diff options
Diffstat (limited to 'MdePkg/Library/BaseLib')
45 files changed, 184 insertions, 77 deletions
diff --git a/MdePkg/Library/BaseLib/Ia32/CpuFlushTlb.asm b/MdePkg/Library/BaseLib/Ia32/CpuFlushTlb.asm index 367412403e..4f0c4f9944 100644 --- a/MdePkg/Library/BaseLib/Ia32/CpuFlushTlb.asm +++ b/MdePkg/Library/BaseLib/Ia32/CpuFlushTlb.asm @@ -33,7 +33,7 @@ ;------------------------------------------------------------------------------
CpuFlushTlb PROC
mov eax, cr3
- mov cr3, eax
+ mov cr3, eax ; moving to CR3 flushes TLB
ret
CpuFlushTlb ENDP
diff --git a/MdePkg/Library/BaseLib/Ia32/DivU64x32Remainder.asm b/MdePkg/Library/BaseLib/Ia32/DivU64x32Remainder.asm index a836e22d0d..e025b22c2d 100644 --- a/MdePkg/Library/BaseLib/Ia32/DivU64x32Remainder.asm +++ b/MdePkg/Library/BaseLib/Ia32/DivU64x32Remainder.asm @@ -33,18 +33,18 @@ ; );
;------------------------------------------------------------------------------
InternalMathDivRemU64x32 PROC
- mov ecx, [esp + 12]
- mov eax, [esp + 8]
+ mov ecx, [esp + 12] ; ecx <- divisor
+ mov eax, [esp + 8] ; eax <- dividend[32..63]
xor edx, edx
- div ecx
+ div ecx ; eax <- quotient[32..63], edx <- remainder
push eax
- mov eax, [esp + 8]
- div ecx
- mov ecx, [esp + 20]
+ mov eax, [esp + 8] ; eax <- dividend[0..31]
+ div ecx ; eax <- quotient[0..31]
+ mov ecx, [esp + 20] ; ecx <- Remainder
jecxz @F ; abandon remainder if Remainder == NULL
mov [ecx], edx
@@:
- pop edx
+ pop edx ; edx <- quotient[32..63]
ret
InternalMathDivRemU64x32 ENDP
diff --git a/MdePkg/Library/BaseLib/Ia32/DivU64x64Remainder.asm b/MdePkg/Library/BaseLib/Ia32/DivU64x64Remainder.asm index 61a53d1e3a..95e57efac1 100644 --- a/MdePkg/Library/BaseLib/Ia32/DivU64x64Remainder.asm +++ b/MdePkg/Library/BaseLib/Ia32/DivU64x64Remainder.asm @@ -36,13 +36,13 @@ EXTERN InternalMathDivRemU64x32:PROC ; );
;------------------------------------------------------------------------------
InternalMathDivRemU64x64 PROC
- mov ecx, [esp + 16]
+ mov ecx, [esp + 16] ; ecx <- divisor[32..63]
test ecx, ecx
jnz _@DivRemU64x64 ; call _@DivRemU64x64 if Divisor > 2^32
mov ecx, [esp + 20]
jecxz @F
- and dword ptr [ecx + 4], 0
- mov [esp + 16], ecx
+ and dword ptr [ecx + 4], 0 ; zero high dword of remainder
+ mov [esp + 16], ecx ; set up stack frame to match DivRemU64x32
@@:
jmp InternalMathDivRemU64x32
InternalMathDivRemU64x64 ENDP
@@ -61,11 +61,11 @@ _@DivRemU64x64 PROC USES ebx esi edi jnz @B
div ebx
mov ebx, eax ; ebx <- quotient
- mov ecx, [esp + 28]
- mul dword ptr [esp + 24]
- imul ecx, ebx
- add edx, ecx
- mov ecx, dword ptr [esp + 32]
+ mov ecx, [esp + 28] ; ecx <- high dword of divisor
+ mul dword ptr [esp + 24] ; edx:eax <- quotient * divisor[0..31]
+ imul ecx, ebx ; ecx <- quotient * divisor[32..63]
+ add edx, ecx ; edx <- (quotient * divisor)[32..63]
+ mov ecx, dword ptr [esp + 32] ; ecx <- addr for Remainder
jc @TooLarge ; product > 2^64
cmp edi, edx ; compare high 32 bits
ja @Correct
@@ -76,7 +76,7 @@ _@DivRemU64x64 PROC USES ebx esi edi dec ebx ; adjust quotient by -1
jecxz @Return ; return if Remainder == NULL
sub eax, dword ptr [esp + 24]
- sbb edx, dword ptr [esp + 28]
+ sbb edx, dword ptr [esp + 28] ; edx:eax <- (quotient - 1) * divisor
@Correct:
jecxz @Return
sub esi, eax
@@ -85,7 +85,7 @@ _@DivRemU64x64 PROC USES ebx esi edi mov [ecx + 4], edi
@Return:
mov eax, ebx ; eax <- quotient
- xor edx, edx
+ xor edx, edx ; quotient is 32 bits long
ret
_@DivRemU64x64 ENDP
diff --git a/MdePkg/Library/BaseLib/Ia32/EnablePaging32.asm b/MdePkg/Library/BaseLib/Ia32/EnablePaging32.asm index cf6f2fe458..ae98b93285 100644 --- a/MdePkg/Library/BaseLib/Ia32/EnablePaging32.asm +++ b/MdePkg/Library/BaseLib/Ia32/EnablePaging32.asm @@ -40,14 +40,14 @@ InternalX86EnablePaging32 PROC mov ecx, [esp + 8]
