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bcecde14 | 1 | /** @file\r |
2 | Call into 16-bit BIOS code\r | |
3 | \r | |
4 | BugBug: Thunker does A20 gate. Can we get rid of this code or\r | |
5 | put it into Legacy16 code.\r | |
6 | \r | |
1a45b15e | 7 | Copyright (c) 1999 - 2014, Intel Corporation. All rights reserved.<BR>\r |
bcecde14 | 8 | \r |
9 | This program and the accompanying materials\r | |
10 | are licensed and made available under the terms and conditions\r | |
11 | of the BSD License which accompanies this distribution. The\r | |
12 | full text of the license may be found at\r | |
13 | http://opensource.org/licenses/bsd-license.php\r | |
14 | \r | |
15 | THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,\r | |
16 | WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.\r | |
17 | \r | |
18 | **/\r | |
19 | \r | |
20 | #include "LegacyBiosInterface.h"\r | |
21 | #include "IpfThunk.h"\r | |
22 | \r | |
23 | /**\r | |
24 | Gets the current flat GDT and IDT descriptors and store them in\r | |
25 | Private->IntThunk. These values are used by the Thunk code.\r | |
26 | This method must be called before every thunk in order to assure\r | |
27 | that the correct GDT and IDT are restored after the thunk.\r | |
28 | \r | |
29 | @param Private Private context for Legacy BIOS\r | |
30 | \r | |
31 | @retval EFI_SUCCESS Should only pass.\r | |
32 | \r | |
33 | **/\r | |
34 | EFI_STATUS\r | |
35 | LegacyBiosGetFlatDescs (\r | |
36 | IN LEGACY_BIOS_INSTANCE *Private\r | |
37 | )\r | |
38 | {\r | |
39 | return EFI_SUCCESS;\r | |
40 | }\r | |
41 | \r | |
42 | \r | |
43 | /**\r | |
44 | BIOS interrupt call function.\r | |
45 | \r | |
46 | @param BiosInt Int number of BIOS call\r | |
47 | @param Segment Segment number\r | |
48 | @param Offset Offset in segment\r | |
49 | @param Regs IA32 Register set.\r | |
50 | @param Stack Base address of stack\r | |
51 | @param StackSize Size of stack\r | |
52 | \r | |
53 | @retval EFI_SUCCESS BIOS interrupt call succeeds.\r | |
54 | \r | |
55 | **/\r | |
56 | EFI_STATUS\r | |
57 | BiosIntCall (\r | |
58 | IN UINT16 BiosInt,\r | |
59 | IN UINT16 Segment,\r | |
60 | IN UINT16 Offset,\r | |
61 | IN EFI_IA32_REGISTER_SET *Regs,\r | |
62 | IN VOID *Stack,\r | |
63 | IN UINTN StackSize\r | |
64 | )\r | |
65 | {\r | |
66 | IPF_DWORD_REGS DwordRegs;\r | |
67 | UINT64 IntTypeVariable;\r | |
68 | \r | |
69 | IntTypeVariable = 0x8000000000000000;\r | |
1a45b15e | 70 | IntTypeVariable |= (UINT64)BiosInt;\r |
bcecde14 | 71 | \r |
72 | DwordRegs.Cs = Segment;\r | |
73 | DwordRegs.Eip = Offset;\r | |
74 | \r | |
75 | DwordRegs.Ds = Regs->X.DS;\r | |
76 | DwordRegs.Es = Regs->X.ES;\r | |
77 | DwordRegs.Fs = Regs->X.ES;\r | |
