);
sigdelset(&fullsigmask, SIGSEGV);
sigdelset(&fullsigmask, SIGSYS);
}

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libexec/rtld-elf/powerpc/reloc.c Normal file
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/* $NetBSD: ppc_reloc.c,v 1.10 2001/09/10 06:09:41 mycroft Exp $ */
/*-
* Copyright (C) 1998 Tsubai Masanari
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* $FreeBSD$
*/
#include <sys/param.h>
#include <sys/mman.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <machine/cpu.h>
#include "debug.h"
#include "rtld.h"
#define _ppc_ha(x) ((((u_int32_t)(x) & 0x8000) ? \
((u_int32_t)(x) + 0x10000) : (u_int32_t)(x)) >> 16)
#define _ppc_la(x) ((u_int32_t)(x) & 0xffff)
/*
* Process the R_PPC_COPY relocations
*/
int
do_copy_relocations(Obj_Entry *dstobj)
{
const Elf_Rela *relalim;
const Elf_Rela *rela;
/*
* COPY relocs are invalid outside of the main program
*/
assert(dstobj->mainprog);
relalim = (const Elf_Rela *) ((caddr_t) dstobj->rela +
dstobj->relasize);
for (rela = dstobj->rela; rela < relalim; rela++) {
void *dstaddr;
const Elf_Sym *dstsym;
const char *name;
unsigned long hash;
size_t size;
const void *srcaddr;
const Elf_Sym *srcsym = NULL;
Obj_Entry *srcobj;
if (ELF_R_TYPE(rela->r_info) != R_PPC_COPY) {
continue;
}
dstaddr = (void *) (dstobj->relocbase + rela->r_offset);
dstsym = dstobj->symtab + ELF_R_SYM(rela->r_info);
name = dstobj->strtab + dstsym->st_name;
hash = elf_hash(name);
size = dstsym->st_size;
for (srcobj = dstobj->next; srcobj != NULL;
srcobj = srcobj->next) {
if ((srcsym = symlook_obj(name, hash, srcobj, false))
!= NULL) {
break;
}
}
if (srcobj == NULL) {
_rtld_error("Undefined symbol \"%s\" "
" referenced from COPY"
" relocation in %s", name, dstobj->path);
return (-1);
}
srcaddr = (const void *) (srcobj->relocbase+srcsym->st_value);
memcpy(dstaddr, srcaddr, size);
dbg("copy_reloc: src=%p,dst=%p,size=%d\n",srcaddr,dstaddr,size);
}
return (0);
}
/*
* Perform early relocation of the run-time linker image
*/
void
reloc_non_plt_self(Elf_Dyn *dynp, Elf_Addr relocbase)
{
const Elf_Rela *rela = 0, *relalim;
Elf_Addr relasz = 0;
Elf_Addr *where;
/*
* Extract the rela/relasz values from the dynamic section
*/
for (; dynp->d_tag != DT_NULL; dynp++) {
switch (dynp->d_tag) {
case DT_RELA:
rela = (const Elf_Rela *)(relocbase+dynp->d_un.d_ptr);
break;
case DT_RELASZ:
relasz = dynp->d_un.d_val;
break;
}
}
/*
* Relocate these values
*/
relalim = (const Elf_Rela *)((caddr_t)rela + relasz);
for (; rela < relalim; rela++) {
where = (Elf_Addr *)(relocbase + rela->r_offset);
*where = (Elf_Addr)(relocbase + rela->r_addend);
}
}
/*
* Relocate a non-PLT object with addend.
*/
static int
reloc_nonplt_object(Obj_Entry *obj_rtld, Obj_Entry *obj, const Elf_Rela *rela,
SymCache *cache)
{
Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
const Elf_Sym *def;
const Obj_Entry *defobj;
Elf_Addr tmp;
switch (ELF_R_TYPE(rela->r_info)) {
case R_PPC_NONE:
break;
case R_PPC_ADDR32: /* word32 S + A */
case R_PPC_GLOB_DAT: /* word32 S + A */
def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj,
false, cache);
if (def == NULL) {
return (-1);
}
tmp = (Elf_Addr)(defobj->relocbase + def->st_value +
rela->r_addend);
/* Don't issue write if unnecessary; avoid COW page fault */
if (*where != tmp) {
*where = tmp;
}
break;
case R_PPC_RELATIVE: /* word32 B + A */
tmp = (Elf_Addr)(obj->relocbase + rela->r_addend);
/* As above, don't issue write unnecessarily */
if (*where != tmp) {
*where = tmp;
}
break;
case R_PPC_COPY:
/*
* These are deferred until all other relocations
* have been done. All we do here is make sure
* that the COPY relocation is not in a shared
* library. They are allowed only in executable
* files.
