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| Commit | Line | Data |
|---|---|---|
| e1f414b6 | 1 | /** @file\r |
| 030cd1a2 | 2 | Real Mode Thunk Functions for IA32 and x64.\r |
| e1f414b6 | 3 | \r |
| 9095d37b | 4 | Copyright (c) 2006 - 2018, Intel Corporation. All rights reserved.<BR>\r |
| 9344f092 | 5 | SPDX-License-Identifier: BSD-2-Clause-Patent\r |
| e1f414b6 | 6 | \r |
| e1f414b6 | 7 | **/\r |
| 8 | \r | |
| 1efcc4ae | 9 | \r |
| 47fc17d8 | 10 | #include "BaseLibInternals.h"\r |
| f734a10a | 11 | \r |
| e1f414b6 | 12 | extern CONST UINT8 m16Start;\r |
| 13 | extern CONST UINT16 m16Size;\r | |
| 14 | extern CONST UINT16 mThunk16Attr;\r | |
| 15 | extern CONST UINT16 m16Gdt;\r | |
| 16 | extern CONST UINT16 m16GdtrBase;\r | |
| 17 | extern CONST UINT16 mTransition;\r | |
| 18 | \r | |
| 19 | /**\r | |
| 20 | Invokes 16-bit code in big real mode and returns the updated register set.\r | |
| 21 | \r | |
| 22 | This function transfers control to the 16-bit code specified by CS:EIP using\r | |
| 23 | the stack specified by SS:ESP in RegisterSet. The updated registers are saved\r | |
| 24 | on the real mode stack and the starting address of the save area is returned.\r | |
| 25 | \r | |
| 26 | @param RegisterSet Values of registers before invocation of 16-bit code.\r | |
| 127010dd | 27 | @param Transition The pointer to the transition code under 1MB.\r |
| e1f414b6 | 28 | \r |
| 29 | @return The pointer to a IA32_REGISTER_SET structure containing the updated\r | |
| 30 | register values.\r | |
| 31 | \r | |
| 32 | **/\r | |
| 33 | IA32_REGISTER_SET *\r | |
| 34 | EFIAPI\r | |
| 35 | InternalAsmThunk16 (\r | |
| 36 | IN IA32_REGISTER_SET *RegisterSet,\r | |
| 37 | IN OUT VOID *Transition\r | |
| 38 | );\r | |
| 39 | \r | |
| 40 | /**\r | |
| 41 | Retrieves the properties for 16-bit thunk functions.\r | |
| 42 | \r | |
| 43 | Computes the size of the buffer and stack below 1MB required to use the\r | |
| 44 | AsmPrepareThunk16(), AsmThunk16() and AsmPrepareAndThunk16() functions. This\r | |
| 45 | buffer size is returned in RealModeBufferSize, and the stack size is returned\r | |
| 46 | in ExtraStackSize. If parameters are passed to the 16-bit real mode code,\r | |
| 47 | then the actual minimum stack size is ExtraStackSize plus the maximum number\r | |
| 48 | of bytes that need to be passed to the 16-bit real mode code.\r | |
| 49 | \r | |
| 50 | If RealModeBufferSize is NULL, then ASSERT().\r | |
| 51 | If ExtraStackSize is NULL, then ASSERT().\r | |
| 52 | \r | |
| 53 | @param RealModeBufferSize A pointer to the size of the buffer below 1MB\r | |
| 54 | required to use the 16-bit thunk functions.\r | |
| 55 | @param ExtraStackSize A pointer to the extra size of stack below 1MB\r | |
| 56 | that the 16-bit thunk functions require for\r | |
| 57 | temporary storage in the transition to and from\r | |
| 58 | 16-bit real mode.\r | |
| 59 | \r | |
| 60 | **/\r | |
| 61 | VOID\r | |
| 62 | EFIAPI\r | |
| 63 | AsmGetThunk16Properties (\r | |
| 64 | OUT UINT32 *RealModeBufferSize,\r | |
| 65 | OUT UINT32 *ExtraStackSize\r | |
| 66 | )\r | |
| 67 | {\r | |
| 68 | ASSERT (RealModeBufferSize != NULL);\r | |
| 69 | ASSERT (ExtraStackSize != NULL);\r | |
| 70 | \r | |
| 71 | *RealModeBufferSize = m16Size;\r | |
| 72 | \r | |
| 73 | //\r | |
| 74 | // Extra 4 bytes for return address, and another 4 bytes for mode transition\r | |
| 75 | //\r | |
| 76 | *ExtraStackSize = sizeof (IA32_DWORD_REGS) + 8;\r | |
