1/*
2 * arch/xtensa/kernel/vectors.S
3 *
4 * This file contains all exception vectors (user, kernel, and double),
5 * as well as the window vectors (overflow and underflow), and the debug
6 * vector. These are the primary vectors executed by the processor if an
7 * exception occurs.
8 *
9 * This file is subject to the terms and conditions of the GNU General
10 * Public License. See the file "COPYING" in the main directory of
11 * this archive for more details.
12 *
13 * Copyright (C) 2005 - 2008 Tensilica, Inc.
14 *
15 * Chris Zankel <chris@zankel.net>
16 *
17 */
18
19/*
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
22 * fast handler or the default handler, if no fast handler was 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.
25 *
26 * Fast handler entry condition:
27 *
28 * a0: trashed, original value saved on stack (PT_AREG0)
29 * a1: a1
30 * a2: new stack pointer, original value in depc
31 * a3: dispatch table
32 * depc: a2, original value saved on stack (PT_DEPC)
33 * excsave_1: a3
34 *
35 * The value for PT_DEPC saved to stack also functions as a boolean to
36 * indicate that the exception is either a double or a regular exception:
37 *
38 * PT_DEPC >= VALID_DOUBLE_EXCEPTION_ADDRESS: double exception
39 * < VALID_DOUBLE_EXCEPTION_ADDRESS: regular exception
40 *
41 * Note: Neither the kernel nor the user exception handler generate literals.
42 *
43 */
44
45#include <linux/linkage.h>
46#include <linux/pgtable.h>
47#include <asm/asmmacro.h>
48#include <asm/ptrace.h>
49#include <asm/current.h>
50#include <asm/asm-offsets.h>
51#include <asm/processor.h>
52#include <asm/page.h>
53#include <asm/thread_info.h>
54#include <asm/vectors.h>
55
56#define WINDOW_VECTORS_SIZE 0x180
57
58
59/*
60 * User exception vector. (Exceptions with PS.UM == 1, PS.EXCM == 0)
61 *
62 * We get here when an exception occurred while we were in userland.
63 * We switch to the kernel stack and jump to the first level handler
64 * associated to the exception cause.
65 *
66 * Note: the saved kernel stack pointer (EXC_TABLE_KSTK) is already
67 * decremented by PT_USER_SIZE.
68 */
69
70 .section .UserExceptionVector.text, "ax"
71
72ENTRY(_UserExceptionVector)
73
74 xsr a3, excsave1 # save a3 and get dispatch table
75 wsr a2, depc # save a2
76 l32i a2, a3, EXC_TABLE_KSTK # load kernel stack to a2
77 s32i a0, a2, PT_AREG0 # save a0 to ESF
78 rsr a0, exccause # retrieve exception cause
79 s32i a0, a2, PT_DEPC # mark it as a regular exception
80 addx4 a0, a0, a3 # find entry in table
81 l32i a0, a0, EXC_TABLE_FAST_USER # load handler
82 xsr a3, excsave1 # restore a3 and dispatch table
83 jx a0
84
85ENDPROC(_UserExceptionVector)
86
87/*
88 * Kernel exception vector. (Exceptions with PS.UM == 0, PS.EXCM == 0)
89 *
90 * We get this exception when we were already in kernel space.
91 * We decrement the current stack pointer (kernel) by PT_KERNEL_SIZE and
92 * jump to the first-level handler associated with the exception cause.
93 *
94 * Note: we need to preserve space for the spill region.
95 */
96
97 .section .KernelExceptionVector.text, "ax"
98
99ENTRY(_KernelExceptionVector)
100
101 xsr a3, excsave1 # save a3, and get dispatch table
102 wsr a2, depc # save a2
103 addi a2, a1, -16 - PT_KERNEL_SIZE # adjust stack pointer
104 s32i a0, a2, PT_AREG0 # save a0 to ESF
105 rsr a0, exccause # retrieve exception cause
106 s32i a0, a2, PT_DEPC # mark it as a regular exception
107 addx4 a0, a0, a3 # find entry in table
108 l32i a0, a0, EXC_TABLE_FAST_KERNEL # load handler address
109 xsr a3, excsave1 # restore a3 and dispatch table
110 jx a0
111
112ENDPROC(_KernelExceptionVector)
113
114/*
115 * Double exception vector (Exceptions with PS.EXCM == 1)
116 * We get this exception when another exception occurs while were are
117 * already in an exception, such as window overflow/underflow exception,
118 * or 'expected' exceptions, for example memory exception when we were trying
119 * to read data from an invalid address in user space.
