Laszlo, Maybe we can add a macro to help:
#define PATCH_X86_ASM(Label,Type,Value) *((Type *)(&Label) - 1) = (Type)(Value) PATCH_X86_ASM (gSmmCr0, UINT32, AsmReadCr0()); Mike > -----Original Message----- > From: Kinney, Michael D > Sent: Tuesday, January 30, 2018 12:31 PM > To: Laszlo Ersek <ler...@redhat.com>; edk2-devel-01 > <edk2-devel@lists.01.org>; Kinney, Michael D > <michael.d.kin...@intel.com> > Cc: Ni, Ruiyu <ruiyu...@intel.com>; Paolo Bonzini > <pbonz...@redhat.com>; Yao, Jiewen > <jiewen....@intel.com>; Dong, Eric <eric.d...@intel.com> > Subject: RE: [edk2] [PATCH 1/3] > UefiCpuPkg/PiSmmCpuDxeSmm: update comments in IA32 > SmmStartup() > > Laszlo, > > We have already used this technique in other NASM files > to remove DBs. > > Let us know if you have suggestions on how to make the > C code that performs the patches easier to read and > maintain. > > Mike > > > -----Original Message----- > > From: edk2-devel [mailto:edk2-devel- > boun...@lists.01.org] > > On Behalf Of Laszlo Ersek > > Sent: Tuesday, January 30, 2018 10:17 AM > > To: Kinney, Michael D <michael.d.kin...@intel.com>; > edk2- > > devel-01 <edk2-devel@lists.01.org> > > Cc: Ni, Ruiyu <ruiyu...@intel.com>; Paolo Bonzini > > <pbonz...@redhat.com>; Yao, Jiewen > > <jiewen....@intel.com>; Dong, Eric > <eric.d...@intel.com> > > Subject: Re: [edk2] [PATCH 1/3] > > UefiCpuPkg/PiSmmCpuDxeSmm: update comments in IA32 > > SmmStartup() > > > > On 01/30/18 18:22, Kinney, Michael D wrote: > > > Laszlo, > > > > > > The DBs can be removed if the label is moved after > > > the instruction and the patch is done to the label > > > minus the size of the patch value. > > > > Indeed I haven't thought of this. > > > > If I understand correctly, it means > > > > extern UINT8 gSmmCr0; > > > > *(UINT32*)(&gSmmCr0 - sizeof (UINT32)) = > > (UINT32)AsmReadCr0 (); > > > > TBH, the DB feels less ugly to me than this :) > > > > Still, if you think it would be an acceptable price to > > pay for removing > > the remaining DBs, I can respin. > > > > Thanks > > Laszlo > > > > >> -----Original Message----- > > >> From: edk2-devel [mailto:edk2-devel- > > boun...@lists.01.org] > > >> On Behalf Of Laszlo Ersek > > >> Sent: Tuesday, January 30, 2018 7:34 AM > > >> To: edk2-devel-01 <edk2-devel@lists.01.org> > > >> Cc: Ni, Ruiyu <ruiyu...@intel.com>; Yao, Jiewen > > >> <jiewen....@intel.com>; Dong, Eric > > <eric.d...@intel.com>; > > >> Paolo Bonzini <pbonz...@redhat.com> > > >> Subject: [edk2] [PATCH 1/3] > UefiCpuPkg/PiSmmCpuDxeSmm: > > >> update comments in IA32 SmmStartup() > > >> > > >> The gSmmCr3, gSmmCr4, gSmmCr0 and gSmmJmpAddr global > > >> variables are used > > >> for patching assembly instructions, thus we can > never > > >> remove the DB > > >> encodings for those instructions. At least we should > > add > > >> the intended > > >> meanings in comments. > > >> > > >> This patch only changes comments. > > >> > > >> Cc: Eric Dong <eric.d...@intel.com> > > >> Cc: Jian J Wang <jian.j.w...@intel.com> > > >> Cc: Jiewen Yao <jiewen....@intel.com> > > >> Cc: Paolo Bonzini <pbonz...@redhat.com> > > >> Cc: Ruiyu Ni <ruiyu...@intel.com> > > >> Contributed-under: TianoCore Contribution Agreement > > 1.1 > > >> Signed-off-by: Laszlo Ersek <ler...@redhat.com> > > >> --- > > >> UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/SmmInit.nasm | 8 > ++++- > > --- > > >> 1 file changed, 4 insertions(+), 4 deletions(-) > > >> > > >> diff --git > > a/UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/SmmInit.nasm > > >> b/UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/SmmInit.nasm > > >> index e96dd8d2392a..08534dba64b7 100644 > > >> --- a/UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/SmmInit.nasm > > >> +++ b/UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/SmmInit.nasm > > >> @@ -44,34 +44,34 @@ global ASM_PFX(SmmStartup) > > >> ASM_PFX(SmmStartup): > > >> DB 0x66 > > >> mov eax, 0x80000001 ; read > > >> capability > > >> cpuid > > >> DB 0x66 > > >> mov ebx, edx ; rdmsr > will > > >> change edx. keep it in ebx. > > >> - DB 0x66, 0xb8 > > >> + DB 0x66, 0xb8 ; mov eax, > > imm32 > > >> ASM_PFX(gSmmCr3): DD 0 > > >> mov cr3, eax > > >> DB 0x67, 0x66 > > >> lgdt [cs:ebp + (ASM_PFX(gcSmiInitGdtr) - > > >> ASM_PFX(SmmStartup))] > > >> - DB 0x66, 0xb8 > > >> + DB 0x66, 0xb8 ; mov eax, > > imm32 > > >> ASM_PFX(gSmmCr4): DD 0 > > >> mov cr4, eax > > >> DB 0x66 > > >> mov ecx, 0xc0000080 ; IA32_EFER > > MSR > > >> rdmsr > > >> DB 0x66 > > >> test ebx, BIT20 ; check NXE > > >> capability > > >> jz .1 > > >> or ah, BIT3 ; set NXE > bit > > >> wrmsr > > >> .1: > > >> - DB 0x66, 0xb8 > > >> + DB 0x66, 0xb8 ; mov eax, > > imm32 > > >> ASM_PFX(gSmmCr0): DD 0 > > >> DB 0xbf, PROTECT_MODE_DS, 0 ; mov di, > > >> PROTECT_MODE_DS > > >> mov cr0, eax > > >> - DB 0x66, 0xea ; jmp far > > >> [ptr48] > > >> + DB 0x66, 0xea ; jmp far > > >> [ptr48] > > >> ASM_PFX(gSmmJmpAddr): > > >> DD @32bit > > >> DW PROTECT_MODE_CS > > >> @32bit: > > >> mov ds, edi > > >> mov es, edi > > >> -- > > >> 2.14.1.3.gb7cf6e02401b > > >> > > >> > > >> _______________________________________________ > > >> edk2-devel mailing list > > >> edk2-devel@lists.01.org > > >> https://lists.01.org/mailman/listinfo/edk2-devel > > > > _______________________________________________ > > edk2-devel mailing list > > edk2-devel@lists.01.org > > https://lists.01.org/mailman/listinfo/edk2-devel _______________________________________________ edk2-devel mailing list edk2-devel@lists.01.org https://lists.01.org/mailman/listinfo/edk2-devel
