system76-edk2/MdeModulePkg/Universal/CapsulePei/X64/X64Entry.c

/** @file
  The X64 entrypoint is used to process capsule in long mode.

Copyright (c) 2011 - 2015, 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 <Library/DebugLib.h>
#include <Library/BaseMemoryLib.h>
#include <Library/CpuExceptionHandlerLib.h>
#include <Library/DebugAgentLib.h>
#include "CommonHeader.h"

#define EXCEPTION_VECTOR_NUMBER     0x22

#define IA32_PG_P                   BIT0
#define IA32_PG_RW                  BIT1
#define IA32_PG_PS                  BIT7

typedef struct _PAGE_FAULT_CONTEXT {
  BOOLEAN                       Page1GSupport;
  UINT64                        PhyMask;
  UINTN                         PageFaultBuffer;
  UINTN                         PageFaultIndex;
  //
  // Store the uplink information for each page being used.
  //
  UINT64                        *PageFaultUplink[EXTRA_PAGE_TABLE_PAGES];
  VOID                          *OriginalHandler;
} PAGE_FAULT_CONTEXT;

typedef struct _PAGE_FAULT_IDT_TABLE {
  PAGE_FAULT_CONTEXT            PageFaultContext;
  IA32_IDT_GATE_DESCRIPTOR      IdtEntryTable[EXCEPTION_VECTOR_NUMBER];
} PAGE_FAULT_IDT_TABLE;

/**
  Page fault handler.

**/
VOID
EFIAPI
PageFaultHandlerHook (
  VOID
  );

/**
  Hook IDT with our page fault handler so that the on-demand paging works on page fault.

  @param[in, out] IdtEntry          Pointer to IDT entry.
  @param[in, out] PageFaultContext  Pointer to page fault context.

**/
VOID
HookPageFaultHandler (
  IN OUT IA32_IDT_GATE_DESCRIPTOR   *IdtEntry,
  IN OUT PAGE_FAULT_CONTEXT         *PageFaultContext
  )
{
  UINT32            RegEax;
  UINT8             PhysicalAddressBits;
  UINTN             PageFaultHandlerHookAddress;

  AsmCpuid (0x80000000, &RegEax, NULL, NULL, NULL);
  if (RegEax >= 0x80000008) {
    AsmCpuid (0x80000008, &RegEax, NULL, NULL, NULL);
    PhysicalAddressBits = (UINT8) RegEax;
  } else {
    PhysicalAddressBits = 36;
  }
  PageFaultContext->PhyMask = LShiftU64 (1, PhysicalAddressBits) - 1;
  PageFaultContext->PhyMask &= (1ull << 48) - SIZE_4KB;

  //
  // Set Page Fault entry to catch >4G access
  //
  PageFaultHandlerHookAddress       = (UINTN)PageFaultHandlerHook;
  PageFaultContext->OriginalHandler = (VOID *)(UINTN)(LShiftU64 (IdtEntry->Bits.OffsetUpper, 32) + IdtEntry->Bits.OffsetLow + (IdtEntry->Bits.OffsetHigh << 16));
  IdtEntry->Bits.OffsetLow          = (UINT16)PageFaultHandlerHookAddress;
  IdtEntry->Bits.Selector           = (UINT16)AsmReadCs ();
  IdtEntry->Bits.Reserved_0         = 0;
  IdtEntry->Bits.GateType           = IA32_IDT_GATE_TYPE_INTERRUPT_32;
  IdtEntry->Bits.OffsetHigh         = (UINT16)(PageFaultHandlerHookAddress >> 16);
  IdtEntry->Bits.OffsetUpper        = (UINT32)(PageFaultHandlerHookAddress >> 32);
  IdtEntry->Bits.Reserved_1         = 0;

  if (PageFaultContext->Page1GSupport) {
    PageFaultContext->PageFaultBuffer = (UINTN)(AsmReadCr3 () & PageFaultContext->PhyMask) + EFI_PAGES_TO_SIZE(2);
  }else {
    PageFaultContext->PageFaultBuffer = (UINTN)(AsmReadCr3 () & PageFaultContext->PhyMask) + EFI_PAGES_TO_SIZE(6);
  }
  PageFaultContext->PageFaultIndex = 0;
  ZeroMem (PageFaultContext->PageFaultUplink, sizeof (PageFaultContext->PageFaultUplink));
}

/**
  Acquire page for page fault.

