root / prex-0.9.0 / bsp / boot / common / elf.c @ 03e9c04a
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/*-
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* Copyright (c) 2005-2006, Kohsuke Ohtani
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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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* 3. Neither the name of the author nor the names of any co-contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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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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/*
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* elf.c - ELF file format support
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*/
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#include <boot.h> |
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#include <load.h> |
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#include <sys/elf.h> |
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#include <elf_reloc.h> |
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/* forward declarations */
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static int load_executable(char *, struct module *); |
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static int load_relocatable(char *, struct module *); |
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#define SHF_VALID (SHF_ALLOC | SHF_EXECINSTR | SHF_ALLOC | SHF_WRITE)
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static char *sect_addr[32]; /* array of section address */ |
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static int strshndx; /* index of string section */ |
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/*
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* Load the program from specified ELF image stored in memory.
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* The boot information is filled after loading the program.
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*/
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int
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load_elf(char *img, struct module *m) |
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{ |
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Elf32_Ehdr *ehdr; |
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Elf32_Phdr *phdr; |
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ELFDBG(("\nelf_load\n"));
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ehdr = (Elf32_Ehdr *)img; |
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/* Check ELF header */
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if ((ehdr->e_ident[EI_MAG0] != ELFMAG0) ||
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(ehdr->e_ident[EI_MAG1] != ELFMAG1) || |
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(ehdr->e_ident[EI_MAG2] != ELFMAG2) || |
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(ehdr->e_ident[EI_MAG3] != ELFMAG3)) { |
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DPRINTF(("Invalid ELF image\n"));
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return -1; |
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} |
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phdr = (Elf32_Phdr *)((paddr_t)ehdr + ehdr->e_ehsize); |
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if (nr_img == 0) { |
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/* Initialize the load address */
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load_base = (vaddr_t)ptokv(phdr->p_paddr); |
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if (load_base == 0) { |
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DPRINTF(("Invalid load address\n"));
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return -1; |
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} |
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ELFDBG(("kernel base=%lx\n", load_base));
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load_start = load_base; |
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} |
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else if (nr_img == 1) { |
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/* 2nd image => Driver */
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ELFDBG(("driver base=%lx\n", load_base));
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} |
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else {
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/* Other images => Boot tasks */
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ELFDBG(("task base=%lx\n", load_base));
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} |
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switch (ehdr->e_type) {
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case ET_EXEC:
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if (load_executable(img, m) != 0) |
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return -1; |
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break;
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case ET_REL:
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if (load_relocatable(img, m) != 0) |
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return -1; |
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break;
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default:
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ELFDBG(("Unsupported file type\n"));
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return -1; |
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} |
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nr_img++; |
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return 0; |
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} |
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static int |
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load_executable(char *img, struct module *m) |
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{ |
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Elf32_Ehdr *ehdr; |
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Elf32_Phdr *phdr; |
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paddr_t phys_base; |
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int i;
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phys_base = load_base; |
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ehdr = (Elf32_Ehdr *)img; |
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phdr = (Elf32_Phdr *)((paddr_t)ehdr + ehdr->e_phoff); |
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m->phys = load_base; |
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phys_base = load_base; |
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ELFDBG(("phys addr=%lx\n", phys_base));
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for (i = 0; i < (int)ehdr->e_phnum; i++, phdr++) { |
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if (phdr->p_type != PT_LOAD)
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continue;
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ELFDBG(("p_flags=%x\n", (int)phdr->p_flags)); |
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ELFDBG(("p_align=%x\n", (int)phdr->p_align)); |
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ELFDBG(("p_paddr=%x\n", phdr->p_paddr));
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if (i >= 2) { |
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ELFDBG(("skipping extra phdr\n"));
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continue;
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} |
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if (phdr->p_flags & PF_X) {
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/* Text */
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m->text = phdr->p_vaddr; |
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m->textsz = (size_t)phdr->p_memsz; |
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} else {
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/* Data & BSS */
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m->data = phdr->p_vaddr; |
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m->datasz = (size_t)phdr->p_filesz; |
