mirror of
https://github.com/CloverHackyColor/CloverBootloader.git
synced 2024-11-27 12:15:19 +01:00
543 lines
15 KiB
NASM
543 lines
15 KiB
NASM
;------------------------------------------------------------------------------
|
|
;
|
|
; Some assembler helper functions plus boot.efi kernel jump callback
|
|
;
|
|
; by dmazar
|
|
;
|
|
; converted to nasm by Slice, finished by dmazar
|
|
;------------------------------------------------------------------------------
|
|
|
|
struc XDTR
|
|
Limit resw 1
|
|
Base resq 1
|
|
endstruc
|
|
|
|
; C callback method called on jump to kernel after boot.efi finishes
|
|
extern ASM_PFX(KernelEntryPatchJumpBack)
|
|
|
|
; saved 64bit state
|
|
global ASM_PFX(SavedGDTR)
|
|
global ASM_PFX(SavedIDTR)
|
|
global ASM_PFX(SavedCR3)
|
|
|
|
; addresses of relocated JumpToKernel code - filled by PrepareJumpFromKernel()
|
|
global ASM_PFX(JumpToKernel32Addr)
|
|
global ASM_PFX(JumpToKernel64Addr)
|
|
|
|
; kernel entry address - filled by KernelEntryPatchJump()
|
|
global ASM_PFX(AsmKernelEntry)
|
|
|
|
; end of EntryPatchCode func
|
|
global ASM_PFX(EntryPatchCodeEnd)
|
|
|
|
; start and end of JumpToKernel
|
|
global ASM_PFX(JumpToKernel)
|
|
global ASM_PFX(JumpToKernel32)
|
|
global ASM_PFX(JumpToKernel64)
|
|
global ASM_PFX(JumpToKernelEnd)
|
|
|
|
SECTION .text
|
|
|
|
;
|
|
; Adding data to code segment to avoid some error:
|
|
; Undefined symbols for architecture x86_64:
|
|
; "_SavedGDTR", referenced from:
|
|
; _AsmPrepareJumpFromKernel in OsxAptioFixDrv.lib(AsmFuncsX64.obj)
|
|
;
|
|
|
|
; variables accessed from both 32 and 64 bit code
|
|
; need to have this exactly in this order
|
|
DataBase:
|
|
|
|
; 64 bit state
|
|
SavedGDTROff EQU $-DataBase
|
|
ASM_PFX(SavedGDTR):
|
|
dw 0
|
|
dq 0
|
|
|
|
SavedIDTROff EQU $-DataBase
|
|
ASM_PFX(SavedIDTR):
|
|
dw 0
|
|
dq 0
|
|
|
|
align 08h, db 0
|
|
|
|
SavedCR3Off EQU $-DataBase
|
|
ASM_PFX(SavedCR3):
|
|
dq 0
|
|
|
|
SavedCSOff EQU $-DataBase
|
|
SavedCS:
|
|
dw 0
|
|
|
|
SavedDSOff EQU $-DataBase
|
|
SavedDS:
|
|
dw 0
|
|
|
|
; 32 bit state
|
|
SavedGDTR32Off EQU $-DataBase
|
|
SavedGDTR32:
|
|
dw 0
|
|
dq 0
|
|
|
|
SavedIDTR32Off EQU $-DataBase
|
|
SavedIDTR32:
|
|
dw 0
|
|
dq 0
|
|
|
|
SavedCS32Off EQU $-DataBase
|
|
SavedCS32:
|
|
dw 0
|
|
|
|
SavedDS32Off EQU $-DataBase
|
|
SavedDS32:
|
|
dw 0
|
|
|
|
SavedESP32Off EQU $-DataBase
|
|
SavedESP32:
|
|
dd 0
|
|
|
|
align 08h, db 0
|
|
|
|
; address of relocated JumpToKernel32 - 64 bit
|
|
JumpToKernel32AddrOff EQU $-DataBase
|
|
ASM_PFX(JumpToKernel32Addr):
|
|
dq 0
|
|
|
|
; address of relocated JumpToKernel64 - 64 bit
|
|
JumpToKernel64AddrOff EQU $-DataBase
|
|
ASM_PFX(JumpToKernel64Addr):
|
|
dq 0
|
|
|
|
; kernel entry - 64 bit
|
|
AsmKernelEntryOff EQU $-DataBase
|
|
ASM_PFX(AsmKernelEntry):
|
|
dq 0
|
|
|
|
align 08h, db 0
|
|
|
|
; 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, db 0
|
|
|
|
; 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:
|
|
|
|
;SECTION .text
|
|
|
|
;------------------------------------------------------------------------------
|
|
; VOID
|
|
; EFIAPI
|
|
; AsmPrepareJumpFromKernel (
|
|
; );
|
|
;------------------------------------------------------------------------------
|
|
global ASM_PFX(AsmPrepareJumpFromKernel)
|
|
ASM_PFX(AsmPrepareJumpFromKernel):
|
|
BITS 64
|
|
; save 64 bit state
|
|
sgdt [REL ASM_PFX(SavedGDTR)]
|
|
sidt [REL ASM_PFX(SavedIDTR)]
|
|
mov rax, cr3
|
|
mov [REL ASM_PFX(SavedCR3)], rax
|
|
mov word [REL SavedCS], cs
|
|
mov word [REL SavedDS], ds
|
|
|
|
; pass DataBase to 32 bit code
|
|
lea rax, [REL DataBase]
|
|
mov dword [REL DataBaseAdr], eax;
|
|
|
|
; prepare EntryPatchCode:
|
|
