include/linux/cfi_types.h

root/include/linux/cfi_types.h
/* SPDX-License-Identifier: GPL-2.0 */
/*
 * Clang Control Flow Integrity (CFI) type definitions.
 */
#ifndef _LINUX_CFI_TYPES_H
#define _LINUX_CFI_TYPES_H

#ifdef __ASSEMBLY__
#include <linux/linkage.h>

#ifdef CONFIG_CFI
/*
 * Use the __kcfi_typeid_<function> type identifier symbol to
 * annotate indirectly called assembly functions. The compiler emits
 * these symbols for all address-taken function declarations in C
 * code.
 */
#ifndef __CFI_TYPE
#define __CFI_TYPE(name)                                \
        .4byte __kcfi_typeid_##name
#endif

#define SYM_TYPED_ENTRY(name, linkage, align...)        \
        linkage(name) ASM_NL                            \
        align ASM_NL                                    \
        __CFI_TYPE(name) ASM_NL                         \
        name:

#define SYM_TYPED_START(name, linkage, align...)        \
        SYM_TYPED_ENTRY(name, linkage, align)

#else /* CONFIG_CFI */

#define SYM_TYPED_START(name, linkage, align...)        \
        SYM_START(name, linkage, align)

#endif /* CONFIG_CFI */

#ifndef SYM_TYPED_FUNC_START
#define SYM_TYPED_FUNC_START(name)                      \
        SYM_TYPED_START(name, SYM_L_GLOBAL, SYM_A_ALIGN)
#endif

#else /* __ASSEMBLY__ */

#ifdef CONFIG_CFI
#define DEFINE_CFI_TYPE(name, func)                                             \
        /*                                                                      \
         * Force a reference to the function so the compiler generates          \
         * __kcfi_typeid_<func>.                                                \
         */                                                                     \
        __ADDRESSABLE(func);                                                    \
        /* u32 name __ro_after_init = __kcfi_typeid_<func> */                   \
        extern u32 name;                                                        \
        asm (                                                                   \
        "       .pushsection    .data..ro_after_init,\"aw\",\%progbits  \n"     \
        "       .type   " #name ",\%object                              \n"     \
        "       .globl  " #name "                                       \n"     \
        "       .p2align        2, 0x0                                  \n"     \
        #name ":                                                        \n"     \
        "       .4byte  __kcfi_typeid_" #func "                         \n"     \
        "       .size   " #name ", 4                                    \n"     \
        "       .popsection                                             \n"     \
        );
#endif

#endif /* __ASSEMBLY__ */
#endif /* _LINUX_CFI_TYPES_H */
Linux