78 | DwordRegs.Gs = Regs->X.ES;\r | |
79 | DwordRegs.Ss = 0xFFFF;\r | |
80 | \r | |
81 | DwordRegs.Eax = Regs->X.AX;\r | |
82 | DwordRegs.Ebx = Regs->X.BX;\r | |
83 | //\r | |
84 | // Sometimes, ECX is used to pass in 32 bit data. For example, INT 1Ah, AX = B10Dh is\r | |
85 | // "PCI BIOS v2.0c + Write Configuration DWORD" and ECX has the dword to write.\r | |
86 | //\r | |
87 | DwordRegs.Ecx = Regs->E.ECX;\r | |
88 | DwordRegs.Edx = Regs->X.DX;\r | |
89 | \r | |
90 | DwordRegs.Ebp = Regs->X.BP;\r | |
91 | DwordRegs.Eflag = *((UINT16 *) &Regs->X.Flags);\r | |
92 | \r | |
93 | DwordRegs.Edi = Regs->X.DI;\r | |
94 | DwordRegs.Esi = Regs->X.SI;\r | |
95 | DwordRegs.Esp = 0xFFFFFFFF;\r | |
96 | \r | |
97 | EfiIaEntryPoint (IntTypeVariable, &DwordRegs, ((UINTN) Stack + StackSize), StackSize);\r | |
98 | \r | |
99 | Regs->X.CS = DwordRegs.Cs;\r | |
100 | \r | |
101 | Regs->X.DS = (UINT16) DwordRegs.Ds;\r | |
102 | Regs->X.SS = (UINT16) DwordRegs.Ss;\r | |
103 | \r | |
104 | Regs->E.EAX = DwordRegs.Eax;\r | |
105 | Regs->E.EBX = DwordRegs.Ebx;\r | |
106 | Regs->E.ECX = DwordRegs.Ecx;\r | |
107 | Regs->E.EDX = DwordRegs.Edx;\r | |
108 | \r | |
109 | Regs->E.EBP = DwordRegs.Ebp;\r | |
110 | CopyMem (&Regs->X.Flags, &DwordRegs.Eflag, sizeof (EFI_FLAGS_REG));\r | |
111 | \r | |
112 | Regs->E.EDI = DwordRegs.Edi;\r | |
113 | Regs->E.ESI = DwordRegs.Esi;\r | |
114 | \r | |
115 | return EFI_SUCCESS;\r | |
116 | }\r | |
117 | \r | |
118 | \r | |
119 | /**\r | |
120 | Template of real mode code.\r | |
121 | \r | |
122 | @param CodeStart Start address of code.\r | |
123 | @param CodeEnd End address of code\r | |
124 | @param ReverseThunkStart Start of reverse thunk.\r | |
125 | @param IntThunk Low memory thunk.\r | |
126 | \r | |
127 | **/\r | |
128 | VOID\r | |
129 | RealModeTemplate (\r | |
130 | OUT UINTN *CodeStart,\r | |
131 | OUT UINTN *CodeEnd,\r | |
132 | OUT UINTN *ReverseThunkStart,\r | |
133 | LOW_MEMORY_THUNK *IntThunk\r | |
134 | )\r | |
135 | {\r | |
136 | SAL_RETURN_REGS SalStatus;\r | |
137 | \r | |
138 | SalStatus = EsalGetReverseThunkAddress ();\r | |
139 | \r | |
140 | *CodeStart = SalStatus.r9;\r | |
141 | *CodeEnd = SalStatus.r10;\r | |
142 | *ReverseThunkStart = SalStatus.r11;\r | |
143 | \r | |
144 | }\r | |
145 | \r | |
146 | \r | |
147 | /**\r | |
148 | Allocate memory < 1 MB and copy the thunker code into low memory. Se up\r | |
149 | all the descriptors.\r | |
150 | \r | |
151 | @param Private Private context for Legacy BIOS\r | |
152 | \r | |
153 | @retval EFI_SUCCESS Should only pass.\r | |
154 | \r | |
155 | **/\r | |
156 | EFI_STATUS\r | |
157 | LegacyBiosInitializeThunk (\r | |
158 | IN LEGACY_BIOS_INSTANCE *Private\r | |
159 | )\r | |
