/*
* Copyright (c) 2016 Jiri Svoboda
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* - 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.
* - The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 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.
*/
/** @addtogroup libcamd64
* @brief
* @{
*/
/**
* @file
*/
#include <mem.h>
#include <stdio.h>
#include <stdlib.h>
#include <libarch/rtld/elf_dyn.h>
#include <rtld/symbol.h>
#include <rtld/rtld.h>
#include <rtld/rtld_debug.h>
#include <rtld/rtld_arch.h>
void module_process_pre_arch(module_t *m)
{
/* Unused */
}
/**
* Process (fixup) all relocations in a relocation table with implicit addends.
*/
void rel_table_process(module_t *m, elf_rel_t *rt, size_t rt_size)
{
DPRINTF("rel table address: 0x%zx, size: %zd\n", (uintptr_t)rt, rt_size);
/* Unused */
(void)m;
(void)rt;
(void)rt_size;
}
/**
* Process (fixup) all relocations in a relocation table with explicit addends.
*/
void rela_table_process(module_t *m, elf_rela_t *rt, size_t rt_size)
{
unsigned i;
size_t rt_entries;
size_t r_offset;
size_t r_addend;
elf_xword r_info;
unsigned rel_type;
elf_word sym_idx;
uintptr_t sym_addr;
elf_symbol_t *sym_table;
elf_symbol_t *sym;
uintptr_t *r_ptr;
uint32_t *r_ptr32;
uintptr_t sym_size;
char *str_tab;
elf_symbol_t *sym_def;
module_t *dest;
DPRINTF("parse relocation table\n");
sym_table = m->dyn.sym_tab;
rt_entries = rt_size / sizeof(elf_rela_t);
str_tab = m->dyn.str_tab;
DPRINTF("rel table address: 0x%zx, entries: %zd\n", (uintptr_t)rt, rt_entries);
for (i = 0; i < rt_entries; ++i) {
#if 0
DPRINTF("symbol %d: ", i);
#endif
r_offset = rt[i].r_offset;
r_info = rt[i].r_info;
r_addend = rt[i].r_addend;
sym_idx = ELF64_R_SYM(r_info);
sym = &sym_table[sym_idx];
#if 0
DPRINTF("name '%s', value 0x%x, size 0x%x\n",
str_tab + sym->st_name,
sym->st_value,
sym->st_size);
#endif
rel_type = ELF64_R_TYPE(r_info);
r_ptr = (uintptr_t *)(r_offset + m->bias);
r_ptr32 = (uint32_t *)r_ptr;
if (sym->st_name != 0) {
DPRINTF("rel_type: %x, rel_offset: 0x%zx\n", rel_type, r_offset);
sym_def = symbol_def_find(str_tab + sym->st_name,
m, ssf_none, &dest);
DPRINTF("dest name: '%s'\n", dest->dyn.soname);
DPRINTF("dest bias: 0x%zx\n", dest->bias);
if (sym_def) {
sym_addr = (uintptr_t)
symbol_get_addr(sym_def, dest, NULL);
DPRINTF("symbol definition found, value=0x%zx addr=0x%zx\n", sym_def->st_value, sym_addr);
} else {
printf("Definition of '%s' not found.\n",
str_tab + sym->st_name);
continue;
}
} else {
sym_addr = 0;
sym_def = NULL;
/*
* DTPMOD with null st_name should return the index
* of the current module.
*/
dest = m;
}
switch (rel_type) {
case R_X86_64_64:
DPRINTF("fixup R_X86_64_64 (S+A)\n");
DPRINTF("*0x%zx = 0x%zx\n", (uintptr_t)r_ptr, sym_addr + r_addend);
*r_ptr = sym_addr + r_addend;
DPRINTF("OK\n");
break;
case R_X86_64_PC32:
DPRINTF("fixup R_X86_64_PC32 (S+A-P)\n");
DPRINTF("(32)*0x%zx = 0x%zx\n", (uintptr_t)r_ptr, sym_addr + r_addend - (uintptr_t) r_ptr);
*r_ptr32 = sym_addr + r_addend - (uintptr_t) r_ptr;
DPRINTF("OK\n");
break;
case R_X86_64_COPY:
/*
* Copy symbol data from shared object to specified
* location. Need to find the 'source', i.e. the
* other instance of the object than the one in the
* executable program.
*/
DPRINTF("fixup R_X86_64_COPY (s)\n");
sym_def = symbol_def_find(str_tab + sym->st_name,
m, ssf_noexec, &dest);
if (sym_def) {
sym_addr = (uintptr_t)
symbol_get_addr(sym_def, dest, NULL);
} else {
printf("Source definition of '%s' not found.\n",
str_tab + sym->st_name);
continue;
}
sym_size = sym->st_size;
if (sym_size != sym_def->st_size) {
printf("Warning: Mismatched symbol sizes.\n");
/* Take the lower value. */
if (sym_size > sym_def->st_size)
sym_size = sym_def->st_size;
}
memcpy(r_ptr, (const void *)sym_addr, sym_size);
DPRINTF("OK\n");
break;
case R_X86_64_GLOB_DAT:
case R_X86_64_JUMP_SLOT:
DPRINTF("fixup R_X86_64_GLOB_DAT/JUMP_SLOT (S)\n");
DPRINTF("*0x%zx = 0x%zx\n", (uintptr_t)r_ptr, sym_addr);
*r_ptr = sym_addr;
DPRINTF("OK\n");
break;
case R_X86_64_RELATIVE:
DPRINTF("fixup R_X86_64_RELATIVE (B+A)\n");
DPRINTF("*0x%zx = 0x%zx\n", (uintptr_t)r_ptr, m->bias + r_addend);
*r_ptr = m->bias + r_addend;
DPRINTF("OK\n");
break;
case R_X86_64_DTPMOD64:
DPRINTF("fixup R_X86_64_DTPMOD64\n");
DPRINTF("*0x%zx = 0x%zx\n", (uintptr_t)r_ptr, (size_t)dest->id);
*r_ptr = dest->id;
DPRINTF("OK\n");
break;
case R_X86_64_DTPOFF64:
DPRINTF("fixup R_X86_64_DTPOFF64\n");
DPRINTF("*0x%zx = 0x%zx\n", (uintptr_t)r_ptr, sym_def->st_value);
*r_ptr = sym_def->st_value;
DPRINTF("OK\n");
break;
case R_X86_64_TPOFF64:
DPRINTF("fixup R_X86_64_TPOFF64\n");
*r_ptr = sym_def->st_value + dest->tpoff;
break;
default:
printf("Error: Unknown relocation type %d\n",
rel_type);
exit(1);
}
}
}
/** Get the adress of a function.
*
* @param sym Symbol
* @param m Module in which the symbol is located
* @return Address of function
*/
void *func_get_addr(elf_symbol_t *sym, module_t *m)
{
return symbol_get_addr(sym, m, __tcb_get());
}
/** @}
*/