Fixed MTP to work with TWRP

arch/xtensa/kernel/vectors.S

@@ -0,0 +1,782 @@
+/*
+ * arch/xtensa/kernel/vectors.S
+ *
+ * This file contains all exception vectors (user, kernel, and double),
+ * as well as the window vectors (overflow and underflow), and the debug
+ * vector. These are the primary vectors executed by the processor if an
+ * exception occurs.
+ *
+ * This file is subject to the terms and conditions of the GNU General
+ * Public License.  See the file "COPYING" in the main directory of
+ * this archive for more details.
+ *
+ * Copyright (C) 2005 - 2008 Tensilica, Inc.
+ *
+ * Chris Zankel <chris@zankel.net>
+ *
+ */
+
+/*
+ * We use a two-level table approach. The user and kernel exception vectors
+ * use a first-level dispatch table to dispatch the exception to a registered
+ * fast handler or the default handler, if no fast handler was registered.
+ * The default handler sets up a C-stack and dispatches the exception to a
+ * registerd C handler in the second-level dispatch table.
+ *
+ * Fast handler entry condition:
+ *
+ *   a0:	trashed, original value saved on stack (PT_AREG0)
+ *   a1:	a1
+ *   a2:	new stack pointer, original value in depc
+ *   a3:	dispatch table
+ *   depc:	a2, original value saved on stack (PT_DEPC)
+ *   excsave_1:	a3
+ *
+ * The value for PT_DEPC saved to stack also functions as a boolean to
+ * indicate that the exception is either a double or a regular exception:
+ *
+ *   PT_DEPC	>= VALID_DOUBLE_EXCEPTION_ADDRESS: double exception
+ *		<  VALID_DOUBLE_EXCEPTION_ADDRESS: regular exception
+ *
+ * Note:  Neither the kernel nor the user exception handler generate literals.
+ *
+ */
+
+#include <linux/linkage.h>
+#include <asm/ptrace.h>
+#include <asm/current.h>
+#include <asm/asm-offsets.h>
+#include <asm/pgtable.h>
+#include <asm/processor.h>
+#include <asm/page.h>
+#include <asm/thread_info.h>
+#include <asm/vectors.h>
+
+#define WINDOW_VECTORS_SIZE   0x180
+
+
+/*
+ * User exception vector. (Exceptions with PS.UM == 1, PS.EXCM == 0)
+ *
+ * We get here when an exception occurred while we were in userland.
+ * We switch to the kernel stack and jump to the first level handler
+ * associated to the exception cause.
+ *
+ * Note: the saved kernel stack pointer (EXC_TABLE_KSTK) is already
+ *       decremented by PT_USER_SIZE.
+ */
+
+	.section .UserExceptionVector.text, "ax"
+
+ENTRY(_UserExceptionVector)
+
+	xsr	a3, excsave1		# save a3 and get dispatch table
+	wsr	a2, depc		# save a2
+	l32i	a2, a3, EXC_TABLE_KSTK	# load kernel stack to a2
+	s32i	a0, a2, PT_AREG0	# save a0 to ESF
+	rsr	a0, exccause		# retrieve exception cause
+	s32i	a0, a2, PT_DEPC		# mark it as a regular exception
+	addx4	a0, a0, a3		# find entry in table
+	l32i	a0, a0, EXC_TABLE_FAST_USER	# load handler
+	xsr	a3, excsave1		# restore a3 and dispatch table
+	jx	a0
+
+ENDPROC(_UserExceptionVector)
+
+/*
+ * Kernel exception vector. (Exceptions with PS.UM == 0, PS.EXCM == 0)
+ *
+ * We get this exception when we were already in kernel space.
+ * We decrement the current stack pointer (kernel) by PT_SIZE and
+ * jump to the first-level handler associated with the exception cause.
+ *
+ * Note: we need to preserve space for the spill region.
