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module: handle ppc64 relocating kcrctabs when CONFIG_RELOCATABLE=y

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powerpc applies relocations to the kcrctab.  They're absolute symbols,
but it's not completely unreasonable: other archs may too, but the
relocation is often 0.

http://lists.ozlabs.org/pipermail/linuxppc-dev/2009-November/077972.html

Inspired-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Tested-by: Neil Horman <nhorman@tuxdriver.com>
Acked-by: Paul Mackerras <paulus@samba.org>
This commit is contained in:
Rusty Russell 2009-12-15 16:28:32 -06:00
parent a8773769d1
commit d4703aefdb
3 changed files with 29 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
arch/powerpc/include/asm/module.h
View File

@ -87,5 +87,10 @@ struct exception_table_entry;
void sort_ex_table(struct exception_table_entry *start,
struct exception_table_entry *finish);
#ifdef CONFIG_MODVERSIONS
#define ARCH_RELOCATES_KCRCTAB
extern const unsigned long reloc_start[];
#endif
#endif /* __KERNEL__ */
#endif /* _ASM_POWERPC_MODULE_H */

3
arch/powerpc/kernel/vmlinux.lds.S
View File

@ -38,6 +38,9 @@ jiffies = jiffies_64 + 4;
#endif
SECTIONS
{
. = 0;
reloc_start = .;
. = KERNELBASE;
/*

28
kernel/module.c
View File

@ -880,11 +880,23 @@ static int try_to_force_load(struct module *mod, const char *reason)
}
#ifdef CONFIG_MODVERSIONS
/* If the arch applies (non-zero) relocations to kernel kcrctab, unapply it. */
static unsigned long maybe_relocated(unsigned long crc,
const struct module *crc_owner)
{
#ifdef ARCH_RELOCATES_KCRCTAB
if (crc_owner == NULL)
return crc - (unsigned long)reloc_start;
#endif
return crc;
}
static int check_version(Elf_Shdr *sechdrs,
unsigned int versindex,
const char *symname,
struct module *mod,
const unsigned long *crc)
const unsigned long *crc,
const struct module *crc_owner)
{
unsigned int i, num_versions;
struct modversion_info *versions;
@ -905,10 +917,10 @@ static int check_version(Elf_Shdr *sechdrs,
if (strcmp(versions[i].name, symname) != 0)
continue;
if (versions[i].crc == *crc)
if (versions[i].crc == maybe_relocated(*crc, crc_owner))
return 1;
DEBUGP("Found checksum %lX vs module %lX\n",
*crc, versions[i].crc);
maybe_relocated(*crc, crc_owner), versions[i].crc);
goto bad_version;
}
@ -931,7 +943,8 @@ static inline int check_modstruct_version(Elf_Shdr *sechdrs,
if (!find_symbol(MODULE_SYMBOL_PREFIX "module_layout", NULL,
&crc, true, false))
BUG();
return check_version(sechdrs, versindex, "module_layout", mod, crc);
return check_version(sechdrs, versindex, "module_layout", mod, crc,
NULL);
}
/* First part is kernel version, which we ignore if module has crcs. */
@ -949,7 +962,8 @@ static inline int check_version(Elf_Shdr *sechdrs,
unsigned int versindex,
const char *symname,
struct module *mod,
const unsigned long *crc)
const unsigned long *crc,
const struct module *crc_owner)
{
return 1;
}
@ -984,8 +998,8 @@ static const struct kernel_symbol *resolve_symbol(Elf_Shdr *sechdrs,
/* use_module can fail due to OOM,
or module initialization or unloading */
if (sym) {
if (!check_version(sechdrs, versindex, name, mod, crc) ||
!use_module(mod, owner))
if (!check_version(sechdrs, versindex, name, mod, crc, owner)
|| !use_module(mod, owner))
sym = NULL;
}
return sym;