mov edx, [esp + 12]
pushfd
- pop edi
+ pop edi ; save flags in edi
cli
mov eax, cr0
bts eax, 31
mov esp, [esp + 16]
mov cr0, eax
push edi
- popfd
+ popfd ; restore flags
push edx
push ecx
call ebx
diff --git a/MdePkg/Library/BaseLib/Ia32/EnablePaging64.asm b/MdePkg/Library/BaseLib/Ia32/EnablePaging64.asm index 354d1fe603..435bb39105 100644 --- a/MdePkg/Library/BaseLib/Ia32/EnablePaging64.asm +++ b/MdePkg/Library/BaseLib/Ia32/EnablePaging64.asm @@ -47,11 +47,11 @@ InternalX86EnablePaging64 PROC or ah, 1 ; set LME
wrmsr
mov eax, cr0
- bts eax, 31
+ bts eax, 31 ; set PG
mov cr0, eax ; enable paging
- retf
+ retf ; topmost 2 dwords hold the address
@@: ; long mode starts here
- DB 67h, 48h
+ DB 67h, 48h ; 32-bit address size, 64-bit operand size
mov ebx, [esp] ; mov rbx, [esp]
DB 67h, 48h
mov ecx, [esp + 8] ; mov rcx, [esp + 8]
@@ -62,7 +62,7 @@ InternalX86EnablePaging64 PROC DB 48h
add esp, -20h ; add rsp, -20h
call ebx ; call rbx
- jmp $
+ hlt ; no one should get here
InternalX86EnablePaging64 ENDP
END
diff --git a/MdePkg/Library/BaseLib/Ia32/FxRestore.asm b/MdePkg/Library/BaseLib/Ia32/FxRestore.asm index 9bcc6ac885..5def311700 100644 --- a/MdePkg/Library/BaseLib/Ia32/FxRestore.asm +++ b/MdePkg/Library/BaseLib/Ia32/FxRestore.asm @@ -34,7 +34,7 @@ ; );
;------------------------------------------------------------------------------
InternalX86FxRestore PROC
- mov eax, [esp + 4]
+ mov eax, [esp + 4] ; Buffer must be 16-byte aligned
fxrstor [eax]
ret
InternalX86FxRestore ENDP
diff --git a/MdePkg/Library/BaseLib/Ia32/FxSave.asm b/MdePkg/Library/BaseLib/Ia32/FxSave.asm index 7d5ea45ffb..d3a9f9cd48 100644 --- a/MdePkg/Library/BaseLib/Ia32/FxSave.asm +++ b/MdePkg/Library/BaseLib/Ia32/FxSave.asm @@ -34,7 +34,7 @@ ; );
;------------------------------------------------------------------------------
InternalX86FxSave PROC
- mov eax, [esp + 4]
+ mov eax, [esp + 4] ; Buffer must be 16-byte aligned
fxsave [eax]
ret
InternalX86FxSave ENDP
diff --git a/MdePkg/Library/BaseLib/Ia32/LongJump.asm b/MdePkg/Library/BaseLib/Ia32/LongJump.asm index a634c4599c..0309f6ae71 100644 --- a/MdePkg/Library/BaseLib/Ia32/LongJump.asm +++ b/MdePkg/Library/BaseLib/Ia32/LongJump.asm @@ -40,7 +40,7 @@ InternalLongJump PROC mov edi, [edx + 8]
mov ebp, [edx + 12]
mov esp, [edx + 16]
- jmp dword ptr [edx + 20]
+ jmp dword ptr [edx + 20] ; restore "eip"
InternalLongJump ENDP
END
diff --git a/MdePkg/Library/BaseLib/Ia32/MultU64x64.asm b/MdePkg/Library/BaseLib/Ia32/MultU64x64.asm index 377aa51972..f3679548f1 100644 --- a/MdePkg/Library/BaseLib/Ia32/MultU64x64.asm +++ b/MdePkg/Library/BaseLib/Ia32/MultU64x64.asm @@ -32,15 +32,15 @@ ; );
;------------------------------------------------------------------------------
InternalMathMultU64x64 PROC USES ebx
- mov ebx, [esp + 8]
- mov edx, [esp + 16]
+ mov ebx, [esp + 8] ; ebx <- M1[0..31]
+ mov edx, [esp + 16] ; edx <- M2[0..31]
mov ecx, ebx
mov eax, edx
- imul ebx, [esp + 20]
- imul edx, [esp + 12]
- add ebx, edx
- mul ecx
- add edx, ebx
+ imul ebx, [esp + 20] ; ebx <- M1[0..31] * M2[32..63]
+ imul edx, [esp + 12] ; edx <- M1[32..63] * M2[0..31]
+ add ebx, edx ; carries are abandoned
+ mul ecx ; edx:eax <- M1[0..31] * M2[0..31]
+ add edx, ebx ; carries are abandoned
ret
InternalMathMultU64x64 ENDP
diff --git a/MdePkg/Library/BaseLib/Ia32/RRotU64.asm b/MdePkg/Library/BaseLib/Ia32/RRotU64.asm index 4c58878ace..fe13abc0d5 100644 --- a/MdePkg/Library/BaseLib/Ia32/RRotU64.asm +++ b/MdePkg/Library/BaseLib/Ia32/RRotU64.asm @@ -40,7 +40,7 @@ InternalMathRRotU64 PROC USES ebx rol ebx, cl
shrd edx, ebx, cl
test cl, 32 ; Count >= 32?