+ */
+
+	.section .KernelExceptionVector.text, "ax"
+
+ENTRY(_KernelExceptionVector)
+
+	xsr	a3, excsave1		# save a3, and get dispatch table
+	wsr	a2, depc		# save a2
+	addi	a2, a1, -16-PT_SIZE	# adjust stack pointer
+	s32i	a0, a2, PT_AREG0	# save a0 to ESF
+	rsr	a0, exccause		# retrieve exception cause
+	s32i	a0, a2, PT_DEPC		# mark it as a regular exception
+	addx4	a0, a0, a3		# find entry in table
+	l32i	a0, a0, EXC_TABLE_FAST_KERNEL	# load handler address
+	xsr	a3, excsave1		# restore a3 and dispatch table
+	jx	a0
+
+ENDPROC(_KernelExceptionVector)
+
+/*
+ * Double exception vector (Exceptions with PS.EXCM == 1)
+ * We get this exception when another exception occurs while were are
+ * already in an exception, such as window overflow/underflow exception,
+ * or 'expected' exceptions, for example memory exception when we were trying
+ * to read data from an invalid address in user space.
+ *
+ * Note that this vector is never invoked for level-1 interrupts, because such
+ * interrupts are disabled (masked) when PS.EXCM is set.
+ *
+ * We decode the exception and take the appropriate action.  However, the
+ * double exception vector is much more careful, because a lot more error
+ * cases go through the double exception vector than through the user and
+ * kernel exception vectors.
+ *
+ * Occasionally, the kernel expects a double exception to occur.  This usually
+ * happens when accessing user-space memory with the user's permissions
+ * (l32e/s32e instructions).  The kernel state, though, is not always suitable
+ * for immediate transfer of control to handle_double, where "normal" exception
+ * processing occurs. Also in kernel mode, TLB misses can occur if accessing
+ * vmalloc memory, possibly requiring repair in a double exception handler.
+ *
+ * The variable at TABLE_FIXUP offset from the pointer in EXCSAVE_1 doubles as
+ * a boolean variable and a pointer to a fixup routine. If the variable
+ * EXC_TABLE_FIXUP is non-zero, this handler jumps to that address. A value of
+ * zero indicates to use the default kernel/user exception handler.
+ * There is only one exception, when the value is identical to the exc_table
+ * label, the kernel is in trouble. This mechanism is used to protect critical
+ * sections, mainly when the handler writes to the stack to assert the stack
+ * pointer is valid. Once the fixup/default handler leaves that area, the
+ * EXC_TABLE_FIXUP variable is reset to the fixup handler or zero.
+ *
+ * Procedures wishing to use this mechanism should set EXC_TABLE_FIXUP to the
+ * nonzero address of a fixup routine before it could cause a double exception
+ * and reset it before it returns.
+ *
+ * Some other things to take care of when a fast exception handler doesn't
+ * specify a particular fixup handler but wants to use the default handlers:
+ *
+ *  - The original stack pointer (in a1) must not be modified. The fast
+ *    exception handler should only use a2 as the stack pointer.
+ *
+ *  - If the fast handler manipulates the stack pointer (in a2), it has to
+ *    register a valid fixup handler and cannot use the default handlers.
+ *
+ *  - The handler can use any other generic register from a3 to a15, but it
+ *    must save the content of these registers to stack (PT_AREG3...PT_AREGx)
+ *
+ *  - These registers must be saved before a double exception can occur.
+ *
+ *  - If we ever implement handling signals while in double exceptions, the
+ *    number of registers a fast handler has saved (excluding a0 and a1) must
+ *    be written to  PT_AREG1. (1 if only a3 is used, 2 for a3 and a4, etc. )
+ *
+ * The fixup handlers are special handlers:
+ *
+ *  - Fixup entry conditions differ from regular exceptions:
+ *
+ *	a0:	   DEPC
+ *	a1: 	   a1
+ *	a2:	   trashed, original value in EXC_TABLE_DOUBLE_SAVE
+ *	a3:	   exctable
+ *	depc:	   a0
+ *	excsave_1: a3
+ *
+ *  - When the kernel enters the fixup handler, it still assumes it is in a
+ *    critical section, so EXC_TABLE_FIXUP variable is set to exc_table.
+ *    The fixup handler, therefore, has to re-register itself as the fixup
+ *    handler before it returns from the double exception.
+ *
+ *  - Fixup handler can share the same exception frame with the fast handler.
+ *    The kernel stack pointer is not changed when entering the fixup handler.
+ *
+ *  - Fixup handlers can jump to the default kernel and user exception
+ *    handlers. Before it jumps, though, it has to setup a exception frame
+ *    on stack. Because the default handler resets the register fixup handler
+ *    the fixup handler must make sure that the default handler returns to
+ *    it instead of the exception address, so it can re-register itself as
+ *    the fixup handler.
+ *
+ * In case of a critical condition where the kernel cannot recover, we jump
+ * to unrecoverable_exception with the following entry conditions.
