CloverBootloader/MemoryFix/OsxAptioFixDrv/X64/AsmFuncsX64.asm

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;------------------------------------------------------------------------------
;
; Some assembler helper functions plus boot.efi kernel jump callback
;
; by dmazar
;
;------------------------------------------------------------------------------
XDTR STRUCT
Limit DW ?
Base DQ ?
XDTR ENDS
; C callback method called on jump to kernel after boot.efi finishes
EXTERN KernelEntryPatchJumpBack:PROC
; saved 64bit state
PUBLIC SavedCR3
PUBLIC SavedGDTR
PUBLIC SavedIDTR
; addresses of relocated MyAsmCopyAndJumpToKernel code - filled by PrepareJumpFromKernel()
PUBLIC MyAsmCopyAndJumpToKernel32Addr
PUBLIC MyAsmCopyAndJumpToKernel64Addr
; kernel entry address - filled by KernelEntryPatchJump()
PUBLIC AsmKernelEntry
; params for kernel image relocation - filled by KernelEntryPatchJumpBack()
PUBLIC AsmKernelImageStartReloc
PUBLIC AsmKernelImageStart
PUBLIC AsmKernelImageSize
; end of MyAsmEntryPatchCode func
PUBLIC MyAsmEntryPatchCodeEnd
; start and end of MyAsmCopyAndJumpToKernel
PUBLIC MyAsmCopyAndJumpToKernel
PUBLIC MyAsmCopyAndJumpToKernel32
PUBLIC MyAsmCopyAndJumpToKernel64
PUBLIC MyAsmCopyAndJumpToKernelEnd
.data
; variables accessed from both 32 and 64 bit code
; need to have this exactly in this order
DataBase:
; 64 bit state
SavedGDTROff EQU $-DataBase
SavedGDTR XDTR <?>
SavedIDTROff EQU $-DataBase
SavedIDTR XDTR <?>
align 08h
SavedCR3Off EQU $-DataBase
SavedCR3 DQ ?
SavedCSOff EQU $-DataBase
SavedCS DW ?
SavedDSOff EQU $-DataBase
SavedDS DW ?
; 32 bit state
SavedGDTR32Off EQU $-DataBase
SavedGDTR32 XDTR <?>
SavedIDTR32Off EQU $-DataBase
SavedIDTR32 XDTR <?>
SavedCS32Off EQU $-DataBase
SavedCS32 DW ?
SavedDS32Off EQU $-DataBase
SavedDS32 DW ?
SavedESP32Off EQU $-DataBase
SavedESP32 DD ?
align 08h
; address of relocated MyAsmCopyAndJumpToKernel32 - 64 bit
MyAsmCopyAndJumpToKernel32AddrOff EQU $-DataBase
MyAsmCopyAndJumpToKernel32Addr DQ 0
; address of relocated MyAsmCopyAndJumpToKernel64 - 64 bit
MyAsmCopyAndJumpToKernel64AddrOff EQU $-DataBase
MyAsmCopyAndJumpToKernel64Addr DQ 0
; kernel entry - 64 bit
AsmKernelEntryOff EQU $-DataBase
AsmKernelEntry DQ 0
;
; for copying kernel image from reloc block to proper mem place
;
; kernel image start in reloc block (source) - 64 bit
AsmKernelImageStartRelocOff EQU $-DataBase
AsmKernelImageStartReloc DQ 0
; kernel image start (destination) - 64 bit
AsmKernelImageStartOff EQU $-DataBase
AsmKernelImageStart DQ 0
; kernel image size - 64 bit
AsmKernelImageSizeOff EQU $-DataBase
AsmKernelImageSize DQ 0
align 08h
; GDT not used since we are reusing UEFI state
; but left here in case will be needed.
