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/* SPDX-License-Identifier: GPL-2.0 */
/*
* GCC stack protector support.
*
* Stack protector works by putting predefined pattern at the start of
* the stack frame and verifying that it hasn't been overwritten when
* returning from the function. The pattern is called stack canary
* and gcc expects it to be defined by a global variable called
* "__stack_chk_guard" on ARM. This unfortunately means that on SMP
* we cannot have a different canary value per task.
*/
#ifndef __ASM_STACKPROTECTOR_H
#define __ASM_STACKPROTECTOR_H
#include <linux/random.h>
#include <linux/version.h>
extern unsigned long __stack_chk_guard;
/*
* Initialize the stackprotector canary value.
*
* NOTE: this must only be called from functions that never return,
* and it must always be inlined.
*/
static __always_inline void boot_init_stack_canary(void)
{
unsigned long canary;
/* Try to get a semi random initial value. */
get_random_bytes(&canary, sizeof(canary));
canary ^= LINUX_VERSION_CODE;
canary &= CANARY_MASK;
current->stack_canary = canary;
if (!IS_ENABLED(CONFIG_STACKPROTECTOR_PER_TASK))
__stack_chk_guard = current->stack_canary;
}
#endif /* _ASM_STACKPROTECTOR_H */
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