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
20extern 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 */
28static __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 */

 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 1
15
16#include <linux/random.h>
17#include <linux/version.h>
18
19extern 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 */
27static __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;
34
35	current->stack_canary = canary;
 
36	__stack_chk_guard = current->stack_canary;
 
37}
38
39#endif	/* _ASM_STACKPROTECTOR_H */