;
; GDR record
GDTROff EQU $-DataBase
GDTR dw GDT_END - GDT_BASE - 1 ; GDT limit
GDTR_BASE dq 0 ; GDT base - needs to be set in code
align 08h
; GDT
GDT_BASE:
; null descriptor
NULL_SEL equ $-GDT_BASE ; 0x00
dw 0 ; limit 15:0
dw 0 ; base 15:0
db 0 ; base 23:16
db 0 ; type
db 0 ; limit 19:16, flags
db 0 ; base 31:24
; 64 bit code segment descriptor
CODE64_SEL equ $-GDT_BASE ; 0x08
dw 0FFFFh ; limit 0xFFFFF
dw 0 ; base 0
db 0
db 09Ah ; P=1 | DPL=00 | S=1 (User) # Type=A=1010: Code/Data=1 | C:Conforming=0 | R:Readable=1 | A:Accessed=0
db 0AFh ; Flags=A=1010: G:Granularity=1 (4K) | D:Default Operand Size=0 (in long mode) | L:Long=1 (64 bit) | AVL=0
db 0
; 32 bit and 64 bit data segment descriptor (in 64 bit almost all is ignored, so can be reused)
DATA_SEL equ $-GDT_BASE ; 0x10
dw 0FFFFh ; limit 0xFFFFF
dw 0 ; base 0
db 0
db 092h ; P=1 | DPL=00 | S=1 (User) # Type=2=0010: Code/Data=0 | E:Expand-Down=0 | W:Writable=1 | A:Accessed=0
db 0CFh ; Flags=C=1100: G:Granularity=1 (4K) | D/B=1 D not used when E=0, for stack B=1 means 32 bit stack | L:Long=0 not used | AVL=0
db 0
; 32 bit code segment descriptor
CODE32_SEL equ $-GDT_BASE ; 0x18
dw 0FFFFh ; limit 0xFFFFF
dw 0 ; base 0
db 0
db 09Ah ; P=1 | DPL=00 | S=1 (User) # Type=A=1010: Code/Data=1 | C:Conforming=0 | R:Readable=1 | A:Accessed=0
db 0CFh ; Flags=C=1100: G:Granularity=1 (4K) | D:Default Operand Size=0 (in long mode) | L:Long=0 (32 bit) | AVL=0
db 0
GDT_END:
.code
;------------------------------------------------------------------------------
; UINT64
; EFIAPI
; MyAsmReadSp (
; VOID
; );
;------------------------------------------------------------------------------
MyAsmReadSp PROC
mov rax, rsp
add rax, 8 ; return SP as caller see it
ret
MyAsmReadSp ENDP
;------------------------------------------------------------------------------
; VOID
; EFIAPI
; MyAsmPrepareJumpFromKernel (
; );
;------------------------------------------------------------------------------
MyAsmPrepareJumpFromKernel PROC
; save 64 bit state
sgdt SavedGDTR
sidt SavedIDTR
mov rax, cr3
mov QWORD PTR SavedCR3, rax
mov WORD PTR SavedCS, cs
mov WORD PTR SavedDS, ds
; pass DataBase to 32 bit code
lea rax, DataBase
mov DWORD PTR DataBaseAdr, eax;
; prepare MyAsmEntryPatchCode:
; patch MyAsmEntryPatchCode with address of MyAsmJumpFromKernel
lea rax, MyAsmJumpFromKernel
mov DWORD PTR MyAsmEntryPatchCodeJumpFromKernelPlaceholder, eax
ret
MyAsmPrepareJumpFromKernel ENDP
;------------------------------------------------------------------------------
; Code that is used for patching kernel entry to jump back
; to our code (to MyAsmJumpFromKernel):
; - load ecx (rcx) with address to MyAsmJumpFromKernel
; - jump to MyAsmJumpFromKernel
; The same generated opcode must run properly in both 32 and 64 bit.
; 64 bit:
; - we must set rcx to 0 (upper 4 bytes) before loading ecx with address (lower 4 bytes of rcx)
; - this requires xor %rcx, %rcx
; - and that opcode contains 0x48 in front of 32 bit xor %ecx, %ecx
; 32 bit:
; - 0x48 opcode is dec %eax in 32 bit
; - and then we must inc %eax later if 32 bit is detected in MyAsmJumpFromKernel
;
; This code is patched with address of MyAsmJumpFromKernel
; (into MyAsmEntryPatchCodeJumpFromKernelPlaceholder)
; and then copied to kernel entry address by KernelEntryPatchJump()
;------------------------------------------------------------------------------
MyAsmEntryPatchCode PROC
; .code32
; dec %eax # -> 48
; xor %ecx, %ecx # -> 31 C9
; .byte 0xb9 # movl $0x11223344, %ecx -> B9 44 33 22 11
;MyAsmEntryPatchCodeJumpFromKernelPlaceholder:
; .long 0x11223344
; call *%ecx # -> FF D1
; jmp *%ecx # -> FF E1
xor rcx, rcx ; -> 48 31 (33) C9
db 0B9h ; mov DWORD PTR ecx, $0x11223344 -> B9 44 33 22 11
MyAsmEntryPatchCodeJumpFromKernelPlaceholder dd 011223344h
call rcx ; -> FF D1
; ;jmp *%rcx ; -> FF E1
MyAsmEntryPatchCode ENDP
MyAsmEntryPatchCodeEnd:
;------------------------------------------------------------------------------
; MyAsmJumpFromKernel
;
; Callback from boot.efi - this is where we jump when boot.efi jumps to kernel.
