linux/arch/sh/kernel/module.c
Linus Torvalds 5336377d62 modules: Fix module_bug_list list corruption race
With all the recent module loading cleanups, we've minimized the code
that sits under module_mutex, fixing various deadlocks and making it
possible to do most of the module loading in parallel.

However, that whole conversion totally missed the rather obscure code
that adds a new module to the list for BUG() handling.  That code was
doubly obscure because (a) the code itself lives in lib/bugs.c (for
dubious reasons) and (b) it gets called from the architecture-specific
"module_finalize()" rather than from generic code.

Calling it from arch-specific code makes no sense what-so-ever to begin
with, and is now actively wrong since that code isn't protected by the
module loading lock any more.

So this commit moves the "module_bug_{finalize,cleanup}()" calls away
from the arch-specific code, and into the generic code - and in the
process protects it with the module_mutex so that the list operations
are now safe.

Future fixups:
 - move the module list handling code into kernel/module.c where it
   belongs.
 - get rid of 'module_bug_list' and just use the regular list of modules
   (called 'modules' - imagine that) that we already create and maintain
   for other reasons.

Reported-and-tested-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Adrian Bunk <bunk@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-10-05 11:29:27 -07:00

160 lines
4.3 KiB
C

/* Kernel module help for SH.
SHcompact version by Kaz Kojima and Paul Mundt.
SHmedia bits:
Copyright 2004 SuperH (UK) Ltd
Author: Richard Curnow
Based on the sh version, and on code from the sh64-specific parts of
modutils, originally written by Richard Curnow and Ben Gaster.
This program 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 2 of the License, or
(at your option) any later version.
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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include <linux/moduleloader.h>
#include <linux/elf.h>
#include <linux/vmalloc.h>
#include <linux/bug.h>
#include <linux/fs.h>
#include <linux/string.h>
#include <linux/kernel.h>
#include <asm/unaligned.h>
#include <asm/dwarf.h>
void *module_alloc(unsigned long size)
{
if (size == 0)
return NULL;
return vmalloc_exec(size);
}
/* Free memory returned from module_alloc */
void module_free(struct module *mod, void *module_region)
{
vfree(module_region);
}
/* We don't need anything special. */
int module_frob_arch_sections(Elf_Ehdr *hdr,
Elf_Shdr *sechdrs,
char *secstrings,
struct module *mod)
{
return 0;
}
int apply_relocate_add(Elf32_Shdr *sechdrs,
const char *strtab,
unsigned int symindex,
unsigned int relsec,
struct module *me)
{
unsigned int i;
Elf32_Rela *rel = (void *)sechdrs[relsec].sh_addr;
Elf32_Sym *sym;
Elf32_Addr relocation;
uint32_t *location;
uint32_t value;
pr_debug("Applying relocate section %u to %u\n", relsec,
sechdrs[relsec].sh_info);
for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
/* This is where to make the change */
location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
+ rel[i].r_offset;
/* This is the symbol it is referring to. Note that all
undefined symbols have been resolved. */
sym = (Elf32_Sym *)sechdrs[symindex].sh_addr
+ ELF32_R_SYM(rel[i].r_info);
relocation = sym->st_value + rel[i].r_addend;
#ifdef CONFIG_SUPERH64
/* For text addresses, bit2 of the st_other field indicates
* whether the symbol is SHmedia (1) or SHcompact (0). If
* SHmedia, the LSB of the symbol needs to be asserted
* for the CPU to be in SHmedia mode when it starts executing
* the branch target. */
relocation |= !!(sym->st_other & 4);
#endif
switch (ELF32_R_TYPE(rel[i].r_info)) {
case R_SH_DIR32:
value = get_unaligned(location);
value += relocation;
put_unaligned(value, location);
break;
case R_SH_REL32:
relocation = (relocation - (Elf32_Addr) location);
value = get_unaligned(location);
value += relocation;
put_unaligned(value, location);
break;
case R_SH_IMM_LOW16:
*location = (*location & ~0x3fffc00) |
((relocation & 0xffff) << 10);
break;
case R_SH_IMM_MEDLOW16:
*location = (*location & ~0x3fffc00) |
(((relocation >> 16) & 0xffff) << 10);
break;
case R_SH_IMM_LOW16_PCREL:
relocation -= (Elf32_Addr) location;
*location = (*location & ~0x3fffc00) |
((relocation & 0xffff) << 10);
break;
case R_SH_IMM_MEDLOW16_PCREL:
relocation -= (Elf32_Addr) location;
*location = (*location & ~0x3fffc00) |
(((relocation >> 16) & 0xffff) << 10);
break;
default:
printk(KERN_ERR "module %s: Unknown relocation: %u\n",
me->name, ELF32_R_TYPE(rel[i].r_info));
return -ENOEXEC;
}
}
return 0;
}
int apply_relocate(Elf32_Shdr *sechdrs,
const char *strtab,
unsigned int symindex,
unsigned int relsec,
struct module *me)
{
printk(KERN_ERR "module %s: REL RELOCATION unsupported\n",
me->name);
return -ENOEXEC;
}
int module_finalize(const Elf_Ehdr *hdr,
const Elf_Shdr *sechdrs,
struct module *me)
{
int ret = 0;
ret |= module_dwarf_finalize(hdr, sechdrs, me);
return ret;
}
void module_arch_cleanup(struct module *mod)
{
module_dwarf_cleanup(mod);
}