1 /* SPDX-License-Identifier: GPL-2.0 */
2 /*
3 * GCC stack protector support.
4 *
5 * Stack protector works by putting predefined pattern at the start of
6 * the stack frame and verifying that it hasn't been overwritten when
7 * returning from the function. The pattern is called stack canary
8 * and gcc expects it to be defined by a global variable called
9 * "__stack_chk_guard" on ARM. This unfortunately means that on SMP
10 * we cannot have a different canary value per task.
11 */
12
13 #ifndef __ASM_STACKPROTECTOR_H
14 #define __ASM_STACKPROTECTOR_H
15
16 #include <asm/pointer_auth.h>
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 #if defined(CONFIG_STACKPROTECTOR)
29 unsigned long canary = get_random_canary();
30
31 current->stack_canary = canary;
32 if (!IS_ENABLED(CONFIG_STACKPROTECTOR_PER_TASK))
33 __stack_chk_guard = current->stack_canary;
34 #endif
35 ptrauth_thread_init_kernel(current);
36 ptrauth_thread_switch_kernel(current);
37 ptrauth_enable();
38 }
39
40 #endif /* _ASM_STACKPROTECTOR_H */
41
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