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여기서 내 마지막 목표는 부동 소수점 예외를 catch하고 스택 추적을 인쇄하고 부동 소수점 예외를 사용하여 실행을 다시 시작하는 방법을 제공하는 것입니다 (결과가 아닌 유한/비 - 값을 사용). 나는 내 original question 이후로 약간 진전을 보였습니다. SSE (기본값은 x64)를 사용할 때 부동 소수점 단위를 지우거나 구성하기 위해 조정해야하는 레지스터가 더 많이 있다는 것을 깨달았습니다.예외를 처리 한 후 컨텍스트를 복구하는 작업은 VS/RTC (런타임 검사)에서만 작동합니다.
나는 아주 간단한 예제를 만들었지 만, 릴리스 빌드로 가면 x64에서 문제가 발생합니다. 디버그/릴리스 빌드는 x86 대상에 대해 잘 작동합니다. 난 "Run-Time-Checks" option of Visual-Studio, 구체적으로 "스택 프레임 런타임 오류 검사를 활성화"RTCs 아래로 문제를 좁혔습니다. (내가 기대하는 것입니다)의 RTC이 활성화
#include "stdafx.h"
#include <float.h>
#include <Windows.h>
#include <xmmintrin.h>
double zero = 0.0;
void printException(EXCEPTION_POINTERS * ExceptionInfo){
bool bFloatingPointRecoverFlag = false;
switch(ExceptionInfo->ExceptionRecord->ExceptionCode)
{
case EXCEPTION_ACCESS_VIOLATION:
fputs(" EXCEPTION_ACCESS_VIOLATION\n", stderr);
break;
case EXCEPTION_ARRAY_BOUNDS_EXCEEDED:
fputs(" EXCEPTION_ARRAY_BOUNDS_EXCEEDED\n", stderr);
break;
case EXCEPTION_BREAKPOINT:
fputs(" EXCEPTION_BREAKPOINT\n", stderr);
break;
case EXCEPTION_DATATYPE_MISALIGNMENT:
fputs(" EXCEPTION_DATATYPE_MISALIGNMENT\n", stderr);
break;
case EXCEPTION_FLT_DENORMAL_OPERAND:
fputs(" EXCEPTION_FLT_DENORMAL_OPERAND\n", stderr);
break;
case EXCEPTION_FLT_DIVIDE_BY_ZERO:
fputs(" EXCEPTION_FLT_DIVIDE_BY_ZERO\n", stderr);
break;
case EXCEPTION_FLT_INEXACT_RESULT:
fputs(" EXCEPTION_FLT_INEXACT_RESULT\n", stderr);
break;
case EXCEPTION_FLT_INVALID_OPERATION:
fputs(" EXCEPTION_FLT_INVALID_OPERATION\n", stderr);
break;
case EXCEPTION_FLT_OVERFLOW:
fputs(" EXCEPTION_FLT_OVERFLOW\n", stderr);
break;
case EXCEPTION_FLT_STACK_CHECK:
fputs(" EXCEPTION_FLT_STACK_CHECK\n", stderr);
break;
case EXCEPTION_FLT_UNDERFLOW:
fputs(" EXCEPTION_FLT_UNDERFLOW\n", stderr);
bFloatingPointRecoverFlag = 1;
break;
case EXCEPTION_ILLEGAL_INSTRUCTION:
fputs(" EXCEPTION_ILLEGAL_INSTRUCTION\n", stderr);
break;
case EXCEPTION_IN_PAGE_ERROR:
fputs(" EXCEPTION_IN_PAGE_ERROR\n", stderr);
break;
case EXCEPTION_INT_DIVIDE_BY_ZERO:
fputs(" EXCEPTION_INT_DIVIDE_BY_ZERO\n", stderr);
break;
case EXCEPTION_INT_OVERFLOW:
fputs(" EXCEPTION_INT_OVERFLOW\n", stderr);
break;
case EXCEPTION_INVALID_DISPOSITION:
fputs(" EXCEPTION_INVALID_DISPOSITION\n", stderr);
break;
case EXCEPTION_NONCONTINUABLE_EXCEPTION:
fputs(" EXCEPTION_NONCONTINUABLE_EXCEPTION\n", stderr);
break;
case EXCEPTION_PRIV_INSTRUCTION:
fputs(" EXCEPTION_PRIV_INSTRUCTION\n", stderr);
break;
case EXCEPTION_SINGLE_STEP:
fputs(" EXCEPTION_SINGLE_STEP\n", stderr);
break;
case EXCEPTION_STACK_OVERFLOW:
fputs(" EXCEPTION_STACK_OVERFLOW\n", stderr);
break;
default:
fputs(" Unrecognized Exception\n", stderr);
