1 /** @file
2 Call into 16-bit BIOS code
3
4 BugBug: Thunker does A20 gate. Can we get rid of this code or
5 put it into Legacy16 code.
6
7 Copyright (c) 1999 - 2014, Intel Corporation. All rights reserved.<BR>
8
9 This program and the accompanying materials
10 are licensed and made available under the terms and conditions
11 of the BSD License which accompanies this distribution. The
12 full text of the license may be found at
13 http://opensource.org/licenses/bsd-license.php
14
15 THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
16 WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
17
18 **/
19
20 #include "LegacyBiosInterface.h"
21 #include "IpfThunk.h"
22
23 /**
24 Gets the current flat GDT and IDT descriptors and store them in
25 Private->IntThunk. These values are used by the Thunk code.
26 This method must be called before every thunk in order to assure
27 that the correct GDT and IDT are restored after the thunk.
28
29 @param Private Private context for Legacy BIOS
30
31 @retval EFI_SUCCESS Should only pass.
32
33 **/
34 EFI_STATUS
LegacyBiosGetFlatDescs(IN LEGACY_BIOS_INSTANCE * Private)35 LegacyBiosGetFlatDescs (
36 IN LEGACY_BIOS_INSTANCE *Private
37 )
38 {
39 return EFI_SUCCESS;
40 }
41
42
43 /**
44 BIOS interrupt call function.
45
46 @param BiosInt Int number of BIOS call
47 @param Segment Segment number
48 @param Offset Offset in segment
49 @param Regs IA32 Register set.
50 @param Stack Base address of stack
51 @param StackSize Size of stack
52
53 @retval EFI_SUCCESS BIOS interrupt call succeeds.
54
55 **/
56 EFI_STATUS
BiosIntCall(IN UINT16 BiosInt,IN UINT16 Segment,IN UINT16 Offset,IN EFI_IA32_REGISTER_SET * Regs,IN VOID * Stack,IN UINTN StackSize)57 BiosIntCall (
58 IN UINT16 BiosInt,
59 IN UINT16 Segment,
60 IN UINT16 Offset,
61 IN EFI_IA32_REGISTER_SET *Regs,
62 IN VOID *Stack,
63 IN UINTN StackSize
64 )
65 {
66 IPF_DWORD_REGS DwordRegs;
67 UINT64 IntTypeVariable;
68
69 IntTypeVariable = 0x8000000000000000;
70 IntTypeVariable |= (UINT64)BiosInt;
71
72 DwordRegs.Cs = Segment;
73 DwordRegs.Eip = Offset;
74
75 DwordRegs.Ds = Regs->X.DS;
76 DwordRegs.Es = Regs->X.ES;
77 DwordRegs.Fs = Regs->X.ES;
78 DwordRegs.Gs = Regs->X.ES;
79 DwordRegs.Ss = 0xFFFF;
80
81 DwordRegs.Eax = Regs->X.AX;
82 DwordRegs.Ebx = Regs->X.BX;
83 //
84 // Sometimes, ECX is used to pass in 32 bit data. For example, INT 1Ah, AX = B10Dh is
85 // "PCI BIOS v2.0c + Write Configuration DWORD" and ECX has the dword to write.
86 //
87 DwordRegs.Ecx = Regs->E.ECX;
88 DwordRegs.Edx = Regs->X.DX;
89
90 DwordRegs.Ebp = Regs->X.BP;
91 DwordRegs.Eflag = *((UINT16 *) &Regs->X.Flags);
92
93 DwordRegs.Edi = Regs->X.DI;
94 DwordRegs.Esi = Regs->X.SI;
95 DwordRegs.Esp = 0xFFFFFFFF;
96
97 EfiIaEntryPoint (IntTypeVariable, &DwordRegs, ((UINTN) Stack + StackSize), StackSize);
98
99 Regs->X.CS = DwordRegs.Cs;
100
101 Regs->X.DS = (UINT16) DwordRegs.Ds;
102 Regs->X.SS = (UINT16) DwordRegs.Ss;
103
104 Regs->E.EAX = DwordRegs.Eax;
105 Regs->E.EBX = DwordRegs.Ebx;
106 Regs->E.ECX = DwordRegs.Ecx;
107 Regs->E.EDX = DwordRegs.Edx;
108
109 Regs->E.EBP = DwordRegs.Ebp;
110 CopyMem (&Regs->X.Flags, &DwordRegs.Eflag, sizeof (EFI_FLAGS_REG));
111
112 Regs->E.EDI = DwordRegs.Edi;
113 Regs->E.ESI = DwordRegs.Esi;
114
115 return EFI_SUCCESS;
116 }
117
118
119 /**
120 Template of real mode code.
121
122 @param CodeStart Start address of code.