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m->bsssz = |
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(size_t)(phdr->p_memsz - phdr->p_filesz); |
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load_base = phys_base + (m->data - m->text); |
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} |
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if (phdr->p_filesz > 0) { |
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memcpy((char *)load_base, img + phdr->p_offset,
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(size_t)phdr->p_filesz); |
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ELFDBG(("load: offset=%lx size=%x\n",
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load_base, (int)phdr->p_filesz));
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} |
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if (!(phdr->p_flags & PF_X)) {
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if (m->bsssz > 0) { |
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/* Zero fill BSS */
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memset((char *)load_base + m->datasz,
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0, m->bsssz);
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} |
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load_base += phdr->p_memsz; |
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} |
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} |
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/* workaround for data/bss size is 0 */
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if (m->data == 0) |
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load_base = phys_base + m->textsz; |
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load_base = round_page(load_base); |
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m->size = (size_t)(load_base - m->phys); |
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m->entry = ehdr->e_entry; |
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ELFDBG(("module size=%x entry=%lx\n", m->size, m->entry));
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if (m->size == 0) |
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panic("Module size is 0!");
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return 0; |
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} |
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static int |
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relocate_section_rela(Elf32_Sym *sym_table, Elf32_Rela *rela, |
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char *target_sect, int nr_reloc, char *strtab) |
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{ |
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Elf32_Sym *sym; |
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Elf32_Addr sym_val; |
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int i;
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for (i = 0; i < nr_reloc; i++) { |
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sym = &sym_table[ELF32_R_SYM(rela->r_info)]; |
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ELFDBG(("%s\n", strtab + sym->st_name));
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if (sym->st_shndx != STN_UNDEF) {
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sym_val = (Elf32_Addr)sect_addr[sym->st_shndx] |
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+ sym->st_value; |
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if (relocate_rela(rela, sym_val, target_sect) != 0) |
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return -1; |
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} else if (ELF32_ST_BIND(sym->st_info) != STB_WEAK) { |
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DPRINTF(("Undefined symbol for rela[%x] sym=%lx\n",
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i, (long)sym));
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return -1; |
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} else {
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DPRINTF(("Undefined weak symbol for rela[%x]\n", i));
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} |
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rela++; |
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} |
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return 0; |
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} |
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static int |
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relocate_section_rel(Elf32_Sym *sym_table, Elf32_Rel *rel, |
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char *target_sect, int nr_reloc, char *strtab) |
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{ |
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Elf32_Sym *sym; |
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Elf32_Addr sym_val; |
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int i;
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for (i = 0; i < nr_reloc; i++) { |
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sym = &sym_table[ELF32_R_SYM(rel->r_info)]; |
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ELFDBG(("%s\n", strtab + sym->st_name));
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if (sym->st_shndx != STN_UNDEF) {
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sym_val = (Elf32_Addr)sect_addr[sym->st_shndx] |
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+ sym->st_value; |
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if (relocate_rel(rel, sym_val, target_sect) != 0) |
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return -1; |
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} else if (ELF32_ST_BIND(sym->st_info) != STB_WEAK) { |
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DPRINTF(("Undefined symbol for rel[%x] sym=%lx\n",
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i, (long)sym));
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return -1; |
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} else {
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DPRINTF(("Undefined weak symbol for rel[%x]\n", i));
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} |
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rel++; |
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} |
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return 0; |
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} |
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static int |
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relocate_section(char *img, Elf32_Shdr *shdr)
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{ |
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Elf32_Sym *symtab; |
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char *target_sect;
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int nr_reloc, error;
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char *strtab;
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ELFDBG(("relocate_section\n"));
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if (shdr->sh_entsize == 0) |
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return 0; |
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if ((target_sect = sect_addr[shdr->sh_info]) == 0) |
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return -1; |
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if ((symtab = (Elf32_Sym *)sect_addr[shdr->sh_link]) == 0) |
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return -1; |
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if ((strtab = sect_addr[strshndx]) == 0) |
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return -1; |
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ELFDBG(("strtab=%x\n", strtab));
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nr_reloc = (int)(shdr->sh_size / shdr->sh_entsize);
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switch (shdr->sh_type) {
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case SHT_REL:
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error = relocate_section_rel(symtab, |
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(Elf32_Rel *)(img + shdr->sh_offset), |
