2 ; Low leve IA32 specific debug support functions.
4 ; Copyright (c) 2006, Intel Corporation. <BR>
5 ; All rights reserved. This program and the accompanying materials
6 ; are licensed and made available under the terms and conditions of the BSD License
7 ; which accompanies this distribution. The full text of the license may be found at
8 ; http://opensource.org/licenses/bsd-license.php
10 ; THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
11 ; WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
18 EXCPT32_DIVIDE_ERROR EQU 0
21 EXCPT32_BREAKPOINT EQU 3
22 EXCPT32_OVERFLOW EQU 4
24 EXCPT32_INVALID_OPCODE EQU 6
25 EXCPT32_DOUBLE_FAULT EQU 8
26 EXCPT32_INVALID_TSS EQU 10
27 EXCPT32_SEG_NOT_PRESENT EQU 11
28 EXCPT32_STACK_FAULT EQU 12
29 EXCPT32_GP_FAULT EQU 13
30 EXCPT32_PAGE_FAULT EQU 14
31 EXCPT32_FP_ERROR EQU 16
32 EXCPT32_ALIGNMENT_CHECK EQU 17
33 EXCPT32_MACHINE_CHECK EQU 18
36 FXSTOR_FLAG EQU 01000000h ; bit cpuid 24 of feature flags
38 ;; The FXSTOR and FXRSTOR commands are used for saving and restoring the x87,
39 ;; MMX, SSE, SSE2, etc registers. The initialization of the debugsupport driver
40 ;; MUST check the CPUID feature flags to see that these instructions are available
41 ;; and fail to init if they are not.
45 db 0fh, 0aeh, 00000111y ; mod = 00, reg/op = 000, r/m = 111 = [edi]
50 db 0fh, 0aeh, 00001110y ; mod = 00, reg/op = 001, r/m = 110 = [esi]
54 public OrigVector, InterruptEntryStub, StubSize, CommonIdtEntry, FxStorSupport
56 StubSize dd InterruptEntryStubEnd - InterruptEntryStub
57 AppEsp dd 11111111h ; ?
58 DebugEsp dd 22222222h ; ?
59 ExtraPush dd 33333333h ; ?
60 ExceptData dd 44444444h ; ?
61 Eflags dd 55555555h ; ?
62 OrigVector dd 66666666h ; ?
64 ;; The declarations below define the memory region that will be used for the debug stack.
65 ;; The context record will be built by pushing register values onto this stack.
66 ;; It is imparitive that alignment be carefully managed, since the FXSTOR and
67 ;; FXRSTOR instructions will GP fault if their memory operand is not 16 byte aligned.
69 ;; The stub will switch stacks from the application stack to the debuger stack
70 ;; and pushes the exception number.
72 ;; Then we building the context record on the stack. Since the stack grows down,
73 ;; we push the fields of the context record from the back to the front. There
74 ;; are 132 bytes of stack used prior allocating the 512 bytes of stack to be
75 ;; used as the memory buffer for the fxstor instruction. Therefore address of
76 ;; the buffer used for the FXSTOR instruction is &Eax - 132 - 512, which
77 ;; must be 16 byte aligned.
79 ;; We carefully locate the stack to make this happen.
81 ;; For reference, the context structure looks like this:
83 ;; UINT32 ExceptionData;
84 ;; FX_SAVE_STATE_IA32 FxSaveState; // 512 bytes, must be 16 byte aligned
85 ;; UINT32 Dr0, Dr1, Dr2, Dr3, Dr6, Dr7;
86 ;; UINT32 Cr0, Cr1, Cr2, Cr3, Cr4;
89 ;; UINT32 Gdtr[2], Idtr[2];
91 ;; UINT32 Gs, Fs, Es, Ds, Cs, Ss;
92 ;; UINT32 Edi, Esi, Ebp, Esp, Ebx, Edx, Ecx, Eax;
93 ;; } SYSTEM_CONTEXT_IA32; // 32 bit system context record
97 DebugStackEnd db "DbgStkEnd >>>>>>" ;; 16 byte long string - must be 16 bytes to preserve alignment
98 dd 1ffdh dup (000000000h) ;; 32K should be enough stack
99 ;; This allocation is coocked to insure
100 ;; that the the buffer for the FXSTORE instruction
101 ;; will be 16 byte aligned also.
