text: /** @file
    Specific relocation fixups for ARM architecture.
  
    Copyright (c) 2006 - 2009, Intel Corporation. All rights reserved.<BR>
    Portions copyright (c) 2008 - 2010, Apple Inc. 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 "BasePeCoffLibInternals.h"
  #include <Library/BaseLib.h>
  
  
  /**
    Pass in a pointer to an ARM MOVT or MOVW immediate instruciton and
    return the immediate data encoded in the instruction.
  
    @param  Instruction   Pointer to ARM MOVT or MOVW immediate instruction
  
    @return Immediate address encoded in the instruction
  
  **/
  UINT16
  ThumbMovtImmediateAddress (
    IN UINT16 *Instruction
    )
  {
    UINT32  Movt;
    UINT16  Address;
  
    // Thumb2 is two 16-bit instructions working together. Not a single 32-bit instruction
    // Example MOVT R0, #0 is 0x0000f2c0 or 0xf2c0 0x0000
    Movt = (*Instruction << 16) | (*(Instruction + 1));
  
    // imm16 = imm4:i:imm3:imm8
    //         imm4 -> Bit19:Bit16
    //         i    -> Bit26
    //         imm3 -> Bit14:Bit12
    //         imm8 -> Bit7:Bit0
    Address  = (UINT16)(Movt & 0x000000ff);         // imm8
    Address |= (UINT16)((Movt >> 4) &  0x0000f700); // imm4 imm3
    Address |= (((Movt & BIT26) != 0) ? BIT11 : 0); // i
    return Address;
  }
  
  
  /**
    Update an ARM MOVT or MOVW immediate instruction immediate data.
  
    @param  Instruction   Pointer to ARM MOVT or MOVW immediate instruction
    @param  Address       New addres to patch into the instruction
  **/
  VOID
  ThumbMovtImmediatePatch (
    IN OUT UINT16 *Instruction,
    IN     UINT16 Address
    )
  {
    UINT16  Patch;
  
    // First 16-bit chunk of instruciton
    Patch  = ((Address >> 12) & 0x000f);            // imm4
    Patch |= (((Address & BIT11) != 0) ? BIT10 : 0); // i
    // Mask out instruction bits and or in address
    *(Instruction) = (*Instruction & ~0x040f) | Patch;
  
    // Second 16-bit chunk of instruction
    Patch  =  Address & 0x000000ff;          // imm8
    Patch |=  ((Address << 4) & 0x00007000); // imm3
    // Mask out instruction bits and or in address
    Instruction++;
    *Instruction = (*Instruction & ~0x70ff) | Patch;
  }
  
  
  
  /**
    Pass in a pointer to an ARM MOVW/MOVT instruciton pair and
    return the immediate data encoded in the two` instruction.
  
    @param  Instructions  Pointer to ARM MOVW/MOVT insturction pair
  
    @return Immediate address encoded in the instructions
  
  **/
  UINT32
  ThumbMovwMovtImmediateAddress (
    IN UINT16 *Instructions
    )
  {
    UINT16  *Word;
    UINT16  *Top;
  
    Word = Instructions;  // MOVW
    Top  = Word + 2;      // MOVT
  
    return (ThumbMovtImmediateAddress (Top) << 16) + ThumbMovtImmediateAddress (Word);
  }
  
  
  /**
    Update an ARM MOVW/MOVT immediate instruction instruction pair.
  
    @param  Instructions  Pointer to ARM MOVW/MOVT instruction pair
    @param  Address       New addres to patch into the instructions
  **/
  VOID
  ThumbMovwMovtImmediatePatch (
    IN OUT UINT16 *Instructions,
    IN     UINT32 Address
    )
  {
    UINT16  *Word;
    UINT16  *Top;
  
    Word = Instructions;  // MOVW
    Top  = Word + 2;      // MOVT
  
    ThumbMovtImmediatePatch (Word, (UINT16)(Address & 0xffff));
    ThumbMovtImmediatePatch (Top, (UINT16)(Address >> 16));
  }
  
  
  
  /**
    Performs an ARM-based specific relocation fixup and is a no-op on other
    instruction sets.
  
