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freebsd-dev/sys/kern/link_elf_obj.c
Peter Wemm e9eabf5983 Checkpoint commit for an alternative WIP kernel module loader that isn't 
as dependent on binutils features/quirks as the current one.  This one
loads plain .o files without having to mess with shared object mode.

This happens to be essential on amd64, because binutils hasn't implemented
all the quirks/features that we need for producing the hack non-PIC shared
objects.  As it turned out, .o format isn't all that inconvenient after
all.  It looks like the ability to use the same .o files for linking
directly into a static kernel or loading as a module might be worth it.

It is still very much a work-in-progress, but it is almost usable.  Other
changes are still needed in order to use it though, these have not been
committed yet.  There is still a memory corruption/overrun bug somewhere.
For example, test modules load and work, but the machine explodes a few
minutes later in vm_forkproc() or the like.  Notable missing things
include kldxref support, and loader(8) support.  I wanted to figure out
a working baseline set of code first.
2004-04-30 16:32:40 +00:00

951 lines
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/*-
* Copyright (c) 1998-2000 Doug Rabson
* Copyright (c) 2004 Peter Wemm
* 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.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "opt_ddb.h"
#include "opt_mac.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/mac.h>
#include <sys/malloc.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/namei.h>
#include <sys/fcntl.h>
#include <sys/vnode.h>
#include <sys/linker.h>
#include <machine/elf.h>
#include <vm/vm.h>
#include <vm/vm_param.h>
#include <vm/vm_object.h>
#include <vm/vm_kern.h>
#include <vm/vm_extern.h>
#include <vm/pmap.h>
#include <vm/vm_map.h>
#include <sys/link_elf.h>
#include "linker_if.h"
typedef struct {
void *addr;
Elf_Off fileoff;
Elf_Off filesz;
int align;
int flags;
int sec; /* Original section */
char *name;
} Elf_progent;
typedef struct {
void *addr;
Elf_Off memsz;
int align;
int flags;
int sec; /* Original section */
char *name;
} Elf_nobitent;
typedef struct {
Elf_Rel *rel;
Elf_Off fileoff;
Elf_Off filesz;
int sec;
} Elf_relent;
typedef struct {
Elf_Rela *rela;
Elf_Off fileoff;
Elf_Off filesz;
int sec;
} Elf_relaent;
typedef struct elf_file {
struct linker_file lf; /* Common fields */
caddr_t address; /* Relocation address */
vm_object_t object; /* VM object to hold file pages */
Elf_Shdr *e_shdr;
Elf_progent *progtab;
int nprogtab;
Elf_nobitent *nobittab;
int nnobittab;
Elf_relaent *relatab;
int nrela;
Elf_relent *reltab;
int nrel;
Elf_Sym *ddbsymtab; /* The symbol table we are using */
long ddbsymcnt; /* Number of symbols */
caddr_t ddbstrtab; /* String table */
long ddbstrcnt; /* number of bytes in string table */
caddr_t shstrtab; /* Section name string table */
long shstrcnt; /* number of bytes in string table */
} *elf_file_t;
static int link_elf_link_preload(linker_class_t cls,
const char *, linker_file_t *);
static int link_elf_link_preload_finish(linker_file_t);
static int link_elf_load_file(linker_class_t, const char *, linker_file_t *);
static int link_elf_lookup_symbol(linker_file_t, const char *,
c_linker_sym_t *);
static int link_elf_symbol_values(linker_file_t, c_linker_sym_t,