; patch EntryPatchCode with address of AsmJumpFromKernel
|
|
lea rax, [REL ASM_PFX(AsmJumpFromKernel)]
|
|
mov dword [REL EntryPatchCodeJumpFromKernelPlaceholder], eax
|
|
|
|
ret
|
|
|
|
;------------------------------------------------------------------------------
|
|
; Code that is used for patching kernel entry to jump back
|
|
; to our code (to AsmJumpFromKernel):
|
|
; - load ecx (rcx) with address to AsmJumpFromKernel
|
|
; - jump to AsmJumpFromKernel
|
|
; 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 AsmJumpFromKernel
|
|
;
|
|
; This code is patched with address of AsmJumpFromKernel
|
|
; (into EntryPatchCodeJumpFromKernelPlaceholder)
|
|
; and then copied to kernel entry address by KernelEntryPatchJump()
|
|
;------------------------------------------------------------------------------
|
|
global ASM_PFX(EntryPatchCode)
|
|
ASM_PFX(EntryPatchCode):
|
|
BITS 32
|
|
dec eax ; -> 48
|
|
xor ecx, ecx ; -> 31 C9
|
|
db 0b9h ; movl $0x11223344, %ecx -> B9 44 33 22 11
|
|
EntryPatchCodeJumpFromKernelPlaceholder:
|
|
dd 011223344h
|
|
call ecx ; -> FF D1
|
|
|
|
;BITS 64
|
|
; xor rcx, rcx ; -> 48 31 C9
|
|
; mov dword ecx, 011223344h ; -> B9 44 33 22 11
|
|
; call rcx ; -> FF D1
|
|
ASM_PFX(EntryPatchCodeEnd):
|
|
|
|
;------------------------------------------------------------------------------
|
|
; AsmJumpFromKernel
|
|
;
|
|
; 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 AsmJumpFromKernel64
|
|
; - else just continue with AsmJumpFromKernel32
|
|
;------------------------------------------------------------------------------
|
|
global ASM_PFX(AsmJumpFromKernel)
|
|
ASM_PFX(AsmJumpFromKernel):
|
|
; writing in 32 bit, but code must run in 64 bit also
|
|
BITS 32
|
|
push eax ; save bootArgs pointer to stack
|
|
mov dword ecx, 0c0000080h ; EFER MSR number.
|
|
rdmsr ; Read EFER.
|
|
bt eax, 8 ; Check if LME==1 -> CF=1.
|
|
pop eax
|
|
jc AsmJumpFromKernel64 ; LME==1 -> jump to 64 bit code
|
|
; otherwise, continue with AsmJumpFromKernel32
|
|
; but first add 1 to it since it was decremented in 32 bit
|
|
; in EntryPatchCode
|
|
inc eax
|
|
|
|
; test the above code in 64 bit - above 32 bit code gives opcode
|
|
; that is equivalent to following in 64 bit
|
|
;BITS 64
|
|
; push rax ; save bootArgs pointer to stack
|
|
; movl ecx, 0c0000080h ; EFER MSR number.
|
|
; rdmsr ; Read EFER.
|
|
; bt eax, 8 ; Check if LME==1 -> CF=1.
|
|
; pop rax
|
|
; jc AsmJumpFromKernel64 ; LME==1 -> jump to 64 bit code
|
|
|
|
;------------------------------------------------------------------------------
|
|
; AsmJumpFromKernel32
|
|
;
|
|
; 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.
|
|
;------------------------------------------------------------------------------
|
|
AsmJumpFromKernel32:
|
|
BITS 32
|
|
; 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 ecx, 011223344h
|
|
; 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 ecx ; 32 bit: pop ecx
|
|
sub ecx, 10
|
|
; and save it
|
|
mov dword [ebx + AsmKernelEntryOff], ecx
|
|
|
|
; lets save 32 bit state to be able to recover it later
|
|
sgdt [ebx + SavedGDTR32Off]
|
|
sidt [ebx + SavedIDTR32Off]
|
|
mov word [ebx + SavedCS32Off], cs
|
|
mov word [ebx + SavedDS32Off], ds
|
|
mov dword [ebx + 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 [ebx + SavedGDTROff]
|
|
lidt [ebx + SavedIDTROff]
|
|
|
|
; enable the 64-bit page-translation-table entries by setting CR4.PAE=1
|
|
mov eax, cr4
|
|
bts eax, 5
|
|
mov cr4, eax
|
|
|
|
; set the long-mode page tables - reuse saved UEFI tables
|
|
mov eax, dword [ebx + SavedCR3Off]
|
|
mov cr3, eax
|
|
|
|
; 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 eax, cr0 ; Read CR0.
