| Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 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/linkage.h> |
| 30 | #include <asm/page_types.h> |
| 31 | #include <asm/errno.h> |
| 32 | #include <asm/asm-offsets.h> |
| 33 | #include <asm/thread_info.h> |
| 34 | #include <asm/asm.h> |
| 35 | #include <asm/smap.h> |
| 36 | #include <asm/export.h> |
| 37 | |
| 38 | .text |
| 39 | ENTRY(__get_user_1) |
| 40 | mov PER_CPU_VAR(current_task), %_ASM_DX |
| 41 | cmp TASK_addr_limit(%_ASM_DX),%_ASM_AX |
| 42 | jae bad_get_user |
| 43 | sbb %_ASM_DX, %_ASM_DX /* array_index_mask_nospec() */ |
| 44 | and %_ASM_DX, %_ASM_AX |
| 45 | ASM_STAC |
| 46 | 1: movzbl (%_ASM_AX),%edx |
| 47 | xor %eax,%eax |
| 48 | ASM_CLAC |
| 49 | ret |
| 50 | ENDPROC(__get_user_1) |
| 51 | EXPORT_SYMBOL(__get_user_1) |
| 52 | |
| 53 | ENTRY(__get_user_2) |
| 54 | add $1,%_ASM_AX |
| 55 | jc bad_get_user |
| 56 | mov PER_CPU_VAR(current_task), %_ASM_DX |
| 57 | cmp TASK_addr_limit(%_ASM_DX),%_ASM_AX |
| 58 | jae bad_get_user |
| 59 | sbb %_ASM_DX, %_ASM_DX /* array_index_mask_nospec() */ |
| 60 | and %_ASM_DX, %_ASM_AX |
| 61 | ASM_STAC |
| 62 | 2: movzwl -1(%_ASM_AX),%edx |
| 63 | xor %eax,%eax |
| 64 | ASM_CLAC |
| 65 | ret |
| 66 | ENDPROC(__get_user_2) |
| 67 | EXPORT_SYMBOL(__get_user_2) |
| 68 | |
| 69 | ENTRY(__get_user_4) |
| 70 | add $3,%_ASM_AX |
| 71 | jc bad_get_user |
| 72 | mov PER_CPU_VAR(current_task), %_ASM_DX |
| 73 | cmp TASK_addr_limit(%_ASM_DX),%_ASM_AX |
| 74 | jae bad_get_user |
| 75 | sbb %_ASM_DX, %_ASM_DX /* array_index_mask_nospec() */ |
| 76 | and %_ASM_DX, %_ASM_AX |
| 77 | ASM_STAC |
| 78 | 3: movl -3(%_ASM_AX),%edx |
| 79 | xor %eax,%eax |
| 80 | ASM_CLAC |
| 81 | ret |
| 82 | ENDPROC(__get_user_4) |
| 83 | EXPORT_SYMBOL(__get_user_4) |
| 84 | |
| 85 | ENTRY(__get_user_8) |
| 86 | #ifdef CONFIG_X86_64 |
| 87 | add $7,%_ASM_AX |
| 88 | jc bad_get_user |
| 89 | mov PER_CPU_VAR(current_task), %_ASM_DX |
| 90 | cmp TASK_addr_limit(%_ASM_DX),%_ASM_AX |
| 91 | jae bad_get_user |
| 92 | sbb %_ASM_DX, %_ASM_DX /* array_index_mask_nospec() */ |
| 93 | and %_ASM_DX, %_ASM_AX |
| 94 | ASM_STAC |
| 95 | 4: movq -7(%_ASM_AX),%rdx |
| 96 | xor %eax,%eax |
| 97 | ASM_CLAC |
| 98 | ret |
| 99 | #else |
| 100 | add $7,%_ASM_AX |
| 101 | jc bad_get_user_8 |
| 102 | mov PER_CPU_VAR(current_task), %_ASM_DX |
| 103 | cmp TASK_addr_limit(%_ASM_DX),%_ASM_AX |
| 104 | jae bad_get_user_8 |
| 105 | sbb %_ASM_DX, %_ASM_DX /* array_index_mask_nospec() */ |
| 106 | and %_ASM_DX, %_ASM_AX |
| 107 | ASM_STAC |
| 108 | 4: movl -7(%_ASM_AX),%edx |
| 109 | 5: movl -3(%_ASM_AX),%ecx |
| 110 | xor %eax,%eax |
| 111 | ASM_CLAC |
| 112 | ret |
| 113 | #endif |
| 114 | ENDPROC(__get_user_8) |
| 115 | EXPORT_SYMBOL(__get_user_8) |
| 116 | |
| 117 | |
| 118 | bad_get_user: |
| 119 | xor %edx,%edx |
| 120 | mov $(-EFAULT),%_ASM_AX |
| 121 | ASM_CLAC |
| 122 | ret |
| 123 | END(bad_get_user) |
| 124 | |
| 125 | #ifdef CONFIG_X86_32 |
| 126 | bad_get_user_8: |
| 127 | xor %edx,%edx |
| 128 | xor %ecx,%ecx |
| 129 | mov $(-EFAULT),%_ASM_AX |
| 130 | ASM_CLAC |
| 131 | ret |
| 132 | END(bad_get_user_8) |
| 133 | #endif |
| 134 | |
| 135 | _ASM_EXTABLE(1b,bad_get_user) |
| 136 | _ASM_EXTABLE(2b,bad_get_user) |
| 137 | _ASM_EXTABLE(3b,bad_get_user) |
| 138 | #ifdef CONFIG_X86_64 |
| 139 | _ASM_EXTABLE(4b,bad_get_user) |
| 140 | #else |
| 141 | _ASM_EXTABLE(4b,bad_get_user_8) |
| 142 | _ASM_EXTABLE(5b,bad_get_user_8) |
| 143 | #endif |