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freebsd-dev/sys/kern/link_elf.c
Marcel Moolenaar d297ad160e Don't use the symbol name to lookup the symbol value when we can use 
the symbol index defined by the relocation. The elf_lookup() support
function is to be used by elf_reloc() when symbol lookups need to be
done. The elf_lookup() function operates on the symbol index and
will do a symbol name based lookup when such is required, otherwise
it uses the symbol index directly. This solves the problem seen on
ia64 where the symbol hash table does not contain local symbols and
a symbol name based lookup would fail for those symbols.

Don't pass the symbol name to elf_reloc(), as it isn't used any more.
2002-04-25 01:22:16 +00:00

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/*-
* Copyright (c) 1998-2000 Doug Rabson
* 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.
*
* $FreeBSD$
*/
#include "opt_ddb.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/lock.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>
#ifdef GPROF
#include <machine/profile.h>
#endif
#include <vm/vm.h>
#include <vm/vm_param.h>
#ifdef SPARSE_MAPPING
#include <vm/vm_object.h>
#include <vm/vm_kern.h>
#include <vm/vm_extern.h>
#endif
#include <vm/pmap.h>
#include <vm/vm_map.h>
#ifdef __AOUT__
#include <nlist.h>
#endif
#include <link.h>
#include "linker_if.h"
typedef struct elf_file {
struct linker_file lf; /* Common fields */
int preloaded; /* Was file pre-loaded */
caddr_t address; /* Relocation address */
#ifdef SPARSE_MAPPING
vm_object_t object; /* VM object to hold file pages */
#endif
Elf_Dyn* dynamic; /* Symbol table etc. */
Elf_Hashelt nbuckets; /* DT_HASH info */
Elf_Hashelt nchains;
const Elf_Hashelt* buckets;
const Elf_Hashelt* chains;
caddr_t hash;
caddr_t strtab; /* DT_STRTAB */
int strsz; /* DT_STRSZ */
const Elf_Sym* symtab; /* DT_SYMTAB */
Elf_Addr* got; /* DT_PLTGOT */
const Elf_Rel* pltrel; /* DT_JMPREL */
int pltrelsize; /* DT_PLTRELSZ */
const Elf_Rela* pltrela; /* DT_JMPREL */
int pltrelasize; /* DT_PLTRELSZ */
const Elf_Rel* rel; /* DT_REL */
int relsize; /* DT_RELSZ */
const Elf_Rela* rela; /* DT_RELA */
int relasize; /* DT_RELASZ */
caddr_t modptr;
const 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 symbase; /* malloc'ed symbold base */
caddr_t strbase; /* malloc'ed string base */
#ifdef DDB
struct link_map gdb; /* hooks for gdb */
#endif
} *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 void link_elf_unload_preload(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 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",
#else
"elf64",
#endif
link_elf_methods, sizeof(struct elf_file)
};
static int parse_dynamic(elf_file_t ef);
static int relocate_file(elf_file_t ef);
static int link_elf_preload_parse_symbols(elf_file_t ef);
#ifdef DDB
static void r_debug_state(struct r_debug *dummy_one,
struct link_map *dummy_two);
/*
* A list of loaded modules for GDB to use for loading symbols.
*/
struct r_debug r_debug;
#define GDB_STATE(s) r_debug.r_state = s; r_debug_state(NULL, NULL);
/*
* Function for the debugger to set a breakpoint on to gain control.
*/
void
r_debug_state(struct r_debug *dummy_one __unused,
struct link_map *dummy_two __unused)
{
}
#endif
#ifdef __ia64__
Elf_Addr link_elf_get_gp(linker_file_t);
#endif
/*
* The kernel symbol table starts here.
