2008-06-04 22:09:59 +02:00
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/*
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* Interrupt Descriptor Table (IDT) setup and interrupt handlers for GDB stub.
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*/
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#include <virtaddr.h>
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#define SIZEOF_I386_REGS 32
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#define SIZEOF_I386_FLAGS 4
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/****************************************************************************
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* Interrupt Descriptor Table
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****************************************************************************
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*/
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.section ".data16"
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.globl idtr
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idtr:
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idt_limit:
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.word idt_length - 1
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idt_base:
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.long 0
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/* IDT entries have the following format:
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* offset_lo, segment selector, flags, offset_hi
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*
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* Since it is not possible to specify relocations in arbitrary
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* expressions like (int_overflow & 0xffff), we initialise the
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* IDT with entries in an incorrect format.
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*
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* The entries are shuffled into the correct format in init_librm().
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*/
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#define IDT_ENTRY_EMPTY(name) .word 0, 0, 0, 0
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#define IDT_ENTRY_PRESENT(name) \
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.long int_##name; \
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.word 0x8e00, VIRTUAL_CS
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.align 16
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idt:
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IDT_ENTRY_PRESENT(divide_error)
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IDT_ENTRY_PRESENT(debug_trap)
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IDT_ENTRY_EMPTY(non_maskable_interrupt)
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IDT_ENTRY_PRESENT(breakpoint)
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IDT_ENTRY_PRESENT(overflow)
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IDT_ENTRY_PRESENT(bound_range_exceeded)
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IDT_ENTRY_PRESENT(invalid_opcode)
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IDT_ENTRY_EMPTY(device_not_available)
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IDT_ENTRY_PRESENT(double_fault)
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IDT_ENTRY_EMPTY(coprocessor_segment_overrun)
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IDT_ENTRY_PRESENT(invalid_tss)
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IDT_ENTRY_PRESENT(segment_not_present)
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IDT_ENTRY_PRESENT(stack_segment_fault)
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IDT_ENTRY_PRESENT(general_protection)
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IDT_ENTRY_PRESENT(page_fault)
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idt_end:
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.equ idt_length, idt_end - idt
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/* The IDT entries are fixed up (once) in init_librm() */
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idt_fixed:
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.byte 0
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/****************************************************************************
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* idt_init (real-mode near call, 16-bit real-mode near return address)
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*
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* Initialise the IDT, called from init_librm.
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*
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* Parameters:
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* %eax : IDT base address
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*
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* Destroys %ax, %bx, and %di.
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****************************************************************************
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*/
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.section ".text16"
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.code16
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.globl idt_init
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idt_init:
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movl %eax, idt_base
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addl $idt, idt_base
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/* IDT entries are only fixed up once */
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movb idt_fixed, %al
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orb %al, %al
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jnz 2f
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movb $1, idt_fixed
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/* Shuffle IDT entries into the correct format */
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movb $(idt_length / 8), %al
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movw $idt, %bx
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or %al, %al
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jz 2f
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1:
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movw 2(%bx), %di
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xchg %di, 6(%bx)
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movw %di, 2(%bx)
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addw $8, %bx
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dec %al
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jnz 1b
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2:
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ret
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/****************************************************************************
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* Interrupt handlers
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****************************************************************************
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*/
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.section ".text"
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.code32
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/* POSIX signal numbers for reporting traps to GDB */
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#define SIGILL 4
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#define SIGTRAP 5
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#define SIGBUS 7