;
; - test if we are in 32 bit or in 64 bit
; - if 64 bit, then jump to MyAsmJumpFromKernel64
; - else just continue with MyAsmJumpFromKernel32
;------------------------------------------------------------------------------
MyAsmJumpFromKernel PROC
; # writing in 32 bit, but code must run in 64 bit also
; .code32
; push %eax # save bootArgs pointer to stack
; movl $0xc0000080, %ecx # EFER MSR number.
; rdmsr # Read EFER.
; bt $8, %eax # Check if LME==1 -> CF=1.
; pop %eax
; jc MyAsmJumpFromKernel64 # LME==1 -> jump to 64 bit code
; # otherwise, continue with MyAsmJumpFromKernel32
; # but first add 1 to it since it was decremented in 32 bit
; # in MyAsmEntryPatchCode
; inc %eax
; above code in 32 bit gives opcode
; that is equivalent to following in 64 bit
push rax ; save bootArgs pointer to stack
mov ecx, 0c0000080h ; EFER MSR number.
rdmsr ; Read EFER.
bt eax, 8 ; Check if LME==1 -> CF=1.
pop rax
jc MyAsmJumpFromKernel64 ; LME==1 -> jump to 64 bit code
; otherwise, continue with MyAsmJumpFromKernel32
; but first add 1 to it since it was decremented in 32 bit
; in MyAsmEntryPatchCode
db 040h ; inc eax
MyAsmJumpFromKernel ENDP
;------------------------------------------------------------------------------
; MyAsmJumpFromKernel32
;
; Callback from boot.efi in 32 bit mode.
; State is prepared for kernel: 32 bit, no paging, pointer to bootArgs in eax.
;
; MS 64 bit compiler generates only 64 bit opcode, but this function needs
; combined 32 and 64 bit code. Code can be written only with 64 bit instructions,
; but generated opcode must be valid 32 bit. This is a big issue.
; Well, I guess I know now how the guys in Intel are feeling when
; they have to work with MS tools on a similar code.
;
; Another problem is that it's not possible to access saved variables
; from 32 bit code (64 bit code has relative addresses, but 32 bit does not
; and depends on fixes during load and that is not happening sice
; generated code is marked 64 bit, or something similar).
; To overcome this, starting address of ou DataBase is passed in runtime - stored
; to DataBaseAdr below as an argument to mov.
;------------------------------------------------------------------------------
MyAsmJumpFromKernel32 PROC
;hlt ; uncomment to stop here for test
; save bootArgs pointer to edi
mov edi, eax
; load ebx with DataBase - we'll access our saved data with it
db 0BBh ; mov ebx, OFFSET DataBase
DataBaseAdr dd 0
; let's find out kernel entry point - we'll need it to jump back.
; we are called with
; dec eax
; xor ecx, ecx
; mov 011223344h, ecx
; call ecx
; and that left return addr on stack. those instructions
; are 10 bytes long, and if we take address from stack and
; substitute 10 from it, we will get kernel entry point.
pop rcx ; 32 bit: pop ecx
sub ecx, 10
; and save it
mov DWORD PTR [rbx + AsmKernelEntryOff], ecx
; lets save 32 bit state to be able to recover it later
; rbx is ebx in 32 bit
sgdt FWORD PTR [rbx + SavedGDTR32Off]
sidt FWORD PTR [rbx + SavedIDTR32Off]
mov WORD PTR [rbx + SavedCS32Off], cs
mov WORD PTR [rbx + SavedDS32Off], ds
mov DWORD PTR [rbx + SavedESP32Off], esp
;
; move to 64 bit mode ...
;
; FIXME: all this with interrupts enabled? no-no
; load saved UEFI GDT, IDT
; will become active after code segment is changed in long jump
; rbx is ebx in 32 bit
lgdt FWORD PTR [rbx + SavedGDTROff]
lidt FWORD PTR [rbx + SavedIDTROff]
; enable the 64-bit page-translation-table entries by setting CR4.PAE=1
mov rax, cr4
bts eax, 5
mov cr4, rax
; set the long-mode page tables - reuse saved UEFI tables
mov eax, DWORD PTR [rbx +SavedCR3Off]
mov cr3, rax
; enable long mode (set EFER.LME=1).
mov ecx, 0c0000080h ; EFER MSR number.
rdmsr ; Read EFER.
bts eax, 8 ; Set LME=1.
wrmsr ; Write EFER.