*/
extern struct _dynamic _DYNAMIC;
static void
link_elf_init(void* arg)
{
#ifdef __ELF__
Elf_Dyn *dp;
caddr_t modptr, baseptr, sizeptr;
elf_file_t ef;
char *modname;
#ifdef DDB
char *newfilename;
#endif
#endif
linker_add_class(&link_elf_class);
#ifdef __ELF__
dp = (Elf_Dyn*) &_DYNAMIC;
modname = NULL;
modptr = preload_search_by_type("elf kernel");
if (modptr)
modname = (char *)preload_search_info(modptr, MODINFO_NAME);
if (modname == NULL)
modname = "kernel";
linker_kernel_file = linker_make_file(modname, &link_elf_class);
if (linker_kernel_file == NULL)
panic("link_elf_init: Can't create linker structures for kernel");
ef = (elf_file_t) linker_kernel_file;
ef->preloaded = 1;
ef->address = 0;
#ifdef SPARSE_MAPPING
ef->object = 0;
#endif
ef->dynamic = dp;
if (dp)
parse_dynamic(ef);
linker_kernel_file->address = (caddr_t) KERNBASE;
linker_kernel_file->size = -(intptr_t)linker_kernel_file->address;
if (modptr) {
ef->modptr = modptr;
baseptr = preload_search_info(modptr, MODINFO_ADDR);
if (baseptr)
linker_kernel_file->address = *(caddr_t *)baseptr;
sizeptr = preload_search_info(modptr, MODINFO_SIZE);
if (sizeptr)
linker_kernel_file->size = *(size_t *)sizeptr;
}
(void)link_elf_preload_parse_symbols(ef);
#ifdef DDB
ef->gdb.l_addr = linker_kernel_file->address;
newfilename = malloc(strlen(modname) + 1, M_LINKER, M_WAITOK);
strcpy(newfilename, modname);
ef->gdb.l_name = newfilename;
ef->gdb.l_ld = dp;
ef->gdb.l_prev = 0;
ef->gdb.l_next = 0;
r_debug.r_map = &ef->gdb;
r_debug.r_brk = r_debug_state;
r_debug.r_state = RT_CONSISTENT;
r_debug_state(NULL, NULL); /* say hello to gdb! */
#endif
#endif
}
SYSINIT(link_elf, SI_SUB_KLD, SI_ORDER_SECOND, link_elf_init, 0);
static int
link_elf_preload_parse_symbols(elf_file_t ef)
{
caddr_t pointer;
caddr_t ssym, esym, base;
caddr_t strtab;
int strcnt;
Elf_Sym* symtab;
int symcnt;
if (ef->modptr == NULL)
return 0;
pointer = preload_search_info(ef->modptr, MODINFO_METADATA|MODINFOMD_SSYM);
if (pointer == NULL)
return 0;
ssym = *(caddr_t *)pointer;
pointer = preload_search_info(ef->modptr, MODINFO_METADATA|MODINFOMD_ESYM);
if (pointer == NULL)
return 0;
esym = *(caddr_t *)pointer;
base = ssym;
symcnt = *(long *)base;
base += sizeof(long);
symtab = (Elf_Sym *)base;
base += roundup(symcnt, sizeof(long));
if (base > esym || base < ssym) {
printf("Symbols are corrupt!\n");
return EINVAL;
}
strcnt = *(long *)base;
base += sizeof(long);
strtab = base;
base += roundup(strcnt, sizeof(long));
if (base > esym || base < ssym) {
printf("Symbols are corrupt!\n");
return EINVAL;
}
ef->ddbsymtab = symtab;
ef->ddbsymcnt = symcnt / sizeof(Elf_Sym);
ef->ddbstrtab = strtab;
ef->ddbstrcnt = strcnt;
return 0;
}
static int
parse_dynamic(elf_file_t ef)
{
Elf_Dyn *dp;
int plttype = DT_REL;
for (dp = ef->dynamic; dp->d_tag != DT_NULL; dp++) {
switch (dp->d_tag) {
case DT_HASH:
{
/* From src/libexec/rtld-elf/rtld.c */
const Elf_Hashelt *hashtab = (const Elf_Hashelt *)
(ef->address + dp->d_un.d_ptr);
ef->nbuckets = hashtab[0];
ef->nchains = hashtab[1];
ef->buckets = hashtab + 2;
ef->chains = ef->buckets + ef->nbuckets;
break;
}
case DT_STRTAB:
ef->strtab = (caddr_t) (ef->address + dp->d_un.d_ptr);
break;
case DT_STRSZ:
