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 #define ASM_CLAC \ 23 ALTERNATIVE "", __ASM_CLAC, X86_FEATURE_SMAP 24 25 #define ASM_STAC \ 26 ALTERNATIVE "", __ASM_STAC, X86_FEATURE_SMAP 27 28 #else /* __ASSEMBLY__ */ 29 30 static __always_inline void clac(void) 31 { 32 /* Note: a barrier is implicit in alternative() */ 33 alternative("", __ASM_CLAC, X86_FEATURE_SMAP); 34 } 35 36 static __always_inline void stac(void) 37 { 38 /* Note: a barrier is implicit in alternative() */ 39 alternative("", __ASM_STAC, X86_FEATURE_SMAP); 40 } 41 42 static __always_inline unsigned long smap_save(void) 43 { 44 unsigned long flags; 45 46 asm volatile ("# smap_save\n\t" 47 ALTERNATIVE("", "pushf; pop %0; " __ASM_CLAC "\n\t", 48 X86_FEATURE_SMAP) 49 : "=rm" (flags) : : "memory", "cc"); 50 51 return flags; 52 } 53 54 static __always_inline void smap_restore(unsigned long flags) 55 { 56 asm volatile ("# smap_restore\n\t" 57 ALTERNATIVE("", "push %0; popf\n\t", 58 X86_FEATURE_SMAP) 59 : : "g" (flags) : "memory", "cc"); 60 } 61 62 /* These macros can be used in asm() statements */ 63 #define ASM_CLAC \ 64 ALTERNATIVE("", __ASM_CLAC, X86_FEATURE_SMAP) 65 #define ASM_STAC \ 66 ALTERNATIVE("", __ASM_STAC, X86_FEATURE_SMAP) 67 68 #endif /* __ASSEMBLY__ */ 69 70 #endif /* _ASM_X86_SMAP_H */ 71