*/
if (!obj->mainprog) {
_rtld_error("%s: Unexpected R_COPY "
" relocation in shared library",
obj->path);
return (-1);
}
break;
case R_PPC_JMP_SLOT:
/*
* These will be handled by the plt/jmpslot routines
*/
break;
default:
_rtld_error("%s: Unsupported relocation type %d"
" in non-PLT relocations\n", obj->path,
ELF_R_TYPE(rela->r_info));
return (-1);
}
return (0);
}
/*
* Process non-PLT relocations
*/
int
reloc_non_plt(Obj_Entry *obj, Obj_Entry *obj_rtld)
{
const Elf_Rela *relalim;
const Elf_Rela *rela;
SymCache *cache;
int bytes = obj->nchains * sizeof(SymCache);
int r = -1;
/*
* The dynamic loader may be called from a thread, we have
* limited amounts of stack available so we cannot use alloca().
*/
cache = mmap(NULL, bytes, PROT_READ|PROT_WRITE, MAP_ANON, -1, 0);
if (cache == MAP_FAILED) {
cache = NULL;
}
if (cache != NULL) {
memset(cache, 0, obj->nchains * sizeof(SymCache));
}
/*
* From the SVR4 PPC ABI:
* "The PowerPC family uses only the Elf32_Rela relocation
* entries with explicit addends."
*/
relalim = (const Elf_Rela *)((caddr_t)obj->rela + obj->relasize);
for (rela = obj->rela; rela < relalim; rela++) {
if (reloc_nonplt_object(obj_rtld, obj, rela, cache) < 0)
goto done;
}
r = 0;
done:
if (cache) {
munmap(cache, bytes);
}
return (r);
}
/*
* Initialise a PLT slot to the resolving trampoline
*/
static int
reloc_plt_object(Obj_Entry *obj, const Elf_Rela *rela)
{
Elf_Word *where = (Elf_Word *)(obj->relocbase + rela->r_offset);
Elf_Addr *pltresolve;
Elf_Addr distance;
int reloff;
reloff = rela - obj->pltrela;
if ((reloff < 0) || (reloff >= 0x8000)) {
return (-1);
}
pltresolve = obj->pltgot + 8;
distance = (Elf_Addr)pltresolve - (Elf_Addr)(where + 1);
dbg(" reloc_plt_object: where=%p,pltres=%p,reloff=%x,distance=%x",
(void *)where, (void *)pltresolve, reloff, distance);
/* li r11,reloff */
/* b pltresolve */
where[0] = 0x39600000 | reloff;
where[1] = 0x48000000 | (distance & 0x03fffffc);
/*
* The icache will be sync'd in init_pltgot, which is called
* after all the slots have been updated
*/
return (0);
}
/*
* Process the PLT relocations.
*/
int
reloc_plt(Obj_Entry *obj)
{
const Elf_Rela *relalim;
const Elf_Rela *rela;
if (obj->pltrelasize != 0) {
relalim = (const Elf_Rela *)((char *)obj->pltrela +
obj->pltrelasize);
for (rela = obj->pltrela; rela < relalim; rela++) {
assert(ELF_R_TYPE(rela->r_info) == R_PPC_JMP_SLOT);
if (reloc_plt_object(obj, rela) < 0) {
return (-1);
}
}
}
return (0);
}
/*
* LD_BIND_NOW was set - force relocation for all jump slots
*/
int
reloc_jmpslots(Obj_Entry *obj)
{
const Obj_Entry *defobj;
const Elf_Rela *relalim;
const Elf_Rela *rela;
const Elf_Sym *def;
Elf_Addr *where;
Elf_Addr target;
relalim = (const Elf_Rela *)((char *)obj->pltrela + obj->pltrelasize);
for (rela = obj->pltrela; rela < relalim; rela++) {
assert(ELF_R_TYPE(rela->r_info) == R_PPC_JMP_SLOT);
where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj,
true, NULL);
if (def == NULL) {
dbg("reloc_jmpslots: sym not found");
return (-1);
}
target = (Elf_Addr)(defobj->relocbase + def->st_value);
#if 0
/* PG XXX */
dbg("\"%s\" in \"%s\" --> %p in \"%s\"",
defobj->strtab + def->st_name, basename(obj->path),
(void *)target, basename(defobj->path));
#endif
reloc_jmpslot(where, target, defobj, obj,
(const Elf_Rel *) rela);
}
obj->jmpslots_done = true;
return (0);
}
/*
* Update the value of a PLT jump slot. Branch directly to the target if
* it is within +/- 32Mb, otherwise go indirectly via the pltcall
* trampoline call and jump table.