+ * All registers a0...a15 are unchanged from the last exception, except:
+ *
+ *	a0:	   last address before we jumped to the unrecoverable_exception.
+ *	excsave_1: a0
+ *
+ *
+ * See the handle_alloca_user and spill_registers routines for example clients.
+ *
+ * FIXME: Note: we currently don't allow signal handling coming from a double
+ *        exception, so the item markt with (*) is not required.
+ */
+
+	.section .DoubleExceptionVector.text, "ax"
+	.begin literal_prefix .DoubleExceptionVector
+	.globl _DoubleExceptionVector_WindowUnderflow
+	.globl _DoubleExceptionVector_WindowOverflow
+
+ENTRY(_DoubleExceptionVector)
+
+	xsr	a3, excsave1
+	s32i	a2, a3, EXC_TABLE_DOUBLE_SAVE
+
+	/* Check for kernel double exception (usually fatal). */
+
+	rsr	a2, ps
+	_bbci.l	a2, PS_UM_BIT, .Lksp
+
+	/* Check if we are currently handling a window exception. */
+	/* Note: We don't need to indicate that we enter a critical section. */
+
+	xsr	a0, depc		# get DEPC, save a0
+
+	movi	a2, WINDOW_VECTORS_VADDR
+	_bltu	a0, a2, .Lfixup
+	addi	a2, a2, WINDOW_VECTORS_SIZE
+	_bgeu	a0, a2, .Lfixup
+
+	/* Window overflow/underflow exception. Get stack pointer. */
+
+	l32i	a2, a3, EXC_TABLE_KSTK
+
+	/* Check for overflow/underflow exception, jump if overflow. */
+
+	bbci.l	a0, 6, _DoubleExceptionVector_WindowOverflow
+
+	/*
+	 * Restart window underflow exception.
+	 * Currently:
+	 *	depc = orig a0,
+	 *	a0 = orig DEPC,
+	 *	a2 = new sp based on KSTK from exc_table
+	 *	a3 = excsave_1
+	 *	excsave_1 = orig a3
+	 *
+	 * We return to the instruction in user space that caused the window
+	 * underflow exception. Therefore, we change window base to the value
+	 * before we entered the window underflow exception and prepare the
+	 * registers to return as if we were coming from a regular exception
+	 * by changing depc (in a0).
+	 * Note: We can trash the current window frame (a0...a3) and depc!
+	 */
+_DoubleExceptionVector_WindowUnderflow:
+	xsr	a3, excsave1
+	wsr	a2, depc		# save stack pointer temporarily
+	rsr	a0, ps
+	extui	a0, a0, PS_OWB_SHIFT, PS_OWB_WIDTH
+	wsr	a0, windowbase
+	rsync
+
+	/* We are now in the previous window frame. Save registers again. */
+
+	xsr	a2, depc		# save a2 and get stack pointer
+	s32i	a0, a2, PT_AREG0
+	xsr	a3, excsave1
+	rsr	a0, exccause
+	s32i	a0, a2, PT_DEPC		# mark it as a regular exception
+	addx4	a0, a0, a3
+	xsr	a3, excsave1
+	l32i	a0, a0, EXC_TABLE_FAST_USER
+	jx	a0
+
+	/*
+	 * We only allow the ITLB miss exception if we are in kernel space.
+	 * All other exceptions are unexpected and thus unrecoverable!
