xref: /openbmc/linux/arch/sh/kernel/traps_32.c (revision 6c33a6f4)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * 'traps.c' handles hardware traps and faults after we have saved some
4  * state in 'entry.S'.
5  *
6  *  SuperH version: Copyright (C) 1999 Niibe Yutaka
7  *                  Copyright (C) 2000 Philipp Rumpf
8  *                  Copyright (C) 2000 David Howells
9  *                  Copyright (C) 2002 - 2010 Paul Mundt
10  */
11 #include <linux/kernel.h>
12 #include <linux/ptrace.h>
13 #include <linux/hardirq.h>
14 #include <linux/init.h>
15 #include <linux/spinlock.h>
16 #include <linux/kallsyms.h>
17 #include <linux/io.h>
18 #include <linux/bug.h>
19 #include <linux/debug_locks.h>
20 #include <linux/kdebug.h>
21 #include <linux/limits.h>
22 #include <linux/sysfs.h>
23 #include <linux/uaccess.h>
24 #include <linux/perf_event.h>
25 #include <linux/sched/task_stack.h>
26 
27 #include <asm/alignment.h>
28 #include <asm/fpu.h>
29 #include <asm/kprobes.h>
30 #include <asm/traps.h>
31 #include <asm/bl_bit.h>
32 
33 #ifdef CONFIG_CPU_SH2
34 # define TRAP_RESERVED_INST	4
35 # define TRAP_ILLEGAL_SLOT_INST	6
36 # define TRAP_ADDRESS_ERROR	9
37 # ifdef CONFIG_CPU_SH2A
38 #  define TRAP_UBC		12
39 #  define TRAP_FPU_ERROR	13
40 #  define TRAP_DIVZERO_ERROR	17
41 #  define TRAP_DIVOVF_ERROR	18
42 # endif
43 #else
44 #define TRAP_RESERVED_INST	12
45 #define TRAP_ILLEGAL_SLOT_INST	13
46 #endif
47 
48 static inline void sign_extend(unsigned int count, unsigned char *dst)
49 {
50 #ifdef __LITTLE_ENDIAN__
51 	if ((count == 1) && dst[0] & 0x80) {
52 		dst[1] = 0xff;
53 		dst[2] = 0xff;
54 		dst[3] = 0xff;
55 	}
56 	if ((count == 2) && dst[1] & 0x80) {
57 		dst[2] = 0xff;
58 		dst[3] = 0xff;
59 	}
60 #else
61 	if ((count == 1) && dst[3] & 0x80) {
62 		dst[2] = 0xff;
63 		dst[1] = 0xff;
64 		dst[0] = 0xff;
65 	}
66 	if ((count == 2) && dst[2] & 0x80) {
67 		dst[1] = 0xff;
68 		dst[0] = 0xff;
69 	}
70 #endif
71 }
72 
73 static struct mem_access user_mem_access = {
74 	copy_from_user,
75 	copy_to_user,
76 };
77 
78 /*
79  * handle an instruction that does an unaligned memory access by emulating the
80  * desired behaviour
81  * - note that PC _may not_ point to the faulting instruction
82  *   (if that instruction is in a branch delay slot)
83  * - return 0 if emulation okay, -EFAULT on existential error
84  */
85 static int handle_unaligned_ins(insn_size_t instruction, struct pt_regs *regs,
86 				struct mem_access *ma)
87 {
88 	int ret, index, count;
89 	unsigned long *rm, *rn;
90 	unsigned char *src, *dst;
91 	unsigned char __user *srcu, *dstu;
92 
93 	index = (instruction>>8)&15;	/* 0x0F00 */
94 	rn = &regs->regs[index];
95 
96 	index = (instruction>>4)&15;	/* 0x00F0 */
97 	rm = &regs->regs[index];
98 
99 	count = 1<<(instruction&3);
100 
101 	switch (count) {
102 	case 1: inc_unaligned_byte_access(); break;
