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 prevents SMP systems from using a
10 * different value for each task unless we enable a GCC plugin that
11 * replaces these symbol references with references to each task's own
12 * value.
13 */
14
15 #ifndef _ASM_STACKPROTECTOR_H
16 #define _ASM_STACKPROTECTOR_H 1
17
18 #include <asm/thread_info.h>
19
20 extern unsigned long __stack_chk_guard;
21
22 /*
23 * Initialize the stackprotector canary value.
24 *
25 * NOTE: this must only be called from functions that never return,
26 * and it must always be inlined.
27 */
28 static __always_inline void boot_init_stack_canary(void)
29 {
30 unsigned long canary = get_random_canary();
31
32 current->stack_canary = canary;
33 #ifndef CONFIG_STACKPROTECTOR_PER_TASK
34 __stack_chk_guard = current->stack_canary;
35 #endif
36 }
37
38 #endif /* _ASM_STACKPROTECTOR_H */
39
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