On 22 February 2018 at 16:28, Ard Biesheuvel <ard.biesheu...@linaro.org> wrote:
> Introduce a variant of BaseDebugLibSerialPort that behaves correctly with
> regards to the use of the serial port after ExitBootServices(). Also, it
> caches PCD values in the constructor so that no calls into PcdLib are
> made at runtime.
>

Actually (and perhaps this is what Mike was trying to point out to
me), the PCDs in question only exist as fixed or patchable in the
first place, so caching them is pointless. I will respin with that
part removed.


> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Ard Biesheuvel <ard.biesheu...@linaro.org>
> ---
>  MdePkg/Library/DxeRuntimeDebugLibSerialPort/DebugLib.c                       
> | 373 ++++++++++++++++++++
>  MdePkg/Library/DxeRuntimeDebugLibSerialPort/DxeRuntimeDebugLibSerialPort.inf 
> |  56 +++
>  MdePkg/Library/DxeRuntimeDebugLibSerialPort/DxeRuntimeDebugLibSerialPort.uni 
> |  21 ++
>  3 files changed, 450 insertions(+)
>
> diff --git a/MdePkg/Library/DxeRuntimeDebugLibSerialPort/DebugLib.c 
> b/MdePkg/Library/DxeRuntimeDebugLibSerialPort/DebugLib.c
> new file mode 100644
> index 000000000000..8579469029a1
> --- /dev/null
> +++ b/MdePkg/Library/DxeRuntimeDebugLibSerialPort/DebugLib.c
> @@ -0,0 +1,373 @@
> +/** @file
> +  DXE runtime Debug library instance based on Serial Port library.
> +  It takes care not to call into SerialPortLib or PcdLib after
> +  ExitBootServices() has been called, to prevent touching hardware that is
> +  no longer owned by the firmware, or invoking protocols that are not safe
> +  for runtime (such as gEfiPcdProtocolGuid)
> +
> +  Copyright (c) 2006 - 2011, Intel Corporation. All rights reserved.<BR>
> +  Copyright (c) 2018, Linaro, Ltd. 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 <Base.h>
> +#include <Library/DebugLib.h>
> +#include <Library/DebugPrintErrorLevelLib.h>
> +#include <Library/BaseLib.h>
> +#include <Library/PrintLib.h>
> +#include <Library/PcdLib.h>
> +#include <Library/BaseMemoryLib.h>
> +#include <Library/SerialPortLib.h>
> +
> +STATIC EFI_EVENT      mEfiExitBootServicesEvent;
> +STATIC BOOLEAN        mEfiAtRuntime;
> +
> +STATIC UINT8          mDebugClearMemoryValue;
> +STATIC UINT8          mDebugPropertyMask;
> +STATIC UINT32         mFixedDebugPrintErrorLevel;
> +
> +//
> +// Define the maximum debug and assert message length that this library 
> supports
> +//
> +#define MAX_DEBUG_MESSAGE_LENGTH  0x100
> +
> +/**
> +  Set AtRuntime flag as TRUE after ExitBootServices.
> +
> +  @param[in]  Event   The Event that is being processed.
> +  @param[in]  Context The Event Context.
> +
> +**/
> +STATIC
> +VOID
> +EFIAPI
> +ExitBootServicesEvent (
> +  IN EFI_EVENT        Event,
> +  IN VOID             *Context
> +  )
> +{
> +  mEfiAtRuntime = TRUE;
> +}
> +
> +/**
> +  The constructor function to initialize the Serial Port library and
> +  register a callback for the ExitBootServices event.
> +
> +  @param[in]  ImageHandle   The firmware allocated handle for the EFI image.
> +  @param[in]  SystemTable   A pointer to the EFI System Table.
> +
> +  @retval EFI_SUCCESS   The operation completed successfully.
> +  @retval other         Either the serial port failed to initialize or the
> +                        ExitBootServices event callback registration failed.