ef->strsz = dp->d_un.d_val;
break;
case DT_SYMTAB:
ef->symtab = (Elf_Sym*) (ef->address + dp->d_un.d_ptr);
break;
case DT_SYMENT:
if (dp->d_un.d_val != sizeof(Elf_Sym))
return ENOEXEC;
break;
case DT_PLTGOT:
ef->got = (Elf_Addr *) (ef->address + dp->d_un.d_ptr);
break;
case DT_REL:
ef->rel = (const Elf_Rel *) (ef->address + dp->d_un.d_ptr);
break;
case DT_RELSZ:
ef->relsize = dp->d_un.d_val;
break;
case DT_RELENT:
if (dp->d_un.d_val != sizeof(Elf_Rel))
return ENOEXEC;
break;
case DT_JMPREL:
ef->pltrel = (const Elf_Rel *) (ef->address + dp->d_un.d_ptr);
break;
case DT_PLTRELSZ:
ef->pltrelsize = dp->d_un.d_val;
break;
case DT_RELA:
ef->rela = (const Elf_Rela *) (ef->address + dp->d_un.d_ptr);
break;
case DT_RELASZ:
ef->relasize = dp->d_un.d_val;
break;
case DT_RELAENT:
if (dp->d_un.d_val != sizeof(Elf_Rela))
return ENOEXEC;
break;
case DT_PLTREL:
plttype = dp->d_un.d_val;
if (plttype != DT_REL && plttype != DT_RELA)
return ENOEXEC;
break;
#ifdef DDB
case DT_DEBUG:
dp->d_un.d_ptr = (Elf_Addr) &r_debug;
break;
#endif
}
}
if (plttype == DT_RELA) {
ef->pltrela = (const Elf_Rela *) ef->pltrel;
ef->pltrel = NULL;
ef->pltrelasize = ef->pltrelsize;
ef->pltrelsize = 0;
}
ef->ddbsymtab = ef->symtab;
ef->ddbsymcnt = ef->nchains;
ef->ddbstrtab = ef->strtab;
ef->ddbstrcnt = ef->strsz;
return 0;
}
static void
link_elf_error(const char *s)
{
printf("kldload: %s\n", s);
}
#ifdef DDB
static void
link_elf_add_gdb(struct link_map *l)
{
struct link_map *prev;
/*
* Scan to the end of the list.
*/
for (prev = r_debug.r_map; prev->l_next != NULL; prev = prev->l_next)
;
/* Link in the new entry. */
l->l_prev = prev;
l->l_next = prev->l_next;
prev->l_next = l;
}
static void
link_elf_delete_gdb(struct link_map *l)
{
if (l->l_prev == NULL) {
if ((r_debug.r_map = l->l_next) != NULL)
l->l_next->l_prev = NULL;
return;
}
if ((l->l_prev->l_next = l->l_next) != NULL)
l->l_next->l_prev = l->l_prev;
}
#endif /* DDB */
static int
link_elf_link_preload(linker_class_t cls,
const char* filename, linker_file_t *result)
{
caddr_t modptr, baseptr, sizeptr, dynptr;
char *type;
elf_file_t ef;
linker_file_t lf;
int error;
vm_offset_t dp;
/* Look to see if we have the file preloaded */
modptr = preload_search_by_name(filename);
if (modptr == NULL)
return ENOENT;
type = (char *)preload_search_info(modptr, MODINFO_TYPE);
baseptr = preload_search_info(modptr, MODINFO_ADDR);
sizeptr = preload_search_info(modptr, MODINFO_SIZE);
dynptr = preload_search_info(modptr, MODINFO_METADATA|MODINFOMD_DYNAMIC);
if (type == NULL || strcmp(type, "elf module") != 0)
return (EFTYPE);
if (baseptr == NULL || sizeptr == NULL || dynptr == NULL)
return (EINVAL);
lf = linker_make_file(filename, &link_elf_class);
if (lf == NULL) {
return ENOMEM;
}
ef = (elf_file_t) lf;
ef->preloaded = 1;
ef->modptr = modptr;
ef->address = *(caddr_t *)baseptr;
#ifdef SPARSE_MAPPING
ef->object = 0;
#endif
dp = (vm_offset_t)ef->address + *(vm_offset_t *)dynptr;
ef->dynamic = (Elf_Dyn *)dp;
lf->address = ef->address;
lf->size = *(size_t *)sizeptr;
error = parse_dynamic(ef);
if (error) {
linker_file_unload(lf);
return error;
}
*result = lf;
return (0);
}
static int
link_elf_link_preload_finish(linker_file_t lf)
{
elf_file_t ef;