linker_symval_t *);
static int link_elf_search_symbol(linker_file_t, caddr_t value,
c_linker_sym_t *sym, long *diffp);
static void link_elf_unload_file(linker_file_t);
static int link_elf_lookup_set(linker_file_t, const char *,
void ***, void ***, int *);
static int link_elf_each_function_name(linker_file_t,
int (*)(const char *, void *), void *);
static void link_elf_reloc_local(linker_file_t);
static Elf_Addr elf_obj_lookup(linker_file_t lf, Elf_Word symidx, int deps);
static kobj_method_t link_elf_methods[] = {
KOBJMETHOD(linker_lookup_symbol, link_elf_lookup_symbol),
KOBJMETHOD(linker_symbol_values, link_elf_symbol_values),
KOBJMETHOD(linker_search_symbol, link_elf_search_symbol),
KOBJMETHOD(linker_unload, link_elf_unload_file),
KOBJMETHOD(linker_load_file, link_elf_load_file),
KOBJMETHOD(linker_link_preload, link_elf_link_preload),
KOBJMETHOD(linker_link_preload_finish, link_elf_link_preload_finish),
KOBJMETHOD(linker_lookup_set, link_elf_lookup_set),
KOBJMETHOD(linker_each_function_name, link_elf_each_function_name),
{ 0, 0 }
};
static struct linker_class link_elf_class = {
#if ELF_TARG_CLASS == ELFCLASS32
"elf32_obj",
#else
"elf64_obj",
#endif
link_elf_methods, sizeof(struct elf_file)
};
static int relocate_file(elf_file_t ef);
static void
link_elf_error(const char *s)
{
printf("kldload: %s\n", s);
}
static void
link_elf_init(void *arg)
{
linker_add_class(&link_elf_class);
}
SYSINIT(link_elf_obj, SI_SUB_KLD, SI_ORDER_SECOND, link_elf_init, 0);
static int
link_elf_link_preload(linker_class_t cls, const char *filename,
linker_file_t *result)
{
/* preload not done this way */
return (EFTYPE);
}
static int
link_elf_link_preload_finish(linker_file_t lf)
{
/* preload not done this way */
return (EFTYPE);
}
static int
link_elf_load_file(linker_class_t cls, const char *filename,
linker_file_t *result)
{
struct nameidata nd;
struct thread *td = curthread; /* XXX */
Elf_Ehdr *hdr;
Elf_Shdr *shdr;
int nbytes, i;
caddr_t mapbase;
size_t mapsize;
int error = 0;
int resid, flags;
elf_file_t ef;
linker_file_t lf;
int symtabindex;
int symstrindex;
int shstrindex;
int nsym;
int pb, nb, rl, ra;
int alignmask;
GIANT_REQUIRED;
shdr = NULL;
lf = NULL;
mapsize = 0;
hdr = NULL;
NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, filename, td);
flags = FREAD;
error = vn_open(&nd, &flags, 0, -1);
if (error)
return error;
NDFREE(&nd, NDF_ONLY_PNBUF);
#ifdef MAC
error = mac_check_kld_load(td->td_ucred, nd.ni_vp);
if (error) {
goto out;
}
#endif
/* Read the elf header from the file. */
hdr = malloc(sizeof(*hdr), M_LINKER, M_WAITOK);
if (hdr == NULL) {
error = ENOMEM;
goto out;
}
error = vn_rdwr(UIO_READ, nd.ni_vp, (void *)hdr, sizeof(*hdr), 0,
UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
&resid, td);
if (error)
goto out;
if (resid != 0){
error = ENOEXEC;
goto out;
}
if (!IS_ELF(*hdr)) {
error = ENOEXEC;
goto out;
}
if (hdr->e_ident[EI_CLASS] != ELF_TARG_CLASS
|| hdr->e_ident[EI_DATA] != ELF_TARG_DATA) {
link_elf_error("Unsupported file layout");
error = ENOEXEC;
goto out;
}
if (hdr->e_ident[EI_VERSION] != EV_CURRENT
|| hdr->e_version != EV_CURRENT) {
link_elf_error("Unsupported file version");
error = ENOEXEC;
goto out;
}
if (hdr->e_type != ET_REL) {
link_elf_error("Unsupported file type");
error = ENOEXEC;
goto out;
}
if (hdr->e_machine != ELF_TARG_MACH) {
