Re: [edk2-devel] [PATCH 1/1] ArmVirtPkg/FdtPL011SerialPortLib: initialize implicitly

["Laszlo Ersek" <lersek@redhat.com>]

On 10/6/23 19:08, Ard Biesheuvel wrote:
> On Mon, 2 Oct 2023 at 16:47, Laszlo Ersek <lersek@redhat.com> wrote:
>>
>> On 9/30/23 23:23, Laszlo Ersek wrote:
>>> FdtPL011SerialPortLib claims that it's usable from the DXE_CORE. That's
>>> not correct: the DXE_CORE calls DEBUG() and ASSERT() before it calls
>>> ProcessLibraryConstructorList(). Via the BaseDebugLibSerialPort instance,
>>> those DEBUG() and ASSERT() calls result in SerialPortWrite() calls, before
>>> ProcessLibraryConstructorList() called either our constructor
>>> FdtPL011SerialPortLibInitialize(), or BaseDebugLibSerialPortConstructor().
>>>
>>> (And even if the DXE_CORE called the latter function early enough, it
>>> would just invoke our SerialPortInitialize() function -- which does
>>> nothing.)
>>>
>>> This means that the earliest DXE_CORE debug messages are lost.
>>>
>>> Rename FdtPL011SerialPortLibInitialize() to SerialPortInitialize(), so
>>> that the same initialization occur through the constructor and the public
>>> SerialPortInitialize() library API.
>>>
>>> Turn SerialPortInitialize() calls after the first one into no-ops.
>>>
>>> Our SerialPortLib APIs already use (mSerialBaseAddress != 0) to track
>>> initialization. Rework those checks to actually initialize the library if
>>> that hasn't happened yet.
>>>
>>> The following new lines appear in the log:
>>>
>>>> CoreInitializeMemoryServices:
>>>>   BaseAddress - 0x48000000 Length - 0xF8000000 MinimalMemorySizeNeeded - 0x38C8000
>>>> InstallProtocolInterface: [EfiLoadedImageProtocol] 46EFC3E0
>>>> ProtectUefiImageCommon - 0x46EFC3E0
>>>>   - 0x0000000046EB2000 - 0x0000000000068000
>>>
>>> (0x46EB2000 is the load address of the DXE Core.)
>>>
>>> Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>
>>> Cc: Gerd Hoffmann <kraxel@redhat.com>
>>> Cc: Leif Lindholm <quic_llindhol@quicinc.com>
>>> Cc: Oliver Smith-Denny <osde@linux.microsoft.com>
>>> Cc: Oliver Steffen <osteffen@redhat.com>
>>> Cc: Sami Mujawar <sami.mujawar@arm.com>
>>> Cc: Sean Brogan <sean.brogan@microsoft.com>
>>> Reported-by: Oliver Smith-Denny <osde@linux.microsoft.com>
>>> Signed-off-by: Laszlo Ersek <lersek@redhat.com>
>>> ---
>>>
>>> Notes:
>>>     In my opinion this is the wrong approach to fix the bug, but the right
>>>     approach would require so much work all over edk2 (and outside of it)
>>>     that it's just not practical.
>>
>> NB I'd still like this patch to be merged; "wrong approach" is too
>> strongly worded. I'd now refine that as "theoretically not 100% pure".
>> Merging this one is a compromise, but an easy one -- I had worked
>> several hours on the "pure approach", and it absolutely spiralled out of
>> control. So this is the only one practical thing to do.
>>
> 
> Reviewed-by: Ard Biesheuvel <ardb@kernel.org>

Thanks!

> 
> I'll queue this up.

... for that, too! (<https://github.com/tianocore/edk2/pull/4893>,
commit 5087a0773645.)