int error;
#ifdef DDB
char *newfilename;
#endif
ef = (elf_file_t) lf;
#if 0 /* this will be more trouble than it's worth for now */
for (dp = ef->dynamic; dp->d_tag != DT_NULL; dp++) {
if (dp->d_tag != DT_NEEDED)
continue;
modname = ef->strtab + dp->d_un.d_val;
error = linker_load_module(modname, lf);
if (error)
goto out;
}
#endif
error = relocate_file(ef);
if (error)
return error;
(void)link_elf_preload_parse_symbols(ef);
#ifdef DDB
GDB_STATE(RT_ADD);
ef->gdb.l_addr = lf->address;
newfilename = malloc(strlen(lf->filename) + 1, M_LINKER, M_WAITOK);
strcpy(newfilename, lf->filename);
ef->gdb.l_name = newfilename;
ef->gdb.l_ld = ef->dynamic;
link_elf_add_gdb(&ef->gdb);
GDB_STATE(RT_CONSISTENT);
#endif
return (0);
}
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;
caddr_t firstpage;
int nbytes, i;
Elf_Phdr *phdr;
Elf_Phdr *phlimit;
Elf_Phdr *segs[2];
int nsegs;
Elf_Phdr *phdyn;
Elf_Phdr *phphdr;
caddr_t mapbase;
size_t mapsize;
Elf_Off base_offset;
Elf_Addr base_vaddr;
Elf_Addr base_vlimit;
int error = 0;
int resid, flags;
elf_file_t ef;
linker_file_t lf;
Elf_Shdr *shdr;
int symtabindex;
int symstrindex;
int symcnt;
int strcnt;
#ifdef DDB
char *newfilename;
#endif
GIANT_REQUIRED;
shdr = NULL;
lf = NULL;
NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, filename, td);
flags = FREAD;
error = vn_open(&nd, &flags, 0);
if (error)
return error;
NDFREE(&nd, NDF_ONLY_PNBUF);
/*
* Read the elf header from the file.
*/
firstpage = malloc(PAGE_SIZE, M_LINKER, M_WAITOK);
if (firstpage == NULL) {
error = ENOMEM;
goto out;
}
hdr = (Elf_Ehdr *)firstpage;
error = vn_rdwr(UIO_READ, nd.ni_vp, firstpage, PAGE_SIZE, 0,
UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, &resid, td);
nbytes = PAGE_SIZE - resid;
if (error)
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_EXEC && hdr->e_type != ET_DYN) {
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;
}
/*
* We rely on the program header being in the first page. This is
* not strictly required by the ABI specification, but it seems to
* always true in practice. And, it simplifies things considerably.
*/
if (!((hdr->e_phentsize == sizeof(Elf_Phdr)) &&
(hdr->e_phoff + hdr->e_phnum*sizeof(Elf_Phdr) <= PAGE_SIZE) &&
(hdr->e_phoff + hdr->e_phnum*sizeof(Elf_Phdr) <= nbytes)))
link_elf_error("Unreadable program headers");
/*
* Scan the program header entries, and save key information.
*
* We rely on there being exactly two load segments, text and data,
* in that order.
*/
phdr = (Elf_Phdr *) (firstpage + hdr->e_phoff);
phlimit = phdr + hdr->e_phnum;
nsegs = 0;
phdyn = NULL;
phphdr = NULL;
while (phdr < phlimit) {
switch (phdr->p_type) {
case PT_LOAD:
if (nsegs == 2) {
link_elf_error("Too many sections");
error = ENOEXEC;
goto out;
}
segs[nsegs] = phdr;
++nsegs;
break;
case PT_PHDR:
phphdr = phdr;
break;
case PT_DYNAMIC:
phdyn = phdr;
break;
case PT_INTERP:
link_elf_error("Unsupported file type");
error = ENOEXEC;
goto out;
}
++phdr;
}
if (phdyn == NULL) {
link_elf_error("Object is not dynamically-linked");
error = ENOEXEC;
goto out;
}
/*
* Allocate the entire address space of the object, to stake out our
* contiguous region, and to establish the base address for relocation.
