| H. Peter Anvin | 51ae4a2 | 2012-09-21 12:43:10 -0700 | [diff] [blame] | 1 | /* |
| 2 | * Supervisor Mode Access Prevention support |
| 3 | * |
| 4 | * Copyright (C) 2012 Intel Corporation |
| 5 | * Author: H. Peter Anvin <hpa@linux.intel.com> |
| 6 | * |
| 7 | * This program is free software; you can redistribute it and/or |
| 8 | * modify it under the terms of the GNU General Public License |
| 9 | * as published by the Free Software Foundation; version 2 |
| 10 | * of the License. |
| 11 | */ |
| 12 | |
| 13 | #ifndef _ASM_X86_SMAP_H |
| 14 | #define _ASM_X86_SMAP_H |
| 15 | |
| 16 | #include <linux/stringify.h> |
| 17 | #include <asm/nops.h> |
| 18 | #include <asm/cpufeature.h> |
| 19 | |
| 20 | /* "Raw" instruction opcodes */ |
| 21 | #define __ASM_CLAC .byte 0x0f,0x01,0xca |
| 22 | #define __ASM_STAC .byte 0x0f,0x01,0xcb |
| 23 | |
| 24 | #ifdef __ASSEMBLY__ |
| 25 | |
| 26 | #include <asm/alternative-asm.h> |
| 27 | |
| 28 | #ifdef CONFIG_X86_SMAP |
| 29 | |
| 30 | #define ASM_CLAC \ |
| 31 | 661: ASM_NOP3 ; \ |
| 32 | .pushsection .altinstr_replacement, "ax" ; \ |
| 33 | 662: __ASM_CLAC ; \ |
| 34 | .popsection ; \ |
| 35 | .pushsection .altinstructions, "a" ; \ |
| 36 | altinstruction_entry 661b, 662b, X86_FEATURE_SMAP, 3, 3 ; \ |
| 37 | .popsection |
| 38 | |
| 39 | #define ASM_STAC \ |
| 40 | 661: ASM_NOP3 ; \ |
| 41 | .pushsection .altinstr_replacement, "ax" ; \ |
| 42 | 662: __ASM_STAC ; \ |
| 43 | .popsection ; \ |
| 44 | .pushsection .altinstructions, "a" ; \ |
| 45 | altinstruction_entry 661b, 662b, X86_FEATURE_SMAP, 3, 3 ; \ |
| 46 | .popsection |
| 47 | |
| 48 | #else /* CONFIG_X86_SMAP */ |
| 49 | |
| 50 | #define ASM_CLAC |
| 51 | #define ASM_STAC |
| 52 | |
| 53 | #endif /* CONFIG_X86_SMAP */ |
| 54 | |
| 55 | #else /* __ASSEMBLY__ */ |
| 56 | |
| 57 | #include <asm/alternative.h> |
| 58 | |
| 59 | #ifdef CONFIG_X86_SMAP |
| 60 | |
| H. Peter Anvin | 63bcff2 | 2012-09-21 12:43:12 -0700 | [diff] [blame] | 61 | static __always_inline void clac(void) |
| H. Peter Anvin | 51ae4a2 | 2012-09-21 12:43:10 -0700 | [diff] [blame] | 62 | { |
| 63 | /* Note: a barrier is implicit in alternative() */ |
| 64 | alternative(ASM_NOP3, __stringify(__ASM_CLAC), X86_FEATURE_SMAP); |
| 65 | } |
| 66 | |
| H. Peter Anvin | 63bcff2 | 2012-09-21 12:43:12 -0700 | [diff] [blame] | 67 | static __always_inline void stac(void) |
| H. Peter Anvin | 51ae4a2 | 2012-09-21 12:43:10 -0700 | [diff] [blame] | 68 | { |
| 69 | /* Note: a barrier is implicit in alternative() */ |
| 70 | alternative(ASM_NOP3, __stringify(__ASM_STAC), X86_FEATURE_SMAP); |
| 71 | } |
| 72 | |
| 73 | /* These macros can be used in asm() statements */ |
| 74 | #define ASM_CLAC \ |
| 75 | ALTERNATIVE(ASM_NOP3, __stringify(__ASM_CLAC), X86_FEATURE_SMAP) |
| 76 | #define ASM_STAC \ |
| 77 | ALTERNATIVE(ASM_NOP3, __stringify(__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 | #define ASM_CLAC |
| 85 | #define ASM_STAC |
| 86 | |
| 87 | #endif /* CONFIG_X86_SMAP */ |
| 88 | |
| 89 | #endif /* __ASSEMBLY__ */ |
| 90 | |
| 91 | #endif /* _ASM_X86_SMAP_H */ |