> +**/
> +EFI_STATUS
> +EFIAPI
> +DxeRuntimeDebugLibSerialPortConstructor (
> +  IN EFI_HANDLE        ImageHandle,
> +  IN EFI_SYSTEM_TABLE  *SystemTable
> +  )
> +{
> +  EFI_STATUS    Status;
> +
> +  mDebugClearMemoryValue      = PcdGet8 (PcdDebugClearMemoryValue);
> +  mDebugPropertyMask          = PcdGet8 (PcdDebugPropertyMask);
> +  mFixedDebugPrintErrorLevel  = PcdGet32 (PcdFixedDebugPrintErrorLevel);
> +
> +  Status = SerialPortInitialize ();
> +  if (EFI_ERROR (Status)) {
> +    return Status;
> +  }
> +
> +  return SystemTable->BootServices->CreateEventEx (EVT_NOTIFY_SIGNAL,
> +                                      TPL_NOTIFY, ExitBootServicesEvent, 
> NULL,
> +                                      &gEfiEventExitBootServicesGuid,
> +                                      &mEfiExitBootServicesEvent);
> +}
> +
> +/**
> +  If a runtime driver exits with an error, it must call this routine
> +  to free the allocated resource before the exiting.
> +
> +  @param[in]  ImageHandle   The firmware allocated handle for the EFI image.
> +  @param[in]  SystemTable   A pointer to the EFI System Table.
> +
> +  @retval     EFI_SUCCESS       The Runtime Driver Lib shutdown successfully.
> +  @retval     EFI_UNSUPPORTED   Runtime Driver lib was not initialized.
> +**/
> +EFI_STATUS
> +EFIAPI
> +DxeRuntimeDebugLibSerialPortDestructor (
> +  IN EFI_HANDLE        ImageHandle,
> +  IN EFI_SYSTEM_TABLE  *SystemTable
> +  )
> +{
> +  return SystemTable->BootServices->CloseEvent (mEfiExitBootServicesEvent);
> +}
> +
> +/**
> +  Prints a debug message to the debug output device if the specified error 
> level
> +  is enabled.
> +
> +  If any bit in ErrorLevel is also set in DebugPrintErrorLevelLib function
> +  GetDebugPrintErrorLevel (), then print the message specified by Format and 
> the
> +  associated variable argument list to the debug output device.
> +
> +  If Format is NULL, then ASSERT().
> +
> +  @param  ErrorLevel  The error level of the debug message.
> +  @param  Format      Format string for the debug message to print.
> +  @param  ...         Variable argument list whose contents are accessed
> +                      based on the format string specified by Format.
> +
> +**/
> +VOID
> +EFIAPI
> +DebugPrint (
> +  IN  UINTN        ErrorLevel,
> +  IN  CONST CHAR8  *Format,
> +  ...
> +  )
> +{
> +  CHAR8    Buffer[MAX_DEBUG_MESSAGE_LENGTH];
> +  VA_LIST  Marker;
> +
> +  if (mEfiAtRuntime) {
> +    return;
> +  }
> +
> +  ASSERT (Format != NULL);
> +
> +  //
> +  // Check driver debug mask value and global mask
> +  //
> +  if ((ErrorLevel & GetDebugPrintErrorLevel ()) == 0) {
> +    return;
> +  }
> +
> +  //
> +  // Convert the DEBUG() message to an ASCII String
> +  //
> +  VA_START (Marker, Format);
> +  AsciiVSPrint (Buffer, sizeof (Buffer), Format, Marker);
> +  VA_END (Marker);
> +
> +  //
> +  // Send the print string to a Serial Port
> +  //
> +  SerialPortWrite ((UINT8 *)Buffer, AsciiStrLen (Buffer));
> +}
> +
> +
> +/**
> +  Prints an assert message containing a filename, line number, and 
> description.
> +  This may be followed by a breakpoint or a dead loop.
> +
> +  Print a message of the form "ASSERT <FileName>(<LineNumber>): 
> <Description>\n"
> +  to the debug output device.  If DEBUG_PROPERTY_ASSERT_BREAKPOINT_ENABLED 
> bit
> +  of PcdDebugProperyMask is set then CpuBreakpoint() is called. Otherwise, if
> +  DEBUG_PROPERTY_ASSERT_DEADLOOP_ENABLED bit of PcdDebugProperyMask is set 
> then
> +  CpuDeadLoop() is called.  If neither of these bits are set, then this 
> function
> +  returns immediately after the message is printed to the debug output 
> device.
