+/*++\r
+\r
+Copyright (c) 2006 - 2007, Intel Corporation\r
+All rights reserved. This program and the accompanying materials\r
+are licensed and made available under the terms and conditions of the BSD License\r
+which accompanies this distribution. The full text of the license may be found at\r
+http://opensource.org/licenses/bsd-license.php\r
+\r
+THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,\r
+WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.\r
+\r
+Module Name:\r
+\r
+ MonotonicCounter.c\r
+\r
+Abstract:\r
+\r
+ Produced the Monotonic Counter Services as defined in the DXE CIS\r
+\r
+Revision History:\r
+\r
+--*/\r
+\r
+#include "MonotonicCounter.h"\r
+\r
+//\r
+// The Monotonic Counter Handle\r
+//\r
+EFI_HANDLE mMonotonicCounterHandle = NULL;\r
+\r
+//\r
+// The current Monotonic count value\r
+//\r
+UINT64 mEfiMtc;\r
+\r
+//\r
+// Event to use to update the Mtc's high part when wrapping\r
+//\r
+EFI_EVENT mEfiMtcEvent;\r
+\r
+//\r
+// EfiMtcName - Variable name of the MTC value\r
+//\r
+CHAR16 *mEfiMtcName = (CHAR16 *) L"MTC";\r
+\r
+//\r
+// EfiMtcGuid - Guid of the MTC value\r
+//\r
+EFI_GUID mEfiMtcGuid = { 0xeb704011, 0x1402, 0x11d3, { 0x8e, 0x77, 0x0, 0xa0, 0xc9, 0x69, 0x72, 0x3b } };\r
+\r
+//\r
+// Worker functions\r
+//\r
+STATIC\r
+EFI_STATUS\r
+EFIAPI\r
+MonotonicCounterDriverGetNextMonotonicCount (\r
+ OUT UINT64 *Count\r
+ )\r
+/*++\r
+\r
+Routine Description:\r
+\r
+Arguments:\r
+\r
+Returns:\r
+\r
+--*/\r
+{\r
+ EFI_TPL OldTpl;\r
+\r
+ //\r
+ // Can not be called after ExitBootServices()\r
+ //\r
+ if (EfiAtRuntime ()) {\r
+ return EFI_UNSUPPORTED;\r
+ }\r
+ //\r
+ // Check input parameters\r
+ //\r
+ if (Count == NULL) {\r
+ return EFI_INVALID_PARAMETER;\r
+ }\r
+ //\r
+ // Update the monotonic counter with a lock\r
+ //\r
+ OldTpl = gBS->RaiseTPL (TPL_HIGH_LEVEL);\r
+ *Count = mEfiMtc;\r
+ mEfiMtc++;\r
+ gBS->RestoreTPL (OldTpl);\r
+\r
+ //\r
+ // If the MSB bit of the low part toggled, then signal that the high\r
+ // part needs updated now\r
+ //\r
+ if ((((UINT32) mEfiMtc) ^ ((UINT32) *Count)) & 0x80000000) {\r
+ gBS->SignalEvent (mEfiMtcEvent);\r
+ }\r
+\r
+ return EFI_SUCCESS;\r
+}\r
+\r
+\r
+/**\r
+ Returns the next high 32 bits of the platform's monotonic counter.\r
+\r
+ The GetNextHighMonotonicCount() function returns the next high 32 bits\r
+ of the platform's monotonic counter. The platform's monotonic counter is\r
+ comprised of two 32 bit quantities: the high 32 bits and the low 32 bits.\r
+ During boot service time the low 32 bit value is volatile: it is reset to\r
+ zero on every system reset and is increased by 1 on every call to GetNextMonotonicCount().\r
+ The high 32 bit value is non-volatile and is increased by 1 whenever the system resets\r
+ or whenever the low 32 bit count [returned by GetNextMonoticCount()] overflows.\r
+ The GetNextMonotonicCount() function is only available at boot services time.\r
+ If the operating system wishes to extend the platform monotonic counter to runtime,\r
+ it may do so by utilizing GetNextHighMonotonicCount(). To do this, before calling\r
+ ExitBootServices() the operating system would call GetNextMonotonicCount() to obtain\r
+ the current platform monotonic count. The operating system would then provide an\r
+ interface that returns the next count by:\r
+ Adding 1 to the last count.\r
+ Before the lower 32 bits of the count overflows, call GetNextHighMonotonicCount().\r
+ This will increase the high 32 bits of the platform's non-volatile portion of the monotonic\r
+ count by 1.\r
+\r
+ This function may only be called at Runtime.\r
+\r
+ @param[out] HighCount Pointer to returned value.\r
+\r
+ @retval EFI_INVALID_PARAMETER If HighCount is NULL.\r
+ @retval EFI_SUCCESS Operation is successful.\r
