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e1f414b6 | 1 | /** @file\r |
030cd1a2 | 2 | Real Mode Thunk Functions for IA32 and x64.\r |
e1f414b6 | 3 | \r |
bb817c56 HT |
4 | Copyright (c) 2006 - 2008, Intel Corporation. All rights reserved.<BR>\r |
5 | This program and the accompanying materials\r | |
e1f414b6 | 6 | are licensed and made available under the terms and conditions of the BSD License\r |
7 | which accompanies this distribution. The full text of the license may be found at\r | |
8 | http://opensource.org/licenses/bsd-license.php\r | |
9 | \r | |
10 | THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,\r | |
11 | WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.\r | |
12 | \r | |
e1f414b6 | 13 | **/\r |
14 | \r | |
1efcc4ae | 15 | \r |
47fc17d8 | 16 | #include "BaseLibInternals.h"\r |
f734a10a | 17 | \r |
e1f414b6 | 18 | \r |
19 | //\r | |
20 | // Byte packed structure for a segment descriptor in a GDT/LDT\r | |
21 | //\r | |
22 | typedef union {\r | |
23 | struct {\r | |
24 | UINT32 LimitLow:16;\r | |
25 | UINT32 BaseLow:16;\r | |
26 | UINT32 BaseMid:8;\r | |
27 | UINT32 Type:4;\r | |
28 | UINT32 S:1;\r | |
29 | UINT32 DPL:2;\r | |
30 | UINT32 P:1;\r | |
31 | UINT32 LimitHigh:4;\r | |
32 | UINT32 AVL:1;\r | |
33 | UINT32 L:1;\r | |
34 | UINT32 DB:1;\r | |
35 | UINT32 G:1;\r | |
36 | UINT32 BaseHigh:8;\r | |
37 | } Bits;\r | |
38 | UINT64 Uint64;\r | |
39 | } IA32_SEGMENT_DESCRIPTOR;\r | |
40 | \r | |
41 | extern CONST UINT8 m16Start;\r | |
42 | extern CONST UINT16 m16Size;\r | |
43 | extern CONST UINT16 mThunk16Attr;\r | |
44 | extern CONST UINT16 m16Gdt;\r | |
45 | extern CONST UINT16 m16GdtrBase;\r | |
46 | extern CONST UINT16 mTransition;\r | |
47 | \r | |
48 | /**\r | |
49 | Invokes 16-bit code in big real mode and returns the updated register set.\r | |
50 | \r | |
51 | This function transfers control to the 16-bit code specified by CS:EIP using\r | |
52 | the stack specified by SS:ESP in RegisterSet. The updated registers are saved\r | |
53 | on the real mode stack and the starting address of the save area is returned.\r | |
54 | \r | |
55 | @param RegisterSet Values of registers before invocation of 16-bit code.\r | |
56 | @param Transition Pointer to the transition code under 1MB.\r | |
57 | \r | |
58 | @return The pointer to a IA32_REGISTER_SET structure containing the updated\r | |
59 | register values.\r | |
60 | \r | |
61 | **/\r | |
62 | IA32_REGISTER_SET *\r | |
63 | EFIAPI\r | |
64 | InternalAsmThunk16 (\r | |
65 | IN IA32_REGISTER_SET *RegisterSet,\r | |
66 | IN OUT VOID *Transition\r | |
67 | );\r | |
68 | \r | |
69 | /**\r | |
70 | Retrieves the properties for 16-bit thunk functions.\r | |
71 | \r | |
72 | Computes the size of the buffer and stack below 1MB required to use the\r | |
73 | AsmPrepareThunk16(), AsmThunk16() and AsmPrepareAndThunk16() functions. This\r | |
74 | buffer size is returned in RealModeBufferSize, and the stack size is returned\r | |
75 | in ExtraStackSize. If parameters are passed to the 16-bit real mode code,\r | |
76 | then the actual minimum stack size is ExtraStackSize plus the maximum number\r | |
77 | of bytes that need to be passed to the 16-bit real mode code.\r | |
78 | \r | |
79 | If RealModeBufferSize is NULL, then ASSERT().\r | |
80 | If ExtraStackSize is NULL, then ASSERT().\r | |
81 | \r | |
82 | @param RealModeBufferSize A pointer to the size of the buffer below 1MB\r | |
83 | required to use the 16-bit thunk functions.\r | |
