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 */
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
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