2 * GCC stack protector support.
4 * Stack protector works by putting predefined pattern at the start of
5 * the stack frame and verifying that it hasn't been overwritten when
6 * returning from the function. The pattern is called stack canary
7 * and gcc expects it to be defined by a global variable called
8 * "__stack_chk_guard" on PPC. This unfortunately means that on SMP
9 * we cannot have a different canary value per task.
12 #ifndef _ASM_STACKPROTECTOR_H
13 #define _ASM_STACKPROTECTOR_H
15 #include <linux/random.h>
16 #include <linux/version.h>
19 extern unsigned long __stack_chk_guard;
22 * Initialize the stackprotector canary value.
24 * NOTE: this must only be called from functions that never return,
25 * and it must always be inlined.
27 static __always_inline void boot_init_stack_canary(void)
31 /* Try to get a semi random initial value. */
32 get_random_bytes(&canary, sizeof(canary));
34 canary ^= LINUX_VERSION_CODE;
36 current->stack_canary = canary;
37 __stack_chk_guard = current->stack_canary;
40 #endif /* _ASM_STACKPROTECTOR_H */