1 /* SPDX-License-Identifier: GPL-2.0-only */ 2 /* 3 * Supervisor Mode Access Prevention support 4 * 5 * Copyright (C) 2012 Intel Corporation 6 * Author: H. Peter Anvin <hpa@linux.intel.com> 7 */ 8 9 #ifndef _ASM_X86_SMAP_H 10 #define _ASM_X86_SMAP_H 11 12 #include <asm/nops.h> 13 #include <asm/cpufeatures.h> 14 #include <asm/alternative.h> 15 16 /* "Raw" instruction opcodes */ 17 #define __ASM_CLAC ".byte 0x0f,0x01,0xca" 18 #define __ASM_STAC ".byte 0x0f,0x01,0xcb" 19 20 #ifdef __ASSEMBLY__ 21 22 #ifdef CONFIG_X86_SMAP 23 24 #define ASM_CLAC \ 25 ALTERNATIVE "", __ASM_CLAC, X86_FEATURE_SMAP 26 27 #define ASM_STAC \ 28 ALTERNATIVE "", __ASM_STAC, X86_FEATURE_SMAP 29 30 #else /* CONFIG_X86_SMAP */ 31 32 #define ASM_CLAC 33 #define ASM_STAC 34 35 #endif /* CONFIG_X86_SMAP */ 36 37 #else /* __ASSEMBLY__ */ 38 39 #ifdef CONFIG_X86_SMAP 40 41 static __always_inline void clac(void) 42 { 43 /* Note: a barrier is implicit in alternative() */ 44 alternative("", __ASM_CLAC, X86_FEATURE_SMAP); 45 } 46 47 static __always_inline void stac(void) 48 { 49 /* Note: a barrier is implicit in alternative() */ 50 alternative("", __ASM_STAC, X86_FEATURE_SMAP); 51 } 52 53 static __always_inline unsigned long smap_save(void) 54 { 55 unsigned long flags; 56 57 asm volatile ("# smap_save\n\t" 58 ALTERNATIVE("", "pushf; pop %0; " __ASM_CLAC "\n\t", 59 X86_FEATURE_SMAP) 60 : "=rm" (flags) : : "memory", "cc"); 61 62 return flags; 63 } 64 65 static __always_inline void smap_restore(unsigned long flags) 66 { 67 asm volatile ("# smap_restore\n\t" 68 ALTERNATIVE("", "push %0; popf\n\t", 69 X86_FEATURE_SMAP) 70 : : "g" (flags) : "memory", "cc"); 71 } 72 73 /* These macros can be used in asm() statements */ 74 #define ASM_CLAC \ 75 ALTERNATIVE("", __ASM_CLAC, X86_FEATURE_SMAP) 76 #define ASM_STAC \ 77 ALTERNATIVE("", __ASM_STAC, X86_FEATURE_SMAP) 78 79 #else /* CONFIG_X86_SMAP */ 80 81 static inline void clac(void) { } 82 static inline void stac(void) { } 83 84 static inline unsigned long smap_save(void) { return 0; } 85 static inline void smap_restore(unsigned long flags) { } 86 87 #define ASM_CLAC 88 #define ASM_STAC 89 90 #endif /* CONFIG_X86_SMAP */ 91 92 #endif /* __ASSEMBLY__ */ 93 94 #endif /* _ASM_X86_SMAP_H */ 95