/*
* Copyright (c) 2008 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 rtld rtld
* @brief
* @{
*/
/**
* @file
*/
#include <elf_dyn.h>
#include <rtld.h>
void __main(void);
void __io_init(void);
void __exit(void);
static void kputint(unsigned i)
{
unsigned dummy;
asm volatile (
"movl $30, %%eax;"
"int $0x30"
: "=d" (dummy) /* output - %edx clobbered */
: "d" (i) /* input */
: "%eax","%ecx" /* all scratch registers clobbered */
);
}
void __bootstrap(void)
{
unsigned bias;
unsigned *got;
elf_dyn_t *dynamic;
void *dptr;
unsigned dval;
int i;
size_t rel_entries;
size_t r_offset;
elf_word r_info;
unsigned rel_type;
elf_word sym_idx;
uintptr_t sym_addr;
elf_symbol_t *sym_table;
elf_rel_t *rel_table;
elf_rel_t *jmp_rel_table;
size_t jmp_rel_entries;
asm volatile (
/* Calculate the bias into %0 */
/* Generates "fake" R_386_RELATIVE run-time relocation */
" call .L0;"
".L0: pop %0;"
" subl $.L0, %0;"
/* Calculate run-time address of _DYNAMIC into %1 */
/* Generates "fake" R_386_RELATIVE run-time relocation */
" movl $_DYNAMIC, %1;" /* Again, at link time 0-based VMA gets in */
" addl %0, %1;" /* Add bias to compute run-time address */
: "=r" (bias), "=r" (dynamic)
);
kputint(bias);
kputint((unsigned)dynamic);
/* parse DYNAMIC */
got = 0;
sym_table = 0;
rel_table = 0;
rel_entries = 0;
jmp_rel_table = 0;
jmp_rel_entries = 0;
i = 0;
while (dynamic[i].d_tag != 0) {
dptr = (void *)(dynamic[i].d_un.d_val + bias);
dval = dynamic[i].d_un.d_val;
switch (dynamic[i].d_tag) {
case 2/* DT_PLTRELSZ */: jmp_rel_entries = dval/8; break;
case 23/* DT_JMPREL */: jmp_rel_table = dptr; break;
case 3 /* DT_PLTGOT */:
/* GOT address */
got = dptr; break;
case 6 /* DT_SYMTAB */ : sym_table = dptr; break;
case 17 /* DT_REL */ : rel_table = dptr; break;
case 18 /* DT_RELSZ */ : rel_entries = dval / 8; break;
default: break;
}
++i;
}
kputint(1);
kputint((unsigned)sym_table);
kputint((unsigned)rel_table);
kputint((unsigned)rel_entries);
/* Now relocate all our dynsyms */
kputint(-1);
for (i=0; i<rel_entries; i++) {
kputint(i);
r_offset = rel_table[i].r_offset;
r_info = rel_table[i].r_info;
rel_type = ELF32_R_TYPE(r_info);
kputint(rel_type);
kputint(r_offset);
switch (rel_type) {
case 6: /* R_386_GLOB_DAT */
case 7: /* R_386_JUMP_SLOT */
kputint(16);
sym_idx = ELF32_R_SYM(r_info);
sym_addr = sym_table[sym_idx].st_value + bias;
kputint(sym_idx);
kputint(sym_addr);
*(unsigned *)(r_offset+bias) = sym_addr;
break;
case 1: /* R_386_32 */
kputint(16);
sym_idx = ELF32_R_SYM(r_info);
sym_addr = sym_table[sym_idx].st_value + bias;
kputint(sym_idx);
kputint(sym_addr);
*(unsigned *)(r_offset+bias) += sym_addr;
break;
case 8: /* R_386_RELATIVE */
kputint(16);
*(unsigned *)(r_offset+bias) += bias;
break;
}
}
kputint(-1);
for (i=0; i<jmp_rel_entries; i++) {
kputint(i);
r_offset = jmp_rel_table[i].r_offset;
r_info = jmp_rel_table[i].r_info;
rel_type = ELF32_R_TYPE(r_info);
kputint(rel_type);
kputint(r_offset);
switch (rel_type) {
case 6: /* R_386_GLOB_DAT */
case 7: /* R_386_JUMP_SLOT */
kputint(16);
sym_idx = ELF32_R_SYM(r_info);
sym_addr = sym_table[sym_idx].st_value + bias;
kputint(sym_idx);
kputint(sym_addr);
*(unsigned *)(r_offset+bias) = sym_addr;
break;
case 1: /* R_386_32 */
kputint(16);
sym_idx = ELF32_R_SYM(r_info);
sym_addr = sym_table[sym_idx].st_value + bias;
kputint(sym_idx);
kputint(sym_addr);
*(unsigned *)(r_offset+bias) += sym_addr;
break;
case 8: /* R_386_RELATIVE */
kputint(16);
*(unsigned *)(r_offset+bias) += bias;
break;
}
}
kputint(-1);
/* Init libc and run rtld main */
__main();
kputint(33);
__io_init();
kputint(34);
_rtld_main();
kputint(35);
__exit();
kputint(36);
asm (
"movl $250, %%eax;"
"int $0x30"
: /* output */
: /* input */
: "%eax","%ecx","%edx" /* all scratch registers clobbered */
);
}
/** @}
*/