1 /* SPDX-License-Identifier: GPL-2.0 */ 2 /* 3 * GCC stack protector support. 4 * 5 * (This is directly adopted from the ARM implementation) 6 * 7 * Stack protector works by putting predefined pattern at the start of 8 * the stack frame and verifying that it hasn't been overwritten when 9 * returning from the function. The pattern is called stack canary 10 * and gcc expects it to be defined by a global variable called 11 * "__stack_chk_guard" on MIPS. This unfortunately means that on SMP 12 * we cannot have a different canary value per task. 13 */ 14 15 #ifndef _ASM_STACKPROTECTOR_H 16 #define _ASM_STACKPROTECTOR_H 1 17 18 extern unsigned long __stack_chk_guard; 19 20 /* 21 * Initialize the stackprotector canary value. 22 * 23 * NOTE: this must only be called from functions that never return, 24 * and it must always be inlined. 25 */ 26 static __always_inline void boot_init_stack_canary(void) 27 { 28 unsigned long canary = get_random_canary(); 29 30 current->stack_canary = canary; 31 __stack_chk_guard = current->stack_canary; 32 } 33 34 #endif /* _ASM_STACKPROTECTOR_H */ 35