120 *
121 * Note that this vector is never invoked for level-1 interrupts, because such
122 * interrupts are disabled (masked) when PS.EXCM is set.
123 *
124 * We decode the exception and take the appropriate action. However, the
125 * double exception vector is much more careful, because a lot more error
126 * cases go through the double exception vector than through the user and
127 * kernel exception vectors.
128 *
129 * Occasionally, the kernel expects a double exception to occur. This usually
130 * happens when accessing user-space memory with the user's permissions
131 * (l32e/s32e instructions). The kernel state, though, is not always suitable
132 * for immediate transfer of control to handle_double, where "normal" exception
133 * processing occurs. Also in kernel mode, TLB misses can occur if accessing
134 * vmalloc memory, possibly requiring repair in a double exception handler.
135 *
136 * The variable at TABLE_FIXUP offset from the pointer in EXCSAVE_1 doubles as
137 * a boolean variable and a pointer to a fixup routine. If the variable
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.
140 * There is only one exception, when the value is identical to the exc_table
141 * label, the kernel is in trouble. This mechanism is used to protect critical
142 * sections, mainly when the handler writes to the stack to assert the stack
143 * pointer is valid. Once the fixup/default handler leaves that area, the
144 * EXC_TABLE_FIXUP variable is reset to the fixup handler or zero.
145 *
146 * Procedures wishing to use this mechanism should set EXC_TABLE_FIXUP to the
147 * nonzero address of a fixup routine before it could cause a double exception
148 * and reset it before it returns.
149 *
150 * Some other things to take care of when a fast exception handler doesn't
151 * specify a particular fixup handler but wants to use the default handlers:
152 *
153 * - The original stack pointer (in a1) must not be modified. The fast
154 * exception handler should only use a2 as the stack pointer.
155 *
156 * - If the fast handler manipulates the stack pointer (in a2), it has to
157 * register a valid fixup handler and cannot use the default handlers.
158 *
159 * - The handler can use any other generic register from a3 to a15, but it
160 * must save the content of these registers to stack (PT_AREG3...PT_AREGx)
161 *
162 * - These registers must be saved before a double exception can occur.
163 *
164 * - If we ever implement handling signals while in double exceptions, the
165 * number of registers a fast handler has saved (excluding a0 and a1) must
166 * be written to PT_AREG1. (1 if only a3 is used, 2 for a3 and a4, etc. )
167 *
168 * The fixup handlers are special handlers:
169 *
170 * - Fixup entry conditions differ from regular exceptions:
171 *
172 * a0: DEPC
173 * a1: a1
174 * a2: trashed, original value in EXC_TABLE_DOUBLE_SAVE
175 * a3: exctable
176 * depc: a0
177 * excsave_1: a3
178 *
179 * - When the kernel enters the fixup handler, it still assumes it is in a
180 * critical section, so EXC_TABLE_FIXUP variable is set to exc_table.
181 * The fixup handler, therefore, has to re-register itself as the fixup
182 * handler before it returns from the double exception.
183 *
184 * - Fixup handler can share the same exception frame with the fast handler.
185 * The kernel stack pointer is not changed when entering the fixup handler.
186 *
187 * - Fixup handlers can jump to the default kernel and user exception
188 * handlers. Before it jumps, though, it has to setup a exception frame
189 * on stack. Because the default handler resets the register fixup handler
190 * the fixup handler must make sure that the default handler returns to
191 * it instead of the exception address, so it can re-register itself as
192 * the fixup handler.
193 *
194 * In case of a critical condition where the kernel cannot recover, we jump
195 * to unrecoverable_exception with the following entry conditions.
196 * All registers a0...a15 are unchanged from the last exception, except:
197 *
198 * a0: last address before we jumped to the unrecoverable_exception.
199 * excsave_1: a0
200 *
201 *
202 * See the handle_alloca_user and spill_registers routines for example clients.