; enable paging to activate long mode (set CR0.PG=1)
mov rax, cr0 ; Read CR0.
bts eax, 31 ; Set PG=1.
mov cr0, rax ; Write CR0.
; jump to the 64-bit code segment
mov ax, WORD PTR [rbx + SavedCSOff]
push rax
call _RETF32
;
; aloha!
; if there is any luck, we are in 64 bit mode now
;
;hlt ; uncomment to stop here for test
; set segmens
mov ax, WORD PTR [rbx + SavedDSOff]
mov ds, ax
; set up stack ...
; not sure if needed, but lets set ss to ds
mov ss, ax ; disables interrupts for 1 instruction to load rsp
; lets align the stack
; mov rax, rsp
; and rax, 0xfffffffffffffff0
; mov rsp, rax
and rsp, 0xfffffffffffffff0
; call our C code
; (calling conv.: always reserve place for 4 args on stack)
; KernelEntryPatchJumpBack (rcx = rax = bootArgs, rdx = 0 = 32 bit kernel jump)
mov rcx, rdi
xor rdx, rdx
push rdx
push rdx
push rdx
push rcx
; TEST 64 bit jump
; mov rax, rdi
; mov rdx, QWORD PTR AsmKernelEntry
; jmp rdx
; TEST end
; KernelEntryPatchJumpBack should be EFIAPI
; and rbx should not be changed by EFIAPI calling convention
call KernelEntryPatchJumpBack
;hlt ; uncomment to stop here for test
; return value in rax is bootArgs pointer
mov rdi, rax
;
; time to go back to 32 bit
;
; FIXME: all this with interrupts enabled? no-no
; load saved 32 bit gdtr
lgdt FWORD PTR [rbx + SavedGDTR32Off]
; push saved cs and rip (with call) to stack and do retf
mov ax, WORD PTR [rbx + SavedCS32Off]
push rax
call _RETF64
;
; ok, 32 bit opcode again from here
;
; disable paging (set CR0.PG=0)
mov rax, cr0 ; Read CR0.
btr eax, 31 ; Set PG=0.
mov cr0, rax ; Write CR0.
; disable long mode (set EFER.LME=0).
mov ecx, 0c0000080h ; EFER MSR number.
rdmsr ; Read EFER.
btr eax, 8 ; Set LME=0.
wrmsr ; Write EFER.
jmp toNext
toNext:
;
; we are in 32 bit protected mode, no paging
;
; now reload saved 32 bit state data
lidt FWORD PTR [rbx + SavedIDTR32Off]
mov ax, WORD PTR [rbx + SavedDS32Off]
mov ds, ax
mov es, ax
mov fs, ax
mov gs, ax
mov ss, ax ; disables interrupts for 1 instruction to load esp
mov esp, DWORD PTR [rbx + SavedESP32Off]
;
; prepare vars for copying kernel to proper mem
; and jump to kernel: set registers as needed
; by MyAsmCopyAndJumpToKernel32
;
; boot args back from edi
mov eax, edi
; kernel entry point
mov edx, DWORD PTR [rbx + AsmKernelEntryOff]
; source, destination and size for kernel copy
mov esi, DWORD PTR [rbx + AsmKernelImageStartRelocOff]
mov edi, DWORD PTR [rbx + AsmKernelImageStartOff]
mov ecx, DWORD PTR [rbx + AsmKernelImageSizeOff]
; address of relocated MyAsmCopyAndJumpToKernel32
mov ebx, DWORD PTR [rbx + MyAsmCopyAndJumpToKernel32AddrOff]
; note: ebx not valid as a pointer to DataBase any more
;
; jump to MyAsmCopyAndJumpToKernel32
;
jmp QWORD PTR rbx ; jmp DWORD PTR ebx in 32 bit
_RETF64:
DB 048h
_RETF32:
retf
; the following is not used - it's here just for a reference
; jump to the 64-bit code segment
; as xnu kernel does it
; example:
; 07f8437a4: 68 28 00 00 cb = push 0cb000008h - last word on stack is segment 0x0008, 07f8437a8h contains CB opcode which is retf
; 07f8437a9: e8 fa ff ff ff = call 07f8437a8h - push EIP on stack and continue with 07f8437a8h which is retf
; retf does far return to next instr after 'call $-1'
push ((0cbh SHL 24) OR CODE64_SEL)
call $-1
MyAsmJumpFromKernel32 ENDP
;------------------------------------------------------------------------------
; MyAsmJumpFromKernel64
;
; Callback from boot.efi in 64 bit mode.
