1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
|
; $Id: except-x86-vcc-asm.asm $
;; @file
; IPRT - Visual C++ Compiler - x86 Exception Handler Support Code.
;
;
; Copyright (C) 2022-2023 Oracle and/or its affiliates.
;
; This file is part of VirtualBox base platform packages, as
; available from https://www.virtualbox.org.
;
; This program is free software; you can redistribute it and/or
; modify it under the terms of the GNU General Public License
; as published by the Free Software Foundation, in version 3 of the
; License.
;
; This program is distributed in the hope that it will be useful, but
; WITHOUT ANY WARRANTY; without even the implied warranty of
; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
; General Public License for more details.
;
; You should have received a copy of the GNU General Public License
; along with this program; if not, see <https://www.gnu.org/licenses>.
;
; The contents of this file may alternatively be used under the terms
; of the Common Development and Distribution License Version 1.0
; (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
; in the VirtualBox distribution, in which case the provisions of the
; CDDL are applicable instead of those of the GPL.
;
; You may elect to license modified versions of this file under the
; terms and conditions of either the GPL or the CDDL or both.
;
; SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
;
;*********************************************************************************************************************************
;* Header Files *
;*********************************************************************************************************************************
%include "iprt/asmdefs.mac"
;*********************************************************************************************************************************
;* Defined Constants And Macros *
;*********************************************************************************************************************************
;; @def WITH_NLG_STUFF
; Enabled NLG debugger hooks/whatever - no idea how it's used.
;
; So far vsdebugeng.manimpl.dll in the VS2019 remote debugger directory is the
; only component with any _NLG_ strings in it. Could not find any references
; to _NLG_ in windbg.
%define WITH_NLG_STUFF 1
;*********************************************************************************************************************************
;* Structures and Typedefs *
;*********************************************************************************************************************************
struc EH4_XCPT_REG_REC_T
.uSavedEsp resd 1 ; 0 / 0x00
.pXctpPtrs resd 1 ; 4 / 0x04
.XcptRec resd 2 ; 8 / 0x08
.uEncodedScopeTable resd 1 ; 16 / 0x10
.uTryLevel resd 1 ; 20 / 0x14
endstruc ; 24 / 0x18
;;
; Scope table record describing __try / __except / __finally blocks (aka
; EH4_SCOPETABLE_RECORD).
;
struc EH4_SCOPE_TAB_REC_T
.uEnclosingLevel resd 1
.pfnFilter resd 1
.pfnHandlerOrFinally resd 1
endstruc
;; Special EH4_SCOPE_TAB_REC_T::uEnclosingLevel used to terminate the chain.
%define EH4_TOPMOST_TRY_LEVEL 0xfffffffe
;;
; Scope table used by _except_handler4 (aka EH4_SCOPETABLE).
;
struc EH4_SCOPE_TAB_T
.offGSCookie resd 1
.offGSCookieXor resd 1
.offEHCookie resd 1
.offEHCookieXor resd 1
.aScopeRecords resb 12
endstruc
;*********************************************************************************************************************************
;* External Symbols *
;*********************************************************************************************************************************
BEGINCODE
extern IMPNAME(RtlUnwind@16)
extern _rtVccEh4DoLocalUnwindHandler@16
;*********************************************************************************************************************************
;* Global Variables *
;*********************************************************************************************************************************
;; Delcare rtVccEh4DoLocalUnwindHandler() in except-x86.cpp as a save exception handler.
; This adds the symbol table number of the exception handler to the special .sxdata section.
safeseh _rtVccEh4DoLocalUnwindHandler@16
%ifdef WITH_NLG_STUFF
BEGINDATA
GLOBALNAME_RAW __NLG_Destination, data, hidden
dd 019930520h
dd 0
dd 0
dd 0
%endif
BEGINCODE
%ifdef WITH_NLG_STUFF
;;
; Some VS debugger interface, I think.
;
; @param EDX Notification code.
; @uses EBP, EAX & ECX are preserved. This differs from other implementation,
; but simplifies the calling code.
;
ALIGNCODE(32)
GLOBALNAME_RAW __NLG_Notify, function, hidden
;
; Save registers.
;
push eax
push ecx
push ebp
push ebx
;
; ECX = notification code.
; EBX = __NLG_Destination
;
mov ecx, edx ; Originally held in ECX, so moving it there for now.
mov ebx, __NLG_Destination
__NLG_Go:
;
; Save info to __NLG_Destination and the stack (same layout).