*/
base_offset = trunc_page(segs[0]->p_offset);
base_vaddr = trunc_page(segs[0]->p_vaddr);
base_vlimit = round_page(segs[1]->p_vaddr + segs[1]->p_memsz);
mapsize = base_vlimit - base_vaddr;
lf = linker_make_file(filename, &link_elf_class);
if (!lf) {
error = ENOMEM;
goto out;
}
ef = (elf_file_t) lf;
#ifdef SPARSE_MAPPING
ef->object = vm_object_allocate(OBJT_DEFAULT, mapsize >> PAGE_SHIFT);
if (ef->object == NULL) {
free(ef, M_LINKER);
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, 1,
VM_PROT_ALL, VM_PROT_ALL, 0);
if (error) {
vm_object_deallocate(ef->object);
ef->object = 0;
goto out;
}
#else
ef->address = malloc(mapsize, M_LINKER, M_WAITOK);
if (!ef->address) {
error = ENOMEM;
goto out;
}
#endif
mapbase = ef->address;
/*
* Read the text and data sections and zero the bss.
*/
for (i = 0; i < 2; i++) {
caddr_t segbase = mapbase + segs[i]->p_vaddr - base_vaddr;
error = vn_rdwr(UIO_READ, nd.ni_vp,
segbase, segs[i]->p_filesz, segs[i]->p_offset,
UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, &resid, td);
if (error) {
goto out;
}
bzero(segbase + segs[i]->p_filesz,
segs[i]->p_memsz - segs[i]->p_filesz);
#ifdef SPARSE_MAPPING
/*
* Wire down the pages
*/
vm_map_pageable(kernel_map,
(vm_offset_t) segbase,
(vm_offset_t) segbase + segs[i]->p_memsz,
FALSE);
#endif
}
#ifdef GPROF
/* Update profiling information with the new text segment. */
kmupetext((uintfptr_t)(mapbase + segs[0]->p_vaddr - base_vaddr +
segs[0]->p_memsz));
#endif
ef->dynamic = (Elf_Dyn *) (mapbase + phdyn->p_vaddr - base_vaddr);
lf->address = ef->address;
lf->size = mapsize;
error = parse_dynamic(ef);
if (error)
goto out;
error = linker_load_dependencies(lf);
if (error)
goto out;
#if 0 /* this will be more trouble than it's worth for now */
for (dp = ef->dynamic; dp->d_tag != DT_NULL; dp++) {
if (dp->d_tag != DT_NEEDED)
continue;
modname = ef->strtab + dp->d_un.d_val;
error = linker_load_module(modname, lf);
if (error)
goto out;
}
#endif
error = relocate_file(ef);
if (error)
goto out;
/* Try and load the symbol table if it's present. (you can strip it!) */
nbytes = hdr->e_shnum * hdr->e_shentsize;
if (nbytes == 0 || hdr->e_shoff == 0)
goto nosyms;
shdr = malloc(nbytes, M_LINKER, M_WAITOK | M_ZERO);
if (shdr == NULL) {
error = ENOMEM;
goto out;
}
error = vn_rdwr(UIO_READ, nd.ni_vp,
(caddr_t)shdr, nbytes, hdr->e_shoff,
UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, &resid, td);
if (error)
goto out;
symtabindex = -1;
symstrindex = -1;
for (i = 0; i < hdr->e_shnum; i++) {
if (shdr[i].sh_type == SHT_SYMTAB) {
symtabindex = i;
symstrindex = shdr[i].sh_link;
}
}
if (symtabindex < 0 || symstrindex < 0)
goto nosyms;
symcnt = shdr[symtabindex].sh_size;
ef->symbase = malloc(symcnt, M_LINKER, M_WAITOK);
strcnt = shdr[symstrindex].sh_size;
ef->strbase = malloc(strcnt, M_LINKER, M_WAITOK);
if (ef->symbase == NULL || ef->strbase == NULL) {
error = ENOMEM;
goto out;
}
error = vn_rdwr(UIO_READ, nd.ni_vp,
ef->symbase, symcnt, shdr[symtabindex].sh_offset,
UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, &resid, td);
if (error)
goto out;
error = vn_rdwr(UIO_READ, nd.ni_vp,
ef->strbase, strcnt, shdr[symstrindex].sh_offset,
UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, &resid, td);
if (error)
goto out;
ef->ddbsymcnt = symcnt / sizeof(Elf_Sym);
ef->ddbsymtab = (const Elf_Sym *)ef->symbase;
ef->ddbstrcnt = strcnt;
ef->ddbstrtab = ef->strbase;
#ifdef DDB
GDB_STATE(RT_ADD);
ef->gdb.l_addr = lf->address;
newfilename = malloc(strlen(filename) + 1, M_LINKER, M_WAITOK);
strcpy(newfilename, filename);
ef->gdb.l_name = (const char *)newfilename;
ef->gdb.l_ld = ef->dynamic;
link_elf_add_gdb(&ef->gdb);
GDB_STATE(RT_CONSISTENT);
#endif
nosyms:
*result = lf;
out:
if (error && lf)
linker_file_unload(lf);
if (shdr)
free(shdr, M_LINKER);
if (firstpage)
free(firstpage, 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;
#ifdef DDB
if (ef->gdb.l_ld) {
GDB_STATE(RT_DELETE);
free((void *)(uintptr_t)ef->gdb.l_name, M_LINKER);
link_elf_delete_gdb(&ef->gdb);
GDB_STATE(RT_CONSISTENT);
}
#endif
if (ef->preloaded) {
link_elf_unload_preload(file);
return;
}
#ifdef SPARSE_MAPPING
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);
}
#else
if (ef->address)
free(ef->address, M_LINKER);
#endif
if (ef->symbase)
free(ef->symbase, M_LINKER);
if (ef->strbase)
free(ef->strbase, M_LINKER);
}
static void
link_elf_unload_preload(linker_file_t file)
{
if (file->filename)
preload_delete_name(file->filename);
}
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->symtab + ELF_R_SYM(r_info);
return ef->strtab + ref->st_name;
} else
return NULL;
}
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;
/* Perform relocations without addend if there are any: */
rel = ef->rel;
if (rel) {
rellim = (const Elf_Rel *)((const char *)ef->rel + ef->relsize);
while (rel < rellim) {
if (elf_reloc(&ef->lf, rel, ELF_RELOC_REL)) {
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: */
rela = ef->rela;
if (rela) {
relalim = (const Elf_Rela *)((const char *)ef->rela + ef->relasize);
while (rela < relalim) {
if (elf_reloc(&ef->lf, rela, ELF_RELOC_RELA)) {
symname = symbol_name(ef, rela->r_info);
printf("link_elf: symbol %s undefined\n", symname);
return ENOENT;
}
rela++;
}
}
/* Perform PLT relocations without addend if there are any: */
rel = ef->pltrel;
if (rel) {
rellim = (const Elf_Rel *)((const char *)ef->pltrel + ef->pltrelsize);
while (rel < rellim) {
if (elf_reloc(&ef->lf, rel, ELF_RELOC_REL)) {
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: */
rela = ef->pltrela;
if (rela) {
relalim = (const Elf_Rela *)((const char *)ef->pltrela + ef->pltrelasize);
while (rela < relalim) {
if (elf_reloc(&ef->lf, rela, ELF_RELOC_RELA)) {
symname = symbol_name(ef, rela->r_info);
printf("link_elf: symbol %s undefined\n", symname);
return ENOENT;
}
rela++;
}
}
return 0;
}
/*
* Hash function for symbol table lookup. Don't even think about changing
* this. It is specified by the System V ABI.