- cmovnz ecx, eax
+ cmovnz ecx, eax ; switch eax & edx if Count >= 32
cmovnz eax, edx
cmovnz edx, ecx
ret
diff --git a/MdePkg/Library/BaseLib/Ia32/RShiftU64.asm b/MdePkg/Library/BaseLib/Ia32/RShiftU64.asm index 793a8f988f..faa4e96771 100644 --- a/MdePkg/Library/BaseLib/Ia32/RShiftU64.asm +++ b/MdePkg/Library/BaseLib/Ia32/RShiftU64.asm @@ -32,10 +32,10 @@ ; );
;------------------------------------------------------------------------------
InternalMathRShiftU64 PROC
- mov cl, [esp + 12]
+ mov cl, [esp + 12] ; cl <- Count
xor edx, edx
mov eax, [esp + 8]
- test cl, 32
+ test cl, 32 ; Count >= 32?
cmovz edx, eax
cmovz eax, [esp + 4]
shrd eax, edx, cl
diff --git a/MdePkg/Library/BaseLib/Ia32/ReadDr4.asm b/MdePkg/Library/BaseLib/Ia32/ReadDr4.asm index d1fffe4ec0..606f26fe2a 100644 --- a/MdePkg/Library/BaseLib/Ia32/ReadDr4.asm +++ b/MdePkg/Library/BaseLib/Ia32/ReadDr4.asm @@ -33,6 +33,13 @@ ; );
;------------------------------------------------------------------------------
AsmReadDr4 PROC
+ ;
+ ; DR4 is alias to DR6 only if DE (in CR4) is cleared. Otherwise, reading
+ ; this register will cause a #UD exception.
+ ;
+ ; MS assembler doesn't support this instruction since no one would use it
+ ; under normal circustances. Here opcode is used.
+ ;
DB 0fh, 21h, 0e0h
ret
AsmReadDr4 ENDP
diff --git a/MdePkg/Library/BaseLib/Ia32/ReadDr5.asm b/MdePkg/Library/BaseLib/Ia32/ReadDr5.asm index bba8b602ba..091792dab9 100644 --- a/MdePkg/Library/BaseLib/Ia32/ReadDr5.asm +++ b/MdePkg/Library/BaseLib/Ia32/ReadDr5.asm @@ -33,6 +33,13 @@ ; );
;------------------------------------------------------------------------------
AsmReadDr5 PROC
+ ;
+ ; DR5 is alias to DR7 only if DE (in CR4) is cleared. Otherwise, reading
+ ; this register will cause a #UD exception.
+ ;
+ ; MS assembler doesn't support this instruction since no one would use it
+ ; under normal circustances. Here opcode is used.
+ ;
DB 0fh, 21h, 0e8h
ret
AsmReadDr5 ENDP
diff --git a/MdePkg/Library/BaseLib/Ia32/SetJump.asm b/MdePkg/Library/BaseLib/Ia32/SetJump.asm index 4d745e29ac..4b7b40c47a 100644 --- a/MdePkg/Library/BaseLib/Ia32/SetJump.asm +++ b/MdePkg/Library/BaseLib/Ia32/SetJump.asm @@ -34,16 +34,16 @@ InternalAssertJumpBuffer PROTO C ;------------------------------------------------------------------------------
SetJump PROC
push [esp + 4]
- call InternalAssertJumpBuffer
- pop ecx
+ call InternalAssertJumpBuffer ; To validate JumpBuffer
pop ecx
+ pop ecx ; ecx <- return address
mov edx, [esp]
mov [edx], ebx
mov [edx + 4], esi
mov [edx + 8], edi
mov [edx + 12], ebp
mov [edx + 16], esp
- mov [edx + 20], ecx
+ mov [edx + 20], ecx ; eip value to restore in LongJump
xor eax, eax
jmp ecx
SetJump ENDP
diff --git a/MdePkg/Library/BaseLib/Ia32/SwapBytes64.asm b/MdePkg/Library/BaseLib/Ia32/SwapBytes64.asm index 186d094eee..7647880202 100644 --- a/MdePkg/Library/BaseLib/Ia32/SwapBytes64.asm +++ b/MdePkg/Library/BaseLib/Ia32/SwapBytes64.asm @@ -33,8 +33,8 @@ ; );
;------------------------------------------------------------------------------
InternalMathSwapBytes64 PROC
- mov eax, [esp + 8]
- mov edx, [esp + 4]
+ mov eax, [esp + 8] ; eax <- upper 32 bits
+ mov edx, [esp + 4] ; edx <- lower 32 bits
bswap eax
bswap edx
ret
diff --git a/MdePkg/Library/BaseLib/Ia32/Thunk16.asm b/MdePkg/Library/BaseLib/Ia32/Thunk16.asm index 5e35799127..5c9bc81a2b 100644 --- a/MdePkg/Library/BaseLib/Ia32/Thunk16.asm +++ b/MdePkg/Library/BaseLib/Ia32/Thunk16.asm @@ -75,6 +75,11 @@ SavedGdt LABEL FWORD ; by user code. It will be shadowed to somewhere in memory below 1MB.
;------------------------------------------------------------------------------
_BackFromUserCode PROC
+ ;
+ ; The order of saved registers on the stack matches the order they appears
+ ; in IA32_REGS structure. This facilitates wrapper function to extract them
+ ; into that structure.
