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#ifndef _ASM_STACKPROTECTOR_H
#define _ASM_STACKPROTECTOR_H 1
#ifdef CONFIG_CC_STACKPROTECTOR
#include <asm/tsc.h>
#include <asm/processor.h>
#include <asm/percpu.h>
#include <linux/random.h>
/*
* 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)
{
u64 canary;
u64 tsc;
/*
* Build time only check to make sure the stack_canary is at
* offset 40 in the pda; this is a gcc ABI requirement
*/
BUILD_BUG_ON(offsetof(union irq_stack_union, stack_canary) != 40);
/*
* We both use the random pool and the current TSC as a source
* of randomness. The TSC only matters for very early init,
* there it already has some randomness on most systems. Later
* on during the bootup the random pool has true entropy too.
*/
get_random_bytes(&canary, sizeof(canary));
tsc = __native_read_tsc();
canary += tsc + (tsc << 32UL);
current->stack_canary = canary;
percpu_write(irq_stack_union.stack_canary, canary);
}
#endif /* CC_STACKPROTECTOR */
#endif /* _ASM_STACKPROTECTOR_H */
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