link_elf_error("Unsupported machine");
error = ENOEXEC;
goto out;
}
lf = linker_make_file(filename, &link_elf_class);
if (!lf) {
error = ENOMEM;
goto out;
}
ef = (elf_file_t) lf;
ef->nprogtab = 0;
ef->nnobittab = 0;
ef->e_shdr = 0;
ef->nrel = 0;
ef->nrela = 0;
/* Allocate and read in the section header */
nbytes = hdr->e_shnum * hdr->e_shentsize;
if (nbytes == 0 || hdr->e_shoff == 0 ||
hdr->e_shentsize != sizeof(Elf_Shdr)) {
error = ENOEXEC;
goto out;
}
shdr = malloc(nbytes, M_LINKER, M_WAITOK | M_ZERO);
if (shdr == NULL) {
error = ENOMEM;
goto out;
}
ef->e_shdr = shdr;
error = vn_rdwr(UIO_READ, nd.ni_vp, (caddr_t)shdr, nbytes, hdr->e_shoff,
UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED, &resid, td);
if (error)
goto out;
if (resid) {
error = ENOEXEC;
goto out;
}
/* Scan the section header for information and table sizing. */
nsym = 0;
symtabindex = -1;
symstrindex = -1;
for (i = 0; i < hdr->e_shnum; i++) {
switch (shdr[i].sh_type) {
case SHT_PROGBITS:
ef->nprogtab++;
break;
case SHT_NOBITS:
ef->nnobittab++;
break;
case SHT_SYMTAB:
nsym++;
symtabindex = i;
symstrindex = shdr[i].sh_link;
break;
case SHT_REL:
ef->nrel++;
break;
case SHT_RELA:
ef->nrela++;
break;
case SHT_STRTAB:
break;
}
}
if (ef->nprogtab == 0 && ef->nnobittab == 0) {
link_elf_error("file has no contents");
error = ENOEXEC;
goto out;
}
if (nsym != 1) {
/* Only allow one symbol table for now */
link_elf_error("file has no valid symbol table");
error = ENOEXEC;
goto out;
}
if (symstrindex < 0 || symstrindex > hdr->e_shnum ||
shdr[symstrindex].sh_type != SHT_STRTAB) {
link_elf_error("file has invalid symbol strings");
error = ENOEXEC;
goto out;
}
/* Allocate space for tracking the load chunks */
/* XXX - maybe unneeded. might be able to use the shdr directly */
if (ef->nprogtab != 0)
ef->progtab = malloc(ef->nprogtab * sizeof(*ef->progtab), M_LINKER, M_WAITOK);
if (ef->nnobittab != 0)
ef->nobittab = malloc(ef->nnobittab * sizeof(*ef->nobittab), M_LINKER, M_WAITOK);
if (ef->nrel != 0)
ef->reltab = malloc(ef->nrel * sizeof(*ef->reltab), M_LINKER, M_WAITOK);
if (ef->nrela != 0)
ef->relatab = malloc(ef->nrela * sizeof(*ef->relatab), M_LINKER, M_WAITOK);
/* XXX check for failures */
/* Space for symbol table */
ef->ddbsymcnt = shdr[symtabindex].sh_size / sizeof(Elf_Sym);
ef->ddbsymtab = malloc(shdr[symtabindex].sh_size, M_LINKER, M_WAITOK);
ef->ddbstrcnt = shdr[symstrindex].sh_size;
ef->ddbstrtab = malloc(shdr[symstrindex].sh_size, M_LINKER, M_WAITOK);
if (ef->ddbsymtab == NULL || ef->ddbstrtab == NULL) {
error = ENOMEM;
goto out;
}
/* Do we have a string table for the section names? */
shstrindex = -1;
if (hdr->e_shstrndx != 0 && shdr[hdr->e_shstrndx].sh_type == SHT_STRTAB) {
shstrindex = hdr->e_shstrndx;
ef->shstrcnt = shdr[shstrindex].sh_size;
ef->shstrtab = malloc(shdr[shstrindex].sh_size, M_LINKER, M_WAITOK);
if (ef->shstrtab == NULL) {
error = ENOMEM;
goto out;
}
error = vn_rdwr(UIO_READ, nd.ni_vp,
ef->shstrtab, shdr[shstrindex].sh_size, shdr[shstrindex].sh_offset,
UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
&resid, td);
if (error)
goto out;
}
/* Size code/data(progbits) and bss(nobits). allocate space for relocs */
pb = 0;
nb = 0;
rl = 0;
ra = 0;
alignmask = 0;
for (i = 0; i < hdr->e_shnum; i++) {
switch (shdr[i].sh_type) {
case SHT_PROGBITS:
case SHT_NOBITS:
alignmask = shdr[i].sh_addralign - 1;
