• hjl's avatar
    Implement x86 interrupt attribute · 5ed3cc7b
    hjl authored
    The interrupt and exception handlers are called by x86 processors.  X86
    hardware pushes information onto stack and calls the handler.  The
    requirements are
    
    1. Both interrupt and exception handlers must use the 'IRET' instruction,
    instead of the 'RET' instruction, to return from the handlers.
    2. All registers are callee-saved in interrupt and exception handlers.
    3. The difference between interrupt and exception handlers is the
    exception handler must pop 'ERROR_CODE' off the stack before the 'IRET'
    instruction.
    
    The design goals of interrupt and exception handlers for x86 processors
    are:
    
    1. Support both 32-bit and 64-bit modes.
    2. Flexible for compilers to optimize.
    3. Easy to use by programmers.
    
    To implement interrupt and exception handlers for x86 processors, a
    compiler should support:
    
    'interrupt' attribute
    
    Use this attribute to indicate that the specified function with
    mandatory arguments is an interrupt or exception handler.  The compiler
    generates function entry and exit sequences suitable for use in an
    interrupt handler when this attribute is present.  The 'IRET' instruction,
    instead of the 'RET' instruction, is used to return from interrupt or
    exception handlers.  All registers, except for the EFLAGS register which
    is restored by the 'IRET' instruction, are preserved by the compiler.
    Since GCC doesn't preserve MPX, SSE, MMX nor x87 states, the GCC option,
    -mgeneral-regs-only, should be used to compile interrupt and exception
    handlers.
    
    Note for compiler implementers: If the compiler generates MPX, SSE, MMX
    or x87 instructions in an interrupt or exception handler, or functions
    called from an interrupt or exception handler may contain MPX, SSE, MMX
    or x87 instructions, the compiler must save and restore the corresponding
    state.
    
    Since the direction flag in the FLAGS register in interrupt (exception)
    handlers is undetermined, cld instruction must be emitted in function
    prologue if rep string instructions are used in interrupt (exception)
    handler or interrupt (exception) handler isn't a leaf function.
    
    Any interruptible-without-stack-switch code must be compiled with
    -mno-red-zone since interrupt handlers can and will, because of the
    hardware design, touch the red zone.
    
    1. interrupt handler must be declared with a mandatory pointer argument:
    
    struct interrupt_frame;
    
    __attribute__ ((interrupt))
    void
    f (struct interrupt_frame *frame)
    {
    ...
    }
    
    and user must properly define the structure the pointer pointing to.
    
    2. exception handler:
    
    The exception handler is very similar to the interrupt handler with
    a different mandatory function signature:
    
    typedef unsigned int uword_t __attribute__ ((mode (__word__)));
    
    struct interrupt_frame;
    
    __attribute__ ((interrupt))
    void
    f (struct interrupt_frame *frame, uword_t error_code)
    {
    ...
    }
    
    and compiler pops the error code off stack before the 'IRET' instruction.
    
    The exception handler should only be used for exceptions which push an
    error code and all other exceptions must use the interrupt handler.
    The system will crash if the wrong handler is used.
    
    'no_caller_saved_registers' attribute
    
    Use this attribute to indicate that the specified function has no
    caller-saved registers.  That is, all registers are callee-saved.
    The compiler generates proper function entry and exit sequences to
    save and restore any modified registers, except for the EFLAGS register.
    Since GCC doesn't preserve MPX, SSE, MMX nor x87 states, the GCC option,
    -mgeneral-regs-only, should be used to compile functions with
    'no_caller_saved_registers'attribute.
    
    Note for compiler implementers: If the compiler generates MPX, SSE,
    MMX or x87 instructions in a function with 'no_caller_saved_registers'
    attribute or functions called from a function with
    'no_caller_saved_registers' attribute may contain MPX, SSE, MMX or x87
    instructions, the compiler must save and restore the corresponding state.
    
    The user can call functions specified with 'no_caller_saved_registers'
    attribute from an interrupt handler without saving and restoring all
    call clobbered registers.
    
    On x86, interrupt handlers are only called by processors which push
    interrupt data onto stack at the address where the normal return address
    is.  Interrupt handlers must access interrupt data via pointers so that
    they can update interrupt data.
    
