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.text
.extern begin_userspace
.extern syscall_handler
.set IA32_EFER, 0xc0000080
.set STAR_MSR, 0xc0000081
.set LSTAR_MSR, 0xc0000082
.global jump_userspace
jump_userspace:
mov $0x1b, %ax
mov %ax, %ds
mov %ax, %es
mov %ax, %fs
mov %ax, %gs
mov $LSTAR_MSR, %rcx
movabs $__syscall, %rax
shr $32, %rax
mov %eax, %edx
movabs $__syscall, %rax
wrmsr
mov $IA32_EFER, %rcx
rdmsr
or $1, %eax
wrmsr
mov $STAR_MSR, %rcx
rdmsr
mov $0x00130008, %edx
wrmsr
movabs $begin_userspace, %rcx
mov $0x202, %r11
sysretq
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