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b2441318 | 1 | /* SPDX-License-Identifier: GPL-2.0 */ |
c0c264ae LA |
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 <linux/random.h> | |
17 | #include <linux/version.h> | |
18 | ||
19 | extern unsigned long __stack_chk_guard; | |
20 | ||
21 | /* | |
22 | * Initialize the stackprotector canary value. | |
23 | * | |
24 | * NOTE: this must only be called from functions that never return, | |
25 | * and it must always be inlined. | |
26 | */ | |
27 | static __always_inline void boot_init_stack_canary(void) | |
28 | { | |
29 | unsigned long canary; | |
30 | ||
31 | /* Try to get a semi random initial value. */ | |
32 | get_random_bytes(&canary, sizeof(canary)); | |
33 | canary ^= LINUX_VERSION_CODE; | |
d21f5498 | 34 | canary &= CANARY_MASK; |
c0c264ae LA |
35 | |
36 | current->stack_canary = canary; | |
37 | __stack_chk_guard = current->stack_canary; | |
38 | } | |
39 | ||
40 | #endif /* _ASM_STACKPROTECTOR_H */ |