diff options
Diffstat (limited to 'Core/MdePkg/Library/BaseLib/X86Thunk.c')
| -rw-r--r-- | Core/MdePkg/Library/BaseLib/X86Thunk.c | 268 |
1 files changed, 268 insertions, 0 deletions
diff --git a/Core/MdePkg/Library/BaseLib/X86Thunk.c b/Core/MdePkg/Library/BaseLib/X86Thunk.c new file mode 100644 index 0000000000..dac1d19374 --- /dev/null +++ b/Core/MdePkg/Library/BaseLib/X86Thunk.c @@ -0,0 +1,268 @@ +/** @file
+ Real Mode Thunk Functions for IA32 and x64.
+
+ Copyright (c) 2006 - 2012, Intel Corporation. All rights reserved.<BR>
+ 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"
+
+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 The 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().
+
+ This interface is limited to be used in either physical mode or virtual modes with paging enabled where the
+ virtual to physical mappings for ThunkContext.RealModeBuffer is mapped 1:1.
+
+ 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 (
+ IN 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.
+
+ The register state from the RealModeState field of ThunkContext is restored just prior
+ to calling the 16-bit real mode entry point. This includes the EFLAGS field of RealModeState,
+ which is used to set the interrupt state when a 16-bit real mode entry point is called.
+ Control is transferred to the 16-bit real mode entry point specified by the CS and Eip fields of RealModeState.
+ The stack is initialized to the SS and ESP fields of RealModeState. Any parameters passed to
+ the 16-bit real mode code must be populated by the caller at SS:ESP prior to calling this function.
+ The 16-bit real mode entry point is invoked with a 16-bit CALL FAR instruction,
+ so when accessing stack contents, the 16-bit real mode code must account for the 16-bit segment
+ and 16-bit offset of the return address that were pushed onto the stack. The 16-bit real mode entry
+ point must exit with a RETF instruction. The register state is captured into RealModeState immediately
+ after the RETF instruction is executed.
+
+ If EFLAGS specifies interrupts enabled, or any of the 16-bit real mode code enables interrupts,
+ or any of the 16-bit real mode code makes a SW interrupt, then the caller is responsible for making sure
+ the IDT at address 0 is initialized to handle any HW or SW interrupts that may occur while in 16-bit real mode.
+
+ If EFLAGS specifies interrupts enabled, or any of the 16-bit real mode code enables interrupts,
+ then the caller is responsible for making sure the 8259 PIC is in a state compatible with 16-bit real mode.
+ This includes the base vectors, the interrupt masks, and the edge/level trigger mode.
+
+ If THUNK_ATTRIBUTE_BIG_REAL_MODE is set in the ThunkAttributes field of ThunkContext, then the user code
+ is invoked in big real mode. Otherwise, the user code is invoked in 16-bit real mode with 64KB segment limits.
+
+ If neither THUNK_ATTRIBUTE_DISABLE_A20_MASK_INT_15 nor THUNK_ATTRIBUTE_DISABLE_A20_MASK_KBD_CTRL are set in
+ ThunkAttributes, then it is assumed that the user code did not enable the A20 mask, and no attempt is made to
+ disable the A20 mask.
+
+ If THUNK_ATTRIBUTE_DISABLE_A20_MASK_INT_15 is set and THUNK_ATTRIBUTE_DISABLE_A20_MASK_KBD_CTRL is clear in
+ ThunkAttributes, then attempt to use the INT 15 service to disable the A20 mask. If this INT 15 call fails,
+ then attempt to disable the A20 mask by directly accessing the 8042 keyboard controller I/O ports.
+
+ If THUNK_ATTRIBUTE_DISABLE_A20_MASK_INT_15 is clear and THUNK_ATTRIBUTE_DISABLE_A20_MASK_KBD_CTRL is set in
+ ThunkAttributes, then attempt to disable the A20 mask by directly accessing the 8042 keyboard controller I/O ports.
+
+ If ThunkContext is NULL, then ASSERT().
+ If AsmPrepareThunk16() was not previously called with ThunkContext, then ASSERT().
+ If both THUNK_ATTRIBUTE_DISABLE_A20_MASK_INT_15 and THUNK_ATTRIBUTE_DISABLE_A20_MASK_KBD_CTRL are set in
+ ThunkAttributes, then ASSERT().
+
+ This interface is limited to be used in either physical mode or virtual modes with paging enabled where the
+ virtual to physical mappings for ThunkContext.RealModeBuffer is mapped 1:1.
+
+ @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);
+ ASSERT (((ThunkContext->ThunkAttributes & (THUNK_ATTRIBUTE_DISABLE_A20_MASK_INT_15 | THUNK_ATTRIBUTE_DISABLE_A20_MASK_KBD_CTRL)) != \
+ (THUNK_ATTRIBUTE_DISABLE_A20_MASK_INT_15 | THUNK_ATTRIBUTE_DISABLE_A20_MASK_KBD_CTRL)));
+
+ 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 interface is limited to be used in either physical mode or virtual modes with paging enabled where the
+ virtual to physical mappings for ThunkContext.RealModeBuffer is mapped 1:1.
+
+ See AsmPrepareThunk16() and AsmThunk16() for the detailed description and ASSERT() conditions.
+
+ @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);
+}
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