123 @param CodeEnd End address of code
124 @param ReverseThunkStart Start of reverse thunk.
125 @param IntThunk Low memory thunk.
126
127 **/
128 VOID
RealModeTemplate(OUT UINTN * CodeStart,OUT UINTN * CodeEnd,OUT UINTN * ReverseThunkStart,LOW_MEMORY_THUNK * IntThunk)129 RealModeTemplate (
130 OUT UINTN *CodeStart,
131 OUT UINTN *CodeEnd,
132 OUT UINTN *ReverseThunkStart,
133 LOW_MEMORY_THUNK *IntThunk
134 )
135 {
136 SAL_RETURN_REGS SalStatus;
137
138 SalStatus = EsalGetReverseThunkAddress ();
139
140 *CodeStart = SalStatus.r9;
141 *CodeEnd = SalStatus.r10;
142 *ReverseThunkStart = SalStatus.r11;
143
144 }
145
146
147 /**
148 Allocate memory < 1 MB and copy the thunker code into low memory. Se up
149 all the descriptors.
150
151 @param Private Private context for Legacy BIOS
152
153 @retval EFI_SUCCESS Should only pass.
154
155 **/
156 EFI_STATUS
LegacyBiosInitializeThunk(IN LEGACY_BIOS_INSTANCE * Private)157 LegacyBiosInitializeThunk (
158 IN LEGACY_BIOS_INSTANCE *Private
159 )
160 {
161 GDT32 *CodeGdt;
162 GDT32 *DataGdt;
163 UINTN CodeStart;
164 UINTN CodeEnd;
165 UINTN ReverseThunkStart;
166 UINT32 Base;
167 LOW_MEMORY_THUNK *IntThunk;
168 UINTN TempData;
169
170 ASSERT (Private);
171
172 IntThunk = Private->IntThunk;
173
174 //
175 // Clear the reserved descriptor
176 //
177 ZeroMem (&(IntThunk->RealModeGdt[0]), sizeof (GDT32));
178
179 //
180 // Setup a descriptor for real-mode code
181 //
182 CodeGdt = &(IntThunk->RealModeGdt[1]);
183
184 //
185 // Fill in the descriptor with our real-mode segment value
186 //
187 CodeGdt->Type = 0xA;
188 //
189 // code/read
190 //
191 CodeGdt->System = 1;
192 CodeGdt->Dpl = 0;
193 CodeGdt->Present = 1;
194 CodeGdt->Software = 0;
195 CodeGdt->Reserved = 0;
196 CodeGdt->DefaultSize = 0;
197 //
198 // 16 bit operands
199 //
200 CodeGdt->Granularity = 0;
201
202 CodeGdt->LimitHi = 0;
203 CodeGdt->LimitLo = 0xffff;
204
205 Base = (*((UINT32 *) &IntThunk->Code));
206 CodeGdt->BaseHi = (Base >> 24) & 0xFF;
207 CodeGdt->BaseMid = (Base >> 16) & 0xFF;
208 CodeGdt->BaseLo = Base & 0xFFFF;
209
210 //
211 // Setup a descriptor for read-mode data
212 //
213 DataGdt = &(IntThunk->RealModeGdt[2]);
214 CopyMem (DataGdt, CodeGdt, sizeof (GDT32));
215
216 DataGdt->Type = 0x2;
217 //
218 // read/write data
219 //
220 DataGdt->BaseHi = 0x0;
221 //
222 // Base = 0
223 //
224 DataGdt->BaseMid = 0x0;
225 //
226 DataGdt->BaseLo = 0x0;
227 //
228 DataGdt->LimitHi = 0x0F;
229 //
230 // Limit = 4Gb
231 //
232 DataGdt->LimitLo = 0xFFFF;
233 //
234 DataGdt->Granularity = 0x1;
235 //
236 //
237 // Compute selector value
238 //
239 IntThunk->RealModeGdtDesc.Limit = (UINT16) (sizeof (IntThunk->RealModeGdt) - 1);
240 CopyMem (&IntThunk->RealModeGdtDesc.Base, (UINT32 *) &IntThunk->RealModeGdt, sizeof (UINT32));