; State is prepared for kernel: 64 bit, pointer to bootArgs in rax.
;------------------------------------------------------------------------------
MyAsmJumpFromKernel64 PROC
; let's find out kernel entry point - we'll need it to jump back.
pop rcx
sub rcx, 10
; and save it
mov QWORD PTR AsmKernelEntry, rcx
; call our C code
; (calling conv.: always reserve place for 4 args on stack)
; KernelEntryPatchJumpBack (rcx = rax = bootArgs, rdx = 1 = 64 bit kernel jump)
mov rcx, rax
xor rdx, rdx
inc edx
push rdx
push rdx
push rdx
push rcx
; KernelEntryPatchJumpBack should be EFIAPI
call KernelEntryPatchJumpBack
;hlt ; uncomment to stop here for test
; return value in rax is bootArgs pointer
;
; prepare vars for copying kernel to proper mem
; and jump to kernel: set registers as needed
; by MyAsmCopyAndJumpToKernel64
;
; kernel entry point
mov rdx, QWORD PTR AsmKernelEntry
; source, destination and size for kernel copy
mov rsi, QWORD PTR AsmKernelImageStartReloc
mov rdi, QWORD PTR AsmKernelImageStart
mov rcx, QWORD PTR AsmKernelImageSize
; address of relocated MyAsmCopyAndJumpToKernel64
mov rbx, QWORD PTR MyAsmCopyAndJumpToKernel64Addr
;
; jump to MyAsmCopyAndJumpToKernel64
;
jmp rbx
ret
MyAsmJumpFromKernel64 ENDP
;------------------------------------------------------------------------------
; MyAsmCopyAndJumpToKernel
;
; This is the last part of the code - it will copy kernel image from reloc
; block to proper mem place and jump to kernel.
; There are separate versions for 32 and 64 bit.
; This code will be relocated (copied) to higher mem by PrepareJumpFromKernel().
;------------------------------------------------------------------------------
align 08h
MyAsmCopyAndJumpToKernel:
;------------------------------------------------------------------------------
; MyAsmCopyAndJumpToKernel32
;
; Expects:
; EAX = address of boot args (proper address, not from reloc block)
; EDX = kernel entry point
; ESI = start of kernel image in reloc block (source)
; EDI = proper start of kernel image (destination)
; ECX = kernel image size in bytes
;------------------------------------------------------------------------------
MyAsmCopyAndJumpToKernel32 PROC
;
; we will move double words (4 bytes)
; so ajust ECX to number of double words.
; just in case ECX is not multiple of 4 - inc by 1
;
shr ecx, 2
db 041h ; inc ecx
;
; copy kernel image from reloc block to proper mem place.
; all params should be already set:
; ECX = number of double words
; DS:ESI = source
; ES:EDI = destination
;
cld ; direction is up
rep movsd
;
; and finally jump to kernel:
; EAX already contains bootArgs pointer,
; and EDX contains kernel entry point
;
;hlt
jmp QWORD PTR rdx ; jmp DWORD PTR edx in 32 bit
MyAsmCopyAndJumpToKernel32 ENDP
MyAsmCopyAndJumpToKernel32End:
;------------------------------------------------------------------------------
; MyAsmCopyAndJumpToKernel64
;
; Expects:
; RAX = address of boot args (proper address, not from reloc block)
; RDX = kernel entry point
; RSI = start of kernel image in reloc block (source)
; RDI = proper start of kernel image (destination)
; RCX = kernel image size in bytes
;------------------------------------------------------------------------------
align 08h
MyAsmCopyAndJumpToKernel64 PROC
;
; we will move quad words (8 bytes)
; so ajust RCX to number of double words.
; just in case RCX is not multiple of 8 - inc by 1
;
shr rcx, 3
inc rcx
;
; copy kernel image from reloc block to proper mem place.
; all params should be already set:
; RCX = number of double words
; RSI = source
; RDI = destination
;
cld ; direction is up
rep movsq
;
; and finally jump to kernel:
; RAX already contains bootArgs pointer,
; and RDX contains kernel entry point
;
; hlt
jmp QWORD PTR rdx
MyAsmCopyAndJumpToKernel64 ENDP
MyAsmCopyAndJumpToKernel64End:
MyAsmCopyAndJumpToKernelEnd:
END