*/
Elf_Addr
reloc_jmpslot(Elf_Addr *wherep, Elf_Addr target, const Obj_Entry *defobj,
const Obj_Entry *obj, const Elf_Rel *rel)
{
Elf_Addr offset;
const Elf_Rela *rela = (const Elf_Rela *) rel;
dbg(" reloc_jmpslot: where=%p, target=%p",
(void *)wherep, (void *)target);
/*
* At the PLT entry pointed at by `wherep', construct
* a direct transfer to the now fully resolved function
* address.
*/
offset = target - (Elf_Addr)wherep;
if (abs(offset) < 32*1024*1024) { /* inside 32MB? */
/* b value # branch directly */
*wherep = 0x48000000 | (offset & 0x03fffffc);
__syncicache(wherep, 4);
} else {
Elf_Addr *pltcall, *jmptab;
int distance;
int N = obj->pltrelasize / sizeof(Elf_Rela);
int reloff = rela - obj->pltrela;
if ((reloff < 0) || (reloff >= 0x8000)) {
return (-1);
}
pltcall = obj->pltgot;
dbg(" reloc_jmpslot: indir, reloff=%d, N=%d\n",
reloff, N);
jmptab = obj->pltgot + 18 + N * 2;
jmptab[reloff] = target;
distance = (Elf_Addr)pltcall - (Elf_Addr)(wherep + 1);
/* li r11,reloff */
/* b pltcall # use indirect pltcall routine */
wherep[0] = 0x39600000 | reloff;
wherep[1] = 0x48000000 | (distance & 0x03fffffc);
__syncicache(wherep, 8);
}
return (target);
}
/*
* Setup the plt glue routines.
*/
#define PLTCALL_SIZE 20
#define PLTRESOLVE_SIZE 24
void
init_pltgot(Obj_Entry *obj)
{
Elf_Word *pltcall, *pltresolve;
Elf_Word *jmptab;
int N = obj->pltrelasize / sizeof(Elf_Rela);
pltcall = obj->pltgot;
if (pltcall == NULL) {
return;
}
/*
* From the SVR4 PPC ABI:
*
* 'The first 18 words (72 bytes) of the PLT are reserved for
* use by the dynamic linker.
* ...
* 'If the executable or shared object requires N procedure
* linkage table entries, the link editor shall reserve 3*N
* words (12*N bytes) following the 18 reserved words. The
* first 2*N of these words are the procedure linkage table
* entries themselves. The static linker directs calls to bytes
* (72 + (i-1)*8), for i between 1 and N inclusive. The remaining
* N words (4*N bytes) are reserved for use by the dynamic linker.'
*/
/*
* Copy the absolute-call assembler stub into the first part of
* the reserved PLT area.
*/
memcpy(pltcall, _rtld_powerpc_pltcall, PLTCALL_SIZE);
/*
* Determine the address of the jumptable, which is the dyn-linker
* reserved area after the call cells. Write the absolute address
* of the jumptable into the absolute-call assembler code so it
* can determine this address.
*/
jmptab = pltcall + 18 + N * 2;
pltcall[1] |= _ppc_ha(jmptab); /* addis 11,11,jmptab@ha */
pltcall[2] |= _ppc_la(jmptab); /* lwz 11,jmptab@l(11) */
/*
* Skip down 32 bytes into the initial reserved area and copy
* in the standard resolving assembler call. Into this assembler,
* insert the absolute address of the _rtld_bind_start routine
* and the address of the relocation object.
