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grub/grub-core/kern/mips/dl.c
Vladimir Serbinenko 8c534b85f1 Revamp relocation handling. 
Move more code to common dl.c. Add missing veneers for arm and arm64.
	Decreases kernel size by 70 bytes on i386-pc (40-50 compressed)
2013-12-06 09:18:55 +01:00

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/* dl-386.c - arch-dependent part of loadable module support */
/*
* GRUB -- GRand Unified Bootloader
* Copyright (C) 2002,2005,2007,2009 Free Software Foundation, Inc.
*
* GRUB is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* GRUB is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with GRUB. If not, see <http://www.gnu.org/licenses/>.
*/
#include <grub/dl.h>
#include <grub/elf.h>
#include <grub/misc.h>
#include <grub/err.h>
#include <grub/cpu/types.h>
#include <grub/mm.h>
#include <grub/i18n.h>
/* Dummy __gnu_local_gp. Resolved by linker. */
static char __gnu_local_gp_dummy;
static char _gp_disp_dummy;
/* Check if EHDR is a valid ELF header. */
grub_err_t
grub_arch_dl_check_header (void *ehdr)
{
Elf_Ehdr *e = ehdr;
/* Check the magic numbers. */
#ifdef GRUB_CPU_WORDS_BIGENDIAN
if (e->e_ident[EI_CLASS] != ELFCLASS32
|| e->e_ident[EI_DATA] != ELFDATA2MSB
|| e->e_machine != EM_MIPS)
#else
if (e->e_ident[EI_CLASS] != ELFCLASS32
|| e->e_ident[EI_DATA] != ELFDATA2LSB
|| e->e_machine != EM_MIPS)
#endif
return grub_error (GRUB_ERR_BAD_OS, N_("invalid arch-dependent ELF magic"));
return GRUB_ERR_NONE;
}
#pragma GCC diagnostic ignored "-Wcast-align"
grub_err_t
grub_arch_dl_get_tramp_got_size (const void *ehdr, grub_size_t *tramp,
grub_size_t *got)
{
const Elf_Ehdr *e = ehdr;
const Elf_Shdr *s;
/* FIXME: suboptimal. */
grub_size_t gp_size = 0;
unsigned i;
*tramp = 0;
*got = 0;
for (i = 0, s = (const Elf_Shdr *) ((const char *) e + e->e_shoff);
i < e->e_shnum;
i++, s = (const Elf_Shdr *) ((const char *) s + e->e_shentsize))
if (s->sh_type == SHT_REL)
{
const Elf_Rel *rel, *max;
for (rel = (const Elf_Rel *) ((const char *) e + s->sh_offset),
max = rel + s->sh_size / s->sh_entsize;
rel < max;
rel++)
switch (ELF_R_TYPE (rel->r_info))
{
case R_MIPS_GOT16:
case R_MIPS_CALL16:
case R_MIPS_GPREL32:
gp_size += 4;
break;
}
}
if (gp_size > 0x08000)
return grub_error (GRUB_ERR_OUT_OF_RANGE, "__gnu_local_gp is too big\n");
*got = gp_size;
return GRUB_ERR_NONE;
}
/* Relocate symbols. */
grub_err_t
grub_arch_dl_relocate_symbols (grub_dl_t mod, void *ehdr,
Elf_Shdr *s, grub_dl_segment_t seg)
{
grub_uint32_t gp0;
Elf_Ehdr *e = ehdr;
if (!mod->reginfo)
{
unsigned i;
Elf_Shdr *ri;
/* Find reginfo. */
for (i = 0, ri = (Elf_Shdr *) ((char *) ehdr + e->e_shoff);
i < e->e_shnum;
i++, ri = (Elf_Shdr *) ((char *) ri + e->e_shentsize))
if (ri->sh_type == SHT_MIPS_REGINFO)
break;
if (i == e->e_shnum)
return grub_error (GRUB_ERR_BAD_MODULE, "no reginfo found");
mod->reginfo = (grub_uint32_t *)((char *) ehdr + ri->sh_offset);
}
gp0 = mod->reginfo[5];
Elf_Rel *rel, *max;
for (rel = (Elf_Rel *) ((char *) e + s->sh_offset),
max = (Elf_Rel *) ((char *) rel + s->sh_size);
rel < max;
rel = (Elf_Rel *) ((char *) rel + s->sh_entsize))
{
grub_uint8_t *addr;
Elf_Sym *sym;
grub_uint32_t sym_value;
if (seg->size < rel->r_offset)
return grub_error (GRUB_ERR_BAD_MODULE,
"reloc offset is out of the segment");
addr = (grub_uint8_t *) ((char *) seg->addr + rel->r_offset);
sym = (Elf_Sym *) ((char *) mod->symtab
+ mod->symsize * ELF_R_SYM (rel->r_info));
sym_value = sym->st_value;
if (sym_value == (grub_addr_t) &__gnu_local_gp_dummy)
sym_value = (grub_addr_t) mod->got;
else if (sym_value == (grub_addr_t) &_gp_disp_dummy)
{
sym_value = (grub_addr_t) mod->got - (grub_addr_t) addr;
if (ELF_R_TYPE (rel->r_info) == R_MIPS_LO16)
/* ABI mandates +4 even if partner lui doesn't
immediately precede addiu. */
sym_value += 4;
}
switch (ELF_R_TYPE (rel->r_info))
{
case R_MIPS_HI16:
{
grub_uint32_t value;
Elf_Rel *rel2;
#ifdef GRUB_CPU_WORDS_BIGENDIAN
addr += 2;
#endif
/* Handle partner lo16 relocation. Lower part is
treated as signed. Hence add 0x8000 to compensate.