+	 */
+
+#ifdef CONFIG_MMU
+	.extern fast_second_level_miss_double_kernel
+
+.Lksp:	/* a0: a0, a1: a1, a2: a2, a3: trashed, depc: depc, excsave: a3 */
+
+	rsr	a3, exccause
+	beqi	a3, EXCCAUSE_ITLB_MISS, 1f
+	addi	a3, a3, -EXCCAUSE_DTLB_MISS
+	bnez	a3, .Lunrecoverable
+1:	movi	a3, fast_second_level_miss_double_kernel
+	jx	a3
+#else
+.equ	.Lksp,	.Lunrecoverable
+#endif
+
+	/* Critical! We can't handle this situation. PANIC! */
+
+	.extern unrecoverable_exception
+
+.Lunrecoverable_fixup:
+	l32i	a2, a3, EXC_TABLE_DOUBLE_SAVE
+	xsr	a0, depc
+
+.Lunrecoverable:
+	rsr	a3, excsave1
+	wsr	a0, excsave1
+	movi	a0, unrecoverable_exception
+	callx0	a0
+
+.Lfixup:/* Check for a fixup handler or if we were in a critical section. */
+
+	/* a0: depc, a1: a1, a2: trash, a3: exctable, depc: a0, excsave1: a3 */
+
+	/* Enter critical section. */
+
+	l32i	a2, a3, EXC_TABLE_FIXUP
+	s32i	a3, a3, EXC_TABLE_FIXUP
+	beq	a2, a3, .Lunrecoverable_fixup	# critical section
+	beqz	a2, .Ldflt			# no handler was registered
+
+	/* a0: depc, a1: a1, a2: trash, a3: exctable, depc: a0, excsave: a3 */
+
+	jx	a2
+
+.Ldflt:	/* Get stack pointer. */
+
+	l32i	a2, a3, EXC_TABLE_DOUBLE_SAVE
+	addi	a2, a2, -PT_USER_SIZE
+
+	/* a0: depc, a1: a1, a2: kstk, a3: exctable, depc: a0, excsave: a3 */
+
+	s32i	a0, a2, PT_DEPC
+	l32i	a0, a3, EXC_TABLE_DOUBLE_SAVE
+	xsr	a0, depc
+	s32i	a0, a2, PT_AREG0
+
+	/* a0: avail, a1: a1, a2: kstk, a3: exctable, depc: a2, excsave: a3 */
+
+	rsr	a0, exccause
+	addx4	a0, a0, a3
+	xsr	a3, excsave1
+	l32i	a0, a0, EXC_TABLE_FAST_USER
+	jx	a0
+
+	/*
+	 * Restart window OVERFLOW exception.
+	 * Currently:
+	 *	depc = orig a0,
+	 *	a0 = orig DEPC,
+	 *	a2 = new sp based on KSTK from exc_table
+	 *	a3 = EXCSAVE_1
+	 *	excsave_1 = orig a3
+	 *
+	 * We return to the instruction in user space that caused the window
+	 * overflow exception. Therefore, we change window base to the value
+	 * before we entered the window overflow exception and prepare the
+	 * registers to return as if we were coming from a regular exception
+	 * by changing DEPC (in a0).
+	 *
+	 * NOTE: We CANNOT trash the current window frame (a0...a3), but we
+	 * can clobber depc.
+	 *
+	 * The tricky part here is that overflow8 and overflow12 handlers
+	 * save a0, then clobber a0.  To restart the handler, we have to restore
+	 * a0 if the double exception was past the point where a0 was clobbered.
+	 *
+	 * To keep things simple, we take advantage of the fact all overflow
+	 * handlers save a0 in their very first instruction.  If DEPC was past
+	 * that instruction, we can safely restore a0 from where it was saved
+	 * on the stack.
+	 *
+	 * a0: depc, a1: a1, a2: kstk, a3: exc_table, depc: a0, excsave1: a3
+	 */
+_DoubleExceptionVector_WindowOverflow:
+	extui	a2, a0, 0, 6	# get offset into 64-byte vector handler
+	beqz	a2, 1f		# if at start of vector, don't restore
+
+	addi	a0, a0, -128
+	bbsi.l	a0, 8, 1f	# don't restore except for overflow 8 and 12
+
+	/*
+	 * This fixup handler is for the extremely unlikely case where the
+	 * overflow handler's reference thru a0 gets a hardware TLB refill
+	 * that bumps out the (distinct, aliasing) TLB entry that mapped its
+	 * prior references thru a9/a13, and where our reference now thru
+	 * a9/a13 gets a 2nd-level miss exception (not hardware TLB refill).
+	 */
+	movi	a2, window_overflow_restore_a0_fixup
+	s32i	a2, a3, EXC_TABLE_FIXUP
+	l32i	a2, a3, EXC_TABLE_DOUBLE_SAVE
+	xsr	a3, excsave1
+
+	bbsi.l	a0, 7, 2f
+
+	/*
+	 * Restore a0 as saved by _WindowOverflow8().
+	 */
+
+	l32e	a0, a9, -16
+	wsr	a0, depc	# replace the saved a0
+	j	3f
+
+2:
+	/*
+	 * Restore a0 as saved by _WindowOverflow12().