160 | {\r | |
161 | GDT32 *CodeGdt;\r | |
162 | GDT32 *DataGdt;\r | |
163 | UINTN CodeStart;\r | |
164 | UINTN CodeEnd;\r | |
165 | UINTN ReverseThunkStart;\r | |
166 | UINT32 Base;\r | |
167 | LOW_MEMORY_THUNK *IntThunk;\r | |
168 | UINTN TempData;\r | |
169 | \r | |
170 | ASSERT (Private);\r | |
171 | \r | |
172 | IntThunk = Private->IntThunk;\r | |
173 | \r | |
174 | //\r | |
175 | // Clear the reserved descriptor\r | |
176 | //\r | |
177 | ZeroMem (&(IntThunk->RealModeGdt[0]), sizeof (GDT32));\r | |
178 | \r | |
179 | //\r | |
180 | // Setup a descriptor for real-mode code\r | |
181 | //\r | |
182 | CodeGdt = &(IntThunk->RealModeGdt[1]);\r | |
183 | \r | |
184 | //\r | |
185 | // Fill in the descriptor with our real-mode segment value\r | |
186 | //\r | |
187 | CodeGdt->Type = 0xA;\r | |
188 | //\r | |
189 | // code/read\r | |
190 | //\r | |
191 | CodeGdt->System = 1;\r | |
192 | CodeGdt->Dpl = 0;\r | |
193 | CodeGdt->Present = 1;\r | |
194 | CodeGdt->Software = 0;\r | |
195 | CodeGdt->Reserved = 0;\r | |
196 | CodeGdt->DefaultSize = 0;\r | |
197 | //\r | |
198 | // 16 bit operands\r | |
199 | //\r | |
200 | CodeGdt->Granularity = 0;\r | |
201 | \r | |
202 | CodeGdt->LimitHi = 0;\r | |
203 | CodeGdt->LimitLo = 0xffff;\r | |
204 | \r | |
205 | Base = (*((UINT32 *) &IntThunk->Code));\r | |
206 | CodeGdt->BaseHi = (Base >> 24) & 0xFF;\r | |
207 | CodeGdt->BaseMid = (Base >> 16) & 0xFF;\r | |
208 | CodeGdt->BaseLo = Base & 0xFFFF;\r | |
209 | \r | |
210 | //\r | |
211 | // Setup a descriptor for read-mode data\r | |
212 | //\r | |
213 | DataGdt = &(IntThunk->RealModeGdt[2]);\r | |
214 | CopyMem (DataGdt, CodeGdt, sizeof (GDT32));\r | |
215 | \r | |
216 | DataGdt->Type = 0x2;\r | |
217 | //\r | |
218 | // read/write data\r | |
219 | //\r | |
220 | DataGdt->BaseHi = 0x0;\r | |
221 | //\r | |
222 | // Base = 0\r | |
223 | //\r | |
224 | DataGdt->BaseMid = 0x0;\r | |
225 | //\r | |
226 | DataGdt->BaseLo = 0x0;\r | |
227 | //\r | |
228 | DataGdt->LimitHi = 0x0F;\r | |
229 | //\r | |
230 | // Limit = 4Gb\r | |
231 | //\r | |
232 | DataGdt->LimitLo = 0xFFFF;\r | |
233 | //\r | |
234 | DataGdt->Granularity = 0x1;\r | |
235 | //\r | |
236 | //\r | |
237 | // Compute selector value\r | |
238 | //\r | |
239 | IntThunk->RealModeGdtDesc.Limit = (UINT16) (sizeof (IntThunk->RealModeGdt) - 1);\r | |
240 | CopyMem (&IntThunk->RealModeGdtDesc.Base, (UINT32 *) &IntThunk->RealModeGdt, sizeof (UINT32));\r | |
241 | //\r | |
242 | // IntThunk->RealModeGdtDesc.Base = *((UINT32*) &IntThunk->RealModeGdt);\r | |
243 | //\r | |
244 | IntThunk->RealModeIdtDesc.Limit = 0xFFFF;\r | |
245 | IntThunk->RealModeIdtDesc.Base = 0;\r | |
246 | IntThunk->LowCodeSelector = (UINT32) ((UINTN) CodeGdt - IntThunk->RealModeGdtDesc.Base);\r | |
