1 /* SPDX-License-Identifier: GPL-2.0 */ 2 /* 3 * GCC stack protector support. 4 * 5 * Stack protector works by putting predefined pattern at the start of 6 * the stack frame and verifying that it hasn't been overwritten when 7 * returning from the function. The pattern is called stack canary 8 * and gcc expects it to be defined by a global variable called 9 * "__stack_chk_guard" on ARM. This unfortunately means that on SMP 10 * we cannot have a different canary value per task. 11 */ 12 13 #ifndef __ASM_STACKPROTECTOR_H 14 #define __ASM_STACKPROTECTOR_H 15 16 #include <asm/pointer_auth.h> 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 #if defined(CONFIG_STACKPROTECTOR) 29 unsigned long canary = get_random_canary(); 30 31 current->stack_canary = canary; 32 if (!IS_ENABLED(CONFIG_STACKPROTECTOR_PER_TASK)) 33 __stack_chk_guard = current->stack_canary; 34 #endif 35 ptrauth_thread_init_kernel(current); 36 ptrauth_thread_switch_kernel(current); 37 ptrauth_enable(); 38 } 39 40 #endif /* _ASM_STACKPROTECTOR_H */ 41