203 *
204 * FIXME: Note: we currently don't allow signal handling coming from a double
205 * exception, so the item markt with (*) is not required.
206 */
207
208 .section .DoubleExceptionVector.text, "ax"
209
210ENTRY(_DoubleExceptionVector)
211
212 xsr a3, excsave1
213 s32i a2, a3, EXC_TABLE_DOUBLE_SAVE
214
215 /* Check for kernel double exception (usually fatal). */
216
217 rsr a2, ps
218 _bbsi.l a2, PS_UM_BIT, 1f
219 j .Lksp
220
221 .align 4
222 .literal_position
2231:
224 /* Check if we are currently handling a window exception. */
225 /* Note: We don't need to indicate that we enter a critical section. */
226
227 xsr a0, depc # get DEPC, save a0
228
229#ifdef SUPPORT_WINDOWED
230 movi a2, WINDOW_VECTORS_VADDR
231 _bltu a0, a2, .Lfixup
232 addi a2, a2, WINDOW_VECTORS_SIZE
233 _bgeu a0, a2, .Lfixup
234
235 /* Window overflow/underflow exception. Get stack pointer. */
236
237 l32i a2, a3, EXC_TABLE_KSTK
238
239 /* Check for overflow/underflow exception, jump if overflow. */
240
241 bbci.l a0, 6, _DoubleExceptionVector_WindowOverflow
242
243 /*
244 * Restart window underflow exception.
245 * Currently:
246 * depc = orig a0,
247 * a0 = orig DEPC,
248 * a2 = new sp based on KSTK from exc_table
249 * a3 = excsave_1
250 * excsave_1 = orig a3
251 *
252 * We return to the instruction in user space that caused the window
253 * underflow exception. Therefore, we change window base to the value
254 * before we entered the window underflow exception and prepare the
255 * registers to return as if we were coming from a regular exception
256 * by changing depc (in a0).
257 * Note: We can trash the current window frame (a0...a3) and depc!
258 */
259_DoubleExceptionVector_WindowUnderflow:
260 xsr a3, excsave1
261 wsr a2, depc # save stack pointer temporarily
262 rsr a0, ps
263 extui a0, a0, PS_OWB_SHIFT, PS_OWB_WIDTH
264 wsr a0, windowbase
265 rsync
266
267 /* We are now in the previous window frame. Save registers again. */
268
269 xsr a2, depc # save a2 and get stack pointer
270 s32i a0, a2, PT_AREG0
271 xsr a3, excsave1
272 rsr a0, exccause
273 s32i a0, a2, PT_DEPC # mark it as a regular exception
274 addx4 a0, a0, a3
275 xsr a3, excsave1
276 l32i a0, a0, EXC_TABLE_FAST_USER
277 jx a0
278
279#else
280 j .Lfixup
281#endif
282
283 /*
284 * We only allow the ITLB miss exception if we are in kernel space.
285 * All other exceptions are unexpected and thus unrecoverable!
286 */
287
288#ifdef CONFIG_MMU
289 .extern fast_second_level_miss_double_kernel
290
291.Lksp: /* a0: a0, a1: a1, a2: a2, a3: trashed, depc: depc, excsave: a3 */
292
293 rsr a3, exccause
294 beqi a3, EXCCAUSE_ITLB_MISS, 1f
295 addi a3, a3, -EXCCAUSE_DTLB_MISS
296 bnez a3, .Lunrecoverable
2971: movi a3, fast_second_level_miss_double_kernel
298 jx a3
299#else
300.equ .Lksp, .Lunrecoverable
301#endif
302
303 /* Critical! We can't handle this situation. PANIC! */
304
305 .extern unrecoverable_exception
306
307.Lunrecoverable_fixup:
308 l32i a2, a3, EXC_TABLE_DOUBLE_SAVE
309 xsr a0, depc
310
311.Lunrecoverable:
312 rsr a3, excsave1
313 wsr a0, excsave1
314 call0 unrecoverable_exception
315
316.Lfixup:/* Check for a fixup handler or if we were in a critical section. */
317
318 /* a0: depc, a1: a1, a2: trash, a3: exctable, depc: a0, excsave1: a3 */
319
320 /* Enter critical section. */
321
322 l32i a2, a3, EXC_TABLE_FIXUP