mapsize += alignmask;
mapsize &= ~alignmask;
break;
}
switch (shdr[i].sh_type) {
case SHT_PROGBITS:
ef->progtab[pb].addr = (void *)(uintptr_t)mapsize;
ef->progtab[pb].fileoff = shdr[i].sh_offset;
ef->progtab[pb].filesz = shdr[i].sh_size;
ef->progtab[pb].align = shdr[i].sh_addralign;
ef->progtab[pb].sec = i;
if (ef->shstrtab && shdr[i].sh_name != 0)
ef->progtab[pb].name = ef->shstrtab + shdr[i].sh_name;
else
ef->progtab[pb].name = "<<PROGBITS>>";
mapsize += shdr[i].sh_size;
pb++;
break;
case SHT_NOBITS:
ef->nobittab[nb].addr = (void *)(uintptr_t)mapsize;
ef->nobittab[nb].memsz = shdr[i].sh_size;
ef->nobittab[nb].align = shdr[i].sh_addralign;
ef->nobittab[nb].sec = i;
if (ef->shstrtab && shdr[i].sh_name != 0)
ef->nobittab[nb].name = ef->shstrtab + shdr[i].sh_name;
else
ef->nobittab[nb].name = "<<NOBITS>>";
mapsize += shdr[i].sh_size;
nb++;
break;
case SHT_REL:
ef->reltab[rl].rel = malloc(shdr[i].sh_size, M_LINKER, M_WAITOK);
ef->reltab[rl].fileoff = shdr[i].sh_offset;
ef->reltab[rl].filesz = shdr[i].sh_size;
ef->reltab[rl].sec = shdr[i].sh_info;
rl++;
break;
case SHT_RELA:
ef->relatab[ra].rela = malloc(shdr[i].sh_size, M_LINKER, M_WAITOK);
ef->relatab[ra].fileoff = shdr[i].sh_offset;
ef->relatab[ra].filesz = shdr[i].sh_size;
ef->relatab[ra].sec = shdr[i].sh_info;
ra++;
break;
}
}
if (pb != ef->nprogtab)
panic("lots progbits");
if (nb != ef->nnobittab)
panic("lots nobits");
if (rl != ef->nrel)
panic("lots rel");
if (ra != ef->nrela)
panic("lots rela");
/*
* We know how much space we need for the text/data/bss/etc.
* This stuff needs to be in a single chunk so that profiling etc
* can get the bounds and gdb can associate offsets with modules
*/
ef->object = vm_object_allocate(OBJT_DEFAULT, round_page(mapsize) >> PAGE_SHIFT);
if (ef->object == NULL) {
error = ENOMEM;
goto out;
}
vm_object_reference(ef->object);
ef->address = (caddr_t) vm_map_min(kernel_map);
error = vm_map_find(kernel_map, ef->object, 0,
(vm_offset_t *) &ef->address, mapsize, TRUE, VM_PROT_ALL, VM_PROT_ALL, FALSE);
if (error) {
vm_object_deallocate(ef->object);
ef->object = 0;
goto out;
}
mapbase = ef->address;
/* Wire the pages */
vm_map_wire(kernel_map, (vm_offset_t)mapbase,
(vm_offset_t)mapbase + round_page(mapsize),
VM_MAP_WIRE_SYSTEM|VM_MAP_WIRE_NOHOLES);
/* Add the base address to the previously calculated/aligned offsets */
for (i = 0; i < ef->nprogtab; i++)
ef->progtab[i].addr = mapbase + (uintptr_t)ef->progtab[i].addr;
for (i = 0; i < ef->nnobittab; i++)
ef->nobittab[i].addr = mapbase + (uintptr_t)ef->nobittab[i].addr;
/* Load the symbol table. */
error = vn_rdwr(UIO_READ, nd.ni_vp,
(void *)ef->ddbsymtab, shdr[symtabindex].sh_size, shdr[symtabindex].sh_offset,
UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
&resid, td);
if (error)
goto out;
error = vn_rdwr(UIO_READ, nd.ni_vp,
ef->ddbstrtab, shdr[symstrindex].sh_size, shdr[symstrindex].sh_offset,
UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
&resid, td);
if (error)
goto out;
/* Read in the text/data/set/etc sections */
for (i = 0; i < ef->nprogtab; i++) {
error = vn_rdwr(UIO_READ, nd.ni_vp,
ef->progtab[i].addr,
ef->progtab[i].filesz,
ef->progtab[i].fileoff,
UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
&resid, td);
if (error)
goto out;
}
/*
* Read in relocation tables. Platforms use rel or rela, but
* usually not both.
