mirror of https://github.com/acidanthera/audk.git
e077a93dc6
When capsule updates are staged for processing after a warm reboot, they are copied into memory with the MMU and caches enabled. When the capsule PEI gets around to coalescing the capsule, the MMU and caches may still be disabled, and so on architectures where uncached accesses are incoherent with the caches (such as ARM and AARCH64), we need to ensure that the data passed into UpdateCapsule() is written back to main memory before performing the warm reboot. Unfortunately, on ARM, the only type of cache maintenance instructions that are suitable for this purpose operate on virtual addresses only, and given that the UpdateCapsule() prototype includes the physical address of a linked list of scatter/gather data structures that are mapped at an address that is unknown to the firmware (and may not even be mapped at all when UpdateCapsule() is invoked), we can only perform this cache maintenance at boot time. Fortunately, both Windows and Linux only invoke UpdateCapsule() before calling ExitBootServices(), so this is not a problem in practice. In the future, we may propose adding a secure firmware service that permits performing the cache maintenance at OS runtime, in which case this code may be enhanced to call that service if available. For now, we just fail any UpdateCapsule() calls performed at OS runtime on ARM. Contributed-under: TianoCore Contribution Agreement 1.1 Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Reviewed-by: Star Zeng <star.zeng@intel.com> Reviewed-by: Jiewen Yao <jiewen.yao@intel.com> |
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| MdeModulePkg.dec | ||
| MdeModulePkg.dsc | ||
| MdeModulePkg.uni | ||
| MdeModulePkgExtra.uni | ||