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Hexagon: Support dynamic module loading.

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Modules should be compiled as ordinary .o's; shared objects are not
supported.

Signed-off-by: Linas Vepstas <linas@codeaurora.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Richard Kuo <rkuo@codeaurora.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Linas Vepstas 2011-10-31 18:40:46 -05:00 committed by Linus Torvalds
parent b39e293e1d
commit 98fb103694
1 changed files with 162 additions and 0 deletions
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162
arch/hexagon/kernel/module.c Normal file
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/*
* Kernel module loader for Hexagon
*
* Copyright (c) 2010-2011, Code Aurora Forum. All rights reserved.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 and
* only version 2 as published by the Free Software Foundation.
*
* This program 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 this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301, USA.
*/
#include <asm/module.h>
#include <linux/elf.h>
#include <linux/module.h>
#include <linux/moduleloader.h>
#include <linux/vmalloc.h>
#if 0
#define DEBUGP printk
#else
#define DEBUGP(fmt , ...)
#endif
/*
* module_frob_arch_sections - tweak got/plt sections.
* @hdr - pointer to elf header
* @sechdrs - pointer to elf load section headers
* @secstrings - symbol names
* @mod - pointer to module
*/
int module_frob_arch_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs,
char *secstrings,
struct module *mod)
{
unsigned int i;
int found = 0;
/* Look for .plt and/or .got.plt and/or .init.plt sections */
for (i = 0; i < hdr->e_shnum; i++) {
DEBUGP("Section %d is %s\n", i,
secstrings + sechdrs[i].sh_name);
if (strcmp(secstrings + sechdrs[i].sh_name, ".plt") == 0)
found = i+1;
if (strcmp(secstrings + sechdrs[i].sh_name, ".got.plt") == 0)
found = i+1;
if (strcmp(secstrings + sechdrs[i].sh_name, ".rela.plt") == 0)
found = i+1;
}
/* At this time, we don't support modules comiled with -shared */
if (found) {
printk(KERN_WARNING
"Module '%s' contains unexpected .plt/.got sections.\n",
mod->name);
/* return -ENOEXEC; */
}
return 0;
}
/*
* apply_relocate_add - perform rela relocations.
* @sechdrs - pointer to section headers
* @strtab - some sort of start address?
* @symindex - symbol index offset or something?
* @relsec - address to relocate to?
* @module - pointer to module
*
* Perform rela relocations.
*/
int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
unsigned int symindex, unsigned int relsec,
struct module *module)
{
unsigned int i;
Elf32_Sym *sym;
uint32_t *location;
uint32_t value;
unsigned int nrelocs = sechdrs[relsec].sh_size / sizeof(Elf32_Rela);
Elf32_Rela *rela = (void *)sechdrs[relsec].sh_addr;
Elf32_Word sym_info = sechdrs[relsec].sh_info;
Elf32_Sym *sym_base = (Elf32_Sym *) sechdrs[symindex].sh_addr;
void *loc_base = (void *) sechdrs[sym_info].sh_addr;
DEBUGP("Applying relocations in section %u to section %u base=%p\n",
relsec, sym_info, loc_base);
for (i = 0; i < nrelocs; i++) {
/* Symbol to relocate */
sym = sym_base + ELF32_R_SYM(rela[i].r_info);
/* Where to make the change */
location = loc_base + rela[i].r_offset;
/* `Everything is relative'. */
value = sym->st_value + rela[i].r_addend;
DEBUGP("%d: value=%08x loc=%p reloc=%d symbol=%s\n",
i, value, location, ELF32_R_TYPE(rela[i].r_info),
sym->st_name ?
&strtab[sym->st_name] : "(anonymous)");
switch (ELF32_R_TYPE(rela[i].r_info)) {
case R_HEXAGON_B22_PCREL: {
int dist = (int)(value - (uint32_t)location);
if ((dist < -0x00800000) ||
(dist >= 0x00800000)) {
printk(KERN_ERR
"%s: %s: %08x=%08x-%08x %s\n",
module->name,
"R_HEXAGON_B22_PCREL reloc out of range",
dist, value, (uint32_t)location,
sym->st_name ?
&strtab[sym->st_name] : "(anonymous)");
return -ENOEXEC;
}
DEBUGP("B22_PCREL contents: %08X.\n", *location);
*location &= ~0x01ff3fff;
*location |= 0x00003fff & dist;
*location |= 0x01ff0000 & (dist<<2);
DEBUGP("Contents after reloc: %08x\n", *location);
break;
}
case R_HEXAGON_HI16:
value = (value>>16) & 0xffff;
/* fallthrough */
case R_HEXAGON_LO16:
*location &= ~0x00c03fff;
*location |= value & 0x3fff;
*location |= (value & 0xc000) << 8;
break;
case R_HEXAGON_32:
*location = value;
break;
case R_HEXAGON_32_PCREL:
*location = value - (uint32_t)location;
break;
case R_HEXAGON_PLT_B22_PCREL:
case R_HEXAGON_GOTOFF_LO16:
case R_HEXAGON_GOTOFF_HI16:
printk(KERN_ERR "%s: GOT/PLT relocations unsupported\n",
module->name);
return -ENOEXEC;
default:
printk(KERN_ERR "%s: unknown relocation: %u\n",
module->name,
ELF32_R_TYPE(rela[i].r_info));
return -ENOEXEC;
}
}
return 0;
}