84 | @param ExtraStackSize A pointer to the extra size of stack below 1MB\r | |
85 | that the 16-bit thunk functions require for\r | |
86 | temporary storage in the transition to and from\r | |
87 | 16-bit real mode.\r | |
88 | \r | |
89 | **/\r | |
90 | VOID\r | |
91 | EFIAPI\r | |
92 | AsmGetThunk16Properties (\r | |
93 | OUT UINT32 *RealModeBufferSize,\r | |
94 | OUT UINT32 *ExtraStackSize\r | |
95 | )\r | |
96 | {\r | |
97 | ASSERT (RealModeBufferSize != NULL);\r | |
98 | ASSERT (ExtraStackSize != NULL);\r | |
99 | \r | |
100 | *RealModeBufferSize = m16Size;\r | |
101 | \r | |
102 | //\r | |
103 | // Extra 4 bytes for return address, and another 4 bytes for mode transition\r | |
104 | //\r | |
105 | *ExtraStackSize = sizeof (IA32_DWORD_REGS) + 8;\r | |
106 | }\r | |
107 | \r | |
108 | /**\r | |
109 | Prepares all structures a code required to use AsmThunk16().\r | |
110 | \r | |
111 | Prepares all structures and code required to use AsmThunk16().\r | |
52fa075c | 112 | \r |
8243b089 | 113 | This interface is limited to be used in either physical mode or virtual modes with paging enabled where the\r |
114 | virtual to physical mappings for ThunkContext.RealModeBuffer is mapped 1:1.\r | |
e1f414b6 | 115 | \r |
116 | If ThunkContext is NULL, then ASSERT().\r | |
117 | \r | |
118 | @param ThunkContext A pointer to the context structure that describes the\r | |
119 | 16-bit real mode code to call.\r | |
120 | \r | |
121 | **/\r | |
122 | VOID\r | |
123 | EFIAPI\r | |
124 | AsmPrepareThunk16 (\r | |
125 | OUT THUNK_CONTEXT *ThunkContext\r | |
126 | )\r | |
127 | {\r | |
128 | IA32_SEGMENT_DESCRIPTOR *RealModeGdt;\r | |
129 | \r | |
130 | ASSERT (ThunkContext != NULL);\r | |
131 | ASSERT ((UINTN)ThunkContext->RealModeBuffer < 0x100000);\r | |
132 | ASSERT (ThunkContext->RealModeBufferSize >= m16Size);\r | |
133 | ASSERT ((UINTN)ThunkContext->RealModeBuffer + m16Size <= 0x100000);\r | |
134 | \r | |
135 | CopyMem (ThunkContext->RealModeBuffer, &m16Start, m16Size);\r | |
136 | \r | |
137 | //\r | |
138 | // Point RealModeGdt to the GDT to be used in transition\r | |
139 | //\r | |
140 | // RealModeGdt[0]: Reserved as NULL descriptor\r | |
141 | // RealModeGdt[1]: Code Segment\r | |
142 | // RealModeGdt[2]: Data Segment\r | |
143 | // RealModeGdt[3]: Call Gate\r | |
144 | //\r | |
145 | RealModeGdt = (IA32_SEGMENT_DESCRIPTOR*)(\r | |
146 | (UINTN)ThunkContext->RealModeBuffer + m16Gdt);\r | |
147 | \r | |
148 | //\r | |
149 | // Update Code & Data Segment Descriptor\r | |
150 | //\r | |
151 | RealModeGdt[1].Bits.BaseLow =\r | |
152 | (UINT32)(UINTN)ThunkContext->RealModeBuffer & ~0xf;\r | |
153 | RealModeGdt[1].Bits.BaseMid =\r | |
154 | (UINT32)(UINTN)ThunkContext->RealModeBuffer >> 16;\r | |
155 | \r | |
156 | //\r | |
157 | // Update transition code entry point offset\r | |
158 | //\r | |
159 | *(UINT32*)((UINTN)ThunkContext->RealModeBuffer + mTransition) +=\r | |
160 | (UINT32)(UINTN)ThunkContext->RealModeBuffer & 0xf;\r | |
161 | \r | |
162 | //\r | |
163 | // Update Segment Limits for both Code and Data Segment Descriptors\r | |
164 | //\r | |
165 | if ((ThunkContext->ThunkAttributes & THUNK_ATTRIBUTE_BIG_REAL_MODE) == 0) {\r | |
166 | //\r | |
167 | // Set segment limits to 64KB\r | |
168 | //\r | |
169 | RealModeGdt[1].Bits.LimitHigh = 0;\r | |
170 | RealModeGdt[1].Bits.G = 0;\r | |
171 | RealModeGdt[2].Bits.LimitHigh = 0;\r | |
172 | RealModeGdt[2].Bits.G = 0;\r | |
173 | }\r | |
174 | \r | |
175 | //\r | |
176 | // Update GDTBASE for this thunk context\r | |