+	 */
+
+	l32e	a0, a13, -16
+	wsr	a0, depc	# replace the saved a0
+3:
+	xsr	a3, excsave1
+	movi	a0, 0
+	s32i	a0, a3, EXC_TABLE_FIXUP
+	s32i	a2, a3, EXC_TABLE_DOUBLE_SAVE
+1:
+	/*
+	 * Restore WindowBase while leaving all address registers restored.
+	 * We have to use ROTW for this, because WSR.WINDOWBASE requires
+	 * an address register (which would prevent restore).
+	 *
+	 * Window Base goes from 0 ... 7 (Module 8)
+	 * Window Start is 8 bits; Ex: (0b1010 1010):0x55 from series of call4s
+	 */
+
+	rsr	a0, ps
+	extui	a0, a0, PS_OWB_SHIFT, PS_OWB_WIDTH
+	rsr	a2, windowbase
+	sub	a0, a2, a0
+	extui	a0, a0, 0, 3
+
+	l32i	a2, a3, EXC_TABLE_DOUBLE_SAVE
+	xsr	a3, excsave1
+	beqi	a0, 1, .L1pane
+	beqi	a0, 3, .L3pane
+
+	rsr	a0, depc
+	rotw	-2
+
+	/*
+	 * We are now in the user code's original window frame.
+	 * Process the exception as a user exception as if it was
+	 * taken by the user code.
+	 *
+	 * This is similar to the user exception vector,
+	 * except that PT_DEPC isn't set to EXCCAUSE.
+	 */
+1:
+	xsr	a3, excsave1
+	wsr	a2, depc
+	l32i	a2, a3, EXC_TABLE_KSTK
+	s32i	a0, a2, PT_AREG0
+	rsr	a0, exccause
+
+	s32i	a0, a2, PT_DEPC
+
+_DoubleExceptionVector_handle_exception:
+	addi	a0, a0, -EXCCAUSE_UNALIGNED
+	beqz	a0, 2f
+	addx4	a0, a0, a3
+	l32i	a0, a0, EXC_TABLE_FAST_USER + 4 * EXCCAUSE_UNALIGNED
+	xsr	a3, excsave1
+	jx	a0
+2:
+	movi	a0, user_exception
+	xsr	a3, excsave1
+	jx	a0
+
+.L1pane:
+	rsr	a0, depc
+	rotw	-1
+	j	1b
+
+.L3pane:
+	rsr	a0, depc
+	rotw	-3
+	j	1b
+
+
+ENDPROC(_DoubleExceptionVector)
+
+/*
+ * Fixup handler for TLB miss in double exception handler for window owerflow.
+ * We get here with windowbase set to the window that was being spilled and
+ * a0 trashed. a0 bit 7 determines if this is a call8 (bit clear) or call12
+ * (bit set) window.
+ *
+ * We do the following here:
+ * - go to the original window retaining a0 value;
+ * - set up exception stack to return back to appropriate a0 restore code
+ *   (we'll need to rotate window back and there's no place to save this
+ *    information, use different return address for that);
+ * - handle the exception;
+ * - go to the window that was being spilled;
+ * - set up window_overflow_restore_a0_fixup as a fixup routine;
+ * - reload a0;
+ * - restore the original window;
+ * - reset the default fixup routine;
+ * - return to user. By the time we get to this fixup handler all information
+ *   about the conditions of the original double exception that happened in
+ *   the window overflow handler is lost, so we just return to userspace to
+ *   retry overflow from start.
+ *
+ * a0: value of depc, original value in depc
+ * a2: trashed, original value in EXC_TABLE_DOUBLE_SAVE
+ * a3: exctable, original value in excsave1
+ */
+
+ENTRY(window_overflow_restore_a0_fixup)
+
+	rsr	a0, ps
+	extui	a0, a0, PS_OWB_SHIFT, PS_OWB_WIDTH
+	rsr	a2, windowbase
+	sub	a0, a2, a0
+	extui	a0, a0, 0, 3
+	l32i	a2, a3, EXC_TABLE_DOUBLE_SAVE
+	xsr	a3, excsave1
+
+	_beqi	a0, 1, .Lhandle_1
+	_beqi	a0, 3, .Lhandle_3
+
+	.macro	overflow_fixup_handle_exception_pane n
+
+	rsr	a0, depc
+	rotw	-\n
+
+	xsr	a3, excsave1
+	wsr	a2, depc
+	l32i	a2, a3, EXC_TABLE_KSTK
+	s32i	a0, a2, PT_AREG0
+
+	movi	a0, .Lrestore_\n
+	s32i	a0, a2, PT_DEPC
+	rsr	a0, exccause
+	j	_DoubleExceptionVector_handle_exception
+
+	.endm
+
+	overflow_fixup_handle_exception_pane 2
+.Lhandle_1:
+	overflow_fixup_handle_exception_pane 1
+.Lhandle_3:
+	overflow_fixup_handle_exception_pane 3
+
+	.macro	overflow_fixup_restore_a0_pane n
+
+	rotw	\n
+	/* Need to preserve a0 value here to be able to handle exception
+	 * that may occur on a0 reload from stack. It may occur because
+	 * TLB miss handler may not be atomic and pointer to page table
+	 * may be lost before we get here. There are no free registers,
+	 * so we need to use EXC_TABLE_DOUBLE_SAVE area.