break;
}
}
LONG WINAPI myfunc(EXCEPTION_POINTERS * ExceptionInfo){
printf("#########Caught Ya:");
printException(ExceptionInfo);
printf("ExceptionAddr = 0x%p\n",ExceptionInfo->ExceptionRecord->ExceptionAddress);
/* clear the exception */
unsigned int stat = _clearfp();
/* disable fp exceptions*/
unsigned int ctrlwrd;
errno_t err = _controlfp_s(&ctrlwrd, _MCW_EM, _MCW_EM);
/* Disable and clear the exceptions in the exception context */
#if _WIN64
/* Get current context to get the values of MxCsr register, which was
* set by the calls to _controlfp above, we need to copy these into
* the exception context so that exceptions really stay disabled.
* References:
* https://msdn.microsoft.com/en-us/library/yxty7t75.aspx
* https://software.intel.com/en-us/articles/x87-and-sse-floating-point-assists-in-ia-32-flush-to-zero-ftz-and-denormals-are-zero-daz
*/
_CONTEXT myContext;
GetThreadContext(GetCurrentThread(),&myContext);
ExceptionInfo->ContextRecord->FltSave.ControlWord = ctrlwrd;
ExceptionInfo->ContextRecord->FltSave.StatusWord = 0;
ExceptionInfo->ContextRecord->FltSave.MxCsr = myContext.FltSave.MxCsr;
ExceptionInfo->ContextRecord->FltSave.MxCsr_Mask = myContext.FltSave.MxCsr_Mask;
ExceptionInfo->ContextRecord->MxCsr = myContext.MxCsr;
#else
ExceptionInfo->ContextRecord->FloatSave.ControlWord = ctrlwrd;
ExceptionInfo->ContextRecord->FloatSave.StatusWord = 0;
#endif
return EXCEPTION_CONTINUE_EXECUTION;
}
int _tmain(int argc, _TCHAR* argv[])
{
double a;
double b;
double c;
double d;
double e;
/* do something so that zero can't get optimized */
if(argc > 999999){
zero = (double) argc;
}
/* Enable fp exceptions */
_controlfp_s(0, 0, _MCW_EM);
/* Setup our unhandled exception filter */
SetUnhandledExceptionFilter(myfunc);
b = 5.0+zero;
/* do something bad */
a = 5.0/zero;
c = a * b;
e = 5.0/zero;
d = 4.0 + e;
printf("a = %f\n",a);
printf("b = %f\n",b);
printf("c = %f\n",c);
printf("d = %f\n",d);
printf("e = %f\n",e);
return 0;
}
는,이 코드는 출력을 생성합니다 : 여기
은 예제 프로그램의 RTC의 비활성화와#########Caught Ya: EXCEPTION_FLT_DIVIDE_BY_ZERO
ExceptionAddr = 0x000000013F7A1638
a = 1.#INF00
b = 5.000000
c = 1.#INF00
d = 1.#INF00
e = 1.#INF00
,이 코드가 생성하는 출력 :
#########Caught Ya: EXCEPTION_FLT_DIVIDE_BY_ZERO
ExceptionAddr = 0x000000013F0415F2
#########Caught Ya: EXCEPTION_ACCESS_VIOLATION
ExceptionAddr = 0x000000007711B519
#########Caught Ya: EXCEPTION_ACCESS_VIOLATION
ExceptionAddr = 0x000000007711B519
#########Caught Ya: EXCEPTION_ACCESS_VIOLATION
ExceptionAddr = 0x000000007711B519
.... repeat forever
요약하면
x86 대상 (WIN32) : 아니오 디버그 또는 릴리스 빌드에 문제가 없습니다!
x64 대상 (WIN64) : RTC가 비활성화 된 경우에만 부동 소수점 예외로부터 복구를 시도한 후 액세스 위반이 발생합니다.