  @param[in, out] PageFaultContext  Pointer to page fault context.
  @param[in, out] Uplink            Pointer to up page table entry.

**/
VOID
AcquirePage (
  IN OUT PAGE_FAULT_CONTEXT     *PageFaultContext,
  IN OUT UINT64                 *Uplink
  )
{
  UINTN             Address;

  Address = PageFaultContext->PageFaultBuffer + EFI_PAGES_TO_SIZE (PageFaultContext->PageFaultIndex);
  ZeroMem ((VOID *) Address, EFI_PAGES_TO_SIZE (1));

  //
  // Cut the previous uplink if it exists and wasn't overwritten.
  //
  if ((PageFaultContext->PageFaultUplink[PageFaultContext->PageFaultIndex] != NULL) && ((*PageFaultContext->PageFaultUplink[PageFaultContext->PageFaultIndex] & PageFaultContext->PhyMask) == Address)) {
    *PageFaultContext->PageFaultUplink[PageFaultContext->PageFaultIndex] = 0;
  }

  //
  // Link & Record the current uplink.
  //
  *Uplink = Address | IA32_PG_P | IA32_PG_RW;
  PageFaultContext->PageFaultUplink[PageFaultContext->PageFaultIndex] = Uplink;

  PageFaultContext->PageFaultIndex = (PageFaultContext->PageFaultIndex + 1) % EXTRA_PAGE_TABLE_PAGES;
}

/**
  The page fault handler that on-demand read >4G memory/MMIO.

  @retval NULL              The page fault is correctly handled.
  @retval OriginalHandler   The page fault is not handled and is passed through to original handler.

**/
VOID *
EFIAPI
PageFaultHandler (
  VOID
  )
{
  IA32_DESCRIPTOR           Idtr;
  PAGE_FAULT_CONTEXT        *PageFaultContext;
  UINT64                    PhyMask;
  UINT64                    *PageTable;
  UINT64                    PFAddress;
  UINTN                     PTIndex;

  //
  // Get the IDT Descriptor.
  //
  AsmReadIdtr ((IA32_DESCRIPTOR *) &Idtr); 
  //
  // Then get page fault context by IDT Descriptor.
  //
  PageFaultContext = (PAGE_FAULT_CONTEXT *) (UINTN) (Idtr.Base - sizeof (PAGE_FAULT_CONTEXT));
  PhyMask = PageFaultContext->PhyMask;

  PFAddress = AsmReadCr2 ();
  DEBUG ((EFI_D_ERROR, "CapsuleX64 - PageFaultHandler: Cr2 - %lx\n", PFAddress));

  if (PFAddress >= PhyMask + SIZE_4KB) {
    return PageFaultContext->OriginalHandler;
  }
  PFAddress &= PhyMask;

  PageTable = (UINT64*)(UINTN)(AsmReadCr3 () & PhyMask);

  PTIndex = BitFieldRead64 (PFAddress, 39, 47);
  // PML4E
  if ((PageTable[PTIndex] & IA32_PG_P) == 0) {
    AcquirePage (PageFaultContext, &PageTable[PTIndex]);
  }
  PageTable = (UINT64*)(UINTN)(PageTable[PTIndex] & PhyMask);
  PTIndex = BitFieldRead64 (PFAddress, 30, 38);
  // PDPTE
  if (PageFaultContext->Page1GSupport) {
    PageTable[PTIndex] = (PFAddress & ~((1ull << 30) - 1)) | IA32_PG_P | IA32_PG_RW | IA32_PG_PS;
  } else {
    if ((PageTable[PTIndex] & IA32_PG_P) == 0) {
      AcquirePage (PageFaultContext, &PageTable[PTIndex]);
    }
    PageTable = (UINT64*)(UINTN)(PageTable[PTIndex] & PhyMask);
    PTIndex = BitFieldRead64 (PFAddress, 21, 29);
    // PD
    PageTable[PTIndex] = (PFAddress & ~((1ull << 21) - 1)) | IA32_PG_P | IA32_PG_RW | IA32_PG_PS;
  }

  return NULL;
}


/**
  The X64 entrypoint is used to process capsule in long mode then
  return to 32-bit protected mode.

