Fennix/Kernel/Architecture/amd64/SystemCallsAssemblyStub.asm
2024-11-20 05:18:19 +02:00

60 lines
1.4 KiB
NASM

[BITS 64]
%macro PushAllSC 0
push rax
push rbx
push rcx
push rdx
push rsi
push rdi
push rbp
push r8
push r9
push r10
push r11
push r12
push r13
push r14
push r15
%endmacro
%macro PopAllSC 0
pop r15
pop r14
pop r13
pop r12
pop r11
pop r10
pop r9
pop r8
pop rbp
pop rdi
pop rsi
pop rdx
pop rcx
pop rbx
%endmacro
ALIGN 4096
extern SystemCallsHandler
global SystemCallHandlerStub
SystemCallHandlerStub:
swapgs ; Swap gs and kernelgs
mov [gs:0x8], rsp ; CPUData->TempStack
mov rsp, [gs:0x0] ; CPUData->SystemCallStack
push qword 0x1b ; User data segment
push qword [gs:0x8] ; Saved stack
push r11 ; Saved rflags
push qword 0x23 ; User code segment
push rcx ; Current instruction pointer
cld ; Clear direction flag
PushAllSC ; Push all registers
mov rdi, rsp ; Pass pointer to registers
mov rbp, 0 ; Pass 0 as return address
call SystemCallsHandler ; Call system call handler
PopAllSC ; Pop all registers except rax
mov rsp, [gs:0x8] ; Restore stack
swapgs ; Swap back gs and kernelgs
sti ; Enable interrupts
o64 sysret ; Return to user mode