| 77 | }\r | |
| 78 | \r | |
| 79 | /**\r | |
| 80 | Prepares all structures a code required to use AsmThunk16().\r | |
| 81 | \r | |
| 82 | Prepares all structures and code required to use AsmThunk16().\r | |
| 9095d37b | 83 | \r |
| 8243b089 | 84 | This interface is limited to be used in either physical mode or virtual modes with paging enabled where the\r |
| 85 | virtual to physical mappings for ThunkContext.RealModeBuffer is mapped 1:1.\r | |
| e1f414b6 | 86 | \r |
| 87 | If ThunkContext is NULL, then ASSERT().\r | |
| 88 | \r | |
| 89 | @param ThunkContext A pointer to the context structure that describes the\r | |
| 90 | 16-bit real mode code to call.\r | |
| 91 | \r | |
| 92 | **/\r | |
| 93 | VOID\r | |
| 94 | EFIAPI\r | |
| 95 | AsmPrepareThunk16 (\r | |
| 1445300f | 96 | IN OUT THUNK_CONTEXT *ThunkContext\r |
| e1f414b6 | 97 | )\r |
| 98 | {\r | |
| 99 | IA32_SEGMENT_DESCRIPTOR *RealModeGdt;\r | |
| 100 | \r | |
| 101 | ASSERT (ThunkContext != NULL);\r | |
| 102 | ASSERT ((UINTN)ThunkContext->RealModeBuffer < 0x100000);\r | |
| 103 | ASSERT (ThunkContext->RealModeBufferSize >= m16Size);\r | |
| 104 | ASSERT ((UINTN)ThunkContext->RealModeBuffer + m16Size <= 0x100000);\r | |
| 105 | \r | |
| 106 | CopyMem (ThunkContext->RealModeBuffer, &m16Start, m16Size);\r | |
| 107 | \r | |
| 108 | //\r | |
| 109 | // Point RealModeGdt to the GDT to be used in transition\r | |
| 110 | //\r | |
| 111 | // RealModeGdt[0]: Reserved as NULL descriptor\r | |
| 112 | // RealModeGdt[1]: Code Segment\r | |
| 113 | // RealModeGdt[2]: Data Segment\r | |
| 114 | // RealModeGdt[3]: Call Gate\r | |
| 115 | //\r | |
| 116 | RealModeGdt = (IA32_SEGMENT_DESCRIPTOR*)(\r | |
| 117 | (UINTN)ThunkContext->RealModeBuffer + m16Gdt);\r | |
| 118 | \r | |
| 119 | //\r | |
| 120 | // Update Code & Data Segment Descriptor\r | |
| 121 | //\r | |
| 122 | RealModeGdt[1].Bits.BaseLow =\r | |
| 123 | (UINT32)(UINTN)ThunkContext->RealModeBuffer & ~0xf;\r | |
| 124 | RealModeGdt[1].Bits.BaseMid =\r | |
| 125 | (UINT32)(UINTN)ThunkContext->RealModeBuffer >> 16;\r | |
| 126 | \r | |
| 127 | //\r | |
| 128 | // Update transition code entry point offset\r | |
| 129 | //\r | |
| 130 | *(UINT32*)((UINTN)ThunkContext->RealModeBuffer + mTransition) +=\r | |
| 131 | (UINT32)(UINTN)ThunkContext->RealModeBuffer & 0xf;\r | |
| 132 | \r | |
| 133 | //\r | |
| 134 | // Update Segment Limits for both Code and Data Segment Descriptors\r | |
| 135 | //\r | |
| 136 | if ((ThunkContext->ThunkAttributes & THUNK_ATTRIBUTE_BIG_REAL_MODE) == 0) {\r | |
| 137 | //\r | |
| 138 | // Set segment limits to 64KB\r | |
| 139 | //\r | |
| 140 | RealModeGdt[1].Bits.LimitHigh = 0;\r | |
| 141 | RealModeGdt[1].Bits.G = 0;\r | |
| 142 | RealModeGdt[2].Bits.LimitHigh = 0;\r | |
| 143 | RealModeGdt[2].Bits.G = 0;\r | |
| 144 | }\r | |
| 145 | \r | |
| 146 | //\r | |
| 147 | // Update GDTBASE for this thunk context\r | |
| 148 | //\r | |
| 149 | *(VOID**)((UINTN)ThunkContext->RealModeBuffer + m16GdtrBase) = RealModeGdt;\r | |
| 150 | \r | |
| 151 | //\r | |
| 152 | // Update Thunk Attributes\r | |
| 153 | //\r | |
| 154 | *(UINT32*)((UINTN)ThunkContext->RealModeBuffer + mThunk16Attr) =\r | |
| 155 | ThunkContext->ThunkAttributes;\r | |
| 156 | }\r | |
| 157 | \r | |
| 158 | /**\r | |
| 159 | Transfers control to a 16-bit real mode entry point and returns the results.\r | |
| 160 | \r | |
| 161 | Transfers control to a 16-bit real mode entry point and returns the results.\r | |