*/
value = (*(grub_uint16_t *) addr << 16)
+ sym_value + 0x8000;
for (rel2 = rel + 1; rel2 < max; rel2++)
if (ELF_R_SYM (rel2->r_info)
== ELF_R_SYM (rel->r_info)
&& ELF_R_TYPE (rel2->r_info) == R_MIPS_LO16)
{
value += *(grub_int16_t *)
((char *) seg->addr + rel2->r_offset
#ifdef GRUB_CPU_WORDS_BIGENDIAN
+ 2
#endif
);
break;
}
*(grub_uint16_t *) addr = (value >> 16) & 0xffff;
}
break;
case R_MIPS_LO16:
#ifdef GRUB_CPU_WORDS_BIGENDIAN
addr += 2;
#endif
*(grub_uint16_t *) addr += sym_value & 0xffff;
break;
case R_MIPS_32:
*(grub_uint32_t *) addr += sym_value;
break;
case R_MIPS_GPREL32:
*(grub_uint32_t *) addr = sym_value
+ *(grub_uint32_t *) addr + gp0 - (grub_uint32_t)mod->got;
break;
case R_MIPS_26:
{
grub_uint32_t value;
grub_uint32_t raw;
raw = (*(grub_uint32_t *) addr) & 0x3ffffff;
value = raw << 2;
value += sym_value;
raw = (value >> 2) & 0x3ffffff;
*(grub_uint32_t *) addr =
raw | ((*(grub_uint32_t *) addr) & 0xfc000000);
}
break;
case R_MIPS_GOT16:
if (ELF_ST_BIND (sym->st_info) == STB_LOCAL)
{
Elf_Rel *rel2;
/* Handle partner lo16 relocation. Lower part is
treated as signed. Hence add 0x8000 to compensate.
*/
sym_value += (*(grub_uint16_t *) addr << 16)
+ 0x8000;
for (rel2 = rel + 1; rel2 < max; rel2++)
if (ELF_R_SYM (rel2->r_info)
== ELF_R_SYM (rel->r_info)
&& ELF_R_TYPE (rel2->r_info) == R_MIPS_LO16)
{
sym_value += *(grub_int16_t *)
((char *) seg->addr + rel2->r_offset
#ifdef GRUB_CPU_WORDS_BIGENDIAN
+ 2
#endif
);
break;
}
sym_value &= 0xffff0000;
*(grub_uint16_t *) addr = 0;
}
case R_MIPS_CALL16:
{
grub_uint32_t *gpptr = mod->gotptr;
/* FIXME: reuse*/
#ifdef GRUB_CPU_WORDS_BIGENDIAN
addr += 2;
#endif
*gpptr = sym_value + *(grub_uint16_t *) addr;
*(grub_uint16_t *) addr
= sizeof (grub_uint32_t) * (gpptr - (grub_uint32_t *) mod->got);
mod->gotptr = gpptr + 1;
break;
}
case R_MIPS_JALR:
break;
default:
{
return grub_error (GRUB_ERR_NOT_IMPLEMENTED_YET,
N_("relocation 0x%x is not implemented yet"),
ELF_R_TYPE (rel->r_info));
}
break;
}
}
return GRUB_ERR_NONE;
}
void
grub_arch_dl_init_linker (void)
{
grub_dl_register_symbol ("__gnu_local_gp", &__gnu_local_gp_dummy, 0, 0);
grub_dl_register_symbol ("_gp_disp", &_gp_disp_dummy, 0, 0);
}
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