include/linux/cfi.h

/* SPDX-License-Identifier: GPL-2.0 */
/*
 * Clang Control Flow Integrity (CFI) support.
 *
 * Copyright (C) 2021 Google LLC
 */
#ifndef _LINUX_CFI_H
#define _LINUX_CFI_H

#ifdef CONFIG_CFI_CLANG
typedef void (*cfi_check_fn)(uint64_t id, void *ptr, void *diag);

/* Compiler-generated function in each module, and the kernel */
extern void __cfi_check(uint64_t id, void *ptr, void *diag);

/*
 * Force the compiler to generate a CFI jump table entry for a function
 * and store the jump table address to __cfi_jt_<function>.
 */
#define __CFI_ADDRESSABLE(fn, __attr) \
	const void *__cfi_jt_ ## fn __visible __attr = (void *)&fn

#ifdef CONFIG_CFI_CLANG_SHADOW

extern void cfi_module_add(struct module *mod, unsigned long base_addr);
extern void cfi_module_remove(struct module *mod, unsigned long base_addr);

#else

static inline void cfi_module_add(struct module *mod, unsigned long base_addr) {}
static inline void cfi_module_remove(struct module *mod, unsigned long base_addr) {}

#endif /* CONFIG_CFI_CLANG_SHADOW */

#else /* !CONFIG_CFI_CLANG */

#ifdef CONFIG_X86_KERNEL_IBT

#define __CFI_ADDRESSABLE(fn, __attr) \
	const void *__cfi_jt_ ## fn __visible __attr = (void *)&fn

#endif /* CONFIG_X86_KERNEL_IBT */

#endif /* CONFIG_CFI_CLANG */

#ifndef __CFI_ADDRESSABLE
#define __CFI_ADDRESSABLE(fn, __attr)
#endif

#endif /* _LINUX_CFI_H */