323 s32i a3, a3, EXC_TABLE_FIXUP
324 beq a2, a3, .Lunrecoverable_fixup # critical section
325 beqz a2, .Ldflt # no handler was registered
326
327 /* a0: depc, a1: a1, a2: trash, a3: exctable, depc: a0, excsave: a3 */
328
329 jx a2
330
331.Ldflt: /* Get stack pointer. */
332
333 l32i a2, a3, EXC_TABLE_DOUBLE_SAVE
334 addi a2, a2, -PT_USER_SIZE
335
336 /* a0: depc, a1: a1, a2: kstk, a3: exctable, depc: a0, excsave: a3 */
337
338 s32i a0, a2, PT_DEPC
339 l32i a0, a3, EXC_TABLE_DOUBLE_SAVE
340 xsr a0, depc
341 s32i a0, a2, PT_AREG0
342
343 /* a0: avail, a1: a1, a2: kstk, a3: exctable, depc: a2, excsave: a3 */
344
345 rsr a0, exccause
346 addx4 a0, a0, a3
347 xsr a3, excsave1
348 l32i a0, a0, EXC_TABLE_FAST_USER
349 jx a0
350
351#ifdef SUPPORT_WINDOWED
352 /*
353 * Restart window OVERFLOW exception.
354 * Currently:
355 * depc = orig a0,
356 * a0 = orig DEPC,
357 * a2 = new sp based on KSTK from exc_table
358 * a3 = EXCSAVE_1
359 * excsave_1 = orig a3
360 *
361 * We return to the instruction in user space that caused the window
362 * overflow exception. Therefore, we change window base to the value
363 * before we entered the window overflow exception and prepare the
364 * registers to return as if we were coming from a regular exception
365 * by changing DEPC (in a0).
366 *
367 * NOTE: We CANNOT trash the current window frame (a0...a3), but we
368 * can clobber depc.
369 *
370 * The tricky part here is that overflow8 and overflow12 handlers
371 * save a0, then clobber a0. To restart the handler, we have to restore
372 * a0 if the double exception was past the point where a0 was clobbered.
373 *
374 * To keep things simple, we take advantage of the fact all overflow
375 * handlers save a0 in their very first instruction. If DEPC was past
376 * that instruction, we can safely restore a0 from where it was saved
377 * on the stack.
378 *
379 * a0: depc, a1: a1, a2: kstk, a3: exc_table, depc: a0, excsave1: a3
380 */
381_DoubleExceptionVector_WindowOverflow:
382 extui a2, a0, 0, 6 # get offset into 64-byte vector handler
383 beqz a2, 1f # if at start of vector, don't restore
384
385 addi a0, a0, -128
386 bbsi.l a0, 8, 1f # don't restore except for overflow 8 and 12
387
388 /*
389 * This fixup handler is for the extremely unlikely case where the
390 * overflow handler's reference thru a0 gets a hardware TLB refill
391 * that bumps out the (distinct, aliasing) TLB entry that mapped its
392 * prior references thru a9/a13, and where our reference now thru
393 * a9/a13 gets a 2nd-level miss exception (not hardware TLB refill).
394 */
395 movi a2, window_overflow_restore_a0_fixup
396 s32i a2, a3, EXC_TABLE_FIXUP
397 l32i a2, a3, EXC_TABLE_DOUBLE_SAVE
398 xsr a3, excsave1
399
400 bbsi.l a0, 7, 2f
401
402 /*
403 * Restore a0 as saved by _WindowOverflow8().
404 */
405
406 l32e a0, a9, -16
407 wsr a0, depc # replace the saved a0
408 j 3f
409
4102:
411 /*
412 * Restore a0 as saved by _WindowOverflow12().
413 */
414
415 l32e a0, a13, -16
416 wsr a0, depc # replace the saved a0
4173:
418 xsr a3, excsave1
419 movi a0, 0
420 s32i a0, a3, EXC_TABLE_FIXUP
421 s32i a2, a3, EXC_TABLE_DOUBLE_SAVE
4221:
423 /*
424 * Restore WindowBase while leaving all address registers restored.
425 * We have to use ROTW for this, because WSR.WINDOWBASE requires
426 * an address register (which would prevent restore).
