XState コンテキストの操作
このドキュメントには、XState コンテキスト関数を使用してスレッドの拡張機能を取得および設定する方法を示す例が含まれています。 次の例では、FeatureId 2 (Feature Mask 4) によって定義される Intel Advanced Vector Extensions (AVX) 状態を操作します。 Intel AVX は、https://go.microsoft.com/fwlink/p/?linkid=212716 から入手できる「Intel Advanced Vector Extensions Programming Reference」(Intel Advanced Vector Extensions プログラミング リファレンス) で定義されています。
Windows 7 SP1: AVX API は、最初に Windows 7 SP1 で実装されます。 SP1 を使用する Windows 7 用 SDK がないため、使用できるヘッダーとライブラリ ファイルはありません。 このような場合、呼び出し元は、このドキュメントから必要な関数を宣言し、「Kernel32.dll」の GetModuleHandle を使用してポインターを取得し、その後に GetProcAddress を呼び出す必要があります。
#include <stdlib.h>
#include <stdio.h>
#include <tchar.h>
#include <windows.h>
#include <winerror.h>
// Windows 7 SP1 is the first version of Windows to support the AVX API.
// The value for CONTEXT_XSTATE has changed between Windows 7 and
// Windows 7 SP1 and greater.
// While the value will be correct for future SDK headers, we need to set
// this value manually when building with a Windows 7 SDK for running on
// Windows 7 SPI OS bits.
#undef CONTEXT_XSTATE
#if defined(_M_X64)
#define CONTEXT_XSTATE (0x00100040)
#else
#define CONTEXT_XSTATE (0x00010040)
#endif
// Since the AVX API is not declared in the Windows 7 SDK headers and
// since we don't have the proper libs to work with, we will declare
// the API as function pointers and get them with GetProcAddress calls
// from kernel32.dll. We also need to set some #defines.
#define XSTATE_AVX (XSTATE_GSSE)
#define XSTATE_MASK_AVX (XSTATE_MASK_GSSE)
typedef DWORD64 (WINAPI *PGETENABLEDXSTATEFEATURES)();
PGETENABLEDXSTATEFEATURES pfnGetEnabledXStateFeatures = NULL;
typedef BOOL (WINAPI *PINITIALIZECONTEXT)(PVOID Buffer, DWORD ContextFlags, PCONTEXT* Context, PDWORD ContextLength);
PINITIALIZECONTEXT pfnInitializeContext = NULL;
typedef BOOL (WINAPI *PGETXSTATEFEATURESMASK)(PCONTEXT Context, PDWORD64 FeatureMask);
PGETXSTATEFEATURESMASK pfnGetXStateFeaturesMask = NULL;
typedef PVOID (WINAPI *LOCATEXSTATEFEATURE)(PCONTEXT Context, DWORD FeatureId, PDWORD Length);
LOCATEXSTATEFEATURE pfnLocateXStateFeature = NULL;
typedef BOOL (WINAPI *SETXSTATEFEATURESMASK)(PCONTEXT Context, DWORD64 FeatureMask);
SETXSTATEFEATURESMASK pfnSetXStateFeaturesMask = NULL;
VOID
PrintThreadAvxState (
__in HANDLE hThread
)
{
PVOID Buffer;
PCONTEXT Context;
DWORD ContextSize;
DWORD64 FeatureMask;
DWORD FeatureLength;
ULONG Index;
BOOL Success;
PM128A Xmm;
PM128A Ymm;
// If this function was called before and we were not running on
// at least Windows 7 SP1, then bail.
if (pfnGetEnabledXStateFeatures == (PGETENABLEDXSTATEFEATURES)-1)
{
_tprintf(_T("This needs to run on Windows 7 SP1 or greater.\n"));
return;
}
// Get the addresses of the AVX XState functions.