    gcc/
    
    	PR target/66960
    	PR target/67630
    	PR target/67634
    	PR target/67841
    	PR target/68037
    	PR target/68618
    	PR target/68661
    	PR target/69575
    	PR target/69596
    	PR target/69734
    	* config/i386/i386-protos.h (ix86_epilogue_uses): New prototype.
    	* config/i386/i386.c (ix86_conditional_register_usage): Preserve
    	all registers, except for function return registers if there are
    	no caller-saved registers.
    	(ix86_set_func_type): New function.
    	(ix86_set_current_function): Call ix86_set_func_type to set
    	no_caller_saved_registers and func_type.  Call reinit_regs if
    	caller-saved registers are changed.  Don't allow MPX, SSE, MMX
    	nor x87 instructions in interrupt handler nor function with
    	no_caller_saved_registers attribute.
    	(ix86_function_ok_for_sibcall): Return false if there are no
    	caller-saved registers.
    	(type_natural_mode): Don't warn ABI change for MMX in interrupt
    	handler.
    	(ix86_function_arg_advance): Skip for callee in interrupt
    	handler.
    	(ix86_function_arg): Return special arguments in interrupt
    	handler.
    	(ix86_promote_function_mode): Promote pointer to word_mode only
    	for normal functions.
    	(ix86_can_use_return_insn_p): Don't use `ret' instruction in
    	interrupt handler.
    	(ix86_epilogue_uses): New function.
    	(ix86_hard_regno_scratch_ok): Likewise.
    	(ix86_save_reg): Preserve all registers in interrupt handler
    	after reload.  Preserve all registers, except for function
    	return registers, if there are no caller-saved registers after
    	reload.
    	(find_drap_reg): Always use callee-saved register if there are
    	no caller-saved registers.
    	(ix86_minimum_incoming_stack_boundary): Return MIN_STACK_BOUNDARY
    	for interrupt handler.
    	(ix86_expand_prologue): Don't allow DRAP in interrupt handler.
    	Emit cld instruction if stringops are used in interrupt handler
    	or interrupt handler isn't a leaf function.
    	(ix86_expand_epilogue): Generate interrupt return for interrupt
    	handler and pop the 'ERROR_CODE' off the stack before interrupt
    	return in exception handler.
    	(ix86_expand_call): Disallow calling interrupt handler directly.
    	If there are no caller-saved registers, mark all registers that
    	are clobbered by the call which returns as clobbered.
    	(ix86_handle_no_caller_saved_registers_attribute): New function.
    	(ix86_handle_interrupt_attribute): Likewise.
    	(ix86_attribute_table): Add interrupt and no_caller_saved_registers
    	attributes.
    	(TARGET_HARD_REGNO_SCRATCH_OK): Likewise.
    	* config/i386/i386.h (ACCUMULATE_OUTGOING_ARGS): Use argument
    	accumulation in interrupt function if stack may be realigned to
    	avoid DRAP.
    	(EPILOGUE_USES): New.
    	(function_type): New enum.
    	(machine_function): Add func_type and no_caller_saved_registers.
    	* config/i386/i386.md (UNSPEC_INTERRUPT_RETURN): New.
    	(interrupt_return): New pattern.
    	* doc/extend.texi: Document x86 interrupt and
    	no_caller_saved_registers attributes.
    
    gcc/testsuite/
    
    	PR target/66960
    	PR target/67630
    	PR target/67634
    	PR target/67841
    	PR target/68037
    	PR target/68618
    	PR target/68661
    	PR target/69575
    	PR target/69596
    	PR target/69734
    	* gcc.dg/guality/pr68037-1.c: New test.
    	* gcc.dg/guality/pr68037-2.c: Likewise.
    	* gcc.dg/guality/pr68037-3.c: Likewise.
    	* gcc.dg/torture/pr68037-1.c: Likewise.
    	* gcc.dg/torture/pr68037-2.c: Likewise.
    	* gcc.dg/torture/pr68037-3.c: Likewise.
    	* gcc.dg/torture/pr68661-1a.c: Likewise.
    	* gcc.dg/torture/pr68661-1b.c: Likewise.
    	* gcc.target/i386/interrupt-1.c: Likewise.
    	* gcc.target/i386/interrupt-2.c: Likewise.
    	* gcc.target/i386/interrupt-3.c: Likewise.
    	* gcc.target/i386/interrupt-4.c: Likewise.
    	* gcc.target/i386/interrupt-5.c: Likewise.
    	* gcc.target/i386/interrupt-6.c: Likewise.
    	* gcc.target/i386/interrupt-7.c: Likewise.
    	* gcc.target/i386/interrupt-8.c: Likewise.
    	* gcc.target/i386/interrupt-9.c: Likewise.
    	* gcc.target/i386/interrupt-10.c: Likewise.
    	* gcc.target/i386/interrupt-11.c: Likewise.
    	* gcc.target/i386/interrupt-12.c: Likewise.
    	* gcc.target/i386/interrupt-13.c: Likewise.
    	* gcc.target/i386/interrupt-14.c: Likewise.
    	* gcc.target/i386/interrupt-15.c: Likewise.
    	* gcc.target/i386/interrupt-16.c: Likewise.
    	* gcc.target/i386/interrupt-17.c: Likewise.
    	* gcc.target/i386/interrupt-18.c: Likewise.
    	* gcc.target/i386/interrupt-19.c: Likewise.
    	* gcc.target/i386/interrupt-20.c: Likewise.
    	* gcc.target/i386/interrupt-21.c: Likewise.
    	* gcc.target/i386/interrupt-22.c: Likewise.
    	* gcc.target/i386/interrupt-23.c: Likewise.
    	* gcc.target/i386/interrupt-24.c: Likewise.
    	* gcc.target/i386/interrupt-25.c: Likewise.
    	* gcc.target/i386/interrupt-26.c: Likewise.
    	* gcc.target/i386/interrupt-27.c: Likewise.
    	* gcc.target/i386/interrupt-28.c: Likewise.
    	* gcc.target/i386/interrupt-387-err-1.c: Likewise.
    	* gcc.target/i386/interrupt-387-err-2.c: Likewise.
    	* gcc.target/i386/interrupt-bnd-err-1.c: Likewise.
    	* gcc.target/i386/interrupt-bnd-err-2.c: Likewise.
    	* gcc.target/i386/interrupt-iamcu.c: Likewise.
    	* gcc.target/i386/interrupt-mmx-err-1.c: Likewise.
    	* gcc.target/i386/interrupt-mmx-err-2.c: Likewise.
    	* gcc.target/i386/interrupt-redzone-1.c: Likewise.
    	* gcc.target/i386/interrupt-redzone-2.c: Likewise.
    	* gcc.target/i386/interrupt-sibcall-1.c: Likewise.
    	* gcc.target/i386/interrupt-sibcall-2.c: Likewise.
    	* gcc.target/i386/interrupt-switch-abi.c: Likewise.
    
    
    git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@237073 138bc75d-0d04-0410-961f-82ee72b054a4
    5ed3cc7b
pr68037-2.c 974 Bytes