;
mov [ebx + 0ch], ebp
push ebp
mov [ebx + 08h], ecx
push ecx
mov [ebx + 04h], eax
push eax
;
; This is presumably the symbol the debugger hooks on to as the string
; "__NLG_Dispatch" was found in vsdebugeng.manimpl.dll in VS2019.
;
global __NLG_Dispatch
__NLG_Dispatch:
; Drop the info structure from the stack.
add esp, 4*3
;
; Restore registers and drop the parameter as we return.
;
; Note! This may sabotage attempts by the debugger to modify the state...
; But that can be fixed once we know this is a requirement. Just
; keep things simple for the caller for now.
;
pop ebx
pop ebp
pop ecx
pop eax
ret
;;
; NLG call + return2.
;
; The "__NLG_Return2" symbol was observed in several vsdebugeng.manimpl.dll
; strings in VS2019.
;
ALIGNCODE(4)
GLOBALNAME_RAW __NLG_Call, function, hidden
call eax
global __NLG_Return2
__NLG_Return2:
ret
%endif
;;
; Calls the filter sub-function for a __finally statement.
;
; This sets all GRPs to zero, except for ESP, EBP and EAX.
;
; @param pfnFilter [ebp + 08h]
; @param fAbend [ebp + 0ch]
; @param pbFrame [ebp + 10h]
;
ALIGNCODE(64)
BEGINPROC rtVccEh4DoFinally
push ebp
mov ebp, esp
push ebx
push edi
push esi
xor edi, edi
xor esi, esi
%ifndef WITH_NLG_STUFF
xor edx, edx
%endif
xor ebx, ebx
mov eax, [ebp + 08h] ; pfnFilter
movzx ecx, byte [ebp + 0ch] ; fAbend
mov ebp, [ebp + 10h] ; pbFrame
%ifdef WITH_NLG_STUFF
mov edx, 101h
call __NLG_Notify
xor edx, edx
call __NLG_Call
%else
call eax
%endif
pop esi
pop edi
pop ebx
pop ebp
ret
ENDPROC rtVccEh4DoFinally
;;
; Calls the filter sub-function for an __except statement.
;
; This sets all GRPs to zero, except for ESP, EBP and ECX.
;
; @param pfnFilter [ebp + 08h]
; @param pbFrame [ebp + 0ch]
;
ALIGNCODE(32)
BEGINPROC rtVccEh4DoFiltering
push ebp
push ebx
push edi
push esi
mov ecx, [esp + 5 * 4 + 0] ; pfnFilter
mov ebp, [esp + 5 * 4 + 4] ; pbFrame
xor edi, edi
xor esi, esi
xor edx, edx
xor ebx, ebx
xor eax, eax
call ecx
pop esi
pop edi
pop ebx
pop ebp
ret
ENDPROC rtVccEh4DoFiltering
;;
; Resumes executing in an __except block (never returns).
;
; @param pfnHandler [ebp + 08h]
; @param pbFrame [ebp + 0ch]
;
ALIGNCODE(32)
BEGINPROC rtVccEh4JumpToHandler
;
; Since we're never returning there is no need to save anything here. So,
; just start by loading parameters into registers.
;
mov esi, [esp + 1 * 4 + 0] ; pfnFilter
mov ebp, [esp + 1 * 4 + 4] ; pbFrame
%ifdef WITH_NLG_STUFF
;
; Notify VS debugger/whatever.
;
mov eax, esi
mov edx, 1
call __NLG_Notify
%endif
;
; Zero all GPRs except for ESP, EBP and ESI.
;
xor edi, edi
xor edx, edx
xor ecx, ecx
xor ebx, ebx
xor eax, eax
jmp esi
ENDPROC rtVccEh4JumpToHandler
;;
; This does global unwinding via RtlUnwind.
;
; The interface kind of requires us to do this from assembly.
;
; @param pXcptRec [ebp + 08h]
; @param pXcptRegRec [ebp + 0ch]
;
ALIGNCODE(32)
BEGINPROC rtVccEh4DoGlobalUnwind
push ebp
mov ebp, esp
; Save all non-volatile registers.
push edi
push esi
push ebx
;
; Call unwind function.
;
push 0 ; ReturnValue
push dword [ebp + 08h] ; ExceptionRecord - pXcptRec
push .return ; TargetIp
push dword [ebp + 0ch] ; TargetFrame - pXcptRegRec
call IMP(RtlUnwind@16)
;
; The RtlUnwind code will place us here if it doesn't return the regular way.
;
.return:
; Restore non-volatile registers.
pop ebx
pop esi
pop edi
leave
ret
ENDPROC rtVccEh4DoGlobalUnwind
|