427 *
428 * Window Base goes from 0 ... 7 (Module 8)
429 * Window Start is 8 bits; Ex: (0b1010 1010):0x55 from series of call4s
430 */
431
432 rsr a0, ps
433 extui a0, a0, PS_OWB_SHIFT, PS_OWB_WIDTH
434 rsr a2, windowbase
435 sub a0, a2, a0
436 extui a0, a0, 0, 3
437
438 l32i a2, a3, EXC_TABLE_DOUBLE_SAVE
439 xsr a3, excsave1
440 beqi a0, 1, .L1pane
441 beqi a0, 3, .L3pane
442
443 rsr a0, depc
444 rotw -2
445
446 /*
447 * We are now in the user code's original window frame.
448 * Process the exception as a user exception as if it was
449 * taken by the user code.
450 *
451 * This is similar to the user exception vector,
452 * except that PT_DEPC isn't set to EXCCAUSE.
453 */
4541:
455 xsr a3, excsave1
456 wsr a2, depc
457 l32i a2, a3, EXC_TABLE_KSTK
458 s32i a0, a2, PT_AREG0
459 rsr a0, exccause
460
461 s32i a0, a2, PT_DEPC
462
463_DoubleExceptionVector_handle_exception:
464 addi a0, a0, -EXCCAUSE_UNALIGNED
465 beqz a0, 2f
466 addx4 a0, a0, a3
467 l32i a0, a0, EXC_TABLE_FAST_USER + 4 * EXCCAUSE_UNALIGNED
468 xsr a3, excsave1
469 jx a0
4702:
471 movi a0, user_exception
472 xsr a3, excsave1
473 jx a0
474
475.L1pane:
476 rsr a0, depc
477 rotw -1
478 j 1b
479
480.L3pane:
481 rsr a0, depc
482 rotw -3
483 j 1b
484#endif
485
486ENDPROC(_DoubleExceptionVector)
487
488#ifdef SUPPORT_WINDOWED
489
490/*
491 * Fixup handler for TLB miss in double exception handler for window owerflow.
492 * We get here with windowbase set to the window that was being spilled and
493 * a0 trashed. a0 bit 7 determines if this is a call8 (bit clear) or call12
494 * (bit set) window.
495 *
496 * We do the following here:
497 * - go to the original window retaining a0 value;
498 * - set up exception stack to return back to appropriate a0 restore code
499 * (we'll need to rotate window back and there's no place to save this
500 * information, use different return address for that);
501 * - handle the exception;
502 * - go to the window that was being spilled;
503 * - set up window_overflow_restore_a0_fixup as a fixup routine;
504 * - reload a0;
505 * - restore the original window;
506 * - reset the default fixup routine;
507 * - return to user. By the time we get to this fixup handler all information
508 * about the conditions of the original double exception that happened in
509 * the window overflow handler is lost, so we just return to userspace to
510 * retry overflow from start.
511 *
512 * a0: value of depc, original value in depc
513 * a2: trashed, original value in EXC_TABLE_DOUBLE_SAVE
514 * a3: exctable, original value in excsave1
515 */
516
517 __XTENSA_HANDLER
518 .literal_position
519
520ENTRY(window_overflow_restore_a0_fixup)
521
522 rsr a0, ps
523 extui a0, a0, PS_OWB_SHIFT, PS_OWB_WIDTH
524 rsr a2, windowbase
525 sub a0, a2, a0
526 extui a0, a0, 0, 3
527 l32i a2, a3, EXC_TABLE_DOUBLE_SAVE
528 xsr a3, excsave1
529
530 _beqi a0, 1, .Lhandle_1
531 _beqi a0, 3, .Lhandle_3
532
533 .macro overflow_fixup_handle_exception_pane n
534
535 rsr a0, depc
536 rotw -\n
537
538 xsr a3, excsave1
539 wsr a2, depc
540 l32i a2, a3, EXC_TABLE_KSTK
541 s32i a0, a2, PT_AREG0
542
543 movi a0, .Lrestore_\n
544 s32i a0, a2, PT_DEPC
545 rsr a0, exccause
546 j _DoubleExceptionVector_handle_exception
547
548 .endm
549
550 overflow_fixup_handle_exception_pane 2
551.Lhandle_1:
552 overflow_fixup_handle_exception_pane 1
553.Lhandle_3:
554 overflow_fixup_handle_exception_pane 3
555
556 .macro overflow_fixup_restore_a0_pane n
557
558 rotw \n
559 /* Need to preserve a0 value here to be able to handle exception
560 * that may occur on a0 reload from stack. It may occur because
561 * TLB miss handler may not be atomic and pointer to page table
562 * may be lost before we get here. There are no free registers,
563 * so we need to use EXC_TABLE_DOUBLE_SAVE area.