247 | IntThunk->LowDataSelector = (UINT32) ((UINTN) DataGdt - IntThunk->RealModeGdtDesc.Base);\r | |
248 | \r | |
249 | //\r | |
250 | // Initialize low real-mode code thunk\r | |
251 | //\r | |
252 | RealModeTemplate (&CodeStart, &CodeEnd, &ReverseThunkStart, IntThunk);\r | |
253 | \r | |
254 | TempData = (UINTN) &(IntThunk->Code);\r | |
255 | IntThunk->LowReverseThunkStart = ((UINT32) TempData + (UINT32) (ReverseThunkStart - CodeStart));\r | |
256 | \r | |
257 | EsalSetSalDataArea (TempData, (UINTN) IntThunk);\r | |
258 | CopyMem (IntThunk->Code, (VOID *) CodeStart, CodeEnd - CodeStart);\r | |
259 | \r | |
260 | IntThunk->EfiToLegacy16InitTable.ReverseThunkCallSegment = EFI_SEGMENT (*((UINT32 *) &IntThunk->LowReverseThunkStart));\r | |
261 | IntThunk->EfiToLegacy16InitTable.ReverseThunkCallOffset = EFI_OFFSET (*((UINT32 *) &IntThunk->LowReverseThunkStart));\r | |
262 | \r | |
263 | return EFI_SUCCESS;\r | |
264 | }\r | |
265 | \r | |
266 | \r | |
267 | /**\r | |
268 | Thunk to 16-bit real mode and execute a software interrupt with a vector\r | |
269 | of BiosInt. Regs will contain the 16-bit register context on entry and\r | |
270 | exit.\r | |
271 | \r | |
272 | @param This Protocol instance pointer.\r | |
273 | @param BiosInt Processor interrupt vector to invoke\r | |
274 | @param Regs Register contexted passed into (and returned) from\r | |
275 | thunk to 16-bit mode\r | |
276 | \r | |
277 | @retval FALSE Thunk completed, and there were no BIOS errors in the\r | |
278 | target code. See Regs for status.\r | |
279 | @retval TRUE There was a BIOS erro in the target code.\r | |
280 | \r | |
281 | **/\r | |
282 | BOOLEAN\r | |
283 | EFIAPI\r | |
284 | LegacyBiosInt86 (\r | |
285 | IN EFI_LEGACY_BIOS_PROTOCOL *This,\r | |
286 | IN UINT8 BiosInt,\r | |
287 | IN EFI_IA32_REGISTER_SET *Regs\r | |
288 | )\r | |
289 | {\r | |
290 | EFI_STATUS Status;\r | |
291 | LEGACY_BIOS_INSTANCE *Private;\r | |
292 | LOW_MEMORY_THUNK *IntThunk;\r | |
293 | UINT16 *Stack16;\r | |
294 | EFI_TPL OriginalTpl;\r | |
295 | UINTN IaSegment;\r | |
296 | UINTN IaOffset;\r | |
297 | UINTN *Address;\r | |
298 | UINTN TempData;\r | |
299 | \r | |
300 | Private = LEGACY_BIOS_INSTANCE_FROM_THIS (This);\r | |
301 | IntThunk = Private->IntThunk;\r | |
302 | \r | |
303 | //\r | |
304 | // Get the current flat GDT, IDT, and SS and store them in Private->IntThunk.\r | |
305 | //\r | |
306 | Status = LegacyBiosGetFlatDescs (Private);\r | |
307 | ASSERT_EFI_ERROR (Status);\r | |
308 | \r | |
309 | Regs->X.Flags.Reserved1 = 1;\r | |
310 | Regs->X.Flags.Reserved2 = 0;\r | |
311 | Regs->X.Flags.Reserved3 = 0;\r | |
312 | Regs->X.Flags.Reserved4 = 0;\r | |