  @param  EntrypointContext   Pointer to the context of long mode.
  @param  ReturnContext       Pointer to the context of 32-bit protected mode.

  @retval This function should never return actually.

**/
EFI_STATUS
EFIAPI
_ModuleEntryPoint (
  SWITCH_32_TO_64_CONTEXT       *EntrypointContext,
  SWITCH_64_TO_32_CONTEXT       *ReturnContext
)
{
  EFI_STATUS                    Status;
  IA32_DESCRIPTOR               Ia32Idtr;
  IA32_DESCRIPTOR               X64Idtr;
  PAGE_FAULT_IDT_TABLE          PageFaultIdtTable;
  IA32_IDT_GATE_DESCRIPTOR      *IdtEntry;

  //
  // Save the IA32 IDT Descriptor
  //
  AsmReadIdtr ((IA32_DESCRIPTOR *) &Ia32Idtr); 

  //
  // Setup X64 IDT table
  //
  ZeroMem (PageFaultIdtTable.IdtEntryTable, sizeof (IA32_IDT_GATE_DESCRIPTOR) * EXCEPTION_VECTOR_NUMBER);
  X64Idtr.Base = (UINTN) PageFaultIdtTable.IdtEntryTable;
  X64Idtr.Limit = (UINT16) (sizeof (IA32_IDT_GATE_DESCRIPTOR) * EXCEPTION_VECTOR_NUMBER - 1);
  AsmWriteIdtr ((IA32_DESCRIPTOR *) &X64Idtr);  

  //
  // Setup the default CPU exception handlers
  //
  Status = InitializeCpuExceptionHandlers (NULL);
  ASSERT_EFI_ERROR (Status);

  //
  // Hook page fault handler to handle >4G request.
  //
  PageFaultIdtTable.PageFaultContext.Page1GSupport = EntrypointContext->Page1GSupport;
  IdtEntry = (IA32_IDT_GATE_DESCRIPTOR *) (X64Idtr.Base + (14 * sizeof (IA32_IDT_GATE_DESCRIPTOR)));
  HookPageFaultHandler (IdtEntry, &(PageFaultIdtTable.PageFaultContext));

  //
  // Initialize Debug Agent to support source level debug
  //
  InitializeDebugAgent (DEBUG_AGENT_INIT_THUNK_PEI_IA32TOX64, (VOID *) &Ia32Idtr, NULL);

  //
  // Call CapsuleDataCoalesce to process capsule.
  //
  Status = CapsuleDataCoalesce (
             NULL,
             (EFI_PHYSICAL_ADDRESS *) (UINTN) EntrypointContext->BlockListAddr,
             (VOID **) (UINTN) EntrypointContext->MemoryBase64Ptr,
             (UINTN *) (UINTN) EntrypointContext->MemorySize64Ptr
             );
  
  ReturnContext->ReturnStatus = Status;

  //
  // Disable interrupt of Debug timer, since the new IDT table cannot work in long mode
  //
  SaveAndSetDebugTimerInterrupt (FALSE);
  //
  // Restore IA32 IDT table
  //
  AsmWriteIdtr ((IA32_DESCRIPTOR *) &Ia32Idtr);  
  
  //
  // Finish to coalesce capsule, and return to 32-bit mode.
  //
  AsmDisablePaging64 (
    ReturnContext->ReturnCs,
    (UINT32) ReturnContext->ReturnEntryPoint,
    (UINT32) (UINTN) EntrypointContext,
    (UINT32) (UINTN) ReturnContext,
    (UINT32) (EntrypointContext->StackBufferBase + EntrypointContext->StackBufferLength)
    );  
  
  //
  // Should never be here.
  //
  ASSERT (FALSE);
  return EFI_SUCCESS;
}