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 #ifdef __ASSEMBLY__ 17 18 #define ASM_CLAC \ 19 ALTERNATIVE "", "clac", X86_FEATURE_SMAP 20 21 #define ASM_STAC \ 22 ALTERNATIVE "", "stac", X86_FEATURE_SMAP 23 24 #else /* __ASSEMBLY__ */ 25 26 static __always_inline void clac(void) 27 { 28 /* Note: a barrier is implicit in alternative() */ 29 alternative("", "clac", X86_FEATURE_SMAP); 30 } 31 32 static __always_inline void stac(void) 33 { 34 /* Note: a barrier is implicit in alternative() */ 35 alternative("", "stac", X86_FEATURE_SMAP); 36 } 37 38 static __always_inline unsigned long smap_save(void) 39 { 40 unsigned long flags; 41 42 asm volatile ("# smap_save\n\t" 43 ALTERNATIVE("", "pushf; pop %0; " "clac" "\n\t", 44 X86_FEATURE_SMAP) 45 : "=rm" (flags) : : "memory", "cc"); 46 47 return flags; 48 } 49 50 static __always_inline void smap_restore(unsigned long flags) 51 { 52 asm volatile ("# smap_restore\n\t" 53 ALTERNATIVE("", "push %0; popf\n\t", 54 X86_FEATURE_SMAP) 55 : : "g" (flags) : "memory", "cc"); 56 } 57 58 /* These macros can be used in asm() statements */ 59 #define ASM_CLAC \ 60 ALTERNATIVE("", "clac", X86_FEATURE_SMAP) 61 #define ASM_STAC \ 62 ALTERNATIVE("", "stac", X86_FEATURE_SMAP) 63 64 #endif /* __ASSEMBLY__ */ 65 66 #endif /* _ASM_X86_SMAP_H */ 67