RTC가 수행하는 작업에 대한 생각과 부동 소수점 예외로부터 복구하는 동작에 영향을주는 이유는 무엇입니까?
편집 : 어셈블리에서 조금 더 디버깅했습니다. 위반은 필터 기능에서 복귀 한 후에 발생하지만 0으로 나누기 재개 전에 발생합니다. 다음은 어셈블리가 액세스 위반까지 선도 (조립의 마지막 줄은 범인입니다) :
000000007711B2EF mov dword ptr [rcx+0F0h],edi
000000007711B2F5 fxsave [rcx+100h]
000000007711B2FC movaps xmmword ptr [rcx+1A0h],xmm0
000000007711B303 movaps xmmword ptr [rcx+1B0h],xmm1
000000007711B30A movaps xmmword ptr [rcx+1C0h],xmm2
000000007711B311 movaps xmmword ptr [rcx+1D0h],xmm3
000000007711B318 movaps xmmword ptr [rcx+1E0h],xmm4
000000007711B31F movaps xmmword ptr [rcx+1F0h],xmm5
000000007711B326 movaps xmmword ptr [rcx+200h],xmm6
000000007711B32D movaps xmmword ptr [rcx+210h],xmm7
000000007711B334 movaps xmmword ptr [rcx+220h],xmm8
000000007711B33C movaps xmmword ptr [rcx+230h],xmm9
000000007711B344 movaps xmmword ptr [rcx+240h],xmm10
000000007711B34C movaps xmmword ptr [rcx+250h],xmm11
000000007711B354 movaps xmmword ptr [rcx+260h],xmm12
000000007711B35C movaps xmmword ptr [rcx+270h],xmm13
000000007711B364 movaps xmmword ptr [rcx+280h],xmm14
000000007711B36C movaps xmmword ptr [rcx+290h],xmm15
000000007711B374 stmxcsr dword ptr [rcx+34h]
000000007711B378 mov rax,qword ptr [rsp+8]
000000007711B37D mov qword ptr [rcx+0F8h],rax
000000007711B384 mov eax,dword ptr [rsp]
000000007711B387 mov dword ptr [rcx+44h],eax
000000007711B38A mov dword ptr [rcx+30h],10000Fh
000000007711B391 add rsp,8
000000007711B395 ret
000000007711B396 int 3
000000007711B397 int 3
000000007711B398 int 3
000000007711B399 int 3
000000007711B39A int 3
000000007711B39B int 3
000000007711B39C nop dword ptr [rax]
000000007711B39F push rbp
000000007711B3A0 push rsi
000000007711B3A1 push rdi
000000007711B3A2 sub rsp,30h
000000007711B3A6 mov rbp,rsp
000000007711B3A9 test rdx,rdx
000000007711B3AC je 000000007711B4E4
000000007711B3B2 cmp dword ptr [rdx],80000029h
000000007711B3B8 jne 000000007711B3C4
000000007711B3BA cmp dword ptr [rdx+18h],1
000000007711B3BE jae 000000007711B634
000000007711B3C4 cmp dword ptr [rdx],80000026h
000000007711B3CA jne 000000007711B4E4
000000007711B3D0 mov rax,qword ptr [rdx+20h]
000000007711B3D4 mov r8,qword ptr [rax+8]
000000007711B3D8 mov qword ptr [rcx+90h],r8
000000007711B3DF mov r8,qword ptr [rax+10h]
000000007711B3E3 mov qword ptr [rcx+98h],r8
000000007711B3EA mov r8,qword ptr [rax+18h]
000000007711B3EE mov qword ptr [rcx+0A0h],r8
000000007711B3F5 mov r8,qword ptr [rax+20h]
000000007711B3F9 mov qword ptr [rcx+0A8h],r8
000000007711B400 mov r8,qword ptr [rax+28h]