    @param  Reloc       The pointer to the relocation record.
    @param  Fixup       The pointer to the address to fix up.
    @param  FixupData   The pointer to a buffer to log the fixups.
    @param  Adjust      The offset to adjust the fixup.
  
    @return Status code.
  
  **/
  RETURN_STATUS
  PeCoffLoaderRelocateImageEx (
    IN UINT16      *Reloc,
    IN OUT CHAR8   *Fixup,
    IN OUT CHAR8   **FixupData,
    IN UINT64      Adjust
    )
  {
    UINT16      *Fixup16;
    UINT32      FixupVal;
  
    Fixup16   = (UINT16 *) Fixup;
  
    switch ((*Reloc) >> 12) {
  
    case EFI_IMAGE_REL_BASED_ARM_MOV32T:
      FixupVal = ThumbMovwMovtImmediateAddress (Fixup16) + (UINT32)Adjust;
      ThumbMovwMovtImmediatePatch (Fixup16, FixupVal);
  
      if (*FixupData != NULL) {
        *FixupData = ALIGN_POINTER(*FixupData, sizeof(UINT64));
        // Fixup16 is not aligned so we must copy it. Thumb instructions are streams of 16 bytes.
        CopyMem (*FixupData, Fixup16, sizeof (UINT64));
        *FixupData = *FixupData + sizeof(UINT64);
      }
      break;
  
    case EFI_IMAGE_REL_BASED_ARM_MOV32A:
       ASSERT (FALSE);
       // break omitted - ARM instruction encoding not implemented
    default:
      return RETURN_UNSUPPORTED;
    }
  
    return RETURN_SUCCESS;
  }
  
  /**
    Returns TRUE if the machine type of PE/COFF image is supported. Supported
    does not mean the image can be executed it means the PE/COFF loader supports
    loading and relocating of the image type. It's up to the caller to support
    the entry point.
  
    @param  Machine   Machine type from the PE Header.
  
    @return TRUE if this PE/COFF loader can load the image
  
  **/
  BOOLEAN
  PeCoffLoaderImageFormatSupported (
    IN  UINT16  Machine
    )
  {
    if ((Machine == IMAGE_FILE_MACHINE_ARMTHUMB_MIXED) || (Machine ==  IMAGE_FILE_MACHINE_EBC)) {
      return TRUE;
    }
  
    return FALSE;
  }
  
  /**
    Performs an ARM-based specific re-relocation fixup and is a no-op on other
    instruction sets. This is used to re-relocated the image into the EFI virtual
    space for runtime calls.
  
    @param  Reloc       The pointer to the relocation record.
    @param  Fixup       The pointer to the address to fix up.
    @param  FixupData   The pointer to a buffer to log the fixups.
    @param  Adjust      The offset to adjust the fixup.
  
    @return Status code.
  
  **/
  RETURN_STATUS
  PeHotRelocateImageEx (
    IN UINT16      *Reloc,
    IN OUT CHAR8   *Fixup,
    IN OUT CHAR8   **FixupData,
    IN UINT64      Adjust
    )
  {
    UINT16  *Fixup16;
    UINT32  FixupVal;
  
    Fixup16 = (UINT16 *)Fixup;
  
    switch ((*Reloc) >> 12) {
  
    case EFI_IMAGE_REL_BASED_ARM_MOV32T:
      *FixupData  = ALIGN_POINTER (*FixupData, sizeof (UINT64));
      if (*(UINT64 *) (*FixupData) == ReadUnaligned64 ((UINT64 *)Fixup16)) {
        FixupVal = ThumbMovwMovtImmediateAddress (Fixup16) + (UINT32)Adjust;
        ThumbMovwMovtImmediatePatch (Fixup16, FixupVal);
      }
      break;
  
    case EFI_IMAGE_REL_BASED_ARM_MOV32A:
      ASSERT (FALSE);
      // break omitted - ARM instruction encoding not implemented
    default:
      DEBUG ((EFI_D_ERROR, "PeHotRelocateEx:unknown fixed type\n"));
      return RETURN_UNSUPPORTED;
    }
  
    return RETURN_SUCCESS;
  }
  
  