Linux kernel mirror (for testing)
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1/* SPDX-License-Identifier: GPL-2.0 */
2/*
3 * GCC stack protector support.
4 *
5 * Stack protector works by putting a 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 the stack canary
8 * and is a unique value for each task.
9 */
10
11#ifndef _ASM_STACKPROTECTOR_H
12#define _ASM_STACKPROTECTOR_H 1
13
14#ifdef CONFIG_STACKPROTECTOR
15
16#include <asm/tsc.h>
17#include <asm/processor.h>
18#include <asm/percpu.h>
19#include <asm/desc.h>
20
21#include <linux/sched.h>
22
23DECLARE_PER_CPU_CACHE_HOT(unsigned long, __stack_chk_guard);
24
25/*
26 * Initialize the stackprotector canary value.
27 *
28 * NOTE: this must only be called from functions that never return
29 * and it must always be inlined.
30 *
31 * In addition, it should be called from a compilation unit for which
32 * stack protector is disabled. Alternatively, the caller should not end
33 * with a function call which gets tail-call optimized as that would
34 * lead to checking a modified canary value.
35 */
36static __always_inline void boot_init_stack_canary(void)
37{
38 unsigned long canary = get_random_canary();
39
40 current->stack_canary = canary;
41 this_cpu_write(__stack_chk_guard, canary);
42}
43
44static inline void cpu_init_stack_canary(int cpu, struct task_struct *idle)
45{
46 per_cpu(__stack_chk_guard, cpu) = idle->stack_canary;
47}
48
49#else /* STACKPROTECTOR */
50
51/* dummy boot_init_stack_canary() is defined in linux/stackprotector.h */
52
53static inline void cpu_init_stack_canary(int cpu, struct task_struct *idle)
54{ }
55
56#endif /* STACKPROTECTOR */
57#endif /* _ASM_STACKPROTECTOR_H */