241 //
242 // IntThunk->RealModeGdtDesc.Base = *((UINT32*) &IntThunk->RealModeGdt);
243 //
244 IntThunk->RealModeIdtDesc.Limit = 0xFFFF;
245 IntThunk->RealModeIdtDesc.Base = 0;
246 IntThunk->LowCodeSelector = (UINT32) ((UINTN) CodeGdt - IntThunk->RealModeGdtDesc.Base);
247 IntThunk->LowDataSelector = (UINT32) ((UINTN) DataGdt - IntThunk->RealModeGdtDesc.Base);
248
249 //
250 // Initialize low real-mode code thunk
251 //
252 RealModeTemplate (&CodeStart, &CodeEnd, &ReverseThunkStart, IntThunk);
253
254 TempData = (UINTN) &(IntThunk->Code);
255 IntThunk->LowReverseThunkStart = ((UINT32) TempData + (UINT32) (ReverseThunkStart - CodeStart));
256
257 EsalSetSalDataArea (TempData, (UINTN) IntThunk);
258 CopyMem (IntThunk->Code, (VOID *) CodeStart, CodeEnd - CodeStart);
259
260 IntThunk->EfiToLegacy16InitTable.ReverseThunkCallSegment = EFI_SEGMENT (*((UINT32 *) &IntThunk->LowReverseThunkStart));
261 IntThunk->EfiToLegacy16InitTable.ReverseThunkCallOffset = EFI_OFFSET (*((UINT32 *) &IntThunk->LowReverseThunkStart));
262
263 return EFI_SUCCESS;
264 }
265
266
267 /**
268 Thunk to 16-bit real mode and execute a software interrupt with a vector
269 of BiosInt. Regs will contain the 16-bit register context on entry and
270 exit.
271
272 @param This Protocol instance pointer.
273 @param BiosInt Processor interrupt vector to invoke
274 @param Regs Register contexted passed into (and returned) from
275 thunk to 16-bit mode
276
277 @retval FALSE Thunk completed, and there were no BIOS errors in the
278 target code. See Regs for status.
279 @retval TRUE There was a BIOS erro in the target code.
280
281 **/
282 BOOLEAN
283 EFIAPI
LegacyBiosInt86(IN EFI_LEGACY_BIOS_PROTOCOL * This,IN UINT8 BiosInt,IN EFI_IA32_REGISTER_SET * Regs)284 LegacyBiosInt86 (
285 IN EFI_LEGACY_BIOS_PROTOCOL *This,
286 IN UINT8 BiosInt,
287 IN EFI_IA32_REGISTER_SET *Regs
288 )
289 {
290 EFI_STATUS Status;
291 LEGACY_BIOS_INSTANCE *Private;
292 LOW_MEMORY_THUNK *IntThunk;
293 UINT16 *Stack16;
294 EFI_TPL OriginalTpl;
295 UINTN IaSegment;
296 UINTN IaOffset;
297 UINTN *Address;
298 UINTN TempData;
299
300 Private = LEGACY_BIOS_INSTANCE_FROM_THIS (This);
301 IntThunk = Private->IntThunk;
302
303 //
304 // Get the current flat GDT, IDT, and SS and store them in Private->IntThunk.
305 //
306 Status = LegacyBiosGetFlatDescs (Private);
307 ASSERT_EFI_ERROR (Status);
308
309 Regs->X.Flags.Reserved1 = 1;
310 Regs->X.Flags.Reserved2 = 0;
311 Regs->X.Flags.Reserved3 = 0;
312 Regs->X.Flags.Reserved4 = 0;
313 Regs->X.Flags.IOPL = 3;
314 Regs->X.Flags.NT = 0;
315 Regs->X.Flags.IF = 1;
316 Regs->X.Flags.TF = 0;
317 Regs->X.Flags.CF = 0;
318 //
319 // Clear the error flag; thunk code may set it.