313 | Regs->X.Flags.IOPL = 3;\r | |
314 | Regs->X.Flags.NT = 0;\r | |
315 | Regs->X.Flags.IF = 1;\r | |
316 | Regs->X.Flags.TF = 0;\r | |
317 | Regs->X.Flags.CF = 0;\r | |
318 | //\r | |
319 | // Clear the error flag; thunk code may set it.\r | |
320 | //\r | |
321 | Stack16 = (UINT16 *) (IntThunk->Stack + LOW_STACK_SIZE);\r | |
322 | \r | |
323 | //\r | |
324 | // Copy regs to low memory stack\r | |
325 | //\r | |
326 | Stack16 -= sizeof (EFI_IA32_REGISTER_SET) / sizeof (UINT16);\r | |
327 | CopyMem (Stack16, Regs, sizeof (EFI_IA32_REGISTER_SET));\r | |
328 | \r | |
329 | //\r | |
330 | // Provide low stack esp\r | |
331 | //\r | |
332 | TempData = ((UINTN) Stack16) - ((UINTN) IntThunk);\r | |
333 | IntThunk->LowStack = *((UINT32 *) &TempData);\r | |
334 | \r | |
335 | //\r | |
336 | // Stack for reverse thunk flat mode.\r | |
337 | // It must point to top of stack (end of stack space).\r | |
338 | //\r | |
339 | TempData = ((UINTN) IntThunk->RevThunkStack) + LOW_STACK_SIZE;\r | |
340 | IntThunk->RevFlatStack = *((UINT32 *) &TempData);\r | |
341 | \r | |
342 | //\r | |
343 | // The call to Legacy16 is a critical section to EFI\r | |
344 | //\r | |
345 | OriginalTpl = gBS->RaiseTPL (TPL_HIGH_LEVEL);\r | |
346 | \r | |
347 | //\r | |
348 | // Set Legacy16 state. 0x08, 0x70 is legacy 8259 vector bases.\r | |
349 | //\r | |
350 | Status = Private->Legacy8259->SetMode (Private->Legacy8259, Efi8259LegacyMode, NULL, NULL);\r | |
351 | ASSERT_EFI_ERROR (Status);\r | |
352 | \r | |
353 | //\r | |
354 | // Call the real mode thunk code\r | |
355 | //\r | |
356 | TempData = BiosInt * 4;\r | |
357 | Address = (UINTN *) TempData;\r | |
358 | IaOffset = 0xFFFF & (*Address);\r | |
359 | IaSegment = 0xFFFF & ((*Address) >> 16);\r | |
360 | \r | |
361 | Status = BiosIntCall (\r | |
362 | BiosInt,\r | |
363 | (UINT16) IaSegment,\r | |
364 | (UINT16) IaOffset,\r | |
365 | (EFI_IA32_REGISTER_SET *) Stack16,\r | |
366 | IntThunk,\r | |
367 | IntThunk->LowStack\r | |
368 | );\r | |
369 | \r | |
370 | //\r | |
371 | // Check for errors with the thunk\r | |
372 | //\r | |
373 | switch (Status) {\r | |
374 | case THUNK_OK:\r | |
375 | break;\r | |
376 | \r | |
377 | case THUNK_ERR_A20_UNSUP:\r | |
378 | case THUNK_ERR_A20_FAILED:\r | |
379 | default:\r | |
380 | //\r | |
381 | // For all errors, set EFLAGS.CF (used by legacy BIOS to indicate error).\r | |
382 | //\r | |
383 | Regs->X.Flags.CF = 1;\r | |
384 | break;\r | |
385 | }\r | |
386 | \r | |
387 | Status = Private->Legacy8259->SetMode (Private->Legacy8259, Efi8259ProtectedMode, NULL, NULL);\r | |
388 | ASSERT_EFI_ERROR (Status);\r | |
389 | \r | |
390 | //\r | |
391 | // End critical section\r | |
392 | //\r | |
