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authorvanjeff <vanjeff@6f19259b-4bc3-4df7-8a09-765794883524>2008-09-25 02:29:34 +0000
committervanjeff <vanjeff@6f19259b-4bc3-4df7-8a09-765794883524>2008-09-25 02:29:34 +0000
commitd914e15e11f386c0c1751f7ea4c5871c5286eab8 (patch)
treeb555c92734dbecfab5b196add136aeaafdab258a /MdePkg/Library/BaseLib/X86Thunk.c
parent76c844dd9af3235ffab538ccf5a22a3721e83dcf (diff)
downloadedk2-platforms-d914e15e11f386c0c1751f7ea4c5871c5286eab8.tar.xz
Change name.
git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@5977 6f19259b-4bc3-4df7-8a09-765794883524
Diffstat (limited to 'MdePkg/Library/BaseLib/X86Thunk.c')
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diff --git a/MdePkg/Library/BaseLib/X86Thunk.c b/MdePkg/Library/BaseLib/X86Thunk.c
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+/** @file
+ Real Mode Thunk Functions for IA32 and X64.
+
+ Copyright (c) 2006, Intel Corporation<BR>
+ All rights reserved. This program and the accompanying materials
+ are licensed and made available under the terms and conditions of the BSD License
+ which accompanies this distribution. The full text of the license may be found at
+ http://opensource.org/licenses/bsd-license.php
+
+ THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
+ WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
+
+**/
+
+
+#include <BaseLibInternals.h>
+
+
+//
+// Byte packed structure for a segment descriptor in a GDT/LDT
+//
+typedef union {
+ struct {
+ UINT32 LimitLow:16;
+ UINT32 BaseLow:16;
+ UINT32 BaseMid:8;
+ UINT32 Type:4;
+ UINT32 S:1;
+ UINT32 DPL:2;
+ UINT32 P:1;
+ UINT32 LimitHigh:4;
+ UINT32 AVL:1;
+ UINT32 L:1;
+ UINT32 DB:1;
+ UINT32 G:1;
+ UINT32 BaseHigh:8;
+ } Bits;
+ UINT64 Uint64;
+} IA32_SEGMENT_DESCRIPTOR;
+
+extern CONST UINT8 m16Start;
+extern CONST UINT16 m16Size;
+extern CONST UINT16 mThunk16Attr;
+extern CONST UINT16 m16Gdt;
+extern CONST UINT16 m16GdtrBase;
+extern CONST UINT16 mTransition;
+
+/**
+ Invokes 16-bit code in big real mode and returns the updated register set.
+
+ This function transfers control to the 16-bit code specified by CS:EIP using
+ the stack specified by SS:ESP in RegisterSet. The updated registers are saved
+ on the real mode stack and the starting address of the save area is returned.
+
+ @param RegisterSet Values of registers before invocation of 16-bit code.
+ @param Transition Pointer to the transition code under 1MB.
+
+ @return The pointer to a IA32_REGISTER_SET structure containing the updated
+ register values.
+
+**/
+IA32_REGISTER_SET *
+EFIAPI
+InternalAsmThunk16 (
+ IN IA32_REGISTER_SET *RegisterSet,
+ IN OUT VOID *Transition
+ );
+
+/**
+ Retrieves the properties for 16-bit thunk functions.
+
+ Computes the size of the buffer and stack below 1MB required to use the
+ AsmPrepareThunk16(), AsmThunk16() and AsmPrepareAndThunk16() functions. This
+ buffer size is returned in RealModeBufferSize, and the stack size is returned
+ in ExtraStackSize. If parameters are passed to the 16-bit real mode code,
+ then the actual minimum stack size is ExtraStackSize plus the maximum number
+ of bytes that need to be passed to the 16-bit real mode code.
+
+ If RealModeBufferSize is NULL, then ASSERT().
+ If ExtraStackSize is NULL, then ASSERT().
+
+ @param RealModeBufferSize A pointer to the size of the buffer below 1MB
+ required to use the 16-bit thunk functions.
+ @param ExtraStackSize A pointer to the extra size of stack below 1MB
+ that the 16-bit thunk functions require for
+ temporary storage in the transition to and from
+ 16-bit real mode.
+
+**/
+VOID
+EFIAPI
+AsmGetThunk16Properties (
+ OUT UINT32 *RealModeBufferSize,
+ OUT UINT32 *ExtraStackSize
+ )
+{
+ ASSERT (RealModeBufferSize != NULL);
+ ASSERT (ExtraStackSize != NULL);
+
+ *RealModeBufferSize = m16Size;
+
+ //
+ // Extra 4 bytes for return address, and another 4 bytes for mode transition
+ //
+ *ExtraStackSize = sizeof (IA32_DWORD_REGS) + 8;
+}
+
+/**
+ Prepares all structures a code required to use AsmThunk16().
+
+ Prepares all structures and code required to use AsmThunk16().
+
+ If ThunkContext is NULL, then ASSERT().
+
+ @param ThunkContext A pointer to the context structure that describes the
+ 16-bit real mode code to call.