+	 */
+	xsr	a3, excsave1
+	s32i	a2, a3, EXC_TABLE_DOUBLE_SAVE
+	movi	a2, window_overflow_restore_a0_fixup
+	s32i	a2, a3, EXC_TABLE_FIXUP
+	l32i	a2, a3, EXC_TABLE_DOUBLE_SAVE
+	xsr	a3, excsave1
+	bbsi.l	a0, 7, 1f
+	l32e	a0, a9, -16
+	j	2f
+1:
+	l32e	a0, a13, -16
+2:
+	rotw	-\n
+
+	.endm
+
+.Lrestore_2:
+	overflow_fixup_restore_a0_pane 2
+
+.Lset_default_fixup:
+	xsr	a3, excsave1
+	s32i	a2, a3, EXC_TABLE_DOUBLE_SAVE
+	movi	a2, 0
+	s32i	a2, a3, EXC_TABLE_FIXUP
+	l32i	a2, a3, EXC_TABLE_DOUBLE_SAVE
+	xsr	a3, excsave1
+	rfe
+
+.Lrestore_1:
+	overflow_fixup_restore_a0_pane 1
+	j	.Lset_default_fixup
+.Lrestore_3:
+	overflow_fixup_restore_a0_pane 3
+	j	.Lset_default_fixup
+
+ENDPROC(window_overflow_restore_a0_fixup)
+
+	.end literal_prefix
+/*
+ * Debug interrupt vector
+ *
+ * There is not much space here, so simply jump to another handler.
+ * EXCSAVE[DEBUGLEVEL] has been set to that handler.
+ */
+
+	.section .DebugInterruptVector.text, "ax"
+
+ENTRY(_DebugInterruptVector)
+
+	xsr	a0, SREG_EXCSAVE + XCHAL_DEBUGLEVEL
+	jx	a0
+
+ENDPROC(_DebugInterruptVector)
+
+
+
+/*
+ * Medium priority level interrupt vectors
+ *
+ * Each takes less than 16 (0x10) bytes, no literals, by placing
+ * the extra 8 bytes that would otherwise be required in the window
+ * vectors area where there is space.  With relocatable vectors,
+ * all vectors are within ~ 4 kB range of each other, so we can
+ * simply jump (J) to another vector without having to use JX.
+ *
+ * common_exception code gets current IRQ level in PS.INTLEVEL
+ * and preserves it for the IRQ handling time.
+ */
+
+	.macro	irq_entry_level level
+
+	.if	XCHAL_EXCM_LEVEL >= \level
+	.section .Level\level\()InterruptVector.text, "ax"
+ENTRY(_Level\level\()InterruptVector)
+	wsr	a0, excsave2
+	rsr	a0, epc\level
+	wsr	a0, epc1
+	movi	a0, EXCCAUSE_LEVEL1_INTERRUPT
+	wsr	a0, exccause
+	rsr	a0, eps\level
+					# branch to user or kernel vector
+	j	_SimulateUserKernelVectorException
+	.endif
+
+	.endm
+
+	irq_entry_level 2
+	irq_entry_level 3
+	irq_entry_level 4
+	irq_entry_level 5
+	irq_entry_level 6
+
+
+/* Window overflow and underflow handlers.
+ * The handlers must be 64 bytes apart, first starting with the underflow
+ * handlers underflow-4 to underflow-12, then the overflow handlers
+ * overflow-4 to overflow-12.
+ *
+ * Note: We rerun the underflow handlers if we hit an exception, so
+ *	 we try to access any page that would cause a page fault early.