+ ;
push ss
push cs
DB 66h
@@ -104,6 +109,11 @@ _ThunkAttr DD ? mov eax, ss
DB 67h
lea bp, [esp + sizeof (IA32_REGS)]
+ ;
+ ; esi's in the following 2 instructions are indeed bp in 16-bit code. Fact
+ ; is "esi" in 32-bit addressing mode has the same encoding of "bp" in 16-
+ ; bit addressing mode.
+ ;
mov word ptr (IA32_REGS ptr [esi - sizeof (IA32_REGS)])._ESP, bp
mov ebx, (IA32_REGS ptr [esi - sizeof (IA32_REGS)])._EIP
shl ax, 4 ; shl eax, 4
@@ -167,7 +177,7 @@ _ToUserCode PROC pop fs
pop gs
popf ; popfd
- DB 66h
+ DB 66h ; Use 32-bit addressing for "retf" below
retf ; transfer control to user code
_ToUserCode ENDP
@@ -197,7 +207,7 @@ GdtEnd LABEL QWORD ; );
;------------------------------------------------------------------------------
InternalAsmThunk16 PROC USES ebp ebx esi edi ds es fs gs
- mov esi, [esp + 36] ; esi <- RegSet
+ mov esi, [esp + 36] ; esi <- RegSet, the 1st parameter
movzx edx, (IA32_REGS ptr [esi])._SS
mov edi, (IA32_REGS ptr [esi])._ESP
add edi, - (sizeof (IA32_REGS) + 4) ; reserve stack space
@@ -227,11 +237,11 @@ InternalAsmThunk16 PROC USES ebp ebx esi edi ds es fs gs push 10h
pop ecx ; ecx <- selector for data segments
lgdt fword ptr [edx + (_16Gdtr - SavedCr0)]
- pushfd
+ pushfd ; Save df/if indeed
call fword ptr [edx + (_EntryPoint - SavedCr0)]
popfd
lidt fword ptr [esp + 36] ; restore protected mode IDTR
- lea eax, [ebp - sizeof (IA32_REGS)]
+ lea eax, [ebp - sizeof (IA32_REGS)] ; eax <- the address of IA32_REGS
ret
InternalAsmThunk16 ENDP
diff --git a/MdePkg/Library/BaseLib/Ia32/WriteDr4.asm b/MdePkg/Library/BaseLib/Ia32/WriteDr4.asm index ca9a839f70..9c10305b4d 100644 --- a/MdePkg/Library/BaseLib/Ia32/WriteDr4.asm +++ b/MdePkg/Library/BaseLib/Ia32/WriteDr4.asm @@ -34,6 +34,13 @@ ;------------------------------------------------------------------------------
AsmWriteDr4 PROC
mov eax, [esp + 4]
+ ;
+ ; DR4 is alias to DR6 only if DE (in CR4) is cleared. Otherwise, writing to
+ ; this register will cause a #UD exception.
+ ;
+ ; MS assembler doesn't support this instruction since no one would use it
+ ; under normal circustances. Here opcode is used.
+ ;
DB 0fh, 23h, 0e0h
ret
AsmWriteDr4 ENDP
diff --git a/MdePkg/Library/BaseLib/Ia32/WriteDr5.asm b/MdePkg/Library/BaseLib/Ia32/WriteDr5.asm index c6def6820c..e10434ef3d 100644 --- a/MdePkg/Library/BaseLib/Ia32/WriteDr5.asm +++ b/MdePkg/Library/BaseLib/Ia32/WriteDr5.asm @@ -34,6 +34,13 @@ ;------------------------------------------------------------------------------
AsmWriteDr5 PROC
mov eax, [esp + 4]
+ ;
+ ; DR5 is alias to DR7 only if DE (in CR4) is cleared. Otherwise, writing to
+ ; this register will cause a #UD exception.
+ ;
+ ; MS assembler doesn't support this instruction since no one would use it
+ ; under normal circustances. Here opcode is used.
+ ;
DB 0fh, 23h, 0e8h
ret
AsmWriteDr5 ENDP
diff --git a/MdePkg/Library/BaseLib/X64/DisablePaging64.asm b/MdePkg/Library/BaseLib/X64/DisablePaging64.asm index 2609c941aa..518137ddc9 100644 --- a/MdePkg/Library/BaseLib/X64/DisablePaging64.asm +++ b/MdePkg/Library/BaseLib/X64/DisablePaging64.asm @@ -36,15 +36,14 @@ ;------------------------------------------------------------------------------
InternalX86DisablePaging64 PROC
cli
- shl rcx, 32
+ shl rcx, 32 ; rcx[32..47] <- Cs
lea eax, @F
- mov ecx, eax
- push rcx
- mov ebx, edx
mov esi, r8d
+ or rcx, rax ; rcx[0..47] <- Cs:@F
mov edi, r9d
- mov eax, [rsp + 28h]
- retf
+ mov eax, [rsp + 28h] ; eax <- New Stack
+ push rcx
+ retf ; switch to compatibility mode
@@:
mov esp, eax ; set up new stack
mov rax, cr0
@@ -57,10 +56,10 @@ InternalX86DisablePaging64 PROC mov rax, cr4
and al, NOT (1 SHL 5) ; clear PAE
mov cr4, rax
- push rdi
- push rsi
- call rbx
- jmp $
+ push rdi ; push Context2
+ push rsi ; push Context1
+ call rdx ; transfer control to EntryPoint
+ hlt ; no one should get here