*/
static unsigned long
elf_hash(const char *name)
{
const unsigned char *p = (const unsigned char *) name;
unsigned long h = 0;
unsigned long g;
while (*p != '\0') {
h = (h << 4) + *p++;
if ((g = h & 0xf0000000) != 0)
h ^= g >> 24;
h &= ~g;
}
return h;
}
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;
unsigned long symnum;
const Elf_Sym* symp;
const char *strp;
unsigned long hash;
int i;
/* First, search hashed global symbols */
hash = elf_hash(name);
symnum = ef->buckets[hash % ef->nbuckets];
while (symnum != STN_UNDEF) {
if (symnum >= ef->nchains) {
printf("link_elf_lookup_symbol: corrupt symbol table\n");
return ENOENT;
}
symp = ef->symtab + symnum;
if (symp->st_name == 0) {
printf("link_elf_lookup_symbol: corrupt symbol table\n");
return ENOENT;
}
strp = ef->strtab + 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;
}
symnum = ef->chains[symnum];
}
/* If we have not found it, look at the full table (if loaded) */
if (ef->symtab == ef->ddbsymtab)
return ENOENT;
/* 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->symtab && ((es - ef->symtab) < ef->nchains)) {
symval->name = ef->strtab + es->st_name;
symval->value = (caddr_t) ef->address + es->st_value;
symval->size = es->st_size;
return 0;
}
if (ef->symtab == ef->ddbsymtab)
return ENOENT;
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)
{
c_linker_sym_t sym;
linker_symval_t symval;
char *setsym;
void **start, **stop;
int len, error = 0, count;
len = strlen(name) + sizeof("__start_set_"); /* sizeof includes \0 */
setsym = malloc(len, M_LINKER, M_WAITOK);
if (setsym == NULL)
return ENOMEM;
/* get address of first entry */
snprintf(setsym, len, "%s%s", "__start_set_", name);
error = link_elf_lookup_symbol(lf, setsym, &sym);
if (error)
goto out;
link_elf_symbol_values(lf, sym, &symval);
if (symval.value == 0) {
error = ESRCH;
goto out;
}
start = (void **)symval.value;
/* get address of last entry */
snprintf(setsym, len, "%s%s", "__stop_set_", name);
error = link_elf_lookup_symbol(lf, setsym, &sym);
if (error)
goto out;
link_elf_symbol_values(lf, sym, &symval);
if (symval.value == 0) {
error = ESRCH;
goto out;
}
stop = (void **)symval.value;
/* and the number of entries */
count = stop - start;
/* and copy out */
if (startp)
*startp = start;
if (stopp)
*stopp = stop;
if (countp)
*countp = count;
out:
free(setsym, M_LINKER);
return error;
}
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);
}
#ifdef __ia64__
/*
* Each KLD has its own GP. The GP value for each load module is given by
* DT_PLTGOT on ia64. We need GP to construct function descriptors, but
* don't have direct access to the ELF file structure. The link_elf_get_gp()
* function returns the GP given a pointer to a generic linker file struct.
*/
Elf_Addr
link_elf_get_gp(linker_file_t lf)
{
elf_file_t ef = (elf_file_t)lf;
return (Elf_Addr)ef->got;
}
#endif
/*
* 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.
*/
Elf_Addr
elf_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;
/* Don't even try to lookup the symbol if the index is bogus. */
if (symidx >= ef->nchains)
return (0);
sym = ef->symtab + symidx;
/*
* Don't do a full lookup when the symbol is local. It may even
* fail because it may not be found through the hash table.
*/
if (ELF_ST_BIND(sym->st_info) == STB_LOCAL) {
/* Force lookup failure when we have an insanity. */
if (sym->st_shndx == SHN_UNDEF || sym->st_value == 0)
return (0);
return ((Elf_Addr)ef->address + sym->st_value);
}
/*
* XXX we can avoid doing a hash table based lookup for global
* symbols as well. This however is not always valid, so we'll
* just do it the hard way for now. Performance tweaks can
* always be added.
*/
symbol = ef->strtab + sym->st_name;
/* Force a lookup failure if the symbol name is bogus. */
if (*symbol == 0)
return (0);
return ((Elf_Addr)linker_file_lookup_symbol(lf, symbol, deps));
}
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