+ */
+
+#define ENTRY_ALIGN64(name)	\
+	.globl name;		\
+	.align 64;		\
+	name:
+
+	.section		.WindowVectors.text, "ax"
+
+
+/* 4-Register Window Overflow Vector (Handler) */
+
+ENTRY_ALIGN64(_WindowOverflow4)
+
+	s32e	a0, a5, -16
+	s32e	a1, a5, -12
+	s32e	a2, a5,  -8
+	s32e	a3, a5,  -4
+	rfwo
+
+ENDPROC(_WindowOverflow4)
+
+
+#if XCHAL_EXCM_LEVEL >= 2
+	/*  Not a window vector - but a convenient location
+	 *  (where we know there's space) for continuation of
+	 *  medium priority interrupt dispatch code.
+	 *  On entry here, a0 contains PS, and EPC2 contains saved a0:
+	 */
+	.align 4
+_SimulateUserKernelVectorException:
+	addi	a0, a0, (1 << PS_EXCM_BIT)
+	wsr	a0, ps
+	bbsi.l	a0, PS_UM_BIT, 1f	# branch if user mode
+	rsr	a0, excsave2		# restore a0
+	j	_KernelExceptionVector	# simulate kernel vector exception
+1:	rsr	a0, excsave2		# restore a0
+	j	_UserExceptionVector	# simulate user vector exception
+#endif
+
+
+/* 4-Register Window Underflow Vector (Handler) */
+
+ENTRY_ALIGN64(_WindowUnderflow4)
+
+	l32e	a0, a5, -16
+	l32e	a1, a5, -12
+	l32e	a2, a5,  -8
+	l32e	a3, a5,  -4
+	rfwu
+
+ENDPROC(_WindowUnderflow4)
+
+/* 8-Register Window Overflow Vector (Handler) */
+
+ENTRY_ALIGN64(_WindowOverflow8)
+
+	s32e	a0, a9, -16
+	l32e	a0, a1, -12
+	s32e	a2, a9,  -8
+	s32e	a1, a9, -12
+	s32e	a3, a9,  -4
+	s32e	a4, a0, -32
+	s32e	a5, a0, -28
+	s32e	a6, a0, -24
+	s32e	a7, a0, -20
+	rfwo
+
+ENDPROC(_WindowOverflow8)
+
+/* 8-Register Window Underflow Vector (Handler) */
+
+ENTRY_ALIGN64(_WindowUnderflow8)
+
+	l32e	a1, a9, -12
+	l32e	a0, a9, -16
+	l32e	a7, a1, -12
+	l32e	a2, a9,  -8
+	l32e	a4, a7, -32
+	l32e	a3, a9,  -4
+	l32e	a5, a7, -28
+	l32e	a6, a7, -24
+	l32e	a7, a7, -20
+	rfwu
+
+ENDPROC(_WindowUnderflow8)
+
+/* 12-Register Window Overflow Vector (Handler) */
+
+ENTRY_ALIGN64(_WindowOverflow12)
+
+	s32e	a0,  a13, -16
+	l32e	a0,  a1,  -12
+	s32e	a1,  a13, -12
+	s32e	a2,  a13,  -8
+	s32e	a3,  a13,  -4
+	s32e	a4,  a0,  -48
+	s32e	a5,  a0,  -44
+	s32e	a6,  a0,  -40
+	s32e	a7,  a0,  -36
+	s32e	a8,  a0,  -32
+	s32e	a9,  a0,  -28
+	s32e	a10, a0,  -24
+	s32e	a11, a0,  -20
+	rfwo
+
+ENDPROC(_WindowOverflow12)
+
+/* 12-Register Window Underflow Vector (Handler) */
+
+ENTRY_ALIGN64(_WindowUnderflow12)
+
+	l32e	a1,  a13, -12
+	l32e	a0,  a13, -16
+	l32e	a11, a1,  -12
+	l32e	a2,  a13,  -8
+	l32e	a4,  a11, -48
+	l32e	a8,  a11, -32
+	l32e	a3,  a13,  -4
+	l32e	a5,  a11, -44
+	l32e	a6,  a11, -40
+	l32e	a7,  a11, -36
+	l32e	a9,  a11, -28
+	l32e	a10, a11, -24
+	l32e	a11, a11, -20
+	rfwu
+
+ENDPROC(_WindowUnderflow12)
+
+	.text