1b2441318SGreg Kroah-Hartman /* SPDX-License-Identifier: GPL-2.0 */ 2c743f380SNicolas Pitre /* 3c743f380SNicolas Pitre * GCC stack protector support. 4c743f380SNicolas Pitre * 5c743f380SNicolas Pitre * Stack protector works by putting predefined pattern at the start of 6c743f380SNicolas Pitre * the stack frame and verifying that it hasn't been overwritten when 7c743f380SNicolas Pitre * returning from the function. The pattern is called stack canary 8c743f380SNicolas Pitre * and gcc expects it to be defined by a global variable called 9189af465SArd Biesheuvel * "__stack_chk_guard" on ARM. This prevents SMP systems from using a 10189af465SArd Biesheuvel * different value for each task unless we enable a GCC plugin that 11189af465SArd Biesheuvel * replaces these symbol references with references to each task's own 12189af465SArd Biesheuvel * value. 13c743f380SNicolas Pitre */ 14c743f380SNicolas Pitre 15c743f380SNicolas Pitre #ifndef _ASM_STACKPROTECTOR_H 16c743f380SNicolas Pitre #define _ASM_STACKPROTECTOR_H 1 17c743f380SNicolas Pitre 18189af465SArd Biesheuvel #include <asm/thread_info.h> 19189af465SArd Biesheuvel 20c743f380SNicolas Pitre extern unsigned long __stack_chk_guard; 21c743f380SNicolas Pitre 22c743f380SNicolas Pitre /* 23c743f380SNicolas Pitre * Initialize the stackprotector canary value. 24c743f380SNicolas Pitre * 25c743f380SNicolas Pitre * NOTE: this must only be called from functions that never return, 26c743f380SNicolas Pitre * and it must always be inlined. 27c743f380SNicolas Pitre */ boot_init_stack_canary(void)28c743f380SNicolas Pitrestatic __always_inline void boot_init_stack_canary(void) 29c743f380SNicolas Pitre { 30*622754e8SJason A. Donenfeld unsigned long canary = get_random_canary(); 31c743f380SNicolas Pitre 32c743f380SNicolas Pitre current->stack_canary = canary; 33189af465SArd Biesheuvel #ifndef CONFIG_STACKPROTECTOR_PER_TASK 34c743f380SNicolas Pitre __stack_chk_guard = current->stack_canary; 35189af465SArd Biesheuvel #endif 36c743f380SNicolas Pitre } 37c743f380SNicolas Pitre 38c743f380SNicolas Pitre #endif /* _ASM_STACKPROTECTOR_H */ 39