> +  DebugAssert() must actively prevent recursion.  If DebugAssert() is called
> +  while processing another DebugAssert(), then DebugAssert() must return
> +  immediately.
> +
> +  If FileName is NULL, then a <FileName> string of "(NULL) Filename" is 
> printed.
> +  If Description is NULL, then a <Description> string of "(NULL) 
> Description" is
> +  printed.
> +
> +  @param  FileName     The pointer to the name of the source file that 
> generated
> +                       the assert condition.
> +  @param  LineNumber   The line number in the source file that generated the
> +                       assert condition
> +  @param  Description  The pointer to the description of the assert 
> condition.
> +
> +**/
> +VOID
> +EFIAPI
> +DebugAssert (
> +  IN CONST CHAR8  *FileName,
> +  IN UINTN        LineNumber,
> +  IN CONST CHAR8  *Description
> +  )
> +{
> +  CHAR8  Buffer[MAX_DEBUG_MESSAGE_LENGTH];
> +
> +  if (!mEfiAtRuntime) {
> +    //
> +    // Generate the ASSERT() message in Ascii format
> +    //
> +    AsciiSPrint (Buffer, sizeof (Buffer), "ASSERT [%a] %a(%d): %a\n",
> +      gEfiCallerBaseName, FileName, LineNumber, Description);
> +
> +    //
> +    // Send the print string to the Console Output device
> +    //
> +    SerialPortWrite ((UINT8 *)Buffer, AsciiStrLen (Buffer));
> +  }
> +
> +  //
> +  // Generate a Breakpoint, DeadLoop, or NOP based on PCD settings
> +  //
> +  if ((mDebugPropertyMask & DEBUG_PROPERTY_ASSERT_BREAKPOINT_ENABLED) != 0) {
> +    CpuBreakpoint ();
> +  } else if ((mDebugPropertyMask &
> +              DEBUG_PROPERTY_ASSERT_DEADLOOP_ENABLED) != 0) {
> +    CpuDeadLoop ();
> +  }
> +}
> +
> +
> +/**
> +  Fills a target buffer with PcdDebugClearMemoryValue, and returns the target
> +  buffer.
> +
> +  This function fills Length bytes of Buffer with the value specified by
> +  PcdDebugClearMemoryValue, and returns Buffer.
> +
> +  If Buffer is NULL, then ASSERT().
> +  If Length is greater than (MAX_ADDRESS - Buffer + 1), then ASSERT().
> +
> +  @param   Buffer  The pointer to the target buffer to be filled with
> +                   PcdDebugClearMemoryValue.
> +  @param   Length  The number of bytes in Buffer to fill with
> +                   PcdDebugClearMemoryValue.
> +
> +  @return  Buffer  The pointer to the target buffer filled with
> +                   PcdDebugClearMemoryValue.
> +
> +**/
> +VOID *
> +EFIAPI
> +DebugClearMemory (
> +  OUT VOID  *Buffer,
> +  IN UINTN  Length
> +  )
> +{
> +  if (!mEfiAtRuntime) {
> +    ASSERT (Buffer != NULL);
> +    ASSERT (Length <= (MAX_ADDRESS - (UINTN)Buffer + 1));
> +  }
> +
> +  return SetMem (Buffer, Length, mDebugClearMemoryValue);
> +}
> +
> +
> +/**
> +  Returns TRUE if ASSERT() macros are enabled.
> +
> +  This function returns TRUE if the DEBUG_PROPERTY_DEBUG_ASSERT_ENABLED bit 
> of
> +  PcdDebugProperyMask is set.  Otherwise FALSE is returned.
> +
> +  @retval  TRUE    The DEBUG_PROPERTY_DEBUG_ASSERT_ENABLED bit of
> +                   PcdDebugProperyMask is set.