InternalX86DisablePaging64 ENDP
END
diff --git a/MdePkg/Library/BaseLib/X64/EnablePaging64.asm b/MdePkg/Library/BaseLib/X64/EnablePaging64.asm index 459120a886..c54843008a 100644 --- a/MdePkg/Library/BaseLib/X64/EnablePaging64.asm +++ b/MdePkg/Library/BaseLib/X64/EnablePaging64.asm @@ -36,7 +36,7 @@ ;------------------------------------------------------------------------------
InternalX86EnablePaging64 PROC
cli
- pop rax
+ pop rax ; skip the return address
call @Base
@Base:
add dword ptr [rsp], @F - @Base ; offset for far retf, seg is the 1st arg
@@ -58,7 +58,7 @@ InternalX86EnablePaging64 PROC mov rsp, [esp + 18h]
add rsp, -20h
call rbx
- jmp $ ; halt processor if EntryPoint() returned
+ hlt ; halt processor if EntryPoint() returned
InternalX86EnablePaging64 ENDP
END
diff --git a/MdePkg/Library/BaseLib/X64/LongJump.asm b/MdePkg/Library/BaseLib/X64/LongJump.asm index 6ef5f964e0..38e5606081 100644 --- a/MdePkg/Library/BaseLib/X64/LongJump.asm +++ b/MdePkg/Library/BaseLib/X64/LongJump.asm @@ -39,7 +39,7 @@ InternalLongJump PROC mov r13, [rcx + 30h]
mov r14, [rcx + 38h]
mov r15, [rcx + 40h]
- mov rax, rdx
+ mov rax, rdx ; set return value
jmp qword ptr [rcx + 48h]
InternalLongJump ENDP
diff --git a/MdePkg/Library/BaseLib/X64/Monitor.asm b/MdePkg/Library/BaseLib/X64/Monitor.asm index 0140494d30..ec9c3f8d03 100644 --- a/MdePkg/Library/BaseLib/X64/Monitor.asm +++ b/MdePkg/Library/BaseLib/X64/Monitor.asm @@ -36,7 +36,7 @@ AsmMonitor PROC mov eax, ecx
mov ecx, edx
mov edx, r8d
- DB 0fh, 1, 0c8h
+ DB 0fh, 1, 0c8h ; monitor
ret
AsmMonitor ENDP
diff --git a/MdePkg/Library/BaseLib/X64/Mwait.asm b/MdePkg/Library/BaseLib/X64/Mwait.asm index 8f76d944f1..aae1d42758 100644 --- a/MdePkg/Library/BaseLib/X64/Mwait.asm +++ b/MdePkg/Library/BaseLib/X64/Mwait.asm @@ -34,7 +34,7 @@ AsmMwait PROC
mov eax, ecx
mov ecx, edx
- DB 0fh, 1, 0c9h
+ DB 0fh, 1, 0c9h ; mwait
ret
AsmMwait ENDP
diff --git a/MdePkg/Library/BaseLib/X64/ReadDr4.asm b/MdePkg/Library/BaseLib/X64/ReadDr4.asm index 97740016b3..2bed12928b 100644 --- a/MdePkg/Library/BaseLib/X64/ReadDr4.asm +++ b/MdePkg/Library/BaseLib/X64/ReadDr4.asm @@ -31,6 +31,10 @@ ; );
;------------------------------------------------------------------------------
AsmReadDr4 PROC
+ ;
+ ; There's no obvious reason to access this register, since it's aliased to
+ ; DR7 when DE=0 or an exception generated when DE=1
+ ;
DB 0fh, 21h, 0e0h
ret
AsmReadDr4 ENDP
diff --git a/MdePkg/Library/BaseLib/X64/ReadDr5.asm b/MdePkg/Library/BaseLib/X64/ReadDr5.asm index 0582502220..3bee3a56ec 100644 --- a/MdePkg/Library/BaseLib/X64/ReadDr5.asm +++ b/MdePkg/Library/BaseLib/X64/ReadDr5.asm @@ -31,6 +31,10 @@ ; );
;------------------------------------------------------------------------------
AsmReadDr5 PROC
+ ;
+ ; There's no obvious reason to access this register, since it's aliased to
+ ; DR7 when DE=0 or an exception generated when DE=1
+ ;
DB 0fh, 21h, 0e8h
ret
AsmReadDr5 ENDP
diff --git a/MdePkg/Library/BaseLib/X64/ReadMm0.asm b/MdePkg/Library/BaseLib/X64/ReadMm0.asm index a81d208298..0ed5c8f8ae 100644 --- a/MdePkg/Library/BaseLib/X64/ReadMm0.asm +++ b/MdePkg/Library/BaseLib/X64/ReadMm0.asm @@ -31,6 +31,9 @@ ; );
;------------------------------------------------------------------------------
AsmReadMm0 PROC
+ ;
+ ; 64-bit MASM doesn't support MMX instructions, so use opcode here
+ ;
DB 48h, 0fh, 7eh, 0c0h
ret
AsmReadMm0 ENDP
diff --git a/MdePkg/Library/BaseLib/X64/ReadMm1.asm b/MdePkg/Library/BaseLib/X64/ReadMm1.asm index 5da8c4f9e5..e24fcb5f9d 100644 --- a/MdePkg/Library/BaseLib/X64/ReadMm1.asm +++ b/MdePkg/Library/BaseLib/X64/ReadMm1.asm @@ -31,6 +31,9 @@ ; );
;------------------------------------------------------------------------------
AsmReadMm1 PROC
+ ;
+ ; 64-bit MASM doesn't support MMX instructions, so use opcode here
+ ;
DB 48h, 0fh, 7eh, 0c8h
ret
AsmReadMm1 ENDP