393 | gBS->RestoreTPL (OriginalTpl);\r | |
394 | \r | |
395 | //\r | |
396 | // Return the resulting registers\r | |
397 | //\r | |
398 | CopyMem (Regs, Stack16, sizeof (EFI_IA32_REGISTER_SET));\r | |
399 | \r | |
400 | return (BOOLEAN) (Regs->X.Flags.CF != 0);\r | |
401 | }\r | |
402 | \r | |
403 | \r | |
404 | /**\r | |
405 | Thunk to 16-bit real mode and call Segment:Offset. Regs will contain the\r | |
406 | 16-bit register context on entry and exit. Arguments can be passed on\r | |
407 | the Stack argument\r | |
408 | \r | |
409 | @param This Protocol instance pointer.\r | |
410 | @param Segment Segemnt of 16-bit mode call\r | |
411 | @param Offset Offset of 16-bit mdoe call\r | |
412 | @param Regs Register contexted passed into (and returned) from\r | |
413 | thunk to 16-bit mode\r | |
414 | @param Stack Caller allocated stack used to pass arguments\r | |
415 | @param StackSize Size of Stack in bytes\r | |
416 | \r | |
417 | @retval FALSE Thunk completed, and there were no BIOS errors in the\r | |
418 | target code. See Regs for status.\r | |
419 | @retval TRUE There was a BIOS erro in the target code.\r | |
420 | \r | |
421 | **/\r | |
422 | BOOLEAN\r | |
423 | EFIAPI\r | |
424 | LegacyBiosFarCall86 (\r | |
425 | IN EFI_LEGACY_BIOS_PROTOCOL *This,\r | |
426 | IN UINT16 Segment,\r | |
427 | IN UINT16 Offset,\r | |
428 | IN EFI_IA32_REGISTER_SET *Regs,\r | |
429 | IN VOID *Stack,\r | |
430 | IN UINTN StackSize\r | |
431 | )\r | |
432 | {\r | |
433 | EFI_STATUS Status;\r | |
434 | LEGACY_BIOS_INSTANCE *Private;\r | |
435 | LOW_MEMORY_THUNK *IntThunk;\r | |
436 | UINT16 *Stack16;\r | |
437 | EFI_TPL OriginalTpl;\r | |
438 | UINTN IaSegment;\r | |
439 | UINTN IaOffset;\r | |
440 | UINTN TempData;\r | |
441 | \r | |
442 | Private = LEGACY_BIOS_INSTANCE_FROM_THIS (This);\r | |
443 | IntThunk = Private->IntThunk;\r | |
444 | IaSegment = Segment;\r | |
445 | IaOffset = Offset;\r | |
446 | \r | |
447 | //\r | |
448 | // Get the current flat GDT and IDT and store them in Private->IntThunk.\r | |
449 | //\r | |
450 | Status = LegacyBiosGetFlatDescs (Private);\r | |
451 | ASSERT_EFI_ERROR (Status);\r | |
452 | \r | |
453 | Regs->X.Flags.Reserved1 = 1;\r | |
454 | Regs->X.Flags.Reserved2 = 0;\r | |
455 | Regs->X.Flags.Reserved3 = 0;\r | |
456 | Regs->X.Flags.Reserved4 = 0;\r | |
457 | Regs->X.Flags.IOPL = 3;\r | |
458 | Regs->X.Flags.NT = 0;\r | |
459 | Regs->X.Flags.IF = 1;\r | |
460 | Regs->X.Flags.TF = 0;\r | |
461 | Regs->X.Flags.CF = 0;\r | |
462 | //\r | |
463 | // Clear the error flag; thunk code may set it.\r | |
464 | //\r | |
465 | Stack16 = (UINT16 *) (IntThunk->Stack + LOW_STACK_SIZE);\r | |
466 | if (Stack != NULL && StackSize != 0) {\r | |
467 | //\r | |