*/
pltresolve = obj->pltgot + 8;
memcpy(pltresolve, _rtld_powerpc_pltresolve, PLTRESOLVE_SIZE);
pltresolve[0] |= _ppc_ha(_rtld_bind_start);
pltresolve[1] |= _ppc_la(_rtld_bind_start);
pltresolve[3] |= _ppc_ha(obj);
pltresolve[4] |= _ppc_la(obj);
/*
* Sync the icache for the byte range represented by the
* trampoline routines and call slots.
*/
__syncicache(pltcall, 72 + N * 8);
}

67
libexec/rtld-elf/powerpc/rtld_machdep.h Normal file
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/*-
* Copyright (c) 1999, 2000 John D. Polstra.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* $FreeBSD$
*/
#ifndef RTLD_MACHDEP_H
#define RTLD_MACHDEP_H 1
#include <machine/atomic.h>
#define atomic_incr_int(p) atomic_add_int((p), 1)
#define atomic_decr_int(p) atomic_subtract_int((p), 1)
#define CACHE_LINE_SIZE 32
struct Struct_Obj_Entry;
/* Return the address of the .dynamic section in the dynamic linker. */
#define rtld_dynamic(obj) (&_DYNAMIC)
Elf_Addr reloc_jmpslot(Elf_Addr *where, Elf_Addr target,
const struct Struct_Obj_Entry *defobj,
const struct Struct_Obj_Entry *obj,
const Elf_Rel *rel);
#define make_function_pointer(def, defobj) \
((defobj)->relocbase + (def)->st_value)
#define call_initfini_pointer(obj, target) \
(((InitFunc)(target))())
/*
* Lazy binding entry point, called via PLT.
*/
void _rtld_bind_start(void);
/*
* PLT functions. Not really correct prototypes, but the
* symbol values are needed.
*/
void _rtld_powerpc_pltresolve(void);
void _rtld_powerpc_pltcall(void);
#endif

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libexec/rtld-elf/powerpc/rtld_start.S Normal file
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/* $NetBSD: rtld_start.S,v 1.4 2001/09/26 04:06:43 mycroft Exp $ */
/*-
* Copyright (C) 1998 Tsubai Masanari
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* $FreeBSD$
*/
#include <machine/asm.h>
.extern _GLOBAL_OFFSET_TABLE_
.extern _DYNAMIC
_ENTRY(.rtld_start)
stwu %r1,-48(%r1) /* 16-byte aligned stack for reg saves +
exit_proc & obj _rtld args +
backchain & lrsave stack frame */
stw %r3,16(%r1) /* argc */
stw %r4,20(%r1) /* argv */
stw %r5,24(%r1) /* envp */
/* stw %r6,28(%r1) *//* obj (always 0) */
/* stw %r7,32(%r1) *//* cleanup (always 0) */
stw %r8,36(%r1) /* ps_strings */
/*
* Perform initial relocation of ld-elf.so. Not as easy as it
* sounds.
* - perform small forward branch to put PC into link reg
* - use link-time constants to determine offset to the
* _DYNAMIC section and the GOT. Add these to the PC to
* convert to absolute addresses.
* - sync icache to allow execution of the SVR4 ABI-specified
* blrl instruction preceding the GOT
* - Use this instruction to determine the GOT absolute address
* - read GOT[0], which is the SVR4 ABI-specified link-time
* value of _DYNAMIC. Subtract this value from the absolute
* value to determine the load address
* - call reloc_non_plt_self() to fix up ld-elf.so's relocations
*/
bl 1f
.long _DYNAMIC-.
.long _GLOBAL_OFFSET_TABLE_-. /* branch lr + 4 */
1:
mflr %r3 /* PC value at .long */
lwz %r4,4(%r3)
add %r4,%r4,%r3 /* &_GLOBAL_OFFSET_TABLE-4, blrl insn. */
dcbst %r0,%r4 /* sync i-cache with d-cache */
sync
icbi %r0,%r4
isync
lwz %r4,0(%r3) /* offset to _DYNAMIC */
add %r3,%r4,%r3 /* r3 = &_DYNAMIC, absolute value */
bl _GLOBAL_OFFSET_TABLE_@local-4
mflr %r4 /* &_GLOBAL_OFFSET_TABLE_, absolute value */
lwz %r4,0(%r4) /* linker &_DYNAMIC, from got[0] */
subf %r4,%r4,%r3 /* subtract to calculate relocbase */
bl reloc_non_plt_self@plt /* reloc_non_plt_self(&_DYNAMIC,base) */
/*
* The _rtld() function likes to see a stack layout containing
* { argc, argv[0], argv[1] ... argv[N], 0, env[0], ... , env[N] }
* Since the PowerPC stack was 16-byte aligned at exec time, the
* original stack layout has to be found by moving back a word
* from the argv pointer.