> +  @retval  FALSE   The DEBUG_PROPERTY_DEBUG_ASSERT_ENABLED bit of
> +                   PcdDebugProperyMask is clear.
> +
> +**/
> +BOOLEAN
> +EFIAPI
> +DebugAssertEnabled (
> +  VOID
> +  )
> +{
> +  return (BOOLEAN)((mDebugPropertyMask &
> +                    DEBUG_PROPERTY_DEBUG_ASSERT_ENABLED) != 0);
> +}
> +
> +
> +/**
> +  Returns TRUE if DEBUG() macros are enabled.
> +
> +  This function returns TRUE if the DEBUG_PROPERTY_DEBUG_PRINT_ENABLED bit of
> +  PcdDebugProperyMask is set.  Otherwise FALSE is returned.
> +
> +  @retval  TRUE    The DEBUG_PROPERTY_DEBUG_PRINT_ENABLED bit of
> +                   PcdDebugProperyMask is set.
> +  @retval  FALSE   The DEBUG_PROPERTY_DEBUG_PRINT_ENABLED bit of
> +                   PcdDebugProperyMask is clear.
> +
> +**/
> +BOOLEAN
> +EFIAPI
> +DebugPrintEnabled (
> +  VOID
> +  )
> +{
> +  return (BOOLEAN)((mDebugPropertyMask &
> +                    DEBUG_PROPERTY_DEBUG_PRINT_ENABLED) != 0);
> +}
> +
> +
> +/**
> +  Returns TRUE if DEBUG_CODE() macros are enabled.
> +
> +  This function returns TRUE if the DEBUG_PROPERTY_DEBUG_CODE_ENABLED bit of
> +  PcdDebugProperyMask is set.  Otherwise FALSE is returned.
> +
> +  @retval  TRUE    The DEBUG_PROPERTY_DEBUG_CODE_ENABLED bit of
> +                   PcdDebugProperyMask is set.
> +  @retval  FALSE   The DEBUG_PROPERTY_DEBUG_CODE_ENABLED bit of
> +                   PcdDebugProperyMask is clear.
> +
> +**/
> +BOOLEAN
> +EFIAPI
> +DebugCodeEnabled (
> +  VOID
> +  )
> +{
> +  return (BOOLEAN)((mDebugPropertyMask &
> +                    DEBUG_PROPERTY_DEBUG_CODE_ENABLED) != 0);
> +}
> +
> +
> +/**
> +  Returns TRUE if DEBUG_CLEAR_MEMORY() macro is enabled.
> +
> +  This function returns TRUE if the DEBUG_PROPERTY_CLEAR_MEMORY_ENABLED bit 
> of
> +  PcdDebugProperyMask is set.  Otherwise FALSE is returned.
> +
> +  @retval  TRUE    The DEBUG_PROPERTY_CLEAR_MEMORY_ENABLED bit of
> +                   PcdDebugProperyMask is set.
> +  @retval  FALSE   The DEBUG_PROPERTY_CLEAR_MEMORY_ENABLED bit of
> +                   PcdDebugProperyMask is clear.
> +
> +**/
> +BOOLEAN
> +EFIAPI
> +DebugClearMemoryEnabled (
> +  VOID
> +  )
> +{
> +  return (BOOLEAN)((mDebugPropertyMask &
> +                    DEBUG_PROPERTY_CLEAR_MEMORY_ENABLED) != 0);
> +}
> +
> +/**
> +  Returns TRUE if any one of the bit is set both in ErrorLevel and
> +  PcdFixedDebugPrintErrorLevel.
> +
> +  This function compares the bit mask of ErrorLevel and
> +  PcdFixedDebugPrintErrorLevel.
> +
> +  @retval  TRUE    Current ErrorLevel is supported.
> +  @retval  FALSE   Current ErrorLevel is not supported.