103 ExceptionNumber dd ? ;; first entry will be the vector number pushed by the stub
105 DebugStackBegin db "<<<< DbgStkBegin" ;; initial debug ESP == DebugStackBegin, set in stub
109 externdef InterruptDistrubutionHub:near
111 ;------------------------------------------------------------------------------
117 ; Abstract: Returns TRUE if FxStor instructions are supported
119 FxStorSupport PROC C PUBLIC
122 ; cpuid corrupts ebx which must be preserved per the C calling convention
136 ;------------------------------------------------------------------------------
139 ; DESCRIPTOR * DestDesc,
140 ; void (*Vector) (void)
143 ; Abstract: Encodes an IDT descriptor with the given physical address
145 Vect2Desc PROC C PUBLIC DestPtr:DWORD, Vector:DWORD
149 mov word ptr [ecx], ax ; write bits 15..0 of offset
151 mov word ptr [ecx+2], dx ; SYS_CODE_SEL from GDT
152 mov word ptr [ecx+4], 0e00h OR 8000h ; type = 386 interrupt gate, present
154 mov word ptr [ecx+6], ax ; write bits 31..16 of offset
162 ;------------------------------------------------------------------------------
165 ; Abstract: This code is not a function, but is a small piece of code that is
166 ; copied and fixed up once for each IDT entry that is hooked.
169 mov AppEsp, esp ; save stack top
170 mov esp, offset DebugStackBegin ; switch to debugger stack
171 push 0 ; push vector number - will be modified before installed
173 dd 0 ; fixed up to relative address of CommonIdtEntry
174 InterruptEntryStubEnd:
178 ;------------------------------------------------------------------------------
181 ; Abstract: This code is not a function, but is the common part for all IDT
186 ;; At this point, the stub has saved the current application stack esp into AppEsp
187 ;; and switched stacks to the debug stack, where it pushed the vector number
189 ;; The application stack looks like this:
192 ;; (last application stack entry)
193 ;; eflags from interrupted task
194 ;; CS from interrupted task
195 ;; EIP from interrupted task
196 ;; Error code <-------------------- Only present for some exeption types
201 ;; The stub switched us to the debug stack and pushed the interrupt number.
203 ;; Next, construct the context record. It will be build on the debug stack by
204 ;; pushing the registers in the correct order so as to create the context structure
205 ;; on the debug stack. The context record must be built from the end back to the
206 ;; beginning because the stack grows down...
208 ;; For reference, the context record looks like this:
212 ;; UINT32 ExceptionData;
213 ;; FX_SAVE_STATE_IA32 FxSaveState;
214 ;; UINT32 Dr0, Dr1, Dr2, Dr3, Dr6, Dr7;
215 ;; UINT32 Cr0, Cr2, Cr3, Cr4;
218 ;; UINT32 Gdtr[2], Idtr[2];
220 ;; UINT32 Gs, Fs, Es, Ds, Cs, Ss;
221 ;; UINT32 Edi, Esi, Ebp, Esp, Ebx, Edx, Ecx, Eax;
222 ;; } SYSTEM_CONTEXT_IA32; // 32 bit system context record
224 ;; UINT32 Edi, Esi, Ebp, Esp, Ebx, Edx, Ecx, Eax;
227 ;; Save interrupt state eflags register...
230 mov dword ptr Eflags, eax
232 ;; We need to determine if any extra data was pushed by the exception, and if so, save it
233 ;; To do this, we check the exception number pushed by the stub, and cache the
234 ;; result in a variable since we'll need this again.
235 .IF ExceptionNumber == EXCPT32_DOUBLE_FAULT
237 .ELSEIF ExceptionNumber == EXCPT32_INVALID_TSS
239 .ELSEIF ExceptionNumber == EXCPT32_SEG_NOT_PRESENT
241 .ELSEIF ExceptionNumber == EXCPT32_STACK_FAULT
243 .ELSEIF ExceptionNumber == EXCPT32_GP_FAULT
245 .ELSEIF ExceptionNumber == EXCPT32_PAGE_FAULT
247 .ELSEIF ExceptionNumber == EXCPT32_ALIGNMENT_CHECK
253 ;; If there's some extra data, save it also, and modify the saved AppEsp to effectively
254 ;; pop this value off the application's stack.