320 //
321 Stack16 = (UINT16 *) (IntThunk->Stack + LOW_STACK_SIZE);
322
323 //
324 // Copy regs to low memory stack
325 //
326 Stack16 -= sizeof (EFI_IA32_REGISTER_SET) / sizeof (UINT16);
327 CopyMem (Stack16, Regs, sizeof (EFI_IA32_REGISTER_SET));
328
329 //
330 // Provide low stack esp
331 //
332 TempData = ((UINTN) Stack16) - ((UINTN) IntThunk);
333 IntThunk->LowStack = *((UINT32 *) &TempData);
334
335 //
336 // Stack for reverse thunk flat mode.
337 // It must point to top of stack (end of stack space).
338 //
339 TempData = ((UINTN) IntThunk->RevThunkStack) + LOW_STACK_SIZE;
340 IntThunk->RevFlatStack = *((UINT32 *) &TempData);
341
342 //
343 // The call to Legacy16 is a critical section to EFI
344 //
345 OriginalTpl = gBS->RaiseTPL (TPL_HIGH_LEVEL);
346
347 //
348 // Set Legacy16 state. 0x08, 0x70 is legacy 8259 vector bases.
349 //
350 Status = Private->Legacy8259->SetMode (Private->Legacy8259, Efi8259LegacyMode, NULL, NULL);
351 ASSERT_EFI_ERROR (Status);
352
353 //
354 // Call the real mode thunk code
355 //
356 TempData = BiosInt * 4;
357 Address = (UINTN *) TempData;
358 IaOffset = 0xFFFF & (*Address);
359 IaSegment = 0xFFFF & ((*Address) >> 16);
360
361 Status = BiosIntCall (
362 BiosInt,
363 (UINT16) IaSegment,
364 (UINT16) IaOffset,
365 (EFI_IA32_REGISTER_SET *) Stack16,
366 IntThunk,
367 IntThunk->LowStack
368 );
369
370 //
371 // Check for errors with the thunk
372 //
373 switch (Status) {
374 case THUNK_OK:
375 break;
376
377 case THUNK_ERR_A20_UNSUP:
378 case THUNK_ERR_A20_FAILED:
379 default:
380 //
381 // For all errors, set EFLAGS.CF (used by legacy BIOS to indicate error).
382 //
383 Regs->X.Flags.CF = 1;
384 break;
385 }
386
387 Status = Private->Legacy8259->SetMode (Private->Legacy8259, Efi8259ProtectedMode, NULL, NULL);
388 ASSERT_EFI_ERROR (Status);
389
390 //
391 // End critical section
392 //
393 gBS->RestoreTPL (OriginalTpl);
394
395 //
396 // Return the resulting registers
397 //
398 CopyMem (Regs, Stack16, sizeof (EFI_IA32_REGISTER_SET));
399
400 return (BOOLEAN) (Regs->X.Flags.CF != 0);
401 }
402
403
404 /**
405 Thunk to 16-bit real mode and call Segment:Offset. Regs will contain the
406 16-bit register context on entry and exit. Arguments can be passed on
407 the Stack argument
408
409 @param This Protocol instance pointer.
410 @param Segment Segemnt of 16-bit mode call
411 @param Offset Offset of 16-bit mdoe call
412 @param Regs Register contexted passed into (and returned) from
413 thunk to 16-bit mode
414 @param Stack Caller allocated stack used to pass arguments
415 @param StackSize Size of Stack in bytes
416
417 @retval FALSE Thunk completed, and there were no BIOS errors in the
418 target code. See Regs for status.
419 @retval TRUE There was a BIOS erro in the target code.
420
421 **/
422 BOOLEAN
423 EFIAPI
LegacyBiosFarCall86(IN EFI_LEGACY_BIOS_PROTOCOL * This,IN UINT16 Segment,IN UINT16 Offset,IN EFI_IA32_REGISTER_SET * Regs,IN VOID * Stack,IN UINTN StackSize)424 LegacyBiosFarCall86 (
425 IN EFI_LEGACY_BIOS_PROTOCOL *This,
426 IN UINT16 Segment,
427 IN UINT16 Offset,
428 IN EFI_IA32_REGISTER_SET *Regs,
429 IN VOID *Stack,
430 IN UINTN StackSize
431 )
432 {
433 EFI_STATUS Status;
434 LEGACY_BIOS_INSTANCE *Private;
435 LOW_MEMORY_THUNK *IntThunk;
436 UINT16 *Stack16;
437 EFI_TPL OriginalTpl;
438 UINTN IaSegment;
439 UINTN IaOffset;
440 UINTN TempData;
441
442 Private = LEGACY_BIOS_INSTANCE_FROM_THIS (This);
443 IntThunk = Private->IntThunk;
444 IaSegment = Segment;
445 IaOffset = Offset;
446
447 //
448 // Get the current flat GDT and IDT and store them in Private->IntThunk.