*/
for (i = 0; i < ef->nrel; i++) {
error = vn_rdwr(UIO_READ, nd.ni_vp,
(void *)ef->reltab[i].rel,
ef->reltab[i].filesz,
ef->reltab[i].fileoff,
UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
&resid, td);
if (error)
goto out;
}
for (i = 0; i < ef->nrela; i++) {
error = vn_rdwr(UIO_READ, nd.ni_vp,
(void *)ef->relatab[i].rela,
ef->relatab[i].filesz,
ef->relatab[i].fileoff,
UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
&resid, td);
if (error)
goto out;
}
/* Inform the kld system about the situation */
lf->address = ef->address = mapbase;
lf->size = mapsize;
/* Local intra-module relocations */
link_elf_reloc_local(lf);
/* Pull in dependencies */
error = linker_load_dependencies(lf);
if (error)
goto out;
/* External relocations */
error = relocate_file(ef);
if (error)
goto out;
/* Notify MD code that a module is being loaded. */
error = elf_cpu_load_file(lf);
if (error)
goto out;
*result = lf;
out:
if (error && lf)
linker_file_unload(lf);
if (hdr)
free(hdr, M_LINKER);
VOP_UNLOCK(nd.ni_vp, 0, td);
vn_close(nd.ni_vp, FREAD, td->td_ucred, td);
return error;
}
static void
link_elf_unload_file(linker_file_t file)
{
elf_file_t ef = (elf_file_t) file;
/* Notify MD code that a module is being unloaded. */
elf_cpu_unload_file(file);
if (ef->object) {
vm_map_remove(kernel_map, (vm_offset_t) ef->address,
(vm_offset_t) ef->address + (ef->object->size << PAGE_SHIFT));
vm_object_deallocate(ef->object);
}
if (ef->e_shdr)
free(ef->e_shdr, M_LINKER);
if (ef->ddbsymtab)
free(ef->ddbsymtab, M_LINKER);
if (ef->ddbstrtab)
free(ef->ddbstrtab, M_LINKER);
}
static const char *
symbol_name(elf_file_t ef, Elf_Word r_info)
{
const Elf_Sym *ref;
if (ELF_R_SYM(r_info)) {
ref = ef->ddbsymtab + ELF_R_SYM(r_info);
return ef->ddbstrtab + ref->st_name;
} else
return NULL;
}
static Elf_Addr
findbase(elf_file_t ef, int sec)
{
int i;
Elf_Addr base = 0;
for (i = 0; i < ef->nprogtab; i++) {
if (sec == ef->progtab[i].sec)
base = (Elf_Addr)ef->progtab[i].addr;
}
if (base == 0) {
for (i = 0; i < ef->nnobittab; i++) {
if (sec == ef->nobittab[i].sec)
base = (Elf_Addr)ef->nobittab[i].addr;
}
}
if (base == 0)
base = (Elf_Addr)ef->address;
return base;
}
static int
relocate_file(elf_file_t ef)
{
const Elf_Rel *rellim;
const Elf_Rel *rel;
const Elf_Rela *relalim;
const Elf_Rela *rela;
const char *symname;
const Elf_Sym *sym;
int i;
Elf_Word symidx;
Elf_Addr base;
/* Perform relocations without addend if there are any: */
for (i = 0; i < ef->nrel; i++) {
rel = ef->reltab[i].rel;
if (rel) {
rellim = (const Elf_Rel *)((const char *)rel + ef->reltab[i].filesz);
base = findbase(ef, ef->reltab[i].sec);
while (rel < rellim) {
symidx = ELF_R_SYM(rel->r_info);
if (symidx < ef->ddbsymcnt) {
sym = ef->ddbsymtab + symidx;
if (ELF64_ST_BIND(sym->st_info) != STB_LOCAL) {
if (elf_reloc(&ef->lf, base, rel, ELF_RELOC_REL, elf_obj_lookup)) {
symname = symbol_name(ef, rel->r_info);
printf("link_elf: symbol %s undefined\n", symname);
return ENOENT;
}
}
}
rel++;
}
}
}
/* Perform relocations with addend if there are any: */
for (i = 0; i < ef->nrela; i++) {
rela = ef->relatab[i].rela;
if (rela) {
relalim = (const Elf_Rela *)((const char *)rela + ef->relatab[i].filesz);
base = findbase(ef, ef->relatab[i].sec);
while (rela < relalim) {
symidx = ELF_R_SYM(rela->r_info);
