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 
17 extern 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  */
boot_init_stack_canary(void)25 static __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 */
34