On Tue, 7 Feb 2023 at 02:18, Taylor Beebe <t...@taylorbeebe.com> wrote: > > I can't see the Bugzilla you referenced so I requested security Bugzilla > access. But, yes, that's the bug to which I was referring :) >
I cannot see that bugzilla entry either. > Once Ard's change to add Memory Attribute Protocol support to ARM > platforms is in, the change you linked may be palatable for the > upstream. However, ARM platforms could run into the infinite loop I > outlined if that change is pushed upstream because of the lack of > per-allocated page tables and a software semaphore to prevent looping. > I still don't see how this happens. There is an ASSERT in CoreInitializeMemoryProtection() to ensure that EfiConventialMemory and EfiBootServicesData have the same memory type, and I added that (in commit 7eb927db3e25a) for precisely this reason, i.e., to ensure that the plumbing of this feature wouldn't recurse. Could this be related to heap guard, perhaps? I could see how changing the boundaries of allocations might trigger a split even if the old and new type should have the exact same type, and perhaps we should use unguarded pages for page tables. > I implemented pre-allocated pages for ARM a while back in a private repo > but never committed it to Mu. Maybe that would also be worth committing > and pushing upstream. > I'd like to understand better whether or not there is a way to avoid the need for this, but if not, I'd be happy to review your solution. Does the issue only exist on ARM? Does it still happen after I rewrote the MMU library? (in 2020) Thanks, Ard. > On 2/3/2023 11:58 AM, Marvin Häuser wrote: > > Hi Taylor, > > > > Do you by any chance mean this bug? > > https://github.com/microsoft/mu_basecore/blob/release/202208/MdeModulePkg/Core/Dxe/Misc/MemoryProtection.c#L1544 > > > > <https://github.com/microsoft/mu_basecore/blob/release/202208/MdeModulePkg/Core/Dxe/Misc/MemoryProtection.c#L1544> > > > > I reported this a while ago at > > https://bugzilla.tianocore.org/show_bug.cgi?id=3316 > > <https://bugzilla.tianocore.org/show_bug.cgi?id=3316> > > > > The Mu fix is by no means a workaround and actually fixes this issue in > > a sane way. It should have been fixed upstream ages ago. > > > > Best regards, > > Marvin > > > > > > > > -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#99723): https://edk2.groups.io/g/devel/message/99723 Mute This Topic: https://groups.io/mt/96664071/21656 Group Owner: devel+ow...@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/unsub [arch...@mail-archive.com] -=-=-=-=-=-=-=-=-=-=-=-