if (symidx < ef->ddbsymcnt) {
sym = ef->ddbsymtab + symidx;
if (ELF64_ST_BIND(sym->st_info) != STB_LOCAL) {
if (elf_reloc(&ef->lf, base, rela, ELF_RELOC_RELA, elf_obj_lookup)) {
symname = symbol_name(ef, rela->r_info);
printf("link_elf: symbol %s undefined\n", symname);
return ENOENT;
}
}
}
rela++;
}
}
}
return 0;
}
static int
link_elf_lookup_symbol(linker_file_t lf, const char *name, c_linker_sym_t *sym)
{
elf_file_t ef = (elf_file_t) lf;
const Elf_Sym *symp;
const char *strp;
int i;
/* XXX search for globals first */
/* Exhaustive search */
for (i = 0, symp = ef->ddbsymtab; i < ef->ddbsymcnt; i++, symp++) {
strp = ef->ddbstrtab + symp->st_name;
if (strcmp(name, strp) == 0) {
if (symp->st_shndx != SHN_UNDEF ||
(symp->st_value != 0 &&
ELF_ST_TYPE(symp->st_info) == STT_FUNC)) {
*sym = (c_linker_sym_t) symp;
return 0;
} else
return ENOENT;
}
}
return ENOENT;
}
static int
link_elf_symbol_values(linker_file_t lf, c_linker_sym_t sym, linker_symval_t *symval)
{
elf_file_t ef = (elf_file_t) lf;
const Elf_Sym *es = (const Elf_Sym*) sym;
if (es >= ef->ddbsymtab && es < (ef->ddbsymtab + ef->ddbsymcnt)) {
symval->name = ef->ddbstrtab + es->st_name;
symval->value = (caddr_t) ef->address + es->st_value;
symval->size = es->st_size;
return 0;
}
return ENOENT;
}
static int
link_elf_search_symbol(linker_file_t lf, caddr_t value,
c_linker_sym_t *sym, long *diffp)
{
elf_file_t ef = (elf_file_t) lf;
u_long off = (uintptr_t) (void *) value;
u_long diff = off;
u_long st_value;
const Elf_Sym *es;
const Elf_Sym *best = 0;
int i;
for (i = 0, es = ef->ddbsymtab; i < ef->ddbsymcnt; i++, es++) {
if (es->st_name == 0)
continue;
st_value = es->st_value + (uintptr_t) (void *) ef->address;
if (off >= st_value) {
if (off - st_value < diff) {
diff = off - st_value;
best = es;
if (diff == 0)
break;
} else if (off - st_value == diff) {
best = es;
}
}
}
if (best == 0)
*diffp = off;
else
*diffp = diff;
*sym = (c_linker_sym_t) best;
return 0;
}
/*
* Look up a linker set on an ELF system.
*/
static int
link_elf_lookup_set(linker_file_t lf, const char *name,
void ***startp, void ***stopp, int *countp)
{
elf_file_t ef = (elf_file_t)lf;
void **start, **stop;
int i, count;
/* Relative to section number */
for (i = 0; i < ef->nprogtab; i++) {
if ((strncmp(ef->progtab[i].name, "set_", 4) == 0) &&
strcmp(ef->progtab[i].name + 4, name) == 0) {
start = (void **)ef->progtab[i].addr;
stop = (void **)((char *)ef->progtab[i].addr + ef->progtab[i].filesz);
count = stop - start;
if (startp)
*startp = start;
if (stopp)
*stopp = stop;
if (countp)
*countp = count;
return (0);
}
}
return (ESRCH);
}
static int
link_elf_each_function_name(linker_file_t file,
int (*callback)(const char *, void *), void *opaque)
{
elf_file_t ef = (elf_file_t)file;
const Elf_Sym *symp;
int i, error;
/* Exhaustive search */
for (i = 0, symp = ef->ddbsymtab; i < ef->ddbsymcnt; i++, symp++) {
if (symp->st_value != 0 &&
ELF_ST_TYPE(symp->st_info) == STT_FUNC) {
error = callback(ef->ddbstrtab + symp->st_name, opaque);
if (error)
return (error);
}
}
return (0);
}
/*
* Symbol lookup function that can be used when the symbol index is known (ie
* in relocations). It uses the symbol index instead of doing a fully fledged
* hash table based lookup when such is valid. For example for local symbols.
