stackprotector.h

 1/*
 2 * GCC stack protector support.
 3 *
 4 * (This is directly adopted from the ARM implementation)
 5 *
 6 * Stack protector works by putting predefined pattern at the start of
 7 * the stack frame and verifying that it hasn't been overwritten when
 8 * returning from the function.  The pattern is called stack canary
 9 * and gcc expects it to be defined by a global variable called
10 * "__stack_chk_guard" on Xtensa.  This unfortunately means that on SMP
11 * we cannot have a different canary value per task.
12 */
13
14#ifndef _ASM_STACKPROTECTOR_H
15#define _ASM_STACKPROTECTOR_H 1
16
17extern unsigned long __stack_chk_guard;
18
19/*
20 * Initialize the stackprotector canary value.
21 *
22 * NOTE: this must only be called from functions that never return,
23 * and it must always be inlined.
24 */
25static __always_inline void boot_init_stack_canary(void)
26{
27	unsigned long canary = get_random_canary();
28
29	current->stack_canary = canary;
30	__stack_chk_guard = current->stack_canary;
31}
32
33#endif	/* _ASM_STACKPROTECTOR_H */