ebcsupport.c

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/*++

Copyright (c) 2004 - 2005, Intel Corporation                                                         
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.             

Module Name:

  EbcSupport.c

Abstract:

  This module contains EBC support routines that are customized based on
  the target processor.

--*/

#include "Tiano.h"
#include "EfiDriverLib.h"

//
// To support the EFI debug support protocol
//
#include EFI_PROTOCOL_DEFINITION (Ebc)
#include EFI_PROTOCOL_DEFINITION (DebugSupport)

#include "EbcInt.h"
#include "EbcExecute.h"

#define VM_STACK_SIZE   (1024 * 32)

#define EBC_THUNK_SIZE  128

//
// For code execution, thunks must be aligned on 16-byte boundary
//
#define EBC_THUNK_ALIGNMENT 16

//
// Per the IA-64 Software Conventions and Runtime Architecture Guide,
// section 3.3.4, IPF stack must always be 16-byte aligned.
//
#define IPF_STACK_ALIGNMENT 16

//
// Opcodes for IPF instructions. We'll need to hand-create thunk code (stuffing
// bits) to insert a jump to the interpreter.
//
#define OPCODE_NOP              (UINT64) 0x00008000000
#define OPCODE_BR_COND_SPTK_FEW (UINT64) 0x00100000000
#define OPCODE_MOV_BX_RX        (UINT64) 0x00E00100000

//
// Opcode for MOVL instruction
//
#define MOVL_OPCODE 0x06

VOID
EbcAsmLLCALLEX (
  IN UINTN    CallAddr,
  IN UINTN    EbcSp
  );

STATIC
EFI_STATUS
WriteBundle (
  IN    VOID    *MemPtr,
  IN    UINT8   Template,
  IN    UINT64  Slot0,
  IN    UINT64  Slot1,
  IN    UINT64  Slot2
  );

STATIC
VOID
PushU64 (
  VM_CONTEXT *VmPtr,
  UINT64     Arg
  )
{
  //
  // Advance the VM stack down, and then copy the argument to the stack.
  // Hope it's aligned.
  //
  VmPtr->R[0] -= sizeof (UINT64);
  *(UINT64 *) VmPtr->R[0] = Arg;
}

UINT64
EbcInterpret (
  UINT64      Arg1,
  ...
  )
{
  //
  // Create a new VM context on the stack
  //
  VM_CONTEXT  VmContext;
  UINTN       Addr;
  VA_LIST     List;
  UINT64      Arg2;
  UINT64      Arg3;
  UINT64      Arg4;
  UINT64      Arg5;
  UINT64      Arg6;
  UINT64      Arg7;
  UINT64      Arg8;
  UINTN       Arg9Addr;
  //
  // Get the EBC entry point from the processor register. Make sure you don't
  // call any functions before this or you could mess up the register the
  // entry point is passed in.
  //
  Addr = EbcLLGetEbcEntryPoint ();
  //
  // Need the args off the stack.
  //
  VA_START (List, Arg1);
  Arg2      = VA_ARG (List, UINT64);
  Arg3      = VA_ARG (List, UINT64);
  Arg4      = VA_ARG (List, UINT64);
  Arg5      = VA_ARG (List, UINT64);
  Arg6      = VA_ARG (List, UINT64);
  Arg7      = VA_ARG (List, UINT64);
  Arg8      = VA_ARG (List, UINT64);
  Arg9Addr  = (UINTN) List;
  //
  // Now clear out our context
  //
  EfiZeroMem ((VOID *) &VmContext, sizeof (VM_CONTEXT));
  //
  // Set the VM instruction pointer to the correct location in memory.
  //
  VmContext.Ip = (VMIP) Addr;
  //
  // Initialize the stack pointer for the EBC. Get the current system stack
  // pointer and adjust it down by the max needed for the interpreter.
  //
  Addr = (UINTN) Arg9Addr;
  //
  // NOTE: Eventually we should have the interpreter allocate memory
  //       for stack space which it will use during its execution. This
  //       would likely improve performance because the interpreter would
  //       no longer be required to test each memory access and adjust
  //       those reading from the stack gap.
  //
  // For IPF, the stack looks like (assuming 10 args passed)
  //   arg10
  //   arg9       (Bottom of high stack)
  //   [ stack gap for interpreter execution ]
  //   [ magic value for detection of stack corruption ]
  //   arg8       (Top of low stack)
  //   arg7....
  //   arg1
  //   [ 64-bit return address ]
  //   [ ebc stack ]
  // If the EBC accesses memory in the stack gap, then we assume that it's
  // actually trying to access args9 and greater. Therefore we need to
  // adjust memory accesses in this region to point above the stack gap.
  //
  VmContext.HighStackBottom = (UINTN) Addr;
  //
  // Now adjust the EBC stack pointer down to leave a gap for interpreter
  // execution. Then stuff a magic value there.
  //
  VmContext.R[0] = (UINT64) Addr;
  VmContext.R[0] -= VM_STACK_SIZE;
  PushU64 (&VmContext, (UINT64) VM_STACK_KEY_VALUE);
  VmContext.StackMagicPtr = (UINTN *) VmContext.R[0];
  VmContext.LowStackTop   = (UINTN) VmContext.R[0];
  //
  // Push the EBC arguments on the stack. Does not matter that they may not
  // all be valid.
  //
  PushU64 (&VmContext, Arg8);
  PushU64 (&VmContext, Arg7);
  PushU64 (&VmContext, Arg6);
  PushU64 (&VmContext, Arg5);
  PushU64 (&VmContext, Arg4);
  PushU64 (&VmContext, Arg3);
  PushU64 (&VmContext, Arg2);
  PushU64 (&VmContext, Arg1);
  //
  // Push a bogus return address on the EBC stack because the
  // interpreter expects one there. For stack alignment purposes on IPF,
  // EBC return addresses are always 16 bytes. Push a bogus value as well.
  //
  PushU64 (&VmContext, 0);
  PushU64 (&VmContext, 0xDEADBEEFDEADBEEF);
  VmContext.StackRetAddr = (UINT64) VmContext.R[0];
  //
  // Begin executing the EBC code
  //
  EbcExecute (&VmContext);
  //
  // Return the value in R[7] unless there was an error
  //
  return (UINT64) VmContext.R[7];
}

