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