504 lines
12 KiB
C
504 lines
12 KiB
C
/*-
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* Copyright (c) 1998 Doug Rabson
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* $Id$
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*/
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#include <sys/param.h>
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#include <sys/kernel.h>
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#include <sys/systm.h>
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#include <sys/malloc.h>
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#include <sys/proc.h>
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#include <sys/namei.h>
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#include <sys/fcntl.h>
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#include <sys/vnode.h>
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#include <sys/linker.h>
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#include <machine/elf.h>
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static int link_elf_load_file(const char*, linker_file_t*);
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static int link_elf_lookup_symbol(linker_file_t, const char*,
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linker_sym_t*);
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static void link_elf_symbol_values(linker_file_t, linker_sym_t, linker_symval_t*);
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static int link_elf_search_symbol(linker_file_t, caddr_t value,
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linker_sym_t* sym, long* diffp);
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static void link_elf_unload(linker_file_t);
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/*
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* The file representing the currently running kernel. This contains
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* the global symbol table.
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*/
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linker_file_t linker_kernel_file;
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static struct linker_class_ops link_elf_class_ops = {
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link_elf_load_file,
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};
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static struct linker_file_ops link_elf_file_ops = {
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link_elf_lookup_symbol,
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link_elf_symbol_values,
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link_elf_search_symbol,
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link_elf_unload,
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};
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typedef struct elf_file {
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caddr_t address; /* Load address */
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Elf_Dyn* dynamic; /* Symbol table etc. */
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Elf_Off nbuckets; /* DT_HASH info */
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Elf_Off nchains;
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const Elf_Off* buckets;
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const Elf_Off* chains;
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caddr_t hash;
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caddr_t strtab; /* DT_STRTAB */
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Elf_Sym* symtab; /* DT_SYMTAB */
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} *elf_file_t;
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static int parse_dynamic(linker_file_t lf);
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static int load_dependancies(linker_file_t lf);
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static int relocate_file(linker_file_t lf);
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/*
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* The kernel symbol table starts here.
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*/
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extern struct _dynamic _DYNAMIC;
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static void
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link_elf_init(void* arg)
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{
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Elf_Dyn* dp = (Elf_Dyn*) &_DYNAMIC;
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#if ELF_TARG_CLASS == ELFCLASS32
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linker_add_class("elf32", NULL, &link_elf_class_ops);
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#else
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linker_add_class("elf64", NULL, &link_elf_class_ops);
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#endif
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if (dp) {
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elf_file_t ef;
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ef = malloc(sizeof(struct elf_file), M_LINKER, M_NOWAIT);
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if (ef == NULL)
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panic("link_elf_init: Can't create linker structures for kernel");
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ef->address = 0;
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ef->dynamic = dp;
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linker_kernel_file =
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linker_make_file(kernelname, ef, &link_elf_file_ops);
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if (linker_kernel_file == NULL)
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panic("link_elf_init: Can't create linker structures for kernel");
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parse_dynamic(linker_kernel_file);
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/*
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* XXX there must be a better way of getting these constants.
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*/
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#ifdef __alpha__
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linker_kernel_file->address = (caddr_t) 0xfffffc0000300000;
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#else
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linker_kernel_file->address = (caddr_t) 0xf0100000;
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#endif
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linker_kernel_file->size = -(long)linker_kernel_file->address;
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linker_current_file = linker_kernel_file;
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}
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}
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SYSINIT(link_elf, SI_SUB_KMEM, SI_ORDER_THIRD, link_elf_init, 0);
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static int
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parse_dynamic(linker_file_t lf)
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{
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elf_file_t ef = lf->priv;
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Elf_Dyn *dp;
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for (dp = ef->dynamic; dp->d_tag != DT_NULL; dp++) {
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switch (dp->d_tag) {
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case DT_HASH:
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{
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/* From src/libexec/rtld-elf/rtld.c */
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const Elf_Off *hashtab = (const Elf_Off *)
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(ef->address + dp->d_un.d_ptr);
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ef->nbuckets = hashtab[0];
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ef->nchains = hashtab[1];
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ef->buckets = hashtab + 2;
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ef->chains = ef->buckets + ef->nbuckets;
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break;
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}
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case DT_STRTAB:
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ef->strtab = (caddr_t) dp->d_un.d_ptr;
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break;
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case DT_SYMTAB:
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ef->symtab = (Elf_Sym*) dp->d_un.d_ptr;
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break;
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case DT_SYMENT:
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if (dp->d_un.d_val != sizeof(Elf_Sym))
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return ENOEXEC;
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}
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}
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return 0;
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}
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static int
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link_elf_load_file(const char* filename, linker_file_t* result)
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{
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#if 0
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struct nameidata nd;
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struct proc* p = curproc; /* XXX */
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int error = 0;
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int resid;
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struct exec header;
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elf_file_t ef;
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linker_file_t lf;
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NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, filename, p);
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error = vn_open(&nd, FREAD, 0);
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if (error)
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return error;
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/*
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* Read the a.out header from the file.
