62 lines
1.0 KiB
ArmAsm
62 lines
1.0 KiB
ArmAsm
|
/* Return to Userspace (from thread creation) */
|
||
|
|
|
||
|
|
.global return_to_userspace
|
||
|
|
.type return_to_userspace, @function
|
||
|
|
|
||
|
|
return_to_userspace:
|
||
|
|
pop %gs
|
||
|
|
pop %fs
|
||
|
|
pop %es
|
||
|
|
pop %ds
|
||
|
|
popa
|
||
|
|
add $8, %esp
|
||
|
|
iret
|
||
|
|
|
||
|
|
/* Enter userspace (ring3) */
|
||
|
|
.global enter_userspace
|
||
|
|
.type enter_userspace, @function
|
||
|
|
|
||
|
|
.set MAGIC, 0xDECADE21
|
||
|
|
|
||
|
|
enter_userspace:
|
||
|
|
pushl %ebp
|
||
|
|
mov %esp, %ebp
|
||
|
|
mov 0xC(%ebp), %edx
|
||
|
|
mov %edx, %esp
|
||
|
|
pushl $MAGIC
|
||
|
|
|
||
|
|
/* Segement selector */
|
||
|
|
mov $0x23,%ax
|
||
|
|
|
||
|
|
/* Save segement registers */
|
||
|
|
mov %eax, %ds
|
||
|
|
mov %eax, %es
|
||
|
|
mov %eax, %fs
|
||
|
|
mov %eax, %gs
|
||
|
|
/* %ss is handled by iret */
|
||
|
|
|
||
|
|
/* Store stack address in %eax */
|
||
|
|
mov %esp, %eax
|
||
|
|
|
||
|
|
/* Data segmenet with bottom 2 bits set for ring3 */
|
||
|
|
pushl $0x23
|
||
|
|
|
||
|
|
/* Push the stack address */
|
||
|
|
pushl %eax
|
||
|
|
|
||
|
|
/* Push flags and fix interrupt flag */
|
||
|
|
pushf
|
||
|
|
popl %eax
|
||
|
|
|
||
|
|
/* Request ring3 */
|
||
|
|
orl $0x200, %eax
|
||
|
|
pushl %eax
|
||
|
|
pushl $0x1B
|
||
|
|
|
||
|
|
/* Push entry point */
|
||
|
|
pushl 0x8(%ebp)
|
||
|
|
|
||
|
|
iret
|
||
|
|
popl %ebp
|
||
|
|
ret
|