|
|
bts eax, 31 ; Set PG=1.
|
|
mov cr0, eax ; Write CR0.
|
|
|
|
; jump to the 64-bit code segment
|
|
mov ax, word [ebx + SavedCSOff]
|
|
push eax
|
|
call _RETF32
|
|
|
|
;
|
|
; aloha!
|
|
; if there is any luck, we are in 64 bit mode now
|
|
;
|
|
|
|
BITS 64
|
|
|
|
; set segmens
|
|
mov ax, word [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
|
|
and rsp, 0fffffffffffffff0h
|
|
|
|
; 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
|
|
|
|
; KernelEntryPatchJumpBack should be EFIAPI
|
|
; and rbx should not be changed by EFIAPI calling convention
|
|
call ASM_PFX(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 [rbx + SavedGDTR32Off]
|
|
; push saved cs and rip (with call) to stack and do retf
|
|
mov ax, WORD [rbx + SavedCS32Off]
|
|
push rax
|
|
call _RETF64
|
|
|
|
;
|
|
; ok, 32 bit opcode again from here
|
|
;
|
|
|
|
BITS 32
|
|
|
|
; disable paging (set CR0.PG=0)
|
|
mov eax, cr0 ; Read CR0.
|
|
btr eax, 31 ; Set PG=0.
|
|
mov cr0, eax ; 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 [ebx + SavedIDTR32Off]
|
|
mov ax, word [ebx + 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 [ebx + SavedESP32Off]
|
|
|
|
; prepare jump to kernel: set registers as needed by JumpToKernel32
|
|
|
|
; boot args back from edi
|
|
mov eax, edi
|
|
; kernel entry point
|
|
mov edx, dword [ebx + AsmKernelEntryOff]
|
|
|
|
; address of relocated JumpToKernel32
|
|
mov ebx, dword [ebx + JumpToKernel32AddrOff]
|
|
; note: ebx not valid as a pointer to DataBase any more
|
|
|
|
; jump to JumpToKernel32
|
|
jmp ebx
|
|
|
|
_RETF64:
|
|
db 048h
|
|
_RETF32:
|
|
retf
|
|
|
|
;------------------------------------------------------------------------------
|
|
; AsmJumpFromKernel64
|
|
;
|
|
; Callback from boot.efi in 64 bit mode.
|
|
; State is prepared for kernel: 64 bit, pointer to bootArgs in rax.
|
|
;------------------------------------------------------------------------------
|
|
AsmJumpFromKernel64:
|
|
BITS 64
|
|
; let's find out kernel entry point - we'll need it to jump back.
|
|
pop rcx
|
|
sub rcx, 10
|
|
; and save it
|
|
mov qword [REL ASM_PFX(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 ASM_PFX(KernelEntryPatchJumpBack)
|
|
; return value in rax is bootArgs pointer
|
|
|
|
; prepare to jump to kernel: set registers as needed by JumpToKernel64
|
|
|
|
; kernel entry point
|
|
mov rdx, [REL ASM_PFX(AsmKernelEntry)]
|
|
|
|
; address of relocated JumpToKernel64
|
|
mov rbx, [REL ASM_PFX(JumpToKernel64Addr)]
|
|
|
|
; jump to JumpToKernel64
|
|
jmp rbx
|
|
;AsmJumpFromKernel64 ENDP
|
|
|
|
;------------------------------------------------------------------------------
|
|
; JumpToKernel
|
|
;
|
|
; This is the last part of the code - it will 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
|
|
global ASM_PFX(JumpToKernel)
|
|
ASM_PFX(JumpToKernel):
|
|
|
|
;------------------------------------------------------------------------------
|
|
; JumpToKernel32
|
|
;
|
|
; Expects:
|
|
; EAX = address of boot args (proper address, not from reloc block)
|
|
; EDX = kernel entry point
|
|
;------------------------------------------------------------------------------
|
|
global ASM_PFX(JumpToKernel32)
|
|
ASM_PFX(JumpToKernel32):
|
|
BITS 32
|
|
; Jump to kernel:
|
|
; EAX already contains bootArgs pointer,
|
|
; and EDX contains kernel entry point
|
|
jmp edx
|
|
;JumpToKernel32 ENDP
|
|
JumpToKernel32End:
|
|
|
|
;------------------------------------------------------------------------------
|
|
; JumpToKernel64
|
|
;
|
|
; Expects:
|
|
; RAX = address of boot args (proper address, not from reloc block)
|
|
; RDX = kernel entry point
|
|
;------------------------------------------------------------------------------
|
|
align 08h
|
|
global ASM_PFX(JumpToKernel64)
|
|
ASM_PFX(JumpToKernel64):
|
|
BITS 64
|
|
; Jump to kernel:
|
|
; RAX already contains bootArgs pointer,
|
|
; and RDX contains kernel entry point
|
|
jmp rdx
|
|
;JumpToKernel64 ENDP
|
|
JumpToKernel64End:
|
|
|
|
global ASM_PFX(JumpToKernelEnd)
|
|
ASM_PFX(JumpToKernelEnd):
|
|
;END
|