468 | // Copy Stack to low memory stack\r | |
469 | //\r | |
470 | Stack16 -= StackSize / sizeof (UINT16);\r | |
471 | CopyMem (Stack16, Stack, StackSize);\r | |
472 | }\r | |
473 | //\r | |
474 | // Copy regs to low memory stack\r | |
475 | //\r | |
476 | Stack16 -= sizeof (EFI_IA32_REGISTER_SET) / sizeof (UINT16);\r | |
477 | CopyMem (Stack16, Regs, sizeof (EFI_IA32_REGISTER_SET));\r | |
478 | \r | |
479 | //\r | |
480 | // Provide low stack esp\r | |
481 | //\r | |
482 | TempData = ((UINTN) Stack16) - ((UINTN) IntThunk);\r | |
483 | IntThunk->LowStack = *((UINT32 *) &TempData);\r | |
484 | \r | |
485 | //\r | |
486 | // The call to Legacy16 is a critical section to EFI\r | |
487 | //\r | |
488 | OriginalTpl = gBS->RaiseTPL (TPL_HIGH_LEVEL);\r | |
489 | \r | |
490 | //\r | |
491 | // Set Legacy16 state. 0x08, 0x70 is legacy 8259 vector bases.\r | |
492 | //\r | |
493 | Status = Private->Legacy8259->SetMode (Private->Legacy8259, Efi8259LegacyMode, NULL, NULL);\r | |
494 | ASSERT_EFI_ERROR (Status);\r | |
495 | \r | |
496 | //\r | |
497 | // Call the real mode thunk code\r | |
498 | //\r | |
499 | Status = BiosIntCall (\r | |
500 | 0x100,\r | |
501 | (UINT16) IaSegment,\r | |
502 | (UINT16) IaOffset,\r | |
503 | (EFI_IA32_REGISTER_SET *) Stack16,\r | |
504 | IntThunk,\r | |
505 | IntThunk->LowStack\r | |
506 | );\r | |
507 | \r | |
508 | //\r | |
509 | // Check for errors with the thunk\r | |
510 | //\r | |
511 | switch (Status) {\r | |
512 | case THUNK_OK:\r | |
513 | break;\r | |
514 | \r | |
515 | case THUNK_ERR_A20_UNSUP:\r | |
516 | case THUNK_ERR_A20_FAILED:\r | |
517 | default:\r | |
518 | //\r | |
519 | // For all errors, set EFLAGS.CF (used by legacy BIOS to indicate error).\r | |
520 | //\r | |
521 | Regs->X.Flags.CF = 1;\r | |
522 | break;\r | |
523 | }\r | |
524 | //\r | |
525 | // Restore protected mode interrupt state\r | |
526 | //\r | |
527 | Status = Private->Legacy8259->SetMode (Private->Legacy8259, Efi8259ProtectedMode, NULL, NULL);\r | |
528 | ASSERT_EFI_ERROR (Status);\r | |
529 | \r | |
530 | //\r | |
531 | // End critical section\r | |
532 | //\r | |
533 | gBS->RestoreTPL (OriginalTpl);\r | |
534 | \r | |
535 | //\r | |
536 | // Return the resulting registers\r | |
537 | //\r | |
538 | CopyMem (Regs, Stack16, sizeof (EFI_IA32_REGISTER_SET));\r | |
539 | Stack16 += sizeof (EFI_IA32_REGISTER_SET) / sizeof (UINT16);\r | |
540 | \r | |
541 | if (Stack != NULL && StackSize != 0) {\r | |
542 | //\r | |
543 | // Copy low memory stack to Stack\r | |
544 | //\r | |
545 | CopyMem (Stack, Stack16, StackSize);\r | |
546 | Stack16 += StackSize / sizeof (UINT16);\r | |
547 | }\r | |
548 | \r | |
549 | return (BOOLEAN) (Regs->X.Flags.CF != 0);\r | |
550 | }\r |