564 */
565 xsr a3, excsave1
566 s32i a2, a3, EXC_TABLE_DOUBLE_SAVE
567 movi a2, window_overflow_restore_a0_fixup
568 s32i a2, a3, EXC_TABLE_FIXUP
569 l32i a2, a3, EXC_TABLE_DOUBLE_SAVE
570 xsr a3, excsave1
571 bbsi.l a0, 7, 1f
572 l32e a0, a9, -16
573 j 2f
5741:
575 l32e a0, a13, -16
5762:
577 rotw -\n
578
579 .endm
580
581.Lrestore_2:
582 overflow_fixup_restore_a0_pane 2
583
584.Lset_default_fixup:
585 xsr a3, excsave1
586 s32i a2, a3, EXC_TABLE_DOUBLE_SAVE
587 movi a2, 0
588 s32i a2, a3, EXC_TABLE_FIXUP
589 l32i a2, a3, EXC_TABLE_DOUBLE_SAVE
590 xsr a3, excsave1
591 rfe
592
593.Lrestore_1:
594 overflow_fixup_restore_a0_pane 1
595 j .Lset_default_fixup
596.Lrestore_3:
597 overflow_fixup_restore_a0_pane 3
598 j .Lset_default_fixup
599
600ENDPROC(window_overflow_restore_a0_fixup)
601
602#endif
603
604/*
605 * Debug interrupt vector
606 *
607 * There is not much space here, so simply jump to another handler.
608 * EXCSAVE[DEBUGLEVEL] has been set to that handler.
609 */
610
611 .section .DebugInterruptVector.text, "ax"
612
613ENTRY(_DebugInterruptVector)
614
615 xsr a3, SREG_EXCSAVE + XCHAL_DEBUGLEVEL
616 s32i a0, a3, DT_DEBUG_SAVE
617 l32i a0, a3, DT_DEBUG_EXCEPTION
618 jx a0
619
620ENDPROC(_DebugInterruptVector)
621
622
623
624/*
625 * Medium priority level interrupt vectors
626 *
627 * Each takes less than 16 (0x10) bytes, no literals, by placing
628 * the extra 8 bytes that would otherwise be required in the window
629 * vectors area where there is space. With relocatable vectors,
630 * all vectors are within ~ 4 kB range of each other, so we can
631 * simply jump (J) to another vector without having to use JX.
632 *
633 * common_exception code gets current IRQ level in PS.INTLEVEL
634 * and preserves it for the IRQ handling time.
635 */
636
637 .macro irq_entry_level level
638
639 .if XCHAL_EXCM_LEVEL >= \level
640 .section .Level\level\()InterruptVector.text, "ax"
641ENTRY(_Level\level\()InterruptVector)
642 wsr a0, excsave2
643 rsr a0, epc\level
644 wsr a0, epc1
645 .if \level <= LOCKLEVEL
646 movi a0, EXCCAUSE_LEVEL1_INTERRUPT
647 .else
648 movi a0, EXCCAUSE_MAPPED_NMI
649 .endif
650 wsr a0, exccause
651 rsr a0, eps\level
652 # branch to user or kernel vector
653 j _SimulateUserKernelVectorException
654 .endif
655
656 .endm
657
658 irq_entry_level 2
659 irq_entry_level 3
660 irq_entry_level 4
661 irq_entry_level 5
662 irq_entry_level 6
663
664#if XCHAL_EXCM_LEVEL >= 2
665 /*
666 * Continuation of medium priority interrupt dispatch code.
