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
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