> +
> +**/
> +BOOLEAN
> +EFIAPI
> +DebugPrintLevelEnabled (
> +  IN  CONST UINTN        ErrorLevel
> +  )
> +{
> +  return (BOOLEAN)((ErrorLevel & mFixedDebugPrintErrorLevel) != 0);
> +}
> diff --git 
> a/MdePkg/Library/DxeRuntimeDebugLibSerialPort/DxeRuntimeDebugLibSerialPort.inf
>  
> b/MdePkg/Library/DxeRuntimeDebugLibSerialPort/DxeRuntimeDebugLibSerialPort.inf
> new file mode 100644
> index 000000000000..d5e9d3f8dee7
> --- /dev/null
> +++ 
> b/MdePkg/Library/DxeRuntimeDebugLibSerialPort/DxeRuntimeDebugLibSerialPort.inf
> @@ -0,0 +1,56 @@
> +## @file
> +#  DXE runtime Debug library instance based on Serial Port library.
> +#  It takes care not to call into SerialPortLib or PcdLib after
> +#  ExitBootServices() has been called, to prevent touching hardware that is
> +#  no longer owned by the firmware, or invoking protocols that are not safe
> +#  for runtime (such as gEfiPcdProtocolGuid)
> +#
> +#  Copyright (c) 2006 - 2015, Intel Corporation. All rights reserved.<BR>
> +#  Copyright (c) 2018, Linaro, Ltd. 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.
> +#
> +#
> +##
> +
> +[Defines]
> +  INF_VERSION                    = 0x0001001A
> +  BASE_NAME                      = DxeRuntimeDebugLibSerialPort
> +  MODULE_UNI_FILE                = DxeRuntimeDebugLibSerialPort.uni
> +  FILE_GUID                      = 9D914E2F-7CCB-41DB-8E74-9AFF8F3BBFBF
> +  MODULE_TYPE                    = DXE_RUNTIME_DRIVER
> +  VERSION_STRING                 = 1.0
> +  LIBRARY_CLASS                  = DebugLib|DXE_RUNTIME_DRIVER
> +  CONSTRUCTOR                    = DxeRuntimeDebugLibSerialPortConstructor
> +  DESTRUCTOR                     = DxeRuntimeDebugLibSerialPortDestructor
> +
> +#
> +#  VALID_ARCHITECTURES           = AARCH64 ARM IA32 X64 IPF EBC
> +#
> +
> +[Sources]
> +  DebugLib.c
> +
> +[Packages]
> +  MdePkg/MdePkg.dec
> +
> +[LibraryClasses]
> +  BaseLib
> +  BaseMemoryLib
> +  DebugPrintErrorLevelLib
> +  PcdLib
> +  PrintLib
> +  SerialPortLib
> +
> +[Guids]
> +  gEfiEventExitBootServicesGuid                         ## CONSUMES ## Event
> +
> +[Pcd]
> +  gEfiMdePkgTokenSpaceGuid.PcdDebugClearMemoryValue     ## CONSUMES
> +  gEfiMdePkgTokenSpaceGuid.PcdDebugPropertyMask         ## CONSUMES
> +  gEfiMdePkgTokenSpaceGuid.PcdFixedDebugPrintErrorLevel ## CONSUMES
> diff --git 
> a/MdePkg/Library/DxeRuntimeDebugLibSerialPort/DxeRuntimeDebugLibSerialPort.uni
>  
> b/MdePkg/Library/DxeRuntimeDebugLibSerialPort/DxeRuntimeDebugLibSerialPort.uni
> new file mode 100644
> index 000000000000..cd65515c4177
> --- /dev/null
> +++ 
> b/MdePkg/Library/DxeRuntimeDebugLibSerialPort/DxeRuntimeDebugLibSerialPort.uni
> @@ -0,0 +1,21 @@
> +// /** @file
> +// Instance of Debug Library based on Serial Port Library.
> +//
> +// It uses Print Library to produce formatted output strings to seiral port 
> device.
> +//
> +// Copyright (c) 2006 - 2014, 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.
> +//
> +// **/
> +
> +
> +#string STR_MODULE_ABSTRACT             #language en-US "Instance of Debug 
> Library based on Serial Port Library"
> +
> +#string STR_MODULE_DESCRIPTION          #language en-US "It uses Print 
> Library to produce formatted output strings to a serial port device."
> +
> --
> 2.11.0
>
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