1 #ifndef _ASM_STACKPROTECTOR_H
2 #define _ASM_STACKPROTECTOR_H 1
5 #include <asm/processor.h>
8 * Initialize the stackprotector canary value.
10 * NOTE: this must only be called from functions that never return,
11 * and it must always be inlined.
13 static __always_inline void boot_init_stack_canary(void)
19 * Build time only check to make sure the stack_canary is at
20 * offset 40 in the pda; this is a gcc ABI requirement
22 BUILD_BUG_ON(offsetof(union irq_stack_union, stack_canary) != 40);
25 * We both use the random pool and the current TSC as a source
26 * of randomness. The TSC only matters for very early init,
27 * there it already has some randomness on most systems. Later
28 * on during the bootup the random pool has true entropy too.
30 get_random_bytes(&canary, sizeof(canary));
31 tsc = __native_read_tsc();
32 canary += tsc + (tsc << 32UL);
34 current->stack_canary = canary;
35 percpu_write(irq_stack_union.stack_canary, canary);