177 | //\r | |
178 | *(VOID**)((UINTN)ThunkContext->RealModeBuffer + m16GdtrBase) = RealModeGdt;\r | |
179 | \r | |
180 | //\r | |
181 | // Update Thunk Attributes\r | |
182 | //\r | |
183 | *(UINT32*)((UINTN)ThunkContext->RealModeBuffer + mThunk16Attr) =\r | |
184 | ThunkContext->ThunkAttributes;\r | |
185 | }\r | |
186 | \r | |
187 | /**\r | |
188 | Transfers control to a 16-bit real mode entry point and returns the results.\r | |
189 | \r | |
190 | Transfers control to a 16-bit real mode entry point and returns the results.\r | |
2fc60b70 | 191 | AsmPrepareThunk16() must be called with ThunkContext before this function is used.\r |
192 | This function must be called with interrupts disabled.\r | |
193 | \r | |
194 | The register state from the RealModeState field of ThunkContext is restored just prior \r | |
195 | to calling the 16-bit real mode entry point. This includes the EFLAGS field of RealModeState, \r | |
196 | which is used to set the interrupt state when a 16-bit real mode entry point is called.\r | |
197 | Control is transferred to the 16-bit real mode entry point specified by the CS and Eip fields of RealModeState.\r | |
198 | The stack is initialized to the SS and ESP fields of RealModeState. Any parameters passed to \r | |
199 | the 16-bit real mode code must be populated by the caller at SS:ESP prior to calling this function. \r | |
200 | The 16-bit real mode entry point is invoked with a 16-bit CALL FAR instruction,\r | |
201 | so when accessing stack contents, the 16-bit real mode code must account for the 16-bit segment \r | |
202 | and 16-bit offset of the return address that were pushed onto the stack. The 16-bit real mode entry \r | |
203 | point must exit with a RETF instruction. The register state is captured into RealModeState immediately \r | |
204 | after the RETF instruction is executed.\r | |
205 | \r | |
206 | If EFLAGS specifies interrupts enabled, or any of the 16-bit real mode code enables interrupts, \r | |
207 | or any of the 16-bit real mode code makes a SW interrupt, then the caller is responsible for making sure \r | |
208 | the IDT at address 0 is initialized to handle any HW or SW interrupts that may occur while in 16-bit real mode. \r | |
209 | \r | |
210 | If EFLAGS specifies interrupts enabled, or any of the 16-bit real mode code enables interrupts, \r | |
211 | then the caller is responsible for making sure the 8259 PIC is in a state compatible with 16-bit real mode. \r | |
212 | This includes the base vectors, the interrupt masks, and the edge/level trigger mode.\r | |
213 | \r | |
214 | If THUNK_ATTRIBUTE_BIG_REAL_MODE is set in the ThunkAttributes field of ThunkContext, then the user code \r | |
215 | is invoked in big real mode. Otherwise, the user code is invoked in 16-bit real mode with 64KB segment limits.\r | |
216 | \r | |
217 | If neither THUNK_ATTRIBUTE_DISABLE_A20_MASK_INT_15 nor THUNK_ATTRIBUTE_DISABLE_A20_MASK_KBD_CTRL are set in \r | |
218 | ThunkAttributes, then it is assumed that the user code did not enable the A20 mask, and no attempt is made to \r | |
219 | disable the A20 mask.\r | |
220 | \r | |
221 | If THUNK_ATTRIBUTE_DISABLE_A20_MASK_INT_15 is set and THUNK_ATTRIBUTE_DISABLE_A20_MASK_KBD_CTRL is clear in \r | |
222 | ThunkAttributes, then attempt to use the INT 15 service to disable the A20 mask. If this INT 15 call fails, \r | |
223 | then attempt to disable the A20 mask by directly accessing the 8042 keyboard controller I/O ports.\r | |
224 | \r | |
