4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync Produce the UEFI boot service GetNextMonotonicCount() and runtime service
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync GetNextHighMonotonicCount().
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsyncCopyright (c) 2006 - 2011, Intel Corporation. All rights reserved.<BR>
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsyncThis program and the accompanying materials
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsyncare licensed and made available under the terms and conditions of the BSD License
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsyncwhich accompanies this distribution. The full text of the license may be found at
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsyncTHE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsyncWITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync// The handle to install Monotonic Counter Architctural Protocol
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync// The current monotonic counter value
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync// Event to update the monotonic Counter's high part when low part overflows.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync Returns a monotonically increasing count for the platform.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync This function returns a 64-bit value that is numerically larger then the last
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync time the function was called.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync The platform monotonic counter is comprised of two parts: the high 32 bits
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync and the low 32 bits. The low 32-bit value is volatile and is reset to zero on
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync every system reset. It is increased by 1 on every call to GetNextMonotonicCount().
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync The high 32-bit value is nonvolatile and is increased by one on whenever the
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync system resets or the low 32-bit counter overflows.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync @param Count Pointer to returned value.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync @retval EFI_SUCCESS The next monotonic count was returned.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync @retval EFI_DEVICE_ERROR The device is not functioning properly.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync @retval EFI_INVALID_PARAMETER Count is NULL.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync @retval EFI_UNSUPPORTED This function is called at runtime.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync // Cannot be called after ExitBootServices()
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync // Check input parameters
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync // Update the monotonic counter with a lock
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync // If the low 32-bit counter overflows (MSB bit toggled),
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync // then signal that the high part needs update now.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync if ((((UINT32) mEfiMtc) ^ ((UINT32) *Count)) & BIT31) {
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync Returns the next high 32 bits of the platform's monotonic counter.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync The GetNextHighMonotonicCount() function returns the next high 32 bits
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync of the platform's monotonic counter. The platform's monotonic counter is
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync comprised of two 32 bit quantities: the high 32 bits and the low 32 bits.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync During boot service time the low 32 bit value is volatile: it is reset to
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync zero on every system reset and is increased by 1 on every call to GetNextMonotonicCount().
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync The high 32 bit value is non-volatile and is increased by 1 whenever the system resets
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync or whenever the low 32 bit count [returned by GetNextMonoticCount()] overflows.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync The GetNextMonotonicCount() function is only available at boot services time.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync If the operating system wishes to extend the platform monotonic counter to runtime,
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync it may do so by utilizing GetNextHighMonotonicCount(). To do this, before calling
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync ExitBootServices() the operating system would call GetNextMonotonicCount() to obtain
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync the current platform monotonic count. The operating system would then provide an
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync interface that returns the next count by:
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync Adding 1 to the last count.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync Before the lower 32 bits of the count overflows, call GetNextHighMonotonicCount().
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync This will increase the high 32 bits of the platform's non-volatile portion of the monotonic
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync count by 1.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync This function may only be called at Runtime.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync @param HighCount Pointer to returned value.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync @retval EFI_SUCCESS The next high monotonic count was returned.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync @retval EFI_INVALID_PARAMETER HighCount is NULL.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync @retval EFI_DEVICE_ERROR The variable could not be saved due to a hardware failure.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync @retval EFI_OUT_OF_RESOURCES If variable service reports that not enough storage
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync is available to hold the variable and its data.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync // Check input parameters
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync // Use a lock if called before ExitBootServices()
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync // Update the NV variable to match the new high part
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_RUNTIME_ACCESS | EFI_VARIABLE_BOOTSERVICE_ACCESS,
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync Monotonic counter event handler. This handler updates the high part of monotonic counter.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync @param Event The event to handle.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync @param Context The event context.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync MonotonicCounterDriverGetNextHighMonotonicCount (&HighCount);
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync Entry point of monotonic counter driver.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync @param ImageHandle The image handle of this driver.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync @param SystemTable The pointer of EFI_SYSTEM_TABLE.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync @retval EFI_SUCCESS The initialization is successful.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync // Make sure the Monotonic Counter Architectural Protocol has not been installed in the system yet.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync ASSERT_PROTOCOL_ALREADY_INSTALLED (NULL, &gEfiMonotonicCounterArchProtocolGuid);
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync // Initialize event to handle low-part overflow
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync // Read the last high part
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync // Set the current value
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync // Increment the upper 32 bits for this boot
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync // Continue even if it fails. It will only fail if the variable services are
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync // not functional.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync MonotonicCounterDriverGetNextHighMonotonicCount (&HighCount);
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync // Fill in the EFI Boot Services and EFI Runtime Services Monotonic Counter Fields
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync gBS->GetNextMonotonicCount = MonotonicCounterDriverGetNextMonotonicCount;
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync gRT->GetNextHighMonotonicCount = MonotonicCounterDriverGetNextHighMonotonicCount;
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync // Install the Monotonic Counter Architctural Protocol onto a new handle