| 2fc60b70 | 162 | AsmPrepareThunk16() must be called with ThunkContext before this function is used.\r |
| 163 | This function must be called with interrupts disabled.\r | |
| 164 | \r | |
| 9095d37b LG |
165 | The register state from the RealModeState field of ThunkContext is restored just prior\r |
| 166 | to calling the 16-bit real mode entry point. This includes the EFLAGS field of RealModeState,\r | |
| 2fc60b70 | 167 | which is used to set the interrupt state when a 16-bit real mode entry point is called.\r |
| 168 | Control is transferred to the 16-bit real mode entry point specified by the CS and Eip fields of RealModeState.\r | |
| 9095d37b LG |
169 | The stack is initialized to the SS and ESP fields of RealModeState. Any parameters passed to\r |
| 170 | the 16-bit real mode code must be populated by the caller at SS:ESP prior to calling this function.\r | |
| 2fc60b70 | 171 | The 16-bit real mode entry point is invoked with a 16-bit CALL FAR instruction,\r |
| 9095d37b LG |
172 | so when accessing stack contents, the 16-bit real mode code must account for the 16-bit segment\r |
| 173 | and 16-bit offset of the return address that were pushed onto the stack. The 16-bit real mode entry\r | |
| 174 | point must exit with a RETF instruction. The register state is captured into RealModeState immediately\r | |
| 2fc60b70 | 175 | after the RETF instruction is executed.\r |
| 9095d37b LG |
176 | \r |
| 177 | If EFLAGS specifies interrupts enabled, or any of the 16-bit real mode code enables interrupts,\r | |
| 178 | or any of the 16-bit real mode code makes a SW interrupt, then the caller is responsible for making sure\r | |
| 179 | the IDT at address 0 is initialized to handle any HW or SW interrupts that may occur while in 16-bit real mode.\r | |
| 180 | \r | |
| 181 | If EFLAGS specifies interrupts enabled, or any of the 16-bit real mode code enables interrupts,\r | |
| 182 | then the caller is responsible for making sure the 8259 PIC is in a state compatible with 16-bit real mode.\r | |
| 2fc60b70 | 183 | This includes the base vectors, the interrupt masks, and the edge/level trigger mode.\r |
| 9095d37b LG |
184 | \r |
| 185 | If THUNK_ATTRIBUTE_BIG_REAL_MODE is set in the ThunkAttributes field of ThunkContext, then the user code\r | |
| 2fc60b70 | 186 | is invoked in big real mode. Otherwise, the user code is invoked in 16-bit real mode with 64KB segment limits.\r |
| 9095d37b LG |
187 | \r |
| 188 | If neither THUNK_ATTRIBUTE_DISABLE_A20_MASK_INT_15 nor THUNK_ATTRIBUTE_DISABLE_A20_MASK_KBD_CTRL are set in\r | |
| 189 | ThunkAttributes, then it is assumed that the user code did not enable the A20 mask, and no attempt is made to\r | |
| 2fc60b70 | 190 | disable the A20 mask.\r |
| 9095d37b LG |
191 | \r |
| 192 | If THUNK_ATTRIBUTE_DISABLE_A20_MASK_INT_15 is set and THUNK_ATTRIBUTE_DISABLE_A20_MASK_KBD_CTRL is clear in\r | |
| 193 | ThunkAttributes, then attempt to use the INT 15 service to disable the A20 mask. If this INT 15 call fails,\r | |
| 2fc60b70 | 194 | then attempt to disable the A20 mask by directly accessing the 8042 keyboard controller I/O ports.\r |
| 9095d37b LG |
195 | \r |
| 196 | If THUNK_ATTRIBUTE_DISABLE_A20_MASK_INT_15 is clear and THUNK_ATTRIBUTE_DISABLE_A20_MASK_KBD_CTRL is set in\r | |
| 2fc60b70 | 197 | ThunkAttributes, then attempt to disable the A20 mask by directly accessing the 8042 keyboard controller I/O ports.\r |