225 | If THUNK_ATTRIBUTE_DISABLE_A20_MASK_INT_15 is clear and THUNK_ATTRIBUTE_DISABLE_A20_MASK_KBD_CTRL is set in \r | |
226 | ThunkAttributes, then attempt to disable the A20 mask by directly accessing the 8042 keyboard controller I/O ports.\r | |
227 | \r | |
e1f414b6 | 228 | If ThunkContext is NULL, then ASSERT().\r |
229 | If AsmPrepareThunk16() was not previously called with ThunkContext, then ASSERT().\r | |
2fc60b70 | 230 | If both THUNK_ATTRIBUTE_DISABLE_A20_MASK_INT_15 and THUNK_ATTRIBUTE_DISABLE_A20_MASK_KBD_CTRL are set in \r |
231 | ThunkAttributes, then ASSERT().\r | |
e1f414b6 | 232 | \r |
8243b089 | 233 | This interface is limited to be used in either physical mode or virtual modes with paging enabled where the\r |
234 | virtual to physical mappings for ThunkContext.RealModeBuffer is mapped 1:1.\r | |
52fa075c | 235 | \r |
e1f414b6 | 236 | @param ThunkContext A pointer to the context structure that describes the\r |
237 | 16-bit real mode code to call.\r | |
238 | \r | |
239 | **/\r | |
240 | VOID\r | |
241 | EFIAPI\r | |
242 | AsmThunk16 (\r | |
243 | IN OUT THUNK_CONTEXT *ThunkContext\r | |
244 | )\r | |
245 | {\r | |
246 | IA32_REGISTER_SET *UpdatedRegs;\r | |
247 | \r | |
248 | ASSERT (ThunkContext != NULL);\r | |
249 | ASSERT ((UINTN)ThunkContext->RealModeBuffer < 0x100000);\r | |
250 | ASSERT (ThunkContext->RealModeBufferSize >= m16Size);\r | |
251 | ASSERT ((UINTN)ThunkContext->RealModeBuffer + m16Size <= 0x100000);\r | |
d1be17ab | 252 | ASSERT (((ThunkContext->ThunkAttributes & (THUNK_ATTRIBUTE_DISABLE_A20_MASK_INT_15 | THUNK_ATTRIBUTE_DISABLE_A20_MASK_KBD_CTRL)) != \\r |
253 | (THUNK_ATTRIBUTE_DISABLE_A20_MASK_INT_15 | THUNK_ATTRIBUTE_DISABLE_A20_MASK_KBD_CTRL)));\r | |
254 | \r | |
e1f414b6 | 255 | UpdatedRegs = InternalAsmThunk16 (\r |
256 | ThunkContext->RealModeState,\r | |
257 | ThunkContext->RealModeBuffer\r | |
258 | );\r | |
259 | \r | |
260 | CopyMem (ThunkContext->RealModeState, UpdatedRegs, sizeof (*UpdatedRegs));\r | |
261 | }\r | |
262 | \r | |
263 | /**\r | |
264 | Prepares all structures and code for a 16-bit real mode thunk, transfers\r | |
265 | control to a 16-bit real mode entry point, and returns the results.\r | |
266 | \r | |
267 | Prepares all structures and code for a 16-bit real mode thunk, transfers\r | |
268 | control to a 16-bit real mode entry point, and returns the results. If the\r | |
269 | caller only need to perform a single 16-bit real mode thunk, then this\r | |
270 | service should be used. If the caller intends to make more than one 16-bit\r | |
271 | real mode thunk, then it is more efficient if AsmPrepareThunk16() is called\r | |
2fc60b70 | 272 | once and AsmThunk16() can be called for each 16-bit real mode thunk.\r |
e1f414b6 | 273 | \r |
8243b089 | 274 | This interface is limited to be used in either physical mode or virtual modes with paging enabled where the\r |
275 | virtual to physical mappings for ThunkContext.RealModeBuffer is mapped 1:1.\r | |
52fa075c | 276 | \r |
2fc60b70 | 277 | See AsmPrepareThunk16() and AsmThunk16() for the detailed description and ASSERT() conditions.\r |
e1f414b6 | 278 | \r |
279 | @param ThunkContext A pointer to the context structure that describes the\r | |
280 | 16-bit real mode code to call.\r | |
281 | \r | |
282 | **/\r | |
283 | VOID\r | |
284 | EFIAPI\r | |
285 | AsmPrepareAndThunk16 (\r | |
286 | IN OUT THUNK_CONTEXT *ThunkContext\r | |
287 | )\r | |
288 | {\r | |
289 | AsmPrepareThunk16 (ThunkContext);\r | |
290 | AsmThunk16 (ThunkContext);\r | |
291 | }\r |