Laszlo

> 
> 
>>>
>>>  ArmVirtPkg/Library/FdtPL011SerialPortLib/FdtPL011SerialPortLib.inf |  2 +-
>>>  ArmVirtPkg/Library/FdtPL011SerialPortLib/FdtPL011SerialPortLib.c   | 84 ++++++++++++--------
>>>  2 files changed, 52 insertions(+), 34 deletions(-)
>>>
>>> diff --git a/ArmVirtPkg/Library/FdtPL011SerialPortLib/FdtPL011SerialPortLib.inf b/ArmVirtPkg/Library/FdtPL011SerialPortLib/FdtPL011SerialPortLib.inf
>>> index 2b9a34aa30d1..c417514e3ed5 100644
>>> --- a/ArmVirtPkg/Library/FdtPL011SerialPortLib/FdtPL011SerialPortLib.inf
>>> +++ b/ArmVirtPkg/Library/FdtPL011SerialPortLib/FdtPL011SerialPortLib.inf
>>> @@ -15,7 +15,7 @@ [Defines]
>>>    MODULE_TYPE                    = BASE
>>>    VERSION_STRING                 = 1.0
>>>    LIBRARY_CLASS                  = SerialPortLib|DXE_CORE DXE_DRIVER UEFI_DRIVER DXE_RUNTIME_DRIVER UEFI_APPLICATION
>>> -  CONSTRUCTOR                    = FdtPL011SerialPortLibInitialize
>>> +  CONSTRUCTOR                    = SerialPortInitialize
>>>
>>>  [Sources.common]
>>>    FdtPL011SerialPortLib.c
>>> diff --git a/ArmVirtPkg/Library/FdtPL011SerialPortLib/FdtPL011SerialPortLib.c b/ArmVirtPkg/Library/FdtPL011SerialPortLib/FdtPL011SerialPortLib.c
>>> index 614ea5a860b9..9d71f369570f 100644
>>> --- a/ArmVirtPkg/Library/FdtPL011SerialPortLib/FdtPL011SerialPortLib.c
>>> +++ b/ArmVirtPkg/Library/FdtPL011SerialPortLib/FdtPL011SerialPortLib.c
>>> @@ -23,49 +23,57 @@
>>>  #include <Library/HobLib.h>
>>>  #include <Guid/EarlyPL011BaseAddress.h>
>>>
>>> -STATIC UINTN  mSerialBaseAddress;
>>> -
>>> -RETURN_STATUS
>>> -EFIAPI
>>> -SerialPortInitialize (
>>> -  VOID
>>> -  )
>>> -{
>>> -  return RETURN_SUCCESS;
>>> -}
>>> +STATIC UINTN          mSerialBaseAddress;
>>> +STATIC RETURN_STATUS  mPermanentStatus = RETURN_SUCCESS;
>>>
>>>  /**
>>> -
>>>    Program hardware of Serial port
>>>
>>> -  @return    RETURN_NOT_FOUND if no PL011 base address could be found
>>> -             Otherwise, result of PL011UartInitializePort () is returned
>>> +  @retval RETURN_SUCCESS    If the serial port was initialized successfully by
>>> +                            this call, or an earlier call, to
>>> +                            SerialPortInitialize().
>>>
>>> +  @retval RETURN_NOT_FOUND  If no PL011 base address could be found.
>>> +
>>> +  @return                   Error codes forwarded from
>>> +                            PL011UartInitializePort().
>>>  **/
>>>  RETURN_STATUS
>>>  EFIAPI
>>> -FdtPL011SerialPortLibInitialize (
>>> +SerialPortInitialize (
>>>    VOID
>>>    )
>>>  {
>>>    VOID                *Hob;
>>> +  RETURN_STATUS       Status;
>>>    CONST UINT64        *UartBase;
>>> +  UINTN               SerialBaseAddress;
>>>    UINT64              BaudRate;
>>>    UINT32              ReceiveFifoDepth;
>>>    EFI_PARITY_TYPE     Parity;
>>>    UINT8               DataBits;
>>>    EFI_STOP_BITS_TYPE  StopBits;
>>>
>>> +  if (mSerialBaseAddress != 0) {
>>> +    return RETURN_SUCCESS;
>>> +  }
>>> +
>>> +  if (RETURN_ERROR (mPermanentStatus)) {
>>> +    return mPermanentStatus;
>>> +  }
>>> +
>>>    Hob = GetFirstGuidHob (&gEarlyPL011BaseAddressGuid);
>>>    if ((Hob == NULL) || (GET_GUID_HOB_DATA_SIZE (Hob) != sizeof *UartBase)) {
>>> -    return RETURN_NOT_FOUND;
