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-rw-r--r--MdePkg/Library/BaseLib/Ia32/CpuFlushTlb.asm2
-rw-r--r--MdePkg/Library/BaseLib/Ia32/DivU64x32Remainder.asm14
-rw-r--r--MdePkg/Library/BaseLib/Ia32/DivU64x64Remainder.asm20
-rw-r--r--MdePkg/Library/BaseLib/Ia32/EnablePaging32.asm4
-rw-r--r--MdePkg/Library/BaseLib/Ia32/EnablePaging64.asm8
-rw-r--r--MdePkg/Library/BaseLib/Ia32/FxRestore.asm2
-rw-r--r--MdePkg/Library/BaseLib/Ia32/FxSave.asm2
-rw-r--r--MdePkg/Library/BaseLib/Ia32/LongJump.asm2
-rw-r--r--MdePkg/Library/BaseLib/Ia32/MultU64x64.asm14
-rw-r--r--MdePkg/Library/BaseLib/Ia32/RRotU64.asm2
-rw-r--r--MdePkg/Library/BaseLib/Ia32/RShiftU64.asm4
-rw-r--r--MdePkg/Library/BaseLib/Ia32/ReadDr4.asm7
-rw-r--r--MdePkg/Library/BaseLib/Ia32/ReadDr5.asm7
-rw-r--r--MdePkg/Library/BaseLib/Ia32/SetJump.asm6
-rw-r--r--MdePkg/Library/BaseLib/Ia32/SwapBytes64.asm4
-rw-r--r--MdePkg/Library/BaseLib/Ia32/Thunk16.asm18
-rw-r--r--MdePkg/Library/BaseLib/Ia32/WriteDr4.asm7
-rw-r--r--MdePkg/Library/BaseLib/Ia32/WriteDr5.asm7
18 files changed, 84 insertions, 46 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
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-08 06:01:12 +0000