UINT64
ExecuteEbcImageEntryPoint (
  IN EFI_HANDLE           ImageHandle,
  IN EFI_SYSTEM_TABLE     *SystemTable
  )
/*++

Routine Description:

  IPF implementation.

  Begin executing an EBC image. The address of the entry point is passed
  in via a processor register, so we'll need to make a call to get the
  value.
  
Arguments:

  ImageHandle   - image handle for the EBC application we're executing
  SystemTable   - standard system table passed into an driver's entry point

Returns:

  The value returned by the EBC application we're going to run.

--*/
{
  //
  // Create a new VM context on the stack
  //
  VM_CONTEXT  VmContext;
  UINTN       Addr;

  //
  // Get the EBC entry point from the processor register. Make sure you don't
  // call any functions before this or you could mess up the register the
  // entry point is passed in.
  //
  Addr = EbcLLGetEbcEntryPoint ();

  //
  // Now clear out our context
  //
  EfiZeroMem ((VOID *) &VmContext, sizeof (VM_CONTEXT));

  //
  // Save the image handle so we can track the thunks created for this image
  //
  VmContext.ImageHandle = ImageHandle;
  VmContext.SystemTable = SystemTable;

  //
  // Set the VM instruction pointer to the correct location in memory.
  //
  VmContext.Ip = (VMIP) Addr;

  //
  // Get the stack pointer. This is the bottom of the upper stack.
  //
  Addr                      = EbcLLGetStackPointer ();
  VmContext.HighStackBottom = (UINTN) Addr;
  VmContext.R[0]            = (INT64) Addr;

  //
  // Allocate stack space for the interpreter. Then put a magic value
  // at the bottom so we can detect stack corruption.
  //
  VmContext.R[0] -= VM_STACK_SIZE;
  PushU64 (&VmContext, (UINT64) VM_STACK_KEY_VALUE);
  VmContext.StackMagicPtr = (UINTN *) (UINTN) VmContext.R[0];

  //
  // When we thunk to external native code, we copy the last 8 qwords from
  // the EBC stack into the processor registers, and adjust the stack pointer
  // up. If the caller is not passing 8 parameters, then we've moved the
  // stack pointer up into the stack gap. If this happens, then the caller
  // can mess up the stack gap contents (in particular our magic value).
  // Therefore, leave another gap below the magic value. Pick 10 qwords down,
  // just as a starting point.
  //
  VmContext.R[0] -= 10 * sizeof (UINT64);

  //
  // Align the stack pointer such that after pushing the system table,
  // image handle, and return address on the stack, it's aligned on a 16-byte
  // boundary as required for IPF.
  //
  VmContext.R[0] &= (INT64)~0x0f;
  VmContext.LowStackTop = (UINTN) VmContext.R[0];
  //
  // Simply copy the image handle and system table onto the EBC stack.
  // Greatly simplifies things by not having to spill the args
  //
  PushU64 (&VmContext, (UINT64) SystemTable);
  PushU64 (&VmContext, (UINT64) ImageHandle);

  //
  // Interpreter assumes 64-bit return address is pushed on the stack.
  // IPF does not do this so pad the stack accordingly. Also, a
  // "return address" is 16 bytes as required for IPF stack alignments.
  //
  PushU64 (&VmContext, (UINT64) 0);
  PushU64 (&VmContext, (UINT64) 0x1234567887654321);
  VmContext.StackRetAddr = (UINT64) VmContext.R[0];

  //
  // Begin executing the EBC code
  //
  EbcExecute (&VmContext);

  //
  // Return the value in R[7] unless there was an error
  //
  return (UINT64) VmContext.R[7];
}

EFI_STATUS
EbcCreateThunks (
  IN EFI_HANDLE   ImageHandle,
  IN VOID         *EbcEntryPoint,
  OUT VOID        **Thunk,
  IN  UINT32      Flags
  )
/*++

Routine Description:

  Create thunks for an EBC image entry point, or an EBC protocol service.
  