>>> +    Status = RETURN_NOT_FOUND;
>>> +    goto Failed;
>>>    }
>>>
>>>    UartBase = GET_GUID_HOB_DATA (Hob);
>>>
>>> -  mSerialBaseAddress = (UINTN)*UartBase;
>>> -  if (mSerialBaseAddress == 0) {
>>> -    return RETURN_NOT_FOUND;
>>> +  SerialBaseAddress = (UINTN)*UartBase;
>>> +  if (SerialBaseAddress == 0) {
>>> +    Status = RETURN_NOT_FOUND;
>>> +    goto Failed;
>>>    }
>>>
>>>    BaudRate         = (UINTN)PcdGet64 (PcdUartDefaultBaudRate);
>>> @@ -74,15 +82,25 @@ FdtPL011SerialPortLibInitialize (
>>>    DataBits         = PcdGet8 (PcdUartDefaultDataBits);
>>>    StopBits         = (EFI_STOP_BITS_TYPE)PcdGet8 (PcdUartDefaultStopBits);
>>>
>>> -  return PL011UartInitializePort (
>>> -           mSerialBaseAddress,
>>> -           FixedPcdGet32 (PL011UartClkInHz),
>>> -           &BaudRate,
>>> -           &ReceiveFifoDepth,
>>> -           &Parity,
>>> -           &DataBits,
>>> -           &StopBits
>>> -           );
>>> +  Status = PL011UartInitializePort (
>>> +             SerialBaseAddress,
>>> +             FixedPcdGet32 (PL011UartClkInHz),
>>> +             &BaudRate,
>>> +             &ReceiveFifoDepth,
>>> +             &Parity,
>>> +             &DataBits,
>>> +             &StopBits
>>> +             );
>>> +  if (RETURN_ERROR (Status)) {
>>> +    goto Failed;
>>> +  }
>>> +
>>> +  mSerialBaseAddress = SerialBaseAddress;
>>> +  return RETURN_SUCCESS;
>>> +
>>> +Failed:
>>> +  mPermanentStatus = Status;
>>> +  return Status;
>>>  }
>>>
>>>  /**
>>> @@ -102,7 +120,7 @@ SerialPortWrite (
>>>    IN UINTN  NumberOfBytes
>>>    )
>>>  {
>>> -  if (mSerialBaseAddress != 0) {
>>> +  if (!RETURN_ERROR (SerialPortInitialize ())) {
>>>      return PL011UartWrite (mSerialBaseAddress, Buffer, NumberOfBytes);
>>>    }
>>>
>>> @@ -126,7 +144,7 @@ SerialPortRead (
>>>    IN  UINTN  NumberOfBytes
>>>    )
>>>  {
>>> -  if (mSerialBaseAddress != 0) {
>>> +  if (!RETURN_ERROR (SerialPortInitialize ())) {
>>>      return PL011UartRead (mSerialBaseAddress, Buffer, NumberOfBytes);
>>>    }
>>>
>>> @@ -146,7 +164,7 @@ SerialPortPoll (
>>>    VOID
>>>    )
>>>  {
>>> -  if (mSerialBaseAddress != 0) {
>>> +  if (!RETURN_ERROR (SerialPortInitialize ())) {
>>>      return PL011UartPoll (mSerialBaseAddress);
>>>    }
>>>
>>> @@ -199,7 +217,7 @@ SerialPortSetAttributes (
>>>  {
>>>    RETURN_STATUS  Status;
>>>
>>> -  if (mSerialBaseAddress == 0) {
>>> +  if (RETURN_ERROR (SerialPortInitialize ())) {
>>>      Status = RETURN_UNSUPPORTED;
>>>    } else {
>>>      Status = PL011UartInitializePort (
>>> @@ -234,7 +252,7 @@ SerialPortSetControl (
>>>  {
>>>    RETURN_STATUS  Status;
>>>
>>> -  if (mSerialBaseAddress == 0) {
>>> +  if (RETURN_ERROR (SerialPortInitialize ())) {
>>>      Status = RETURN_UNSUPPORTED;
>>>    } else {
>>>      Status = PL011UartSetControl (mSerialBaseAddress, Control);
>>> @@ -261,7 +279,7 @@ SerialPortGetControl (
>>>  {
>>>    RETURN_STATUS  Status;
>>>
>>> -  if (mSerialBaseAddress == 0) {
>>> +  if (RETURN_ERROR (SerialPortInitialize ())) {
>>>      Status = RETURN_UNSUPPORTED;
>>>    } else {
>>>      Status = PL011UartGetControl (mSerialBaseAddress, Control);
>>>
>>>
>>>
>>>
>>>
>>
>>
>>
>>
>>
>>
> 
> 
> 
> 
> 



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