449 //
450 Status = LegacyBiosGetFlatDescs (Private);
451 ASSERT_EFI_ERROR (Status);
452
453 Regs->X.Flags.Reserved1 = 1;
454 Regs->X.Flags.Reserved2 = 0;
455 Regs->X.Flags.Reserved3 = 0;
456 Regs->X.Flags.Reserved4 = 0;
457 Regs->X.Flags.IOPL = 3;
458 Regs->X.Flags.NT = 0;
459 Regs->X.Flags.IF = 1;
460 Regs->X.Flags.TF = 0;
461 Regs->X.Flags.CF = 0;
462 //
463 // Clear the error flag; thunk code may set it.
464 //
465 Stack16 = (UINT16 *) (IntThunk->Stack + LOW_STACK_SIZE);
466 if (Stack != NULL && StackSize != 0) {
467 //
468 // Copy Stack to low memory stack
469 //
470 Stack16 -= StackSize / sizeof (UINT16);
471 CopyMem (Stack16, Stack, StackSize);
472 }
473 //
474 // Copy regs to low memory stack
475 //
476 Stack16 -= sizeof (EFI_IA32_REGISTER_SET) / sizeof (UINT16);
477 CopyMem (Stack16, Regs, sizeof (EFI_IA32_REGISTER_SET));
478
479 //
480 // Provide low stack esp
481 //
482 TempData = ((UINTN) Stack16) - ((UINTN) IntThunk);
483 IntThunk->LowStack = *((UINT32 *) &TempData);
484
485 //
486 // The call to Legacy16 is a critical section to EFI
487 //
488 OriginalTpl = gBS->RaiseTPL (TPL_HIGH_LEVEL);
489
490 //
491 // Set Legacy16 state. 0x08, 0x70 is legacy 8259 vector bases.
492 //
493 Status = Private->Legacy8259->SetMode (Private->Legacy8259, Efi8259LegacyMode, NULL, NULL);
494 ASSERT_EFI_ERROR (Status);
495
496 //
497 // Call the real mode thunk code
498 //
499 Status = BiosIntCall (
500 0x100,
501 (UINT16) IaSegment,
502 (UINT16) IaOffset,
503 (EFI_IA32_REGISTER_SET *) Stack16,
504 IntThunk,
505 IntThunk->LowStack
506 );
507
508 //
509 // Check for errors with the thunk
510 //
511 switch (Status) {
512 case THUNK_OK:
513 break;
514
515 case THUNK_ERR_A20_UNSUP:
516 case THUNK_ERR_A20_FAILED:
517 default:
518 //
519 // For all errors, set EFLAGS.CF (used by legacy BIOS to indicate error).
520 //
521 Regs->X.Flags.CF = 1;
522 break;
523 }
524 //
525 // Restore protected mode interrupt state
526 //
527 Status = Private->Legacy8259->SetMode (Private->Legacy8259, Efi8259ProtectedMode, NULL, NULL);
528 ASSERT_EFI_ERROR (Status);
529
530 //
531 // End critical section
532 //
533 gBS->RestoreTPL (OriginalTpl);
534
535 //
536 // Return the resulting registers
537 //
538 CopyMem (Regs, Stack16, sizeof (EFI_IA32_REGISTER_SET));
539 Stack16 += sizeof (EFI_IA32_REGISTER_SET) / sizeof (UINT16);
540
541 if (Stack != NULL && StackSize != 0) {
542 //
543 // Copy low memory stack to Stack
544 //
545 CopyMem (Stack, Stack16, StackSize);
546 Stack16 += StackSize / sizeof (UINT16);
547 }
548
549 return (BOOLEAN) (Regs->X.Flags.CF != 0);
550 }
551