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*/
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error = vn_rdwr(UIO_READ, nd.ni_vp, (void*) &header, sizeof header, 0,
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UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid, p);
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if (error)
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goto out;
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if (N_BADMAG(header) || !(N_GETFLAG(header) & EX_DYNAMIC))
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goto out;
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/*
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* We have an a.out file, so make some space to read it in.
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*/
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ef = malloc(sizeof(struct elf_file), M_LINKER, M_WAITOK);
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ef->address = malloc(header.a_text + header.a_data + header.a_bss,
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M_LINKER, M_WAITOK);
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/*
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* Read the text and data sections and zero the bss.
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*/
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error = vn_rdwr(UIO_READ, nd.ni_vp, (void*) ef->address,
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header.a_text + header.a_data, 0,
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UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid, p);
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if (error)
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goto out;
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bzero(ef->address + header.a_text + header.a_data, header.a_bss);
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/*
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* Assume _DYNAMIC is the first data item.
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*/
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ef->dynamic = (struct _dynamic*) (ef->address + header.a_text);
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if (ef->dynamic->d_version != LD_VERSION_BSD) {
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free(ef->address, M_LINKER);
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free(ef, M_LINKER);
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goto out;
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}
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(long) ef->dynamic->d_un.d_sdt += ef->address;
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lf = linker_make_file(filename, ef, &link_elf_file_ops);
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if (lf == NULL) {
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free(ef->address, M_LINKER);
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free(ef, M_LINKER);
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error = ENOMEM;
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goto out;
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}
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lf->address = ef->address;
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lf->size = header.a_text + header.a_data + header.a_bss;
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if ((error = load_dependancies(lf)) != 0
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|| (error = relocate_file(lf)) != 0) {
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linker_file_unload(lf);
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goto out;
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}
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*result = lf;
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out:
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VOP_UNLOCK(nd.ni_vp, 0, p);
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vn_close(nd.ni_vp, FREAD, p->p_ucred, p);
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return error;
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#else
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return ENOEXEC;
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#endif
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}
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static void
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link_elf_unload(linker_file_t file)
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{
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elf_file_t ef = file->priv;
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if (ef) {
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if (ef->address)
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free(ef->address, M_LINKER);
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free(ef, M_LINKER);
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}
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}
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#define ELF_RELOC(ef, type, off) (type*) ((ef)->address + (off))
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static int
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load_dependancies(linker_file_t lf)
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{
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#if 0
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elf_file_t ef = lf->priv;
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linker_file_t lfdep;
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long off;
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struct sod* sodp;
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char* name;
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char* filename = 0;
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int error = 0;
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/*
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* All files are dependant on /kernel.
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*/
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linker_kernel_file->refs++;
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linker_file_add_dependancy(lf, linker_kernel_file);
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off = LD_NEED(ef->dynamic);
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/*
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* Load the dependancies.
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*/
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while (off != 0) {
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sodp = ELF_RELOC(ef, struct sod, off);
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name = ELF_RELOC(ef, char, sodp->sod_name);
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/*
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* Prepend pathname if dep is not an absolute filename.
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*/
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if (name[0] != '/') {
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char* p;
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filename = malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
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p = lf->filename + strlen(lf->filename) - 1;
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while (p >= lf->filename && *p != '/')
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p--;
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if (p >= lf->filename) {
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strncpy(filename, lf->filename, p - lf->filename);
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filename[p - lf->filename] = '\0';
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strcat(filename, "/");
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strcat(filename, name);
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name = filename;
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}
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}
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error = linker_load_file(name, &lfdep);
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if (error)
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goto out;
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error = linker_file_add_dependancy(lf, lfdep);
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if (error)
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goto out;
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off = sodp->sod_next;
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}
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out:
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if (filename)
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free(filename, M_TEMP);
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return error;
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#else
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return ENOEXEC;
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#endif
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}
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#if 0
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/*
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* XXX i386 dependant.
