/* SPDX-License-Identifier: GPL-2.0 */ /* * GCC stack protector support. * * Stack protector works by putting predefined pattern at the start of * the stack frame and verifying that it hasn't been overwritten when * returning from the function. The pattern is called stack canary * and gcc expects it to be defined by a global variable called * "__stack_chk_guard" on ARM. This prevents SMP systems from using a * different value for each task unless we enable a GCC plugin that * replaces these symbol references with references to each task's own * value. */ #ifndef _ASM_STACKPROTECTOR_H #define _ASM_STACKPROTECTOR_H 1 #include <linux/random.h> #include <linux/version.h> #include <asm/thread_info.h> extern unsigned long __stack_chk_guard; /* * Initialize the stackprotector canary value. * * NOTE: this must only be called from functions that never return, * and it must always be inlined. */ static __always_inline void boot_init_stack_canary(void) { unsigned long canary; /* Try to get a semi random initial value. */ get_random_bytes(&canary, sizeof(canary)); canary ^= LINUX_VERSION_CODE; current->stack_canary = canary; #ifndef CONFIG_STACKPROTECTOR_PER_TASK __stack_chk_guard = current->stack_canary; #endif } #endif /* _ASM_STACKPROTECTOR_H */