linux/arch/arm/include/asm/stackprotector.h
Nicolas Pitre c743f38013 ARM: initial stack protector (-fstack-protector) support
This is the very basic stuff without the changing canary upon
task switch yet.  Just the Kconfig option and a constant canary
value initialized at boot time.

Signed-off-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2010-06-14 21:31:00 -04:00

38 lines
1.1 KiB
C

/*
* GCC stack protector support.
*
* Stack protector works by putting predefined pattern at the start of
* the stack frame and verifying that it hasn't been overwritten when
* returning from the function. The pattern is called stack canary
* and gcc expects it to be defined by a global variable called
* "__stack_chk_guard" on ARM. This unfortunately means that on SMP
* we cannot have a different canary value per task.
*/
#ifndef _ASM_STACKPROTECTOR_H
#define _ASM_STACKPROTECTOR_H 1
#include <linux/random.h>
#include <linux/version.h>
extern unsigned long __stack_chk_guard;
/*
* Initialize the stackprotector canary value.
*
* NOTE: this must only be called from functions that never return,
* and it must always be inlined.
*/
static __always_inline void boot_init_stack_canary(void)
{
unsigned long canary;
/* Try to get a semi random initial value. */
get_random_bytes(&canary, sizeof(canary));
canary ^= LINUX_VERSION_CODE;
current->stack_canary = canary;
__stack_chk_guard = current->stack_canary;
}
#endif /* _ASM_STACKPROTECTOR_H */