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#define SIGFPE 8
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#define SIGSEGV 11
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#define SIGSTKFLT 16
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int_divide_error:
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pushl $SIGFPE
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jmp do_interrupt
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int_debug_trap:
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int_breakpoint:
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pushl $SIGTRAP
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jmp do_interrupt
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int_overflow:
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int_bound_range_exceeded:
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pushl $SIGSTKFLT
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jmp do_interrupt
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int_invalid_opcode:
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pushl $SIGILL
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jmp do_interrupt
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int_double_fault:
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movl $SIGBUS, (%esp)
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jmp do_interrupt
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int_invalid_tss:
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int_segment_not_present:
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int_stack_segment_fault:
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int_general_protection:
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int_page_fault:
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movl $SIGSEGV, (%esp)
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jmp do_interrupt
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/* When invoked, the stack contains: eflags, cs, eip, signo. */
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#define IH_OFFSET_GDB_REGS ( 0 )
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#define IH_OFFSET_GDB_EIP ( IH_OFFSET_GDB_REGS + SIZEOF_I386_REGS )
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#define IH_OFFSET_GDB_EFLAGS ( IH_OFFSET_GDB_EIP + 4 )
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#define IH_OFFSET_GDB_SEG_REGS ( IH_OFFSET_GDB_EFLAGS + SIZEOF_I386_FLAGS )
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#define IH_OFFSET_GDB_END ( IH_OFFSET_GDB_SEG_REGS + 6 * 4 )
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#define IH_OFFSET_SIGNO ( IH_OFFSET_GDB_END )
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#define IH_OFFSET_OLD_EIP ( IH_OFFSET_SIGNO + 4 )
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#define IH_OFFSET_OLD_CS ( IH_OFFSET_OLD_EIP + 4 )
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#define IH_OFFSET_OLD_EFLAGS ( IH_OFFSET_OLD_CS + 4 )
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#define IH_OFFSET_END ( IH_OFFSET_OLD_EFLAGS + 4 )
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/* We also access the stack whilst still storing or restoring
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* the register snapshot. Since ESP is in flux, we need
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* special offsets.
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*/
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#define IH_OFFSET_FLUX_OLD_CS ( IH_OFFSET_OLD_CS - 44 )
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#define IH_OFFSET_FLUX_OLD_EFLAGS ( IH_OFFSET_OLD_EFLAGS - 40 )
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#define IH_OFFSET_FLUX_OLD_EIP ( IH_OFFSET_OLD_EIP - 36 )
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#define IH_OFFSET_FLUX_END ( IH_OFFSET_END - 20 )
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do_interrupt:
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/* Store CPU state in GDB register snapshot */
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2008-06-13 11:26:49 +02:00
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pushw $0
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pushw %gs
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pushw $0
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pushw %fs
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pushw $0
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pushw %es
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pushw $0
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pushw %ds
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pushw $0
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pushw %ss
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pushw $0
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pushw IH_OFFSET_FLUX_OLD_CS + 2(%esp)
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2008-06-04 22:09:59 +02:00
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pushl IH_OFFSET_FLUX_OLD_EFLAGS(%esp)
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pushl IH_OFFSET_FLUX_OLD_EIP(%esp)
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pushl %edi
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pushl %esi
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pushl %ebp
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leal IH_OFFSET_FLUX_END(%esp), %edi
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pushl %edi /* old ESP */
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pushl %ebx
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pushl %edx
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pushl %ecx
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pushl %eax
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/* Call GDB stub exception handler */
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pushl %esp
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pushl (IH_OFFSET_SIGNO + 4)(%esp)
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2008-06-12 17:56:20 +02:00
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call gdbmach_handler
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2008-06-04 22:09:59 +02:00
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addl $8, %esp
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/* Restore CPU state from GDB register snapshot */
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popl %eax
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popl %ecx
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popl %edx
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popl %ebx
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addl $4, %esp /* Changing ESP currently not supported */
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popl %ebp
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popl %esi
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popl %edi
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popl IH_OFFSET_FLUX_OLD_EIP(%esp)
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popl IH_OFFSET_FLUX_OLD_EFLAGS(%esp)
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popl IH_OFFSET_FLUX_OLD_CS(%esp)
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popl %ss
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popl %ds
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popl %es
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popl %fs
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popl %gs
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addl $4, %esp /* drop signo */
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iret
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