667 * On entry here, a0 contains PS, and EPC2 contains saved a0:
668 */
669 __XTENSA_HANDLER
670 .align 4
671_SimulateUserKernelVectorException:
672 addi a0, a0, (1 << PS_EXCM_BIT)
673#if !XTENSA_FAKE_NMI
674 wsr a0, ps
675#endif
676 bbsi.l a0, PS_UM_BIT, 1f # branch if user mode
677 xsr a0, excsave2 # restore a0
678 j _KernelExceptionVector # simulate kernel vector exception
6791: xsr a0, excsave2 # restore a0
680 j _UserExceptionVector # simulate user vector exception
681#endif
682
683
684/* Window overflow and underflow handlers.
685 * The handlers must be 64 bytes apart, first starting with the underflow
686 * handlers underflow-4 to underflow-12, then the overflow handlers
687 * overflow-4 to overflow-12.
688 *
689 * Note: We rerun the underflow handlers if we hit an exception, so
690 * we try to access any page that would cause a page fault early.
691 */
692
693#define ENTRY_ALIGN64(name) \
694 .globl name; \
695 .align 64; \
696 name:
697
698 .section .WindowVectors.text, "ax"
699
700
701#ifdef SUPPORT_WINDOWED
702
703/* 4-Register Window Overflow Vector (Handler) */
704
705ENTRY_ALIGN64(_WindowOverflow4)
706
707 s32e a0, a5, -16
708 s32e a1, a5, -12
709 s32e a2, a5, -8
710 s32e a3, a5, -4
711 rfwo
712
713ENDPROC(_WindowOverflow4)
714
715/* 4-Register Window Underflow Vector (Handler) */
716
717ENTRY_ALIGN64(_WindowUnderflow4)
718
719 l32e a0, a5, -16
720 l32e a1, a5, -12
721 l32e a2, a5, -8
722 l32e a3, a5, -4
723 rfwu
724
725ENDPROC(_WindowUnderflow4)
726
727/* 8-Register Window Overflow Vector (Handler) */
728
729ENTRY_ALIGN64(_WindowOverflow8)
730
731 s32e a0, a9, -16
732 l32e a0, a1, -12
733 s32e a2, a9, -8
734 s32e a1, a9, -12
735 s32e a3, a9, -4
736 s32e a4, a0, -32
737 s32e a5, a0, -28
738 s32e a6, a0, -24
739 s32e a7, a0, -20
740 rfwo
741
742ENDPROC(_WindowOverflow8)
743
744/* 8-Register Window Underflow Vector (Handler) */
745
746ENTRY_ALIGN64(_WindowUnderflow8)
747
748 l32e a1, a9, -12
749 l32e a0, a9, -16
750 l32e a7, a1, -12
751 l32e a2, a9, -8
752 l32e a4, a7, -32
753 l32e a3, a9, -4
754 l32e a5, a7, -28
755 l32e a6, a7, -24
756 l32e a7, a7, -20
757 rfwu
758
759ENDPROC(_WindowUnderflow8)
760
761/* 12-Register Window Overflow Vector (Handler) */
762
763ENTRY_ALIGN64(_WindowOverflow12)
764
765 s32e a0, a13, -16
766 l32e a0, a1, -12
767 s32e a1, a13, -12
768 s32e a2, a13, -8
769 s32e a3, a13, -4
770 s32e a4, a0, -48
771 s32e a5, a0, -44
772 s32e a6, a0, -40
773 s32e a7, a0, -36
774 s32e a8, a0, -32
775 s32e a9, a0, -28
776 s32e a10, a0, -24
777 s32e a11, a0, -20
778 rfwo
779
780ENDPROC(_WindowOverflow12)
781
782/* 12-Register Window Underflow Vector (Handler) */
783
784ENTRY_ALIGN64(_WindowUnderflow12)
785
786 l32e a1, a13, -12
787 l32e a0, a13, -16
788 l32e a11, a1, -12
789 l32e a2, a13, -8
790 l32e a4, a11, -48
791 l32e a8, a11, -32
792 l32e a3, a13, -4
793 l32e a5, a11, -44
794 l32e a6, a11, -40
795 l32e a7, a11, -36
796 l32e a9, a11, -28
797 l32e a10, a11, -24
798 l32e a11, a11, -20
799 rfwu
800
801ENDPROC(_WindowUnderflow12)
802
803#endif
804
805 .text
806

source code of linux/arch/xtensa/kernel/vectors.S