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target_sect, nr_reloc, strtab); |
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break;
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case SHT_RELA:
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error = relocate_section_rela(symtab, |
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(Elf32_Rela *)(img + shdr->sh_offset), |
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target_sect, nr_reloc, strtab); |
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break;
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default:
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error = -1;
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break;
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} |
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return error;
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} |
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static int |
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load_relocatable(char *img, struct module *m) |
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{ |
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Elf32_Ehdr *ehdr; |
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Elf32_Shdr *shdr; |
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paddr_t sect_base, bss_base; |
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int i;
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strshndx = 0;
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ehdr = (Elf32_Ehdr *)img; |
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shdr = (Elf32_Shdr *)((paddr_t)ehdr + ehdr->e_shoff); |
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bss_base = 0;
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m->phys = load_base; |
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ELFDBG(("phys addr=%lx\n", load_base));
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/* Copy sections */
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for (i = 0; i < (int)ehdr->e_shnum; i++, shdr++) { |
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sect_addr[i] = 0;
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if (shdr->sh_type == SHT_PROGBITS) {
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ELFDBG(("sh_addr=%x\n", shdr->sh_addr));
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ELFDBG(("sh_size=%x\n", shdr->sh_size));
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ELFDBG(("sh_offset=%x\n", shdr->sh_offset));
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ELFDBG(("sh_flags=%x\n", shdr->sh_flags));
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switch (shdr->sh_flags & SHF_VALID) {
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case (SHF_ALLOC | SHF_EXECINSTR):
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/* Text */
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m->text = (vaddr_t)ptokv(load_base); |
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break;
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case (SHF_ALLOC | SHF_WRITE):
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/* Data */
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if (m->data == 0) { |
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m->data = (vaddr_t)ptokv(load_base + |
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shdr->sh_addr); |
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} |
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break;
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case SHF_ALLOC:
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/* rodata */
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/* Note: rodata is treated as text. */
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break;
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default:
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continue;
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} |
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sect_base = load_base + shdr->sh_addr; |
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memcpy((char *)sect_base, img + shdr->sh_offset,
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(size_t)shdr->sh_size); |
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ELFDBG(("load: offset=%lx size=%x\n",
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sect_base, (int)shdr->sh_size));
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sect_addr[i] = (char *)sect_base;
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} else if (shdr->sh_type == SHT_NOBITS) { |
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/* BSS */
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m->bsssz = (size_t)shdr->sh_size; |
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sect_base = load_base + shdr->sh_addr; |
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bss_base = sect_base; |
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/* Zero fill BSS */
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memset((char *)bss_base, 0, (size_t)shdr->sh_size); |
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sect_addr[i] = (char *)sect_base;
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} else if (shdr->sh_type == SHT_SYMTAB) { |
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/* Symbol table */
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ELFDBG(("load: symtab index=%d link=%d\n",
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i, shdr->sh_link)); |
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sect_addr[i] = img + shdr->sh_offset; |
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if (strshndx != 0) |
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panic("Multiple symtab found!");
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strshndx = (int)shdr->sh_link;
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} else if (shdr->sh_type == SHT_STRTAB) { |
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/* String table */
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sect_addr[i] = img + shdr->sh_offset; |
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ELFDBG(("load: strtab index=%d addr=%x\n",
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i, sect_addr[i])); |
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} |
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} |
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m->textsz = (size_t)(m->data - m->text); |
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m->datasz = (size_t)((char *)ptokv(bss_base) - m->data);
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load_base = bss_base + m->bsssz; |
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load_base = round_page(load_base); |
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ELFDBG(("module load_base=%lx text=%lx\n", load_base, m->text));
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m->size = (size_t)(load_base - kvtop(m->text)); |
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m->entry = (vaddr_t)ptokv(ehdr->e_entry + m->phys); |
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ELFDBG(("module size=%x entry=%lx\n", m->size, m->entry));
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/* Process relocation */
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shdr = (Elf32_Shdr *)((paddr_t)ehdr + ehdr->e_shoff); |
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for (i = 0; i < (int)ehdr->e_shnum; i++, shdr++) { |
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if (shdr->sh_type == SHT_REL || shdr->sh_type == SHT_RELA) {
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if (relocate_section(img, shdr) != 0) { |
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DPRINTF(("Relocation error: module=%s\n", m->name));
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return -1; |
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} |
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} |
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} |
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return 0; |
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} |