000000007711B404 mov qword ptr [rcx+0B0h],r8
000000007711B40B mov r8,qword ptr [rax+30h]
000000007711B40F mov qword ptr [rcx+0D8h],r8
000000007711B416 mov r8,qword ptr [rax+38h]
000000007711B41A mov qword ptr [rcx+0E0h],r8
000000007711B421 mov r8,qword ptr [rax+40h]
000000007711B425 mov qword ptr [rcx+0E8h],r8
000000007711B42C mov r8,qword ptr [rax+48h]
000000007711B430 mov qword ptr [rcx+0F0h],r8
000000007711B437 mov r8,qword ptr [rax+50h]
000000007711B43B mov qword ptr [rcx+0F8h],r8
000000007711B442 mov r8d,dword ptr [rax+58h]
000000007711B446 mov dword ptr [rcx+34h],r8d
000000007711B44A mov dword ptr [rcx+118h],r8d
000000007711B451 mov r8w,word ptr [rax+5Ch]
000000007711B456 mov word ptr [rcx+100h],r8w
000000007711B45E movaps xmm0,xmmword ptr [rax+60h]
000000007711B462 movaps xmmword ptr [rcx+200h],xmm0
000000007711B469 movaps xmm0,xmmword ptr [rax+70h]
000000007711B46D movaps xmmword ptr [rcx+210h],xmm0
000000007711B474 movaps xmm0,xmmword ptr [rax+80h]
000000007711B47B movaps xmmword ptr [rcx+220h],xmm0
000000007711B482 movaps xmm0,xmmword ptr [rax+90h]
000000007711B489 movaps xmmword ptr [rcx+230h],xmm0
000000007711B490 movaps xmm0,xmmword ptr [rax+0A0h]
000000007711B497 movaps xmmword ptr [rcx+240h],xmm0
000000007711B49E movaps xmm0,xmmword ptr [rax+0B0h]
000000007711B4A5 movaps xmmword ptr [rcx+250h],xmm0
000000007711B4AC movaps xmm0,xmmword ptr [rax+0C0h]
000000007711B4B3 movaps xmmword ptr [rcx+260h],xmm0
000000007711B4BA movaps xmm0,xmmword ptr [rax+0D0h]
000000007711B4C1 movaps xmmword ptr [rcx+270h],xmm0
000000007711B4C8 movaps xmm0,xmmword ptr [rax+0E0h]
000000007711B4CF movaps xmmword ptr [rcx+280h],xmm0
000000007711B4D6 movaps xmm0,xmmword ptr [rax+0F0h]
000000007711B4DD movaps xmmword ptr [rcx+290h],xmm0
000000007711B4E4 mov eax,dword ptr [rcx+30h]
000000007711B4E7 and eax,100040h
000000007711B4EC cmp eax,100040h
000000007711B4F1 jne 000000007711B519
000000007711B4F3 mov r8d,dword ptr [rcx+34h]
000000007711B4F7 movsxd rax,dword ptr [rcx+4E0h]
000000007711B4FE lea rbx,[rcx+2D0h]
000000007711B505 add rbx,rax
000000007711B508 xchg r8d,dword ptr [rbx+18h]
000000007711B50C mov eax,0FFFFFFFCh
000000007711B511 cdq
000000007711B512 xrstor [rbx]
000000007711B515 mov dword ptr [rbx+18h],r8d
000000007711B519 fxrstor [rcx+100h]
"RCX"의 디버거의 값은 0x30e340이며, Visual Studio에서 예외 메시지를 읽습니다 " fptest.exe에서 0x7711b519의 첫 번째 예외 : 0xC0000005 : 0xffffffffffffffff 위치를 읽는 액세스 위반. "
VS가 0xffffffffffffffff를 읽으려고한다고보고하는 이유는 무엇입니까?