Hi Kun, When we unset a guarded page to unguarded, from page table perspective, it's to set a non-present page to present. I think it's reasonable that we should specific memory attribute to appropriate value when map non-present range to present. In smm initial page table, free page is set to present, writable and executable(with Present bit(bit0) and R/W bit(bit1) set to 1, XD(bit 63) set to 0). So that's why I also clear xp.
Thanks, Dun -----Original Message----- From: Kun Qin <kuqi...@gmail.com> Sent: Wednesday, May 17, 2023 3:05 AM To: devel@edk2.groups.io; Tan, Dun <dun....@intel.com> Cc: Gao, Liming <gaolim...@byosoft.com.cn>; Ni, Ray <ray...@intel.com>; Wang, Jian J <jian.j.w...@intel.com> Subject: Re: [edk2-devel] [Patch V4 04/15] MdeModulePkg: Remove RO and NX protection when unset guard page Hi Dun, I might have missed the context, but could you please explain why we need to clear "EFI_MEMORY_XP"? It is understandable that you would like to clear RO. But would it make more sense to clear XP only when needed (i.e. code page allocation)? Thanks, Kun On 5/16/2023 2:59 AM, duntan wrote: > Remove RO and NX protection when unset guard page. > When UnsetGuardPage(), remove all the memory attribute protection for > guarded page. > > Signed-off-by: Dun Tan <dun....@intel.com> > Cc: Liming Gao <gaolim...@byosoft.com.cn> > Cc: Ray Ni <ray...@intel.com> > Cc: Jian J Wang <jian.j.w...@intel.com> > --- > MdeModulePkg/Core/PiSmmCore/HeapGuard.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/MdeModulePkg/Core/PiSmmCore/HeapGuard.c > b/MdeModulePkg/Core/PiSmmCore/HeapGuard.c > index 8f3bab6fee..7daeeccf13 100644 > --- a/MdeModulePkg/Core/PiSmmCore/HeapGuard.c > +++ b/MdeModulePkg/Core/PiSmmCore/HeapGuard.c > @@ -553,7 +553,7 @@ UnsetGuardPage ( > mSmmMemoryAttribute, > BaseAddress, > EFI_PAGE_SIZE, > - EFI_MEMORY_RP > + > + EFI_MEMORY_RP|EFI_MEMORY_RO|EFI_MEMORY_XP > ); > ASSERT_EFI_ERROR (Status); > mOnGuarding = FALSE; -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#104967): https://edk2.groups.io/g/devel/message/104967 Mute This Topic: https://groups.io/mt/98922929/21656 Group Owner: devel+ow...@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/unsub [arch...@mail-archive.com] -=-=-=-=-=-=-=-=-=-=-=-
