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/* TODO include gdt.h */
.set SEG_r0code, 1
.set SEG_r3code, 3
.set SEG_r3data, 4
.set IA32_SYSENTER_CS, 0x174
.set IA32_SYSENTER_ESP, 0x175
.set IA32_SYSENTER_EIP, 0x176
.section .text
.global sysenter_setup
.type sysenter_setup, @function
sysenter_setup:
xor %rdx, %rdx
mov $(SEG_r0code << 3), %rax
mov $IA32_SYSENTER_CS, %rcx
wrmsr
mov $IA32_SYSENTER_ESP, %rcx
mov $0, %rax // unused
wrmsr
mov $IA32_SYSENTER_EIP, %rcx
mov $sysenter_stage1, %rax
wrmsr
ret
.section .shared
.global stored_eax
stored_eax:
.long 0
.global pagedir_current
// a hack to maintain compat with the old arch api, TODO
pagedir_current:
.long 0
.global _sysexit_real
.type _sysexit_real, @function
_sysexit_real:
xchgw %bx, %bx
mov $(SEG_r3data << 3 | 3), %ax
mov %ax, %ds
mov %ax, %es
mov %ax, %fs
mov %ax, %gs
// restore the registers
mov $_sysexit_regs, %rsp
pop %rdi
pop %rsi
pop %rbp
add $8, %rsp
pop %rbx
pop %rdx
pop %rcx
pop %rax
// enable paging
// %rsp used as a scratch register
mov (pagedir_current), %rsp
mov %rsp, %cr3
sysexit
sysenter_stage1:
cli /* prevent random IRQs in the middle of kernel code */
xchgw %bx, %bx
// disable paging
// I don't want to damage any of the registers passed in by the user,
// so i'm using ESP as a temporary register. At this point there's nothing
// useful in it, it's == _bss_end.
mov %cr0, %rsp
and $0x7FFFFFFF, %rsp // disable paging
mov %rsp, %cr0
// save the registers
mov $(_sysexit_regs + 64), %rsp
push %rax
push %rcx
push %rdx
push %rbx
push $0x0 // pushal pushes %rsp here, but that's worthless
push %rbp
push %rsi
push %rdi
mov $_bss_end, %rsp
jmp sysenter_stage2
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