Thanks/Ray
> -----Original Message----- > From: Wang, Jian J > Sent: Saturday, March 3, 2018 9:32 AM > To: Ni, Ruiyu <[email protected]>; Laszlo Ersek <[email protected]>; > [email protected] > Cc: Dong, Eric <[email protected]> > Subject: RE: [PATCH] UefiCpuPkg/MpInitLib: put mReservedApLoopFunc in > executable memory > > > > Regards, > Jian > > > > -----Original Message----- > > From: Ni, Ruiyu > > Sent: Friday, March 02, 2018 7:58 PM > > To: Laszlo Ersek <[email protected]>; Wang, Jian J > > <[email protected]>; [email protected] > > Cc: Dong, Eric <[email protected]> > > Subject: Re: [PATCH] UefiCpuPkg/MpInitLib: put mReservedApLoopFunc in > > executable memory > > > > On 3/2/2018 7:45 PM, Laszlo Ersek wrote: > > > 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 > > > > > > > Checking PCD is not very good I think. > > If checking is really needed, how about check MemDesc.Attributes > > EFI_MEMORY_XP bit? > > > > > > a. Page attributes update has to be in page unit. If we want to avoid making > stack memory executable, reserving it in a separate memory page is the only > way I can think of. > > b. Checking MemDesc.Attributes against EFI_MEMORY_XP doesn't work > here. The reason is that EFI_MEMORY_XP is set to configured type of > memory via CPU Arch protocol in DxeCore code, which won't be recorded in > GCD service data. Maybe checking PCD BIT0 is the only way according current > situation. Will MEMORY_XP be recorded in GCD in future? Based on today's implementation, I prefer to not check. > > > -- > > Thanks, > > Ray _______________________________________________ edk2-devel mailing list [email protected] https://lists.01.org/mailman/listinfo/edk2-devel
