start_kernel---boot_init_stack_canary<四>

In init/main.c

1 /*
2      * Set up the the initial canary ASAP:
3 */
4     boot_init_stack_canary();

in arch/arm/include/asm/stackprotector.h

 1 /*
 2  * Initialize the stackprotector canary value.
 3  *
 4  * NOTE: this must only be called from functions that never return,
 5  * and it must always be inlined.
 6  */
 7 static __always_inline void boot_init_stack_canary(void)
 8 {
 9     unsigned long canary;
10 
11     /* Try to get a semi random initial value. */
12     get_random_bytes(&canary, sizeof(canary));
13     canary ^= LINUX_VERSION_CODE;
14 
15     current->stack_canary = canary;
16     __stack_chk_guard = current->stack_canary;
17 }

得到随机数字&kernel version，用于版本检测？