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/* SPDX-License-Identifier: GPL-2.0 */
/*
* GCC stack protector support.
*
* Stack protector works by putting a 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 the stack canary
* and is a unique value for each task.
*/
#ifndef _ASM_STACKPROTECTOR_H
#define _ASM_STACKPROTECTOR_H 1
#ifdef CONFIG_STACKPROTECTOR
#include <asm/tsc.h>
#include <asm/processor.h>
#include <asm/percpu.h>
#include <asm/desc.h>
#include <linux/sched.h>
DECLARE_PER_CPU_CACHE_HOT(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.
*
* In addition, it should be called from a compilation unit for which
* stack protector is disabled. Alternatively, the caller should not end
* with a function call which gets tail-call optimized as that would
* lead to checking a modified canary value.
*/
static __always_inline void boot_init_stack_canary(void)
{
unsigned long canary = get_random_canary();
current->stack_canary = canary;
this_cpu_write(__stack_chk_guard, canary);
}
static inline void cpu_init_stack_canary(int cpu, struct task_struct *idle)
{
per_cpu(__stack_chk_guard, cpu) = idle->stack_canary;
}
#else /* STACKPROTECTOR */
/* dummy boot_init_stack_canary() is defined in linux/stackprotector.h */
static inline void cpu_init_stack_canary(int cpu, struct task_struct *idle)
{ }
#endif /* STACKPROTECTOR */
#endif /* _ASM_STACKPROTECTOR_H */
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