diff --git a/MdePkg/Library/BaseLib/X64/ReadMm2.asm b/MdePkg/Library/BaseLib/X64/ReadMm2.asm index 3b2b1e3af3..860326b375 100644 --- a/MdePkg/Library/BaseLib/X64/ReadMm2.asm +++ b/MdePkg/Library/BaseLib/X64/ReadMm2.asm @@ -31,6 +31,9 @@ ; );
;------------------------------------------------------------------------------
AsmReadMm2 PROC
+ ;
+ ; 64-bit MASM doesn't support MMX instructions, so use opcode here
+ ;
DB 48h, 0fh, 7eh, 0d0h
ret
AsmReadMm2 ENDP
diff --git a/MdePkg/Library/BaseLib/X64/ReadMm3.asm b/MdePkg/Library/BaseLib/X64/ReadMm3.asm index 6283c30285..aca6f3d2df 100644 --- a/MdePkg/Library/BaseLib/X64/ReadMm3.asm +++ b/MdePkg/Library/BaseLib/X64/ReadMm3.asm @@ -31,6 +31,9 @@ ; );
;------------------------------------------------------------------------------
AsmReadMm3 PROC
+ ;
+ ; 64-bit MASM doesn't support MMX instructions, so use opcode here
+ ;
DB 48h, 0fh, 7eh, 0d8h
ret
AsmReadMm3 ENDP
diff --git a/MdePkg/Library/BaseLib/X64/ReadMm4.asm b/MdePkg/Library/BaseLib/X64/ReadMm4.asm index a65f130283..dd52f99436 100644 --- a/MdePkg/Library/BaseLib/X64/ReadMm4.asm +++ b/MdePkg/Library/BaseLib/X64/ReadMm4.asm @@ -31,6 +31,9 @@ ; );
;------------------------------------------------------------------------------
AsmReadMm4 PROC
+ ;
+ ; 64-bit MASM doesn't support MMX instructions, so use opcode here
+ ;
DB 48h, 0fh, 7eh, 0e0h
ret
AsmReadMm4 ENDP
diff --git a/MdePkg/Library/BaseLib/X64/ReadMm5.asm b/MdePkg/Library/BaseLib/X64/ReadMm5.asm index 5295c38ae0..1f30e4bed4 100644 --- a/MdePkg/Library/BaseLib/X64/ReadMm5.asm +++ b/MdePkg/Library/BaseLib/X64/ReadMm5.asm @@ -31,6 +31,9 @@ ; );
;------------------------------------------------------------------------------
AsmReadMm5 PROC
+ ;
+ ; 64-bit MASM doesn't support MMX instructions, so use opcode here
+ ;
DB 48h, 0fh, 7eh, 0e8h
ret
AsmReadMm5 ENDP
diff --git a/MdePkg/Library/BaseLib/X64/ReadMm6.asm b/MdePkg/Library/BaseLib/X64/ReadMm6.asm index acdc99b888..4e1f2a824b 100644 --- a/MdePkg/Library/BaseLib/X64/ReadMm6.asm +++ b/MdePkg/Library/BaseLib/X64/ReadMm6.asm @@ -31,6 +31,9 @@ ; );
;------------------------------------------------------------------------------
AsmReadMm6 PROC
+ ;
+ ; 64-bit MASM doesn't support MMX instructions, so use opcode here
+ ;
DB 48h, 0fh, 7eh, 0f0h
ret
AsmReadMm6 ENDP
diff --git a/MdePkg/Library/BaseLib/X64/ReadMm7.asm b/MdePkg/Library/BaseLib/X64/ReadMm7.asm index 7a1b4e6111..d871a9f8dc 100644 --- a/MdePkg/Library/BaseLib/X64/ReadMm7.asm +++ b/MdePkg/Library/BaseLib/X64/ReadMm7.asm @@ -31,6 +31,9 @@ ; );
;------------------------------------------------------------------------------
AsmReadMm7 PROC
+ ;
+ ; 64-bit MASM doesn't support MMX instructions, so use opcode here
+ ;
DB 48h, 0fh, 7eh, 0f8h
ret
AsmReadMm7 ENDP
diff --git a/MdePkg/Library/BaseLib/X64/Thunk16.asm b/MdePkg/Library/BaseLib/X64/Thunk16.asm index 642310869b..556a8b47e3 100644 --- a/MdePkg/Library/BaseLib/X64/Thunk16.asm +++ b/MdePkg/Library/BaseLib/X64/Thunk16.asm @@ -66,6 +66,14 @@ SavedGdt LABEL FWORD ; by user code. It will be shadowed to somewhere in memory below 1MB.
;------------------------------------------------------------------------------
_BackFromUserCode PROC
+ ;
+ ; The order of saved registers on the stack matches the order they appears
+ ; in IA32_REGS structure. This facilitates wrapper function to extract them
+ ; into that structure.
+ ;
+ ; Some instructions for manipulation of segment registers have to be written
+ ; in opcode since 64-bit MASM prevents accesses to those registers.
+ ;
DB 16h ; push ss
DB 0eh ; push cs
DB 66h
@@ -115,7 +123,7 @@ SavedCr4 DD ? ;
; rdi in the instruction below is indeed bx in 16-bit code
;
- DB 66h, 2eh
+ DB 66h, 2eh ; 2eh is "cs:" segment override
lgdt fword ptr [rdi + (SavedGdt - @Base)]
DB 66h
mov ecx, 0c0000080h
@@ -129,9 +137,8 @@ SavedCr0 DD ? @64Eip DD ?