* This is not only more efficient, it's also more correct. It's not always
* the case that the symbol can be found through the hash table.
*/
static Elf_Addr
elf_obj_lookup(linker_file_t lf, Elf_Word symidx, int deps)
{
elf_file_t ef = (elf_file_t)lf;
const Elf_Sym *sym;
const char *symbol;
Elf_Addr ret;
int i;
/* Don't even try to lookup the symbol if the index is bogus. */
if (symidx >= ef->ddbsymcnt)
return (0);
sym = ef->ddbsymtab + symidx;
/* Theoretically we can avoid a lookup for some locals */
switch (ELF64_ST_BIND(sym->st_info)) {
case STB_LOCAL:
/* Local, but undefined? huh? */
if (sym->st_shndx == SHN_UNDEF)
return (0);
ret = 0;
/* Relative to section number */
for (i = 0; i < ef->nprogtab; i++) {
if (sym->st_shndx == ef->progtab[i].sec) {
ret = (Elf_Addr)ef->progtab[i].addr;
break;
}
}
if (ret == 0) {
for (i = 0; i < ef->nnobittab; i++) {
if (sym->st_shndx == ef->nobittab[i].sec) {
ret = (Elf_Addr)ef->nobittab[i].addr;
break;
}
}
}
return ret + sym->st_value;
case STB_GLOBAL:
/* Relative to Data or Function name */
symbol = ef->ddbstrtab + sym->st_name;
/* Force a lookup failure if the symbol name is bogus. */
if (*symbol == 0)
return (0);
ret = ((Elf_Addr)linker_file_lookup_symbol(lf, symbol, deps));
return ret;
case STB_WEAK:
printf("Weak symbols not supported\n");
return (0);
default:
return (0);
}
}
static void
link_elf_reloc_local(linker_file_t lf)
{
elf_file_t ef = (elf_file_t)lf;
const Elf_Rel *rellim;
const Elf_Rel *rel;
const Elf_Rela *relalim;
const Elf_Rela *rela;
const Elf_Sym *sym;
Elf_Addr base;
int i;
Elf_Word symidx;
/* Perform relocations without addend if there are any: */
for (i = 0; i < ef->nrel; i++) {
rel = ef->reltab[i].rel;
if (rel) {
rellim = (const Elf_Rel *)((const char *)rel + ef->reltab[i].filesz);
base = findbase(ef, ef->reltab[i].sec);
while (rel < rellim) {
symidx = ELF_R_SYM(rel->r_info);
if (symidx < ef->ddbsymcnt) {
sym = ef->ddbsymtab + symidx;
if (ELF64_ST_BIND(sym->st_info) == STB_LOCAL)
elf_reloc_local(lf, base, rel, ELF_RELOC_REL, elf_obj_lookup);
}
rel++;
}
}
}
/* Perform relocations with addend if there are any: */
for (i = 0; i < ef->nrela; i++) {
rela = ef->relatab[i].rela;
if (rela) {
relalim = (const Elf_Rela *)((const char *)rela + ef->relatab[i].filesz);
base = findbase(ef, ef->relatab[i].sec);
while (rela < relalim) {
symidx = ELF_R_SYM(rela->r_info);
if (symidx < ef->ddbsymcnt) {
sym = ef->ddbsymtab + symidx;
if (ELF64_ST_BIND(sym->st_info) == STB_LOCAL)
elf_reloc_local(lf, base, rela, ELF_RELOC_RELA, elf_obj_lookup);
}
rela++;
}
}
}
}
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