linux/arch/arm/include/asm/module.h
Ard Biesheuvel 7d485f647c ARM: 8220/1: allow modules outside of bl range
Loading modules far away from the kernel in memory is problematic
because the 'bl' instruction only has limited reach, and modules are not
built with PLTs. Instead of using the -mlong-calls option (which affects
all compiler emitted bl instructions, but not the ones in assembler),
this patch allocates some additional space at module load time, and
populates it with PLT like veneers when encountering relocations that
are out of range.

This should work with all relocations against symbols exported by the
kernel, including those resulting from GCC generated implicit function
calls for ftrace etc.

The module memory size increases by about 5% on average, regardless of
whether any PLT entries were actually needed. However, due to the page
based rounding that occurs when allocating module memory, the average
memory footprint increase is negligible.

Reviewed-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2015-05-08 10:42:34 +01:00

60 lines
1.3 KiB
C

#ifndef _ASM_ARM_MODULE_H
#define _ASM_ARM_MODULE_H
#include <asm-generic/module.h>
struct unwind_table;
#ifdef CONFIG_ARM_UNWIND
enum {
ARM_SEC_INIT,
ARM_SEC_DEVINIT,
ARM_SEC_CORE,
ARM_SEC_EXIT,
ARM_SEC_DEVEXIT,
ARM_SEC_HOT,
ARM_SEC_UNLIKELY,
ARM_SEC_MAX,
};
#endif
struct mod_arch_specific {
#ifdef CONFIG_ARM_UNWIND
struct unwind_table *unwind[ARM_SEC_MAX];
#endif
#ifdef CONFIG_ARM_MODULE_PLTS
struct elf32_shdr *core_plt;
struct elf32_shdr *init_plt;
int core_plt_count;
int init_plt_count;
#endif
};
u32 get_module_plt(struct module *mod, unsigned long loc, Elf32_Addr val);
/*
* Add the ARM architecture version to the version magic string
*/
#define MODULE_ARCH_VERMAGIC_ARMVSN "ARMv" __stringify(__LINUX_ARM_ARCH__) " "
/* Add __virt_to_phys patching state as well */
#ifdef CONFIG_ARM_PATCH_PHYS_VIRT
#define MODULE_ARCH_VERMAGIC_P2V "p2v8 "
#else
#define MODULE_ARCH_VERMAGIC_P2V ""
#endif
/* Add instruction set architecture tag to distinguish ARM/Thumb kernels */
#ifdef CONFIG_THUMB2_KERNEL
#define MODULE_ARCH_VERMAGIC_ARMTHUMB "thumb2 "
#else
#define MODULE_ARCH_VERMAGIC_ARMTHUMB ""
#endif
#define MODULE_ARCH_VERMAGIC \
MODULE_ARCH_VERMAGIC_ARMVSN \
MODULE_ARCH_VERMAGIC_ARMTHUMB \
MODULE_ARCH_VERMAGIC_P2V
#endif /* _ASM_ARM_MODULE_H */