SavedCs DW ?
@64BitCode:
- DB 48h, 0b8h ; mov rax, imm64
-SavedRip DQ ?
- jmp rax ; return to caller
+ mov rsp, r8 ; restore stack
+ ret
_BackFromUserCode ENDP
_EntryPoint DD _ToUserCode - m16Start
@@ -160,14 +167,14 @@ _ToUserCode PROC mov cr4, rbp
mov ss, esi ; set up 16-bit stack segment
mov sp, bx ; set up 16-bit stack pointer
- DB 66h
+ DB 66h ; make the following call 32-bit
call @Base ; push eip
@Base:
pop bp ; ebp <- address of @Base
push [esp + sizeof (IA32_REGS) + 2]
- lea eax, [rsi + (@RealMode - @Base)]
+ lea eax, [rsi + (@RealMode - @Base)] ; rsi is "bp" in 16-bit code
push rax
- retf
+ retf ; execution begins at next instruction
@RealMode:
DB 66h, 2eh ; CS and operand size override
lidt fword ptr [rsi + (_16Idtr - @Base)]
@@ -178,7 +185,7 @@ _ToUserCode PROC pop gs
popf ; popfd
lea sp, [esp + 4] ; skip high order 32 bits of EFlags
- DB 66h
+ DB 66h ; make the following retf 32-bit
retf ; transfer control to user code
_ToUserCode ENDP
@@ -220,8 +227,8 @@ GDT_SIZE = $ - _NullSeg ; );
;------------------------------------------------------------------------------
InternalAsmThunk16 PROC USES rbp rbx rsi rdi
- mov r10d, ds
- mov r11d, es
+ mov r10d, ds ; r9 ~ r11 are not accessible in 16-bit
+ mov r11d, es ; so use them for saving seg registers
mov r9d, ss
push fs
push gs
@@ -238,8 +245,8 @@ InternalAsmThunk16 PROC USES rbp rbx rsi rdi lea ecx, [rdx + (SavedCr4 - m16Start)]
mov eax, edx ; eax <- transition code address
and edx, 0fh
- shl eax, 12
- lea ax, [rdx + (_BackFromUserCode - m16Start)]
+ shl eax, 12 ; segment address in high order 16 bits
+ lea ax, [rdx + (_BackFromUserCode - m16Start)] ; offset address
stosd ; [edi] <- return address of user code
sgdt fword ptr [rcx + (SavedGdt - SavedCr4)]
sidt fword ptr [rsp + 38h] ; save IDT stack in argument space
@@ -257,13 +264,12 @@ InternalAsmThunk16 PROC USES rbp rbx rsi rdi pushfq
lea edx, [rdx + DATA16 - DATA32]
lea r8, @RetFromRealMode
- mov [rcx + (SavedRip - SavedCr4)], r8
+ push r8
mov r8d, cs
mov [rcx + (SavedCs - SavedCr4)], r8w
mov r8, rsp
jmp fword ptr [rcx + (_EntryPoint - SavedCr4)]
@RetFromRealMode:
- mov rsp, r8
popfq
lidt fword ptr [rsp + 38h] ; restore protected mode IDTR
lea eax, [rbp - sizeof (IA32_REGS)]
diff --git a/MdePkg/Library/BaseLib/X64/WriteDr4.asm b/MdePkg/Library/BaseLib/X64/WriteDr4.asm index ad618f1089..188a9d4ddc 100644 --- a/MdePkg/Library/BaseLib/X64/WriteDr4.asm +++ b/MdePkg/Library/BaseLib/X64/WriteDr4.asm @@ -31,6 +31,10 @@ ; );
;------------------------------------------------------------------------------
AsmWriteDr4 PROC
+ ;
+ ; There's no obvious reason to access this register, since it's aliased to
+ ; DR6 when DE=0 or an exception generated when DE=1
+ ;
DB 0fh, 23h, 0e1h
mov rax, rcx
ret
diff --git a/MdePkg/Library/BaseLib/X64/WriteDr5.asm b/MdePkg/Library/BaseLib/X64/WriteDr5.asm index 91eeef20e3..86009c3287 100644 --- a/MdePkg/Library/BaseLib/X64/WriteDr5.asm +++ b/MdePkg/Library/BaseLib/X64/WriteDr5.asm @@ -31,6 +31,10 @@ ; );
;------------------------------------------------------------------------------
AsmWriteDr5 PROC
+ ;
+ ; There's no obvious reason to access this register, since it's aliased to
+ ; DR7 when DE=0 or an exception generated when DE=1
+ ;
DB 0fh, 23h, 0e9h
mov rax, rcx
ret
diff --git a/MdePkg/Library/BaseLib/X64/WriteMm0.asm b/MdePkg/Library/BaseLib/X64/WriteMm0.asm index 0ad65e366d..7496362d86 100644 --- a/MdePkg/Library/BaseLib/X64/WriteMm0.asm +++ b/MdePkg/Library/BaseLib/X64/WriteMm0.asm @@ -31,6 +31,9 @@ ; );
;------------------------------------------------------------------------------
AsmWriteMm0 PROC
+ ;
+ ; 64-bit MASM doesn't support MMX instructions, so use opcode here
+ ;
DB 48h, 0fh, 6eh, 0c1h
ret
AsmWriteMm0 ENDP