*/
lwz %r4,20(%r1) /* restore argv */
addi %r3,%r4,-4 /* locate argc ptr, &argv[-1] */
addi %r4,%r1,8 /* &exit_proc on stack */
addi %r5,%r1,12 /* &obj_main on stack */
bl _rtld@plt /* &_start = _rtld(sp, &exit_proc, &obj_main)*/
mtlr %r3
/*
* Restore args, with new obj/exit proc
*/
lwz %r3,16(%r1) /* argc */
lwz %r4,20(%r1) /* argv */
lwz %r5,24(%r1) /* envp */
lwz %r6,12(%r1) /* obj */
lwz %r7,8(%r1) /* exit proc */
lwz %r8,36(%r1) /* ps_strings */
addi %r1,%r1,48 /* restore original stackptr */
blrl /* _start(argc, argv, envp, obj, cleanup, ps_strings) */
li %r0,1 /* _exit() */
sc
/*
* _rtld_bind_start()
*
* Call into the MI binder. This routine is reached via the PLT call cell,
* and then _rtld_powerpc_pltresolve().
* On entry, %r11 contains the index of the PLT cell, and %r12 contains
* a pointer to the ELF object for the file.
* Save all registers, call into the binder to resolve and fixup the external
* routine, and then transfer to the external routine on return.
*/
.globl _rtld_bind
_ENTRY(_rtld_bind_start)
stwu %r1,-160(%r1) # stack space for 29 regs + r0/lr/cr
stw %r0,20(%r1) # save r0
mflr %r0
stw %r0,16(%r1) # save lr
mfcr %r0
stw %r0,12(%r1) # save cr
stmw %r3,24(%r1) # save r3-r31
mr %r3,%r12 # obj
mulli %r4,%r11,12 # rela index * sizeof(Elf_Rela)
bl _rtld_bind@PLT # target addr = _rtld_bind(obj, reloff)
mtctr %r3 # move absolute target addr into ctr
lmw %r3,24(%r1) # restore r3-r31
lwz %r0,12(%r1) # restore cr
mtcr %r0
lwz %r0,16(%r1) # restore lr
mtlr %r0
lwz %r0,20(%r1) # restore r0
addi %r1,%r1,160 # restore stack
bctr # jump to target
/*
* _rtld_powerpc_pltresolve()
*
* This routine is copied into the latter part of the 72-byte reserved
* area at the start of the PLT. The absolute address of the _rtld_bind_start
* routine, and the ELF object for the loaded file, are inserted into
* the code by the reloc.c:init_pltgot() routine.
* The first time an external routine is called, the PLT slot will
* set up %r11 to the offset of the slot, and will jump to this routine.
* The ELF object is shifted into %r11, and _rtld_bind_start is called
* to complete the binding.
*/
_ENTRY(_rtld_powerpc_pltresolve)
lis %r12,0 # lis 12,_rtld_bind_start@ha
addi %r12,%r12,0 # addi 12,12,_rtld_bind_start@l
mtctr %r12
lis %r12,0 # lis 12,obj@ha
addi %r12,%r12,0 # addi 12,12,obj@l
bctr
/*
* _rtld_powerpc_pltcall()
*
* This routine is copied into the 72-byte reserved area at the
* start of the PLT. The reloc.c:init_pltgot() routine inserts
* the absolute address of the jumptable.
* Control is transferred to this routine when the binder has
* located the external routine, but determined that it is > 32Mb
* from the PLT slot. Code is inserted into the PLT slot to set up
* %r11 with the jumptable index, and jump to here, where the
* absolute address of the external routine is loaded from the
* jumptable and transferred to
*/
_ENTRY(_rtld_powerpc_pltcall)
slwi %r11,%r11,2 # jmptab offset = index * 4
addis %r11,%r11,0 # addis 11,11,jmptab@ha
lwz %r11,0(%r11) # lwz 11,jmptab@l(11)
mtctr %r11
bctr # (*jmptab[index])()