On 03/02/18 06:58, Jian J Wang wrote: > if PcdDxeNxMemoryProtectionPolicy is enabled for EfiReservedMemoryType > of memory, #PF will be triggered for each APs after ExitBootServices > in SCRT test. The root cause is that AP wakeup code executed at that > time is stored in memory of type EfiReservedMemoryType (referenced by > global mReservedApLoopFunc), which is marked as non-executable. > > This patch fixes this issue by setting memory of mReservedApLoopFunc to > be executable immediately after allocation. > > Cc: Ruiyu Ni <[email protected]> > Cc: Eric Dong <[email protected]> > Cc: Laszlo Ersek <[email protected]> > Contributed-under: TianoCore Contribution Agreement 1.1 > Signed-off-by: Jian J Wang <[email protected]> > --- > UefiCpuPkg/Library/MpInitLib/DxeMpLib.c | 15 +++++++++++++++ > 1 file changed, 15 insertions(+) > > diff --git a/UefiCpuPkg/Library/MpInitLib/DxeMpLib.c > b/UefiCpuPkg/Library/MpInitLib/DxeMpLib.c > index fd2317924f..5fcb08677c 100644 > --- a/UefiCpuPkg/Library/MpInitLib/DxeMpLib.c > +++ b/UefiCpuPkg/Library/MpInitLib/DxeMpLib.c > @@ -399,6 +399,21 @@ InitMpGlobalData ( > &Address > ); > ASSERT_EFI_ERROR (Status); > + > + // > + // Make sure that the buffer memory is executable. > + // > + Status = gDS->GetMemorySpaceDescriptor (Address, &MemDesc); > + if (!EFI_ERROR (Status)) { > + gDS->SetMemorySpaceAttributes ( > + Address, > + EFI_PAGES_TO_SIZE (EFI_SIZE_TO_PAGES ( > + CpuMpData->AddressMap.RelocateApLoopFuncSize > + )), > + MemDesc.Attributes & (~EFI_MEMORY_XP) > + ); > + } > + > mReservedApLoopFunc = (VOID *) (UINTN) Address; > ASSERT (mReservedApLoopFunc != NULL); > mReservedTopOfApStack = (UINTN) Address + EFI_PAGES_TO_SIZE > (EFI_SIZE_TO_PAGES (ApSafeBufferSize)); >
Honestly, I see little point in the "Dxe Nx Memory Protection Policy" when we then override it *every time* it gets in our way. "RelocateApLoopFuncSize" is likely significantly smaller than a full page, so we're making a good chunk of the "safe stack(s)" executable too. Anyway, can you perhaps check BIT0 (standing for EfiReservedMemoryType) in PcdDxeNxMemoryProtectionPolicy, to see if the above hack is necessary? Thanks Laszlo _______________________________________________ edk2-devel mailing list [email protected] https://lists.01.org/mailman/listinfo/edk2-devel
