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2973 svoboda 1
/*
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 * Copyright (c) 2008 Jiri Svoboda
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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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 *
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 * - 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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 * - 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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 * - The name of the author may not be used to endorse or promote products
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 *   derived from this software without specific prior written permission.
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 *
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 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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 */
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/** @addtogroup rtld rtld
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 * @brief
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 * @{
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 */
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/**
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 * @file
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 */
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#include <stdio.h>
3688 svoboda 38
#include <stdlib.h>
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#include <elf_dyn.h>
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#include <symbol.h>
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#include <rtld.h>
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3688 svoboda 44
#include <rtld_arch.h>
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2996 svoboda 46
void module_process_pre_arch(module_t *m)
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{
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    /* Unused */
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}
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2973 svoboda 52
/**
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 * Process (fixup) all relocations in a relocation table.
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 */
2980 svoboda 55
void rel_table_process(module_t *m, elf_rel_t *rt, size_t rt_size)
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{
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    int i;
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    size_t rt_entries;
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    size_t r_offset;
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    elf_word r_info;
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    unsigned rel_type;
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    elf_word sym_idx;
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    uintptr_t sym_addr;
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    elf_symbol_t *sym_table;
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    elf_symbol_t *sym;
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    uint32_t *r_ptr;
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    uint32_t sym_size;
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    char *str_tab;
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    elf_symbol_t *sym_def;
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    module_t *dest;
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3562 svoboda 75
    DPRINTF("parse relocation table\n");
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    sym_table = m->dyn.sym_tab;
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    rt_entries = rt_size / sizeof(elf_rel_t);
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    str_tab = m->dyn.str_tab;
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    DPRINTF("address: 0x%x, entries: %d\n", (uintptr_t)rt, rt_entries);
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    for (i = 0; i < rt_entries; ++i) {
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//      DPRINTF("symbol %d: ", i);
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        r_offset = rt[i].r_offset;
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        r_info = rt[i].r_info;
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        sym_idx = ELF32_R_SYM(r_info);
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        sym = &sym_table[sym_idx];
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/*      DPRINTF("name '%s', value 0x%x, size 0x%x\n",
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            str_tab + sym->st_name,
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            sym->st_value,
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            sym->st_size);
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*/
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        rel_type = ELF32_R_TYPE(r_info);
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        r_ptr = (uint32_t *)(r_offset + m->bias);
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        if (sym->st_name != 0) {
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//          DPRINTF("rel_type: %x, rel_offset: 0x%x\n", rel_type, r_offset);
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            sym_def = symbol_def_find(str_tab + sym->st_name,
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                m, &dest);
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//          DPRINTF("dest name: '%s'\n", dest->dyn.soname);
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//          DPRINTF("dest bias: 0x%x\n", dest->bias);
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            if (sym_def) {
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                sym_addr = symbol_get_addr(sym_def, dest);
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//              DPRINTF("symbol definition found, addr=0x%x\n", sym_addr);
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            } else {
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                DPRINTF("symbol definition not found\n");
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                continue;
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            }
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        }
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        switch (rel_type) {
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        case R_386_GLOB_DAT:
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        case R_386_JUMP_SLOT:
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            DPRINTF("fixup R_386_GLOB_DAT/JUMP_SLOT (b+v)\n");
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            *r_ptr = sym_addr;
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            break;
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        case R_386_32:
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            DPRINTF("fixup R_386_32 (b+v+a)\n");
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            *r_ptr += sym_addr;
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            break;
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        case R_386_PC32:
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            DPRINTF("fixup R_386_PC32 (b+v+a-p)\n");
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            *r_ptr += sym_addr - (uint32_t) r_ptr;
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            break;
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        case R_386_COPY:
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            /*
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             * Copy symbol data from shared object to specified
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             * location.
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             */
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            DPRINTF("fixup R_386_COPY (s)\n");
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            sym_size = sym->st_size;
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            if (sym_size != sym_def->st_size) {
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                printf("Warning: Mismatched symbol sizes.\n");
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                /* Take the lower value. */
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                if (sym_size > sym_def->st_size)
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                    sym_size = sym_def->st_size;
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            }
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            memcpy(r_ptr, (const void *)sym_addr, sym_size);
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            break;
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        case R_386_RELATIVE:
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            DPRINTF("fixup R_386_RELATIVE (b+a)\n");
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            *r_ptr += m->bias;
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            break;
3681 svoboda 151
 
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        case R_386_TLS_DTPMOD32:
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            /*
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             * We can ignore this as long as the only module
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             * with TLS variables is libc.so.
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             */
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            DPRINTF("Ignoring R_386_TLS_DTPMOD32\n");
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            break;
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3681 svoboda 160
        default:
3688 svoboda 161
            printf("Error: Unknown relocation type %d\n",
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                rel_type);
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            exit(1);
2978 svoboda 164
        }
3681 svoboda 165
 
2973 svoboda 166
    }
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}
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2996 svoboda 170
void rela_table_process(module_t *m, elf_rela_t *rt, size_t rt_size)
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{
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    /* Unused */
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    (void)m; (void)rt; (void)rt_size;
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}
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2973 svoboda 176
/** @}
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 */