if (pfnGetEnabledXStateFeatures == NULL)
{
HMODULE hm = GetModuleHandle(_T("kernel32.dll"));
if (hm == NULL)
{
pfnGetEnabledXStateFeatures = (PGETENABLEDXSTATEFEATURES)-1;
_tprintf(_T("GetModuleHandle failed (error == %d).\n"), GetLastError());
return;
}
pfnGetEnabledXStateFeatures = (PGETENABLEDXSTATEFEATURES)GetProcAddress(hm, "GetEnabledXStateFeatures");
pfnInitializeContext = (PINITIALIZECONTEXT)GetProcAddress(hm, "InitializeContext");
pfnGetXStateFeaturesMask = (PGETXSTATEFEATURESMASK)GetProcAddress(hm, "GetXStateFeaturesMask");
pfnLocateXStateFeature = (LOCATEXSTATEFEATURE)GetProcAddress(hm, "LocateXStateFeature");
pfnSetXStateFeaturesMask = (SETXSTATEFEATURESMASK)GetProcAddress(hm, "SetXStateFeaturesMask");
if (pfnGetEnabledXStateFeatures == NULL
|| pfnInitializeContext == NULL
|| pfnGetXStateFeaturesMask == NULL
|| pfnLocateXStateFeature == NULL
|| pfnSetXStateFeaturesMask == NULL)
{
pfnGetEnabledXStateFeatures = (PGETENABLEDXSTATEFEATURES)-1;
_tprintf(_T("This needs to run on Windows 7 SP1 or greater.\n"));
return;
}
}
FeatureMask = pfnGetEnabledXStateFeatures();
if ((FeatureMask & XSTATE_MASK_AVX) == 0)
{
_tprintf(_T("The AVX feature is not enabled.\n"));
return;
}
ContextSize = 0;
Success = pfnInitializeContext(NULL,
CONTEXT_ALL | CONTEXT_XSTATE,
NULL,
&ContextSize);
if ((Success == TRUE) || (GetLastError() != ERROR_INSUFFICIENT_BUFFER))
{
_tprintf(_T("Unexpected result from InitializeContext (success == %d, error == %d).\n"),
Success,
GetLastError());
}
Buffer = malloc(ContextSize);
if (Buffer == NULL)
{
_tprintf(_T("Out of memory.\n"));
return;
}
Success = pfnInitializeContext(Buffer,
CONTEXT_ALL | CONTEXT_XSTATE,
&Context,
&ContextSize);
if (Success == FALSE)
{
_tprintf(_T("InitializeContext failed (error == %d).\n"), GetLastError());
goto Cleanup;
}
Success = pfnSetXStateFeaturesMask(Context, XSTATE_MASK_AVX);
if (Success == FALSE)
{
_tprintf(_T("SetXStateFeaturesMask failed (error == %d).\n"), GetLastError());
goto Cleanup;
}
Success = GetThreadContext(hThread, Context);
// Note: Thread state may not be accurate. For best results, suspend
// the thread and use the CONTEXT_EXCEPTION_REQUEST flags prior to
// calling GetThreadContext.
if (Success == FALSE)
{
_tprintf(_T("GetThreadContext failed (error == %d).\n"), GetLastError());
goto Cleanup;
}
Success = pfnGetXStateFeaturesMask(Context, &FeatureMask);
if (Success == FALSE)
{
_tprintf(_T("GetXStateFeatureMask failed (error == %d).\n"), GetLastError());
goto Cleanup;
}
//
// The AVX feature consists of 8 (x86) or 16 (x64) 256-bit Ymm registers.
// The lower 128 bits share storage with the corresponding Xmm (SSE)
// registers and the high 128 bits are denoted by Ymm_H0 - Ymm_Hn.
//
if ((FeatureMask & XSTATE_MASK_AVX) == 0)
{
_tprintf(_T("AVX is in the INIT state (YMM_H registers are all zero).\n"));
goto Cleanup;
}
Xmm = (PM128A)pfnLocateXStateFeature(Context, XSTATE_LEGACY_SSE, &FeatureLength);
Ymm = (PM128A)pfnLocateXStateFeature(Context, XSTATE_AVX, NULL);
//
// Print values in the YMM registers.
//
for (Index = 0; Index < FeatureLength / sizeof(Xmm[0]); Index += 1)
{
_tprintf(_T("Ymm%d: %I64d %I64d %I64d %I64d\n"),
Index,
Xmm[Index].Low,
Xmm[Index].High,
Ymm[Index].Low,
Ymm[Index].High);
}
Cleanup:
free(Buffer);
return;
}
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