1 /* SPDX-License-Identifier: GPL-2.0 */
2 /*
3  * GCC stack protector support.
4  *
5  * (This is directly adopted from the ARM implementation)
6  *
7  * Stack protector works by putting predefined pattern at the start of
8  * the stack frame and verifying that it hasn't been overwritten when
9  * returning from the function.  The pattern is called stack canary
10  * and gcc expects it to be defined by a global variable called
11  * "__stack_chk_guard" on MIPS.  This unfortunately means that on SMP
12  * we cannot have a different canary value per task.
13  */
14 
15 #ifndef _ASM_STACKPROTECTOR_H
16 #define _ASM_STACKPROTECTOR_H 1
17 
18 extern unsigned long __stack_chk_guard;
19 
20 /*
21  * Initialize the stackprotector canary value.
22  *
23  * NOTE: this must only be called from functions that never return,
24  * and it must always be inlined.
25  */
26 static __always_inline void boot_init_stack_canary(void)
27 {
28 	unsigned long canary = get_random_canary();
29 
30 	current->stack_canary = canary;
31 	__stack_chk_guard = current->stack_canary;
32 }
33 
34 #endif	/* _ASM_STACKPROTECTOR_H */
35