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MIPS: Fix race condition in module relocation code.

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The relocation code was essentially taken from the 2.4 modutils which
perform relocation in userspace.  In 2.6 relocation of multiple modules
may be performed in parallel by the in-kernel loader so the global
variable mips_hi16_list won't fly anymore.  Fix race by moving it into
mod_arch_specific.

[ralf@linux-mips.org: folded in Tony's followup fix.  Thanks Tony!]

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Tony Wu <tung7970@gmail.com>
Cc:  linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/4189/
This commit is contained in:
Ralf Baechle 2012-08-08 16:59:43 +02:00
parent d3cac35cd0
commit 861667dc82
2 changed files with 7 additions and 7 deletions
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1
arch/mips/include/asm/module.h
View file

@ -10,6 +10,7 @@ struct mod_arch_specific {
struct list_head dbe_list;
const struct exception_table_entry *dbe_start;
const struct exception_table_entry *dbe_end;
struct mips_hi16 *r_mips_hi16_list;
};
typedef uint8_t Elf64_Byte; /* Type for a 8-bit quantity. */

13
arch/mips/kernel/module.c
View file

@ -39,8 +39,6 @@ struct mips_hi16 {
Elf_Addr value;
};
static struct mips_hi16 *mips_hi16_list;
static LIST_HEAD(dbe_list);
static DEFINE_SPINLOCK(dbe_lock);
@ -128,8 +126,8 @@ static int apply_r_mips_hi16_rel(struct module *me, u32 *location, Elf_Addr v)
n->addr = (Elf_Addr *)location;
n->value = v;
n->next = mips_hi16_list;
mips_hi16_list = n;
n->next = me->arch.r_mips_hi16_list;
me->arch.r_mips_hi16_list = n;
return 0;
}
@ -151,9 +149,9 @@ static int apply_r_mips_lo16_rel(struct module *me, u32 *location, Elf_Addr v)
/* Sign extend the addend we extract from the lo insn. */
vallo = ((insnlo & 0xffff) ^ 0x8000) - 0x8000;
if (mips_hi16_list != NULL) {
if (me->arch.r_mips_hi16_list != NULL) {
l = mips_hi16_list;
l = me->arch.r_mips_hi16_list;
while (l != NULL) {
unsigned long insn;
@ -187,7 +185,7 @@ static int apply_r_mips_lo16_rel(struct module *me, u32 *location, Elf_Addr v)
l = next;
}
mips_hi16_list = NULL;
me->arch.r_mips_hi16_list = NULL;
}
/*
@ -278,6 +276,7 @@ int apply_relocate(Elf_Shdr *sechdrs, const char *strtab,
pr_debug("Applying relocate section %u to %u\n", relsec,
sechdrs[relsec].sh_info);
me->arch.r_mips_hi16_list = NULL;
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