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freebsd-skq/sys/kern/link_elf.c
Peter Wemm f41325db5f With this commit, I hereby pronounce gensetdefs past its use-by date. 
Replace the a.out emulation of 'struct linker_set' with something
a little more flexible.  <sys/linker_set.h> now provides macros for
accessing elements and completely hides the implementation.

The linker_set.h macros have been on the back burner in various
forms since 1998 and has ideas and code from Mike Smith (SET_FOREACH()),
John Polstra (ELF clue) and myself (cleaned up API and the conversion
of the rest of the kernel to use it).

The macros declare a strongly typed set.  They return elements with the
type that you declare the set with, rather than a generic void *.

For ELF, we use the magic ld symbols (__start_<setname> and
__stop_<setname>).  Thanks to Richard Henderson <rth@redhat.com> for the
trick about how to force ld to provide them for kld's.

For a.out, we use the old linker_set struct.

NOTE: the item lists are no longer null terminated.  This is why
the code impact is high in certain areas.

The runtime linker has a new method to find the linker set
boundaries depending on which backend format is in use.

linker sets are still module/kld unfriendly and should never be used
for anything that may be modular one day.

Reviewed by:	eivind
2001-06-13 10:58:39 +00:00

1139 lines
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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>
#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_Off nbuckets; /* DT_HASH info */
Elf_Off nchains;
const Elf_Off* buckets;
const Elf_Off* 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 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),
{ 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
/*
* The kernel symbol table starts here.
*/
#ifndef __ia64__
extern struct _dynamic _DYNAMIC;
#endif
static void
link_elf_init(void* arg)
{
#ifdef __ELF__
Elf_Dyn *dp;
caddr_t modptr, baseptr, sizeptr;
elf_file_t ef;
char *modname;
#endif
linker_add_class(&link_elf_class);
#ifdef __ELF__
#ifndef __ia64__
dp = (Elf_Dyn*) &_DYNAMIC;
#else
dp = 0;
#endif
if (dp) {
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;
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;
ef->gdb.l_name = modname;
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_Off *hashtab = (const Elf_Off *)
(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;
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;
ef->gdb.l_name = lf->filename;
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 proc* p = curproc; /* 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;
shdr = NULL;
lf = NULL;
NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, filename, p);
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, p->p_ucred, &resid, p);
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
mtx_lock(&vm_mtx);
ef->object = vm_object_allocate(OBJT_DEFAULT, mapsize >> PAGE_SHIFT);
if (ef->object == NULL) {
mtx_unlock(&vm_mtx);
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);
mtx_unlock(&vm_mtx);
ef->object = 0;
goto out;
}
mtx_unlock(&vm_mtx);
#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, p->p_ucred, &resid, p);
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
*/
mtx_lock(&vm_mtx);
vm_map_pageable(kernel_map,
(vm_offset_t) segbase,
(vm_offset_t) segbase + segs[i]->p_memsz,
FALSE);
mtx_unlock(&vm_mtx);
#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_dependancies(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, p->p_ucred, &resid, p);
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, p->p_ucred, &resid, p);
if (error)
goto out;
error = vn_rdwr(UIO_READ, nd.ni_vp,
ef->strbase, strcnt, shdr[symstrindex].sh_offset,
UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid, p);
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;
ef->gdb.l_name = filename;
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, p);
vn_close(nd.ni_vp, FREAD, p->p_ucred, p);
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);
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) {
mtx_lock(&vm_mtx);
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);
mtx_unlock(&vm_mtx);
}
#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) {
symname = symbol_name(ef, rel->r_info);
if (elf_reloc(&ef->lf, rel, ELF_RELOC_REL, symname)) {
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) {
symname = symbol_name(ef, rela->r_info);
if (elf_reloc(&ef->lf, rela, ELF_RELOC_RELA, symname)) {
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) {
symname = symbol_name(ef, rel->r_info);
if (elf_reloc(&ef->lf, rel, ELF_RELOC_REL, symname)) {
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) {
symname = symbol_name(ef, rela->r_info);
if (elf_reloc(&ef->lf, rela, ELF_RELOC_RELA, symname)) {
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;
}
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