1/* SPDX-License-Identifier: GPL-2.0 */ 2/* 3 * __get_user functions. 4 * 5 * (C) Copyright 1998 Linus Torvalds 6 * (C) Copyright 2005 Andi Kleen 7 * (C) Copyright 2008 Glauber Costa 8 * 9 * These functions have a non-standard call interface 10 * to make them more efficient, especially as they 11 * return an error value in addition to the "real" 12 * return value. 13 */ 14 15/* 16 * __get_user_X 17 * 18 * Inputs: %[r|e]ax contains the address. 19 * 20 * Outputs: %[r|e]ax is error code (0 or -EFAULT) 21 * %[r|e]dx contains zero-extended value 22 * %ecx contains the high half for 32-bit __get_user_8 23 * 24 * 25 * These functions should not modify any other registers, 26 * as they get called from within inline assembly. 27 */ 28 29#include <linux/export.h> 30#include <linux/linkage.h> 31#include <asm/page_types.h> 32#include <asm/errno.h> 33#include <asm/asm-offsets.h> 34#include <asm/thread_info.h> 35#include <asm/asm.h> 36#include <asm/smap.h> 37 38#define ASM_BARRIER_NOSPEC ALTERNATIVE "", "lfence", X86_FEATURE_LFENCE_RDTSC 39 40.macro check_range size:req 41.if IS_ENABLED(CONFIG_X86_64) 42 mov %rax, %rdx 43 sar $63, %rdx 44 or %rdx, %rax 45.else 46 cmp $TASK_SIZE_MAX-\size+1, %eax 47 jae .Lbad_get_user 48 sbb %edx, %edx /* array_index_mask_nospec() */ 49 and %edx, %eax 50.endif 51.endm 52 53 .text 54SYM_FUNC_START(__get_user_1) 55 check_range size=1 56 ASM_STAC 571: movzbl (%_ASM_AX),%edx 58 xor %eax,%eax 59 ASM_CLAC 60 RET 61SYM_FUNC_END(__get_user_1) 62EXPORT_SYMBOL(__get_user_1) 63 64SYM_FUNC_START(__get_user_2) 65 check_range size=2 66 ASM_STAC 672: movzwl (%_ASM_AX),%edx 68 xor %eax,%eax 69 ASM_CLAC 70 RET 71SYM_FUNC_END(__get_user_2) 72EXPORT_SYMBOL(__get_user_2) 73 74SYM_FUNC_START(__get_user_4) 75 check_range size=4 76 ASM_STAC 773: movl (%_ASM_AX),%edx 78 xor %eax,%eax 79 ASM_CLAC 80 RET 81SYM_FUNC_END(__get_user_4) 82EXPORT_SYMBOL(__get_user_4) 83 84SYM_FUNC_START(__get_user_8) 85 check_range size=8 86 ASM_STAC 87#ifdef CONFIG_X86_64 884: movq (%_ASM_AX),%rdx 89#else 904: movl (%_ASM_AX),%edx 915: movl 4(%_ASM_AX),%ecx 92#endif 93 xor %eax,%eax 94 ASM_CLAC 95 RET 96SYM_FUNC_END(__get_user_8) 97EXPORT_SYMBOL(__get_user_8) 98 99/* .. and the same for __get_user, just without the range checks */ 100SYM_FUNC_START(__get_user_nocheck_1) 101 ASM_STAC 102 ASM_BARRIER_NOSPEC 1036: movzbl (%_ASM_AX),%edx 104 xor %eax,%eax 105 ASM_CLAC 106 RET 107SYM_FUNC_END(__get_user_nocheck_1) 108EXPORT_SYMBOL(__get_user_nocheck_1) 109 110SYM_FUNC_START(__get_user_nocheck_2) 111 ASM_STAC 112 ASM_BARRIER_NOSPEC 1137: movzwl (%_ASM_AX),%edx 114 xor %eax,%eax 115 ASM_CLAC 116 RET 117SYM_FUNC_END(__get_user_nocheck_2) 118EXPORT_SYMBOL(__get_user_nocheck_2) 119 120SYM_FUNC_START(__get_user_nocheck_4) 121 ASM_STAC 122 ASM_BARRIER_NOSPEC 1238: movl (%_ASM_AX),%edx 124 xor %eax,%eax 125 ASM_CLAC 126 RET 127SYM_FUNC_END(__get_user_nocheck_4) 128EXPORT_SYMBOL(__get_user_nocheck_4) 129 130SYM_FUNC_START(__get_user_nocheck_8) 131 ASM_STAC 132 ASM_BARRIER_NOSPEC 133#ifdef CONFIG_X86_64 1349: movq (%_ASM_AX),%rdx 135#else 1369: movl (%_ASM_AX),%edx 13710: movl 4(%_ASM_AX),%ecx 138#endif 139 xor %eax,%eax 140 ASM_CLAC 141 RET 142SYM_FUNC_END(__get_user_nocheck_8) 143EXPORT_SYMBOL(__get_user_nocheck_8) 144 145 146SYM_CODE_START_LOCAL(__get_user_handle_exception) 147 ASM_CLAC 148.Lbad_get_user: 149 xor %edx,%edx 150 mov $(-EFAULT),%_ASM_AX 151 RET 152SYM_CODE_END(__get_user_handle_exception) 153 154#ifdef CONFIG_X86_32 155SYM_CODE_START_LOCAL(__get_user_8_handle_exception) 156 ASM_CLAC 157bad_get_user_8: 158 xor %edx,%edx 159 xor %ecx,%ecx 160 mov $(-EFAULT),%_ASM_AX 161 RET 162SYM_CODE_END(__get_user_8_handle_exception) 163#endif 164 165/* get_user */ 166 _ASM_EXTABLE(1b, __get_user_handle_exception) 167 _ASM_EXTABLE(2b, __get_user_handle_exception) 168 _ASM_EXTABLE(3b, __get_user_handle_exception) 169#ifdef CONFIG_X86_64 170 _ASM_EXTABLE(4b, __get_user_handle_exception) 171#else 172 _ASM_EXTABLE(4b, __get_user_8_handle_exception) 173 _ASM_EXTABLE(5b, __get_user_8_handle_exception) 174#endif 175 176/* __get_user */ 177 _ASM_EXTABLE(6b, __get_user_handle_exception) 178 _ASM_EXTABLE(7b, __get_user_handle_exception) 179 _ASM_EXTABLE(8b, __get_user_handle_exception) 180#ifdef CONFIG_X86_64 181 _ASM_EXTABLE(9b, __get_user_handle_exception) 182#else 183 _ASM_EXTABLE(9b, __get_user_8_handle_exception) 184 _ASM_EXTABLE(10b, __get_user_8_handle_exception) 185#endif 186