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*/
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static long
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read_relocation(struct relocation_info* r, char* addr)
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{
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int length = r->r_length;
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if (length == 0)
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return *(u_char*) addr;
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else if (length == 1)
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return *(u_short*) addr;
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else if (length == 2)
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return *(u_int*) addr;
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else
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printf("link_elf: unsupported relocation size %d\n", r->r_length);
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return 0;
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}
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static void
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write_relocation(struct relocation_info* r, char* addr, long value)
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{
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int length = r->r_length;
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if (length == 0)
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*(u_char*) addr = value;
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else if (length == 1)
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*(u_short*) addr = value;
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else if (length == 2)
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*(u_int*) addr = value;
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else
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printf("link_elf: unsupported relocation size %d\n", r->r_length);
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}
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static int
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relocate_file(linker_file_t lf)
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{
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elf_file_t ef = lf->priv;
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struct relocation_info* rel;
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struct relocation_info* erel;
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struct relocation_info* r;
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struct nzlist* symbolbase;
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char* stringbase;
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struct nzlist* np;
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char* sym;
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long relocation;
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rel = ELF_RELOC(ef, struct relocation_info, LD_REL(ef->dynamic));
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erel = ELF_RELOC(ef, struct relocation_info,
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LD_REL(ef->dynamic) + LD_RELSZ(ef->dynamic));
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symbolbase = ELF_RELOC(ef, struct nzlist, LD_SYMBOL(ef->dynamic));
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stringbase = ELF_RELOC(ef, char, LD_STRINGS(ef->dynamic));
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for (r = rel; r < erel; r++) {
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char* addr;
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if (r->r_address == 0)
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break;
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addr = ELF_RELOC(ef, char, r->r_address);
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if (r->r_extern) {
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np = &symbolbase[r->r_symbolnum];
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sym = &stringbase[np->nz_strx];
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if (sym[0] != '_') {
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printf("link_elf: bad symbol name %s\n", sym);
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relocation = 0;
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} else
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relocation = (long)
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linker_file_lookup_symbol(lf, sym + 1,
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np->nz_type != (N_SETV+N_EXT));
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if (!relocation) {
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printf("link_elf: symbol %s not found\n", sym);
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return ENOENT;
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}
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relocation += read_relocation(r, addr);
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if (r->r_jmptable) {
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printf("link_elf: can't cope with jump table relocations\n");
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continue;
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}
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if (r->r_pcrel)
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relocation -= (long) ef->address;
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if (r->r_copy) {
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printf("link_elf: can't cope with copy relocations\n");
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continue;
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}
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write_relocation(r, addr, relocation);
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} else {
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write_relocation(r, addr,
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(long)(read_relocation(r, addr) + ef->address));
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}
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}
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return 0;
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}
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static long
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symbol_hash_value(elf_file_t ef, const char* name)
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{
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long hashval;
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const char* p;
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hashval = '_'; /* fake a starting '_' for C symbols */
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for (p = name; *p; p++)
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hashval = (hashval << 1) + *p;
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return (hashval & 0x7fffffff) % LD_BUCKETS(ef->dynamic);
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}
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#endif
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int
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link_elf_lookup_symbol(linker_file_t lf, const char* name, linker_sym_t* sym)
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{
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elf_file_t ef = lf->priv;
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int symcount = ef->nchains;
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Elf_Sym* es;
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int i;
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/* XXX use hash table */
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for (i = 0, es = ef->symtab; i < ef->nchains; i++, es++) {
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if (es->st_name == 0)
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continue;
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if (!strcmp(ef->strtab + es->st_name, name)) {
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*sym = (linker_sym_t) es;
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return 0;
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}
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}
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return ENOENT;
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}
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static void
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link_elf_symbol_values(linker_file_t lf, linker_sym_t sym, linker_symval_t* symval)
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{
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elf_file_t ef = lf->priv;
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Elf_Sym* es = (Elf_Sym*) sym;
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symval->name = ef->strtab + es->st_name;
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symval->value = (caddr_t) es->st_value;
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symval->size = es->st_size;
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}
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static int
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link_elf_search_symbol(linker_file_t lf, caddr_t value,
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linker_sym_t* sym, long* diffp)
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{
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elf_file_t ef = lf->priv;
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u_long off = (u_long) value;
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u_long diff = off;
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int symcount = ef->nchains;
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Elf_Sym* es;
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Elf_Sym* best = 0;
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int i;
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for (i = 0, es = ef->symtab; i < ef->nchains; i++, es++) {
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if (es->st_name == 0)
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continue;
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if (off >= es->st_value) {
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if (off - es->st_value < diff) {
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diff = off - es->st_value;
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best = es;
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if (diff == 0)
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break;
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} else if (off - es->st_value == diff) {
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best = es;
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}
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}
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}
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if (best == 0)
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*diffp = off;
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else
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*diffp = diff;
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*sym = (linker_sym_t) best;
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return 0;
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}
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