On Wed, 19 Apr 2023 at 19:45, Marvin Häuser <mhaeu...@posteo.de> wrote: > > > On 19. Apr 2023, at 19:40, Ard Biesheuvel <a...@kernel.org> wrote: > > On Wed, 19 Apr 2023 at 19:14, Marvin Häuser <mhaeu...@posteo.de> wrote: > > > Hi all, > > While testing Ard's suggestion for V3, I noticed I got a broken FD where > ArmReplaceLiveTranslationEntry() is misaligned, but does not cross a 4 KB > boundary. > > > Which platform are you building? > > > ArmVirtPkg / AARCH64 / DEBUG / GCC5 (GCC 12.2.0). > > > To not just hide the issue via this patch, can someone please try to explain > the exact requirements this function has (the comments read like 0x200 was > just the lowest value to guarantee staying within a page)? Why would it be > broken if misaligned, but not crossing a page? > > > 0x200 is a log2 upper bound for the size of the function, so it's just > the smallest value that fits that requirement, determined manually > iirc > > And the only reason we have this is that we can cheaply decide whether > or not unmapping a page will unmap this function or not, but we could > actually just use the address and size to decide this. > > In any case, if the FD is constructed in a way that violates the > alignment, there is something wrong with the build tools you are > using. > > > The tools are stock edk2, the only changes made are those in the latest > commit of the linked branch. > > > Is there any chance the FD is somehow misaligned in memory, thus shifting the > function across a page in the process? Or is the FD mapped to a fixed address > like with x86? Is code after ArmReplaceLiveTranslationEntry() crossing page > boundaries the actual issue (and is implicitly fixed by aligning it)? > > > If you are building ArmVirtQemu.dsc, the FD is mapped at address 0x0 > and the FV is mapped at 0x1000 > > > Then the function simply is not crossing a page boundary... which means the > patch did fix a valid bug, but it wasn't what actually caused the corruption. > Any help is appreciated. :) >
Your branch seems to be missing 16e0969ef775b898ac700f3261d76030b8ab9ef0 "ArmVirtPkg/ArmVirtQemu: Use PEI flavor of ArmMmuLib for all PEIMs" -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#103235): https://edk2.groups.io/g/devel/message/103235 Mute This Topic: https://groups.io/mt/98325898/21656 Group Owner: devel+ow...@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/unsub [arch...@mail-archive.com] -=-=-=-=-=-=-=-=-=-=-=-
