/* 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 unfortunately means that on SMP * we cannot have a different canary value per task. */ #ifndef __ASM_STACKPROTECTOR_H #define __ASM_STACKPROTECTOR_H #include <linux/random.h> #include <linux/version.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; canary &= CANARY_MASK; current->stack_canary = canary; __stack_chk_guard = current->stack_canary; } #endif /* _ASM_STACKPROTECTOR_H */