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Commit d4703aef authored by Rusty Russell's avatar Rusty Russell
Browse files

module: handle ppc64 relocating kcrctabs when CONFIG_RELOCATABLE=y 

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: default avatarNeil Horman <nhorman@tuxdriver.com>
Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
Tested-by: default avatarNeil Horman <nhorman@tuxdriver.com>
Acked-by: default avatarPaul Mackerras <paulus@samba.org>
parent a8773769

arch/powerpc/include/asm/module.h

+5 −0
Original line number Diff line number Diff line
@@ -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 */

arch/powerpc/kernel/vmlinux.lds.S

+3 −0
Original line number Diff line number Diff line
@@ -38,6 +38,9 @@ jiffies = jiffies_64 + 4; 
#endif

SECTIONS

{

	. = 0;

	reloc_start = .;



	. = KERNELBASE;



/*

kernel/module.c

+21 −7
Original line number Diff line number Diff line
@@ -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;