ArmVirtPkg/FdtPL011SerialPortLib: initialize implicitly

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.)

Reported-by: Oliver Smith-Denny <osde@linux.microsoft.com>
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>

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);

ArmVirtPkg/Library/FdtPL011SerialPortLib/FdtPL011SerialPortLib.inf

@@ -15,7 +15,7 @@
   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