265 ;; The "pushad" above pushed the debug stack esp. Since what we're actually doing
266 ;; is building the context record on the debug stack, we need to save the pushed
267 ;; debug ESP, and replace it with the application's last stack entry...
272 ; application stack has eflags, cs, & eip, so
273 ; last actual application stack entry is
274 ; 12 bytes into the application stack.
277 ;; continue building context record
278 ;; UINT32 Gs, Fs, Es, Ds, Cs, Ss; insure high 16 bits of each is zero
282 ; CS from application is one entry back in application stack
284 movzx eax, word ptr [eax + 4]
297 ; Eip from application is on top of application stack
301 ;; UINT32 Gdtr[2], Idtr[2];
317 ;; Eflags from application is two entries back in application stack
319 push dword ptr [eax + 8]
321 ;; UINT32 Cr0, Cr1, Cr2, Cr3, Cr4;
322 ;; insure FXSAVE/FXRSTOR is enabled in CR4...
323 ;; ... while we're at it, make sure DE is also enabled...
336 ;; UINT32 Dr0, Dr1, Dr2, Dr3, Dr6, Dr7;
339 ;; clear Dr7 while executing debugger itself
345 ;; insure all status bits in dr6 are clear...
358 ;; FX_SAVE_STATE_IA32 FxSaveState;
361 ; IMPORTANT!! The debug stack has been carefully constructed to
362 ; insure that esp and edi are 16 byte aligned when we get here.
363 ; They MUST be. If they are not, a GP fault will occur.
366 ;; UINT32 ExceptionData;
370 ; call to C code which will in turn call registered handler
371 ; pass in the vector number
374 mov eax, ExceptionNumber
376 call InterruptDistrubutionHub
380 ;; UINT32 ExceptionData;
383 ;; FX_SAVE_STATE_IA32 FxSaveState;
388 ;; UINT32 Dr0, Dr1, Dr2, Dr3, Dr6, Dr7;
397 ;; skip restore of dr6. We cleared dr6 during the context save.
402 ;; UINT32 Cr0, Cr1, Cr2, Cr3, Cr4;
415 pop dword ptr [eax + 8]
418 ;; UINT32 Gdtr[2], Idtr[2];
419 ;; Best not let anyone mess with these particular registers...
425 ;; UINT32 SegGs, SegFs, SegEs, SegDs, SegCs, SegSs;
426 ;; NOTE - modified segment registers could hang the debugger... We
427 ;; could attempt to insulate ourselves against this possibility,
428 ;; but that poses risks as well.
438 ;; The next stuff to restore is the general purpose registers that were pushed
439 ;; using the "pushad" instruction.
441 ;; The value of ESP as stored in the context record is the application ESP
442 ;; including the 3 entries on the application stack caused by the exception
443 ;; itself. It may have been modified by the debug agent, so we need to
444 ;; determine if we need to relocate the application stack.
446 mov ebx, [esp + 12] ; move the potentially modified AppEsp into ebx
456 mov ecx, [eax + 4] ; CS
459 mov ecx, [eax + 8] ; EFLAGS
462 mov eax, ebx ; modify the saved AppEsp to the new AppEsp
465 mov eax, DebugEsp ; restore the DebugEsp on the debug stack
466 ; so our "popad" will not cause a stack switch
469 cmp ExceptionNumber, 068h
474 ;; Restore eflags so when we chain, the flags will be exactly as if we were never here.
475 ;; We gin up the stack to do an iretd so we can get ALL the flags.
478 and ebx, NOT 300h ; special handling for IF and TF
485 ;; UINT32 Edi, Esi, Ebp, Esp, Ebx, Edx, Ecx, Eax;
488 ;; Switch back to application stack
491 ;; Jump to original handler
495 ;; UINT32 Edi, Esi, Ebp, Esp, Ebx, Edx, Ecx, Eax;
498 ;; Switch back to application stack
501 ;; We're outa here...