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redesign of the boot code

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This commit is contained in:
Stefan Lankes 2015-07-30 22:06:15 +02:00
parent e6e0f918b7
commit c43964872e
2 changed files with 18 additions and 14 deletions
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10
hermit/arch/x86/kernel/entry.asm
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@ -104,7 +104,7 @@ start64:
sub rax, kernel_start
add rax, [base]
mov QWORD [rdi+511*8], rax
; remap kernel
mov rdi, kernel_start
shr rdi, 18 ; (edi >> 21) * 8 (index for boot_pgd)
@ -313,8 +313,8 @@ global isrsyscall
align 16
; used to realize system calls
isrsyscall:
; IF flag is already cleared
; cli
; IF flag is already cleared
; cli
; only called from user space => get kernel-level selector
swapgs
; get kernel stack
@ -334,8 +334,8 @@ isrsyscall:
push rdi
push rsi
; push system call number
; push rax
; push system call number
; push rax
; syscall stores in rcx the return address
; => using of r10 for the temporary storage of the 4th argument

22
hermit/tools/init.asm
View file

@ -72,6 +72,10 @@ datasel equ $-gdt
gdt_end:
ALIGN 4
GDTR64:
dw GDT64_end - GDT64 - 1 ; Limit.
dq GDT64 ; Base.
; we need a new GDT to switch in the 64bit modus
GDT64: ; Global Descriptor Table (64-bit).
.Null: equ $ - GDT64 ; The null descriptor.
@ -95,9 +99,7 @@ GDT64: ; Global Descriptor Table (64-bit).
db 10010010b ; Access.
db 00000000b ; Granularity.
db 0 ; Base (high).
.Pointer: ; The GDT-pointer.
dw $ - GDT64 - 1 ; Limit.
dq GDT64 ; Base.
GDT64_end:
ALIGN 4
stublet:
@ -141,15 +143,17 @@ cpu_init:
; initialize page tables
; map kernel at link address, use a page size of 2M
mov eax, 0x00 ; dummy value
mov eax, 0x00 ; lower part of the page addres, Linux will relocate this value
and eax, 0xFFE00000
or eax, 0x183
mov ebx, 0x00 ; higher part of the page address, Linux will relocate this value
mov edi, kernel_start
and edi, 0xFFE00000
shr edi, 18 ; (edi >> 21) * 8 (index for boot_pgd)
add edi, boot_pgd
add edi, ebp
or eax, 0x183
mov DWORD [edi], eax
mov DWORD [edi+4], ebx
; check for long mode
@ -205,21 +209,21 @@ cpu_init:
; Set CR0 (PM-bit is already set)
mov eax, cr0
and eax, ~(1 << 2) ; disable FPU emulation
or eax, (1 << 1) ; enable FPU montitoring
or eax, (1 << 1) ; enable FPU montitoring
and eax, ~(1 << 30) ; enable caching
and eax, ~(1 << 29) ; disable write through caching
and eax, ~(1 << 16) ; allow kernel write access to read-only pages
or eax, (1 << 31) ; enable paging
mov cr0, eax
lgdt [GDT64.Pointer] ; Load the 64-bit global descriptor table.
lgdt [GDTR64] ; Load the 64-bit global descriptor table.
jmp GDT64.Code:start64 ; Set the code segment and enter 64-bit long mode.
[BITS 64]
ALIGN 8
start64:
mov rax, kernel_start
jmp rax
push kernel_start
ret
ALIGN 16
global boot_stack