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.
Mike > -----Original Message----- > From: edk2-devel [mailto:[email protected]] > On Behalf Of Laszlo Ersek > Sent: Tuesday, January 30, 2018 7:34 AM > To: edk2-devel-01 <[email protected]> > Cc: Ni, Ruiyu <[email protected]>; Yao, Jiewen > <[email protected]>; Dong, Eric <[email protected]>; > Paolo Bonzini <[email protected]> > 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 <[email protected]> > Cc: Jian J Wang <[email protected]> > Cc: Jiewen Yao <[email protected]> > Cc: Paolo Bonzini <[email protected]> > Cc: Ruiyu Ni <[email protected]> > Contributed-under: TianoCore Contribution Agreement 1.1 > Signed-off-by: Laszlo Ersek <[email protected]> > --- > 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 > [email protected] > https://lists.01.org/mailman/listinfo/edk2-devel _______________________________________________ edk2-devel mailing list [email protected] https://lists.01.org/mailman/listinfo/edk2-devel
