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 41static __always_inline void clac(void) 42{ 43 /* Note: a barrier is implicit in alternative() */ 44 alternative("", __ASM_CLAC, X86_FEATURE_SMAP); 45} 46 47static __always_inline void stac(void) 48{ 49 /* Note: a barrier is implicit in alternative() */ 50 alternative("", __ASM_STAC, X86_FEATURE_SMAP); 51} 52 53static __always_inline unsigned long smap_save(void) 54{ 55 unsigned long flags; 56 57 asm volatile ("# smap_save\n\t" 58 ALTERNATIVE("jmp 1f", "", X86_FEATURE_SMAP) 59 "pushf; pop %0; " __ASM_CLAC "\n\t" 60 "1:" 61 : "=rm" (flags) : : "memory", "cc"); 62 63 return flags; 64} 65 66static __always_inline void smap_restore(unsigned long flags) 67{ 68 asm volatile ("# smap_restore\n\t" 69 ALTERNATIVE("jmp 1f", "", X86_FEATURE_SMAP) 70 "push %0; popf\n\t" 71 "1:" 72 : : "g" (flags) : "memory", "cc"); 73} 74 75/* These macros can be used in asm() statements */ 76#define ASM_CLAC \ 77 ALTERNATIVE("", __ASM_CLAC, X86_FEATURE_SMAP) 78#define ASM_STAC \ 79 ALTERNATIVE("", __ASM_STAC, X86_FEATURE_SMAP) 80 81#else /* CONFIG_X86_SMAP */ 82 83static inline void clac(void) { } 84static inline void stac(void) { } 85 86static inline unsigned long smap_save(void) { return 0; } 87static inline void smap_restore(unsigned long flags) { } 88 89#define ASM_CLAC 90#define ASM_STAC 91 92#endif /* CONFIG_X86_SMAP */ 93 94#endif /* __ASSEMBLY__ */ 95 96#endif /* _ASM_X86_SMAP_H */ 97