| 9095d37b | 198 | \r |
| e1f414b6 | 199 | If ThunkContext is NULL, then ASSERT().\r |
| 200 | If AsmPrepareThunk16() was not previously called with ThunkContext, then ASSERT().\r | |
| 9095d37b | 201 | If both THUNK_ATTRIBUTE_DISABLE_A20_MASK_INT_15 and THUNK_ATTRIBUTE_DISABLE_A20_MASK_KBD_CTRL are set in\r |
| 2fc60b70 | 202 | ThunkAttributes, then ASSERT().\r |
| e1f414b6 | 203 | \r |
| 8243b089 | 204 | This interface is limited to be used in either physical mode or virtual modes with paging enabled where the\r |
| 205 | virtual to physical mappings for ThunkContext.RealModeBuffer is mapped 1:1.\r | |
| 9095d37b | 206 | \r |
| e1f414b6 | 207 | @param ThunkContext A pointer to the context structure that describes the\r |
| 208 | 16-bit real mode code to call.\r | |
| 209 | \r | |
| 210 | **/\r | |
| 211 | VOID\r | |
| 212 | EFIAPI\r | |
| 213 | AsmThunk16 (\r | |
| 214 | IN OUT THUNK_CONTEXT *ThunkContext\r | |
| 215 | )\r | |
| 216 | {\r | |
| 217 | IA32_REGISTER_SET *UpdatedRegs;\r | |
| 218 | \r | |
| 219 | ASSERT (ThunkContext != NULL);\r | |
| 220 | ASSERT ((UINTN)ThunkContext->RealModeBuffer < 0x100000);\r | |
| 221 | ASSERT (ThunkContext->RealModeBufferSize >= m16Size);\r | |
| 222 | ASSERT ((UINTN)ThunkContext->RealModeBuffer + m16Size <= 0x100000);\r | |
| d1be17ab | 223 | ASSERT (((ThunkContext->ThunkAttributes & (THUNK_ATTRIBUTE_DISABLE_A20_MASK_INT_15 | THUNK_ATTRIBUTE_DISABLE_A20_MASK_KBD_CTRL)) != \\r |
| 224 | (THUNK_ATTRIBUTE_DISABLE_A20_MASK_INT_15 | THUNK_ATTRIBUTE_DISABLE_A20_MASK_KBD_CTRL)));\r | |
| 9095d37b | 225 | \r |
| e1f414b6 | 226 | UpdatedRegs = InternalAsmThunk16 (\r |
| 227 | ThunkContext->RealModeState,\r | |
| 228 | ThunkContext->RealModeBuffer\r | |
| 229 | );\r | |
| 230 | \r | |
| 231 | CopyMem (ThunkContext->RealModeState, UpdatedRegs, sizeof (*UpdatedRegs));\r | |
| 232 | }\r | |
| 233 | \r | |
| 234 | /**\r | |
| 235 | Prepares all structures and code for a 16-bit real mode thunk, transfers\r | |
| 236 | control to a 16-bit real mode entry point, and returns the results.\r | |
| 237 | \r | |
| 238 | Prepares all structures and code for a 16-bit real mode thunk, transfers\r | |
| 239 | control to a 16-bit real mode entry point, and returns the results. If the\r | |
| 240 | caller only need to perform a single 16-bit real mode thunk, then this\r | |
| 241 | service should be used. If the caller intends to make more than one 16-bit\r | |
| 242 | real mode thunk, then it is more efficient if AsmPrepareThunk16() is called\r | |
| 2fc60b70 | 243 | once and AsmThunk16() can be called for each 16-bit real mode thunk.\r |
| e1f414b6 | 244 | \r |
| 8243b089 | 245 | This interface is limited to be used in either physical mode or virtual modes with paging enabled where the\r |
| 246 | virtual to physical mappings for ThunkContext.RealModeBuffer is mapped 1:1.\r | |
| 9095d37b | 247 | \r |
| 2fc60b70 | 248 | See AsmPrepareThunk16() and AsmThunk16() for the detailed description and ASSERT() conditions.\r |
| e1f414b6 | 249 | \r |
| 250 | @param ThunkContext A pointer to the context structure that describes the\r | |
| 251 | 16-bit real mode code to call.\r | |
| 252 | \r | |
| 253 | **/\r | |
| 254 | VOID\r | |
| 255 | EFIAPI\r | |
| 256 | AsmPrepareAndThunk16 (\r | |
| 257 | IN OUT THUNK_CONTEXT *ThunkContext\r | |
| 258 | )\r | |
| 259 | {\r | |
| 260 | AsmPrepareThunk16 (ThunkContext);\r | |
| 261 | AsmThunk16 (ThunkContext);\r | |
| 262 | }\r |