xtensa/kernel/vectors.S

4  * This file contains all exception vectors (user, kernel, and double),
13  * Copyright (C) 2005 - 2008 Tensilica, Inc.
20  * We use a two-level table approach. The user and kernel exception vectors
21  * use a first-level dispatch table to dispatch the exception to a registered
23  * The default handler sets up a C-stack and dispatches the exception to a
24  * registerd C handler in the second-level dispatch table.
41  * Note:  Neither the kernel nor the user exception handler generate literals.
50 #include <asm/asm-offsets.h>
60  * User exception vector. (Exceptions with PS.UM == 1, PS.EXCM == 0)
63  * We switch to the kernel stack and jump to the first level handler
92  * jump to the first-level handler associated with the exception cause.
103 	addi	a2, a1, -16-PT_SIZE	# adjust stack pointer
119  * to read data from an invalid address in user space.
121  * Note that this vector is never invoked for level-1 interrupts, because such
126  * cases go through the double exception vector than through the user and
130  * happens when accessing user-space memory with the user's permissions
138  * EXC_TABLE_FIXUP is non-zero, this handler jumps to that address. A value of
139  * zero indicates to use the default kernel/user exception handler.
153  *  - The original stack pointer (in a1) must not be modified. The fast
156  *  - If the fast handler manipulates the stack pointer (in a2), it has to
159  *  - The handler can use any other generic register from a3 to a15, but it
162  *  - These registers must be saved before a double exception can occur.
164  *  - If we ever implement handling signals while in double exceptions, the
170  *  - Fixup entry conditions differ from regular exceptions:
179  *  - When the kernel enters the fixup handler, it still assumes it is in a
181  *    The fixup handler, therefore, has to re-register itself as the fixup
184  *  - Fixup handler can share the same exception frame with the fast handler.
187  *  - Fixup handlers can jump to the default kernel and user exception
191  *    it instead of the exception address, so it can re-register itself as
251 	 * We return to the instruction in user space that caused the window
290 	addi	a3, a3, -EXCCAUSE_DTLB_MISS
329 	addi	a2, a2, -PT_USER_SIZE
355 	 * We return to the instruction in user space that caused the window
376 	extui	a2, a0, 0, 6	# get offset into 64-byte vector handler
379 	addi	a0, a0, -128
387 	 * a9/a13 gets a 2nd-level miss exception (not hardware TLB refill).
400 	l32e	a0, a9, -16
409 	l32e	a0, a13, -16
438 	rotw	-2
441 	 * We are now in the user code's original window frame.
442 	 * Process the exception as a user exception as if it was
443 	 * taken by the user code.
445 	 * This is similar to the user exception vector,
458 	addi	a0, a0, -EXCCAUSE_UNALIGNED
471 	rotw	-1
476 	rotw	-3
488  * - go to the original window retaining a0 value;
489  * - set up exception stack to return back to appropriate a0 restore code
492  * - handle the exception;
493  * - go to the window that was being spilled;
494  * - set up window_overflow_restore_a0_fixup as a fixup routine;
495  * - reload a0;
496  * - restore the original window;
497  * - reset the default fixup routine;
498  * - return to user. By the time we get to this fixup handler all information
527 	rotw	-\n
563 	l32e	a0, a9, -16
566 	l32e	a0, a13, -16
568 	rotw	-\n
614  * Medium priority level interrupt vectors
622  * common_exception code gets current IRQ level in PS.INTLEVEL
626 	.macro	irq_entry_level level  argument
628 	.if	XCHAL_EXCM_LEVEL >= \level
629 	.section .Level\level\()InterruptVector.text, "ax"
630 ENTRY(_Level\level\()InterruptVector)
632 	rsr	a0, epc\level
634 	.if	\level <= LOCKLEVEL
640 	rsr	a0, eps\level
641 					# branch to user or kernel vector
656  * handlers underflow-4 to underflow-12, then the overflow handlers
657  * overflow-4 to overflow-12.
671 /* 4-Register Window Overflow Vector (Handler) */
675 	s32e	a0, a5, -16
676 	s32e	a1, a5, -12
677 	s32e	a2, a5,  -8
678 	s32e	a3, a5,  -4
685 	/*  Not a window vector - but a convenient location
696 	bbsi.l	a0, PS_UM_BIT, 1f	# branch if user mode
700 	j	_UserExceptionVector	# simulate user vector exception
704 /* 4-Register Window Underflow Vector (Handler) */
708 	l32e	a0, a5, -16
709 	l32e	a1, a5, -12
710 	l32e	a2, a5,  -8
711 	l32e	a3, a5,  -4
716 /* 8-Register Window Overflow Vector (Handler) */
720 	s32e	a0, a9, -16
721 	l32e	a0, a1, -12
722 	s32e	a2, a9,  -8
723 	s32e	a1, a9, -12
724 	s32e	a3, a9,  -4
725 	s32e	a4, a0, -32
726 	s32e	a5, a0, -28
727 	s32e	a6, a0, -24
728 	s32e	a7, a0, -20
733 /* 8-Register Window Underflow Vector (Handler) */
737 	l32e	a1, a9, -12
738 	l32e	a0, a9, -16
739 	l32e	a7, a1, -12
740 	l32e	a2, a9,  -8
741 	l32e	a4, a7, -32
742 	l32e	a3, a9,  -4
743 	l32e	a5, a7, -28
744 	l32e	a6, a7, -24
745 	l32e	a7, a7, -20
750 /* 12-Register Window Overflow Vector (Handler) */
754 	s32e	a0,  a13, -16
755 	l32e	a0,  a1,  -12
756 	s32e	a1,  a13, -12
757 	s32e	a2,  a13,  -8
758 	s32e	a3,  a13,  -4
759 	s32e	a4,  a0,  -48
760 	s32e	a5,  a0,  -44
761 	s32e	a6,  a0,  -40
762 	s32e	a7,  a0,  -36
763 	s32e	a8,  a0,  -32
764 	s32e	a9,  a0,  -28
765 	s32e	a10, a0,  -24
766 	s32e	a11, a0,  -20
771 /* 12-Register Window Underflow Vector (Handler) */
775 	l32e	a1,  a13, -12
776 	l32e	a0,  a13, -16
777 	l32e	a11, a1,  -12
778 	l32e	a2,  a13,  -8
779 	l32e	a4,  a11, -48
780 	l32e	a8,  a11, -32
781 	l32e	a3,  a13,  -4
782 	l32e	a5,  a11, -44
783 	l32e	a6,  a11, -40
784 	l32e	a7,  a11, -36
785 	l32e	a9,  a11, -28
786 	l32e	a10, a11, -24
787 	l32e	a11, a11, -20