+
+**/
+VOID
+EFIAPI
+AsmPrepareThunk16 (
+ OUT THUNK_CONTEXT *ThunkContext
+ )
+{
+ IA32_SEGMENT_DESCRIPTOR *RealModeGdt;
+
+ ASSERT (ThunkContext != NULL);
+ ASSERT ((UINTN)ThunkContext->RealModeBuffer < 0x100000);
+ ASSERT (ThunkContext->RealModeBufferSize >= m16Size);
+ ASSERT ((UINTN)ThunkContext->RealModeBuffer + m16Size <= 0x100000);
+
+ CopyMem (ThunkContext->RealModeBuffer, &m16Start, m16Size);
+
+ //
+ // Point RealModeGdt to the GDT to be used in transition
+ //
+ // RealModeGdt[0]: Reserved as NULL descriptor
+ // RealModeGdt[1]: Code Segment
+ // RealModeGdt[2]: Data Segment
+ // RealModeGdt[3]: Call Gate
+ //
+ RealModeGdt = (IA32_SEGMENT_DESCRIPTOR*)(
+ (UINTN)ThunkContext->RealModeBuffer + m16Gdt);
+
+ //
+ // Update Code & Data Segment Descriptor
+ //
+ RealModeGdt[1].Bits.BaseLow =
+ (UINT32)(UINTN)ThunkContext->RealModeBuffer & ~0xf;
+ RealModeGdt[1].Bits.BaseMid =
+ (UINT32)(UINTN)ThunkContext->RealModeBuffer >> 16;
+
+ //
+ // Update transition code entry point offset
+ //
+ *(UINT32*)((UINTN)ThunkContext->RealModeBuffer + mTransition) +=
+ (UINT32)(UINTN)ThunkContext->RealModeBuffer & 0xf;
+
+ //
+ // Update Segment Limits for both Code and Data Segment Descriptors
+ //
+ if ((ThunkContext->ThunkAttributes & THUNK_ATTRIBUTE_BIG_REAL_MODE) == 0) {
+ //
+ // Set segment limits to 64KB
+ //
+ RealModeGdt[1].Bits.LimitHigh = 0;
+ RealModeGdt[1].Bits.G = 0;
+ RealModeGdt[2].Bits.LimitHigh = 0;
+ RealModeGdt[2].Bits.G = 0;
+ }
+
+ //
+ // Update GDTBASE for this thunk context
+ //
+ *(VOID**)((UINTN)ThunkContext->RealModeBuffer + m16GdtrBase) = RealModeGdt;
+
+ //
+ // Update Thunk Attributes
+ //
+ *(UINT32*)((UINTN)ThunkContext->RealModeBuffer + mThunk16Attr) =
+ ThunkContext->ThunkAttributes;
+}
+
+/**
+ Transfers control to a 16-bit real mode entry point and returns the results.
+
+ Transfers control to a 16-bit real mode entry point and returns the results.
+ AsmPrepareThunk16() must be called with ThunkContext before this function is
+ used. This function must be called with interrupts disabled.
+
+ If ThunkContext is NULL, then ASSERT().
+ If AsmPrepareThunk16() was not previously called with ThunkContext, then ASSERT().
+
+ @param ThunkContext A pointer to the context structure that describes the
+ 16-bit real mode code to call.
+
+**/
+VOID
+EFIAPI
+AsmThunk16 (
+ IN OUT THUNK_CONTEXT *ThunkContext
+ )
+{
+ IA32_REGISTER_SET *UpdatedRegs;
+
+ ASSERT (ThunkContext != NULL);
+ ASSERT ((UINTN)ThunkContext->RealModeBuffer < 0x100000);
+ ASSERT (ThunkContext->RealModeBufferSize >= m16Size);
+ ASSERT ((UINTN)ThunkContext->RealModeBuffer + m16Size <= 0x100000);
+
+ UpdatedRegs = InternalAsmThunk16 (
+ ThunkContext->RealModeState,
+ ThunkContext->RealModeBuffer
+ );
+
+ CopyMem (ThunkContext->RealModeState, UpdatedRegs, sizeof (*UpdatedRegs));
+}
+
+/**
+ Prepares all structures and code for a 16-bit real mode thunk, transfers
+ control to a 16-bit real mode entry point, and returns the results.
+
+ Prepares all structures and code for a 16-bit real mode thunk, transfers
+ control to a 16-bit real mode entry point, and returns the results. If the
+ caller only need to perform a single 16-bit real mode thunk, then this
+ service should be used. If the caller intends to make more than one 16-bit
+ real mode thunk, then it is more efficient if AsmPrepareThunk16() is called
+ once and AsmThunk16() can be called for each 16-bit real mode thunk. This
+ function must be called with interrupts disabled.
+
+ If ThunkContext is NULL, then ASSERT().
+
+ @param ThunkContext A pointer to the context structure that describes the
+ 16-bit real mode code to call.
+
+**/
+VOID
+EFIAPI
+AsmPrepareAndThunk16 (
+ IN OUT THUNK_CONTEXT *ThunkContext
+ )
+{
+ AsmPrepareThunk16 (ThunkContext);
+ AsmThunk16 (ThunkContext);
+}