diff --git a/MdePkg/Library/BaseLib/X64/WriteMm1.asm b/MdePkg/Library/BaseLib/X64/WriteMm1.asm index 66425a43c2..a00f551f8a 100644 --- a/MdePkg/Library/BaseLib/X64/WriteMm1.asm +++ b/MdePkg/Library/BaseLib/X64/WriteMm1.asm @@ -31,6 +31,9 @@ ; );
;------------------------------------------------------------------------------
AsmWriteMm1 PROC
+ ;
+ ; 64-bit MASM doesn't support MMX instructions, so use opcode here
+ ;
DB 48h, 0fh, 6eh, 0c9h
ret
AsmWriteMm1 ENDP
diff --git a/MdePkg/Library/BaseLib/X64/WriteMm2.asm b/MdePkg/Library/BaseLib/X64/WriteMm2.asm index bd0f0a0e1a..01db79007d 100644 --- a/MdePkg/Library/BaseLib/X64/WriteMm2.asm +++ b/MdePkg/Library/BaseLib/X64/WriteMm2.asm @@ -31,6 +31,9 @@ ; );
;------------------------------------------------------------------------------
AsmWriteMm2 PROC
+ ;
+ ; 64-bit MASM doesn't support MMX instructions, so use opcode here
+ ;
DB 48h, 0fh, 6eh, 0d1h
ret
AsmWriteMm2 ENDP
diff --git a/MdePkg/Library/BaseLib/X64/WriteMm3.asm b/MdePkg/Library/BaseLib/X64/WriteMm3.asm index fa36ea64bb..59464641eb 100644 --- a/MdePkg/Library/BaseLib/X64/WriteMm3.asm +++ b/MdePkg/Library/BaseLib/X64/WriteMm3.asm @@ -31,6 +31,9 @@ ; );
;------------------------------------------------------------------------------
AsmWriteMm3 PROC
+ ;
+ ; 64-bit MASM doesn't support MMX instructions, so use opcode here
+ ;
DB 48h, 0fh, 6eh, 0d9h
ret
AsmWriteMm3 ENDP
diff --git a/MdePkg/Library/BaseLib/X64/WriteMm4.asm b/MdePkg/Library/BaseLib/X64/WriteMm4.asm index d9bc46e16c..6848dbf7ec 100644 --- a/MdePkg/Library/BaseLib/X64/WriteMm4.asm +++ b/MdePkg/Library/BaseLib/X64/WriteMm4.asm @@ -31,6 +31,9 @@ ; );
;------------------------------------------------------------------------------
AsmWriteMm4 PROC
+ ;
+ ; 64-bit MASM doesn't support MMX instructions, so use opcode here
+ ;
DB 48h, 0fh, 6eh, 0e1h
ret
AsmWriteMm4 ENDP
diff --git a/MdePkg/Library/BaseLib/X64/WriteMm5.asm b/MdePkg/Library/BaseLib/X64/WriteMm5.asm index f268bea8ec..fbe44ae078 100644 --- a/MdePkg/Library/BaseLib/X64/WriteMm5.asm +++ b/MdePkg/Library/BaseLib/X64/WriteMm5.asm @@ -31,6 +31,9 @@ ; );
;------------------------------------------------------------------------------
AsmWriteMm5 PROC
+ ;
+ ; 64-bit MASM doesn't support MMX instructions, so use opcode here
+ ;
DB 48h, 0fh, 6eh, 0e9h
ret
AsmWriteMm5 ENDP
diff --git a/MdePkg/Library/BaseLib/X64/WriteMm6.asm b/MdePkg/Library/BaseLib/X64/WriteMm6.asm index cb32ea6dc3..cd5938828d 100644 --- a/MdePkg/Library/BaseLib/X64/WriteMm6.asm +++ b/MdePkg/Library/BaseLib/X64/WriteMm6.asm @@ -31,6 +31,9 @@ ; );
;------------------------------------------------------------------------------
AsmWriteMm6 PROC
+ ;
+ ; 64-bit MASM doesn't support MMX instructions, so use opcode here
+ ;
DB 48h, 0fh, 6eh, 0f1h
ret
AsmWriteMm6 ENDP
diff --git a/MdePkg/Library/BaseLib/X64/WriteMm7.asm b/MdePkg/Library/BaseLib/X64/WriteMm7.asm index f5713823bb..9636a4cd8d 100644 --- a/MdePkg/Library/BaseLib/X64/WriteMm7.asm +++ b/MdePkg/Library/BaseLib/X64/WriteMm7.asm @@ -31,6 +31,9 @@ ; );
;------------------------------------------------------------------------------
AsmWriteMm7 PROC
+ ;
+ ; 64-bit MASM doesn't support MMX instructions, so use opcode here
+ ;
DB 48h, 0fh, 6eh, 0f9h
ret
AsmWriteMm7 ENDP
diff --git a/MdePkg/Library/BaseLib/X64/WriteMsr64.asm b/MdePkg/Library/BaseLib/X64/WriteMsr64.asm index 6b8066f922..b7704b8185 100644 --- a/MdePkg/Library/BaseLib/X64/WriteMsr64.asm +++ b/MdePkg/Library/BaseLib/X64/WriteMsr64.asm @@ -32,8 +32,8 @@ ; );
;------------------------------------------------------------------------------
AsmWriteMsr64 PROC
- mov rax, rdx
- shr rdx, 20h
+ mov rax, rdx ; meanwhile, rax <- return value
+ shr rdx, 20h ; edx:eax contains the value to write
wrmsr
ret
AsmWriteMsr64 ENDP
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