Laszlo, I revisited code of MpInitLib. I found that CPU_INFO_IN_HOB.ApTopOfStack was assigned to CpuMpData->Buffer in MpInitLibInitialize()
(line1501) InitializeApData (CpuMpData, 0, 0, CpuMpData->Buffer); but in (line598) ApTopOfStack = CpuMpData->Buffer + (ProcessorNumber + 1) * CpuMpData->CpuApStackSize; (line608) InitializeApData (CpuMpData, ProcessorNumber, BistData, ApTopOfStack); Since InitMpGlobalData() is called just after first situation, my patch is correct. I think the problem here is that ApTopOfStack initialized at line 1501 is not correct. Regards, Jian > -----Original Message----- > From: Laszlo Ersek [mailto:ler...@redhat.com] > Sent: Thursday, January 04, 2018 1:33 AM > To: Wang, Jian J <jian.j.w...@intel.com>; edk2-devel@lists.01.org > Cc: Yao, Jiewen <jiewen....@intel.com>; Dong, Eric <eric.d...@intel.com>; > Jeff Fan <vanjeff_...@hotmail.com> > Subject: Re: [edk2] [PATCH] UefiCpuPkg/MpInitLib: fix wrong base address set > as Stack Guard > > (CC Jeff) > > Sorry about the delay. > > I have some light comments below; I expect at least a few of them to be > incorrect :) > > On 12/29/17 09:36, Jian J Wang wrote: > > The reason is that DXE part initialization will reuse the stack allocated > > at PEI phase, if MP was initialized before. Some code added to check this > > situation and use stack base address saved in HOB passed from PEI. > > > > Cc: Jiewen Yao <jiewen....@intel.com> > > Cc: Eric Dong <eric.d...@intel.com> > > Cc: Laszlo Ersek <ler...@redhat.com> > > Contributed-under: TianoCore Contribution Agreement 1.1 > > Signed-off-by: Jian J Wang <jian.j.w...@intel.com> > > --- > > UefiCpuPkg/Library/MpInitLib/DxeMpLib.c | 17 +++++++++++++++-- > > 1 file changed, 15 insertions(+), 2 deletions(-) > > > > diff --git a/UefiCpuPkg/Library/MpInitLib/DxeMpLib.c > b/UefiCpuPkg/Library/MpInitLib/DxeMpLib.c > > index 40c1bf407a..05484c9ff3 100644 > > --- a/UefiCpuPkg/Library/MpInitLib/DxeMpLib.c > > +++ b/UefiCpuPkg/Library/MpInitLib/DxeMpLib.c > > @@ -295,6 +295,7 @@ InitMpGlobalData ( > > UINTN Index; > > EFI_GCD_MEMORY_SPACE_DESCRIPTOR MemDesc; > > UINTN StackBase; > > + CPU_INFO_IN_HOB *CpuInfoInHob; > > > > SaveCpuMpData (CpuMpData); > > > > @@ -314,9 +315,18 @@ InitMpGlobalData ( > > ASSERT (FALSE); > > } > > > > - for (Index = 0; Index < CpuMpData->CpuCount; ++Index) { > > - StackBase = CpuMpData->Buffer + Index * CpuMpData->CpuApStackSize; > > + // > > + // DXE will reuse stack allocated for APs at PEI phase if it's > > available. > > + // Let's check it here. > > + // > > + CpuInfoInHob = (CPU_INFO_IN_HOB *)(UINTN)CpuMpData- > >CpuInfoInHob; > > + if (CpuInfoInHob != NULL && CpuInfoInHob->ApTopOfStack != 0) { > > + StackBase = CpuInfoInHob->ApTopOfStack; > > + } else { > > + StackBase = CpuMpData->Buffer; > > + } > > So, if the HOB is not found, then StackBase is set okay. > > However, I'm unsure about the other case. The > CPU_INFO_IN_HOB.ApTopOfStack field identifies the *top* of the stack > (highest address, and the stack grows down); however the loop below > *increments* StackBase. Given the incrementing nature of the loop, > shouldn't we first calculate the actual base (= lowest address) from the > CPU_INFO_IN_HOB.ApTopOfStack field? > > Actually... I'm even more confused. The CpuMpData->CpuInfoInHob field > points to an *array* of CPU_INFO_IN_HOB structures. Therefore, for any > given processor #N, we should not calculate the stack base as > > CpuMpData->CpuInfoInHob->ApTopOfStack + N * CpuMpData- > >CpuApStackSize > > instead we should calculate the stack base as something like: > > CpuMpData->CpuInfoInHob[N].ApTopOfStack - CpuMpData->CpuApStackSize > > See > - the InitializeApData() function, > - and its call site in the ApWakeupFunction() function. > > (To my surprise, I personally modified InitializeApData() earlier, in > commit dd3fa0cd72de ("UefiCpuPkg/MpInitLib: support 64-bit AP stack > addresses", 2016-11-17) -- I've totally forgotten about that by now!) > > What do you think? > > > > > + for (Index = 0; Index < CpuMpData->CpuCount; ++Index) { > > Status = gDS->GetMemorySpaceDescriptor (StackBase, &MemDesc); > > ASSERT_EFI_ERROR (Status); > > > > @@ -326,6 +336,9 @@ InitMpGlobalData ( > > MemDesc.Attributes | EFI_MEMORY_RP > > ); > > ASSERT_EFI_ERROR (Status); > > + > > + DEBUG ((DEBUG_VERBOSE, "Stack Guard set at %x [cpu%d]!\n", > StackBase, Index)); > > StackBase has type UINTN, and so it should not be printed with %x. It > should be cast to (UINT64), and then printed with %Lx. > > Similarly, Index has type UINTN. It should not be printed with %d. It > should be cast to (UINT64) and printed with %Lu. > > > > + StackBase += CpuMpData->CpuApStackSize; > > Again, I don't think the simple increment applies when the > CpuMpData->CpuInfoInHob array exists. > > > } > > } > > > > > > Thanks, > Laszlo _______________________________________________ edk2-devel mailing list edk2-devel@lists.01.org https://lists.01.org/mailman/listinfo/edk2-devel