+ @retval EFI_OUT_OF_RESOURCES If variable service reports that not enough storage\r
+ is available to hold the variable and its data.\r
+ @retval EFI_DEVICE_ERROR The variable could not be saved due to a hardware failure.\r
+\r
+**/\r
+STATIC\r
+EFI_STATUS\r
+EFIAPI\r
+MonotonicCounterDriverGetNextHighMonotonicCount (\r
+ OUT UINT32 *HighCount\r
+ )\r
+/*++\r
+\r
+Routine Description:\r
+\r
+Arguments:\r
+\r
+Returns:\r
+\r
+--*/\r
+{\r
+ EFI_TPL OldTpl;\r
+\r
+ //\r
+ // Check input parameters\r
+ //\r
+ if (HighCount == NULL) {\r
+ return EFI_INVALID_PARAMETER;\r
+ }\r
+\r
+ if (!EfiAtRuntime ()) {\r
+ //\r
+ // Use a lock if called before ExitBootServices()\r
+ //\r
+ OldTpl = gBS->RaiseTPL (TPL_HIGH_LEVEL);\r
+ *HighCount = (UINT32) RShiftU64 (mEfiMtc, 32) + 1;\r
+ mEfiMtc = LShiftU64 (*HighCount, 32);\r
+ gBS->RestoreTPL (OldTpl);\r
+ } else {\r
+ *HighCount = (UINT32) RShiftU64 (mEfiMtc, 32) + 1;\r
+ mEfiMtc = LShiftU64 (*HighCount, 32);\r
+ }\r
+ //\r
+ // Update the NvRam store to match the new high part\r
+ //\r
+ return EfiSetVariable (\r
+ mEfiMtcName,\r
+ &mEfiMtcGuid,\r
+ EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_RUNTIME_ACCESS | EFI_VARIABLE_BOOTSERVICE_ACCESS,\r
+ sizeof (UINT32),\r
+ HighCount\r
+ );\r
+\r
+}\r
+\r
+STATIC\r
+VOID\r
+EFIAPI\r
+EfiMtcEventHandler (\r
+ IN EFI_EVENT Event,\r
+ IN VOID *Context\r
+ )\r
+/*++\r
+\r
+Routine Description:\r
+\r
+ Monotonic count event handler. This handler updates the high monotonic count.\r
+\r
+Arguments:\r
+\r
+ Event The event to handle\r
+ Context The event context\r
+\r
+Returns:\r
+\r
+ EFI_SUCCESS The event has been handled properly\r
+ EFI_NOT_FOUND An error occurred updating the variable.\r
+\r
+--*/\r
+{\r
+ UINT32 HighCount;\r
+\r
+ MonotonicCounterDriverGetNextHighMonotonicCount (&HighCount);\r
+}\r
+\r
+EFI_STATUS\r
+EFIAPI\r
+MonotonicCounterDriverInitialize (\r
+ IN EFI_HANDLE ImageHandle,\r
+ IN EFI_SYSTEM_TABLE *SystemTable\r
+ )\r
+/*++\r
+\r
+Routine Description:\r
+\r
+Arguments:\r
+ (Standard EFI Image entry - EFI_IMAGE_ENTRY_POINT)\r
+\r
+Returns:\r
+\r
+--*/\r
+{\r
+ EFI_STATUS Status;\r
+ UINT32 HighCount;\r
+ UINTN BufferSize;\r
+\r
+ //\r
+ // Make sure the Monotonic Counter Architectural Protocol is not already installed in the system\r
+ //\r
+ ASSERT_PROTOCOL_ALREADY_INSTALLED (NULL, &gEfiMonotonicCounterArchProtocolGuid);\r
+\r
+ //\r
+ // Initialize event to handle overflows\r
+ //\r
+ Status = gBS->CreateEvent (\r
+ EVT_NOTIFY_SIGNAL,\r
+ TPL_CALLBACK,\r
+ EfiMtcEventHandler,\r
+ NULL,\r
+ &mEfiMtcEvent\r
+ );\r
+\r
+ ASSERT_EFI_ERROR (Status);\r
+\r
+ //\r
+ // Read the last high part\r
+ //\r
+ BufferSize = sizeof (UINT32);\r
+ Status = EfiGetVariable (\r
+ mEfiMtcName,\r
+ &mEfiMtcGuid,\r
+ NULL,\r
+ &BufferSize,\r
+ &HighCount\r
+ );\r
+ if (EFI_ERROR (Status)) {\r
+ HighCount = 0;\r
+ }\r
+ //\r
+ // Set the current value\r
+ //\r
+ mEfiMtc = LShiftU64 (HighCount, 32);\r
+\r
+ //\r
+ // Increment the upper 32 bits for this boot\r
+ // Continue even if it fails. It will only fail if the variable services are\r
+ // not functional.\r
+ //\r
+ Status = MonotonicCounterDriverGetNextHighMonotonicCount (&HighCount);\r
+\r
+ //\r
+ // Fill in the EFI Boot Services and EFI Runtime Services Monotonic Counter Fields\r
+ //\r
+ gBS->GetNextMonotonicCount = MonotonicCounterDriverGetNextMonotonicCount;\r
+ gRT->GetNextHighMonotonicCount = MonotonicCounterDriverGetNextHighMonotonicCount;\r
+\r
+ //\r
+ // Install the Monotonic Counter Architctural Protocol onto a new handle\r
+ //\r
+ Status = gBS->InstallMultipleProtocolInterfaces (\r
+ &mMonotonicCounterHandle,\r
+ &gEfiMonotonicCounterArchProtocolGuid,\r
+ NULL,\r
+ NULL\r
+ );\r
+ ASSERT_EFI_ERROR (Status);\r
+\r
+ return EFI_SUCCESS;\r
+}\r
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