Arguments:

  ImageHandle     - Image handle for the EBC image. If not null, then we're
                    creating a thunk for an image entry point.
  EbcEntryPoint   - Address of the EBC code that the thunk is to call
  Thunk           - Returned thunk we create here
  Flags           - Flags indicating options for creating the thunk
  
Returns:

  Standard EFI status.
  
--*/
{
  UINT8       *Ptr;
  UINT8       *ThunkBase;
  UINT64      Addr;
  UINT64        Code[3];    // Code in a bundle
  UINT64        RegNum;     // register number for MOVL
  UINT64        I;          // bits of MOVL immediate data
  UINT64        Ic;         // bits of MOVL immediate data
  UINT64        Imm5c;      // bits of MOVL immediate data
  UINT64        Imm9d;      // bits of MOVL immediate data
  UINT64        Imm7b;      // bits of MOVL immediate data
  UINT64        Br;         // branch register for loading and jumping
  UINT64      *Data64Ptr;
  UINT32      ThunkSize;
  UINT32      Size;
  EFI_STATUS  Status;

  //
  // Check alignment of pointer to EBC code, which must always be aligned
  // on a 2-byte boundary.
  //
  if ((UINT32) (UINTN) EbcEntryPoint & 0x01) {
    return EFI_INVALID_PARAMETER;
  }
  //
  // Allocate memory for the thunk. Make the (most likely incorrect) assumption
  // that the returned buffer is not aligned, so round up to the next
  // alignment size.
  //
  Size      = EBC_THUNK_SIZE + EBC_THUNK_ALIGNMENT - 1;
  ThunkSize = Size;
  Status = gBS->AllocatePool (
                  EfiBootServicesData,
                  Size,
                  (VOID *) &Ptr
                  );
  if (Status != EFI_SUCCESS) {
    return EFI_OUT_OF_RESOURCES;
  }
  //
  // Save the start address of the buffer.
  //
  ThunkBase = Ptr;

  //
  // Make sure it's aligned for code execution. If not, then
  // round up.
  //
  if ((UINT32) (UINTN) Ptr & (EBC_THUNK_ALIGNMENT - 1)) {
    Ptr = (UINT8 *) (((UINTN) Ptr + (EBC_THUNK_ALIGNMENT - 1)) &~ (UINT64) (EBC_THUNK_ALIGNMENT - 1));
  }
  //
  // Return the pointer to the thunk to the caller to user as the
  // image entry point.
  //
  *Thunk = (VOID *) Ptr;

  //
  // Clear out the thunk entry
  // EfiZeroMem(Ptr, Size);
  //
  // For IPF, when you do a call via a function pointer, the function pointer
  // actually points to a function descriptor which consists of a 64-bit
  // address of the function, followed by a 64-bit gp for the function being
  // called. See the the Software Conventions and Runtime Architecture Guide
  // for details.
  // So first off in our thunk, create a descriptor for our actual thunk code.
  // This means we need to create a pointer to the thunk code (which follows
  // the descriptor we're going to create), followed by the gp of the Vm
  // interpret function we're going to eventually execute.
  //
  Data64Ptr = (UINT64 *) Ptr;

  //
  // Write the function's entry point (which is our thunk code that follows
  // this descriptor we're creating).
  //
  *Data64Ptr = (UINT64) (Data64Ptr + 2);
  //
  // Get the gp from the descriptor for EbcInterpret and stuff it in our thunk
  // descriptor.
  //
  *(Data64Ptr + 1) = *(UINT64 *) ((UINT64 *) (UINTN) EbcInterpret + 1);
  //
  // Advance our thunk data pointer past the descriptor. Since the
  // descriptor consists of 16 bytes, the pointer is still aligned for
  // IPF code execution (on 16-byte boundary).
  //
  Ptr += sizeof (UINT64) * 2;

  //
  // *************************** MAGIC BUNDLE ********************************
  //
  // Write magic code bundle for: movl r8 = 0xca112ebcca112ebc to help the VM
  // to recognize it is a thunk.
  //
  Addr = (UINT64) 0xCA112EBCCA112EBC;

  //
  // Now generate the code bytes. First is nop.m 0x0
  //
  Code[0] = OPCODE_NOP;

  //
  // Next is simply Addr[62:22] (41 bits) of the address
  //
  Code[1] = RightShiftU64 (Addr, 22) & 0x1ffffffffff;

  //
  // Extract bits from the address for insertion into the instruction
  // i = Addr[63:63]
  //