103 	case 2: inc_unaligned_word_access(); break;
104 	case 4: inc_unaligned_dword_access(); break;
105 	case 8: inc_unaligned_multi_access(); break;
106 	}
107 
108 	ret = -EFAULT;
109 	switch (instruction>>12) {
110 	case 0: /* mov.[bwl] to/from memory via r0+rn */
111 		if (instruction & 8) {
112 			/* from memory */
113 			srcu = (unsigned char __user *)*rm;
114 			srcu += regs->regs[0];
115 			dst = (unsigned char *)rn;
116 			*(unsigned long *)dst = 0;
117 
118 #if !defined(__LITTLE_ENDIAN__)
119 			dst += 4-count;
120 #endif
121 			if (ma->from(dst, srcu, count))
122 				goto fetch_fault;
123 
124 			sign_extend(count, dst);
125 		} else {
126 			/* to memory */
127 			src = (unsigned char *)rm;
128 #if !defined(__LITTLE_ENDIAN__)
129 			src += 4-count;
130 #endif
131 			dstu = (unsigned char __user *)*rn;
132 			dstu += regs->regs[0];
133 
134 			if (ma->to(dstu, src, count))
135 				goto fetch_fault;
136 		}
137 		ret = 0;
138 		break;
139 
140 	case 1: /* mov.l Rm,@(disp,Rn) */
141 		src = (unsigned char*) rm;
142 		dstu = (unsigned char __user *)*rn;
143 		dstu += (instruction&0x000F)<<2;
144 
145 		if (ma->to(dstu, src, 4))
146 			goto fetch_fault;
147 		ret = 0;
148 		break;
149 
150 	case 2: /* mov.[bwl] to memory, possibly with pre-decrement */
151 		if (instruction & 4)
152 			*rn -= count;
153 		src = (unsigned char*) rm;
154 		dstu = (unsigned char __user *)*rn;
155 #if !defined(__LITTLE_ENDIAN__)
156 		src += 4-count;
157 #endif
158 		if (ma->to(dstu, src, count))
159 			goto fetch_fault;
160 		ret = 0;
161 		break;
162 
163 	case 5: /* mov.l @(disp,Rm),Rn */
164 		srcu = (unsigned char __user *)*rm;
165 		srcu += (instruction & 0x000F) << 2;
166 		dst = (unsigned char *)rn;
167 		*(unsigned long *)dst = 0;
168 
169 		if (ma->from(dst, srcu, 4))
170 			goto fetch_fault;
171 		ret = 0;
172 		break;
173 
174 	case 6:	/* mov.[bwl] from memory, possibly with post-increment */
175 		srcu = (unsigned char __user *)*rm;
176 		if (instruction & 4)
177 			*rm += count;
178 		dst = (unsigned char*) rn;
179 		*(unsigned long*)dst = 0;
180 
181 #if !defined(__LITTLE_ENDIAN__)
182 		dst += 4-count;
183 #endif
184 		if (ma->from(dst, srcu, count))
185 			goto fetch_fault;
186 		sign_extend(count, dst);
187 		ret = 0;
188 		break;
189 
190 	case 8:
191 		switch ((instruction&0xFF00)>>8) {
192 		case 0x81: /* mov.w R0,@(disp,Rn) */
193 			src = (unsigned char *) &regs->regs[0];
194 #if !defined(__LITTLE_ENDIAN__)
195 			src += 2;
196 #endif
197 			dstu = (unsigned char __user *)*rm; /* called Rn in the spec */
198 			dstu += (instruction & 0x000F) << 1;
199 
200 			if (ma->to(dstu, src, 2))
201 				goto fetch_fault;
202 			ret = 0;
203 			break;
204 
205 		case 0x85: /* mov.w @(disp,Rm),R0 */
206 			srcu = (unsigned char __user *)*rm;
207 			srcu += (instruction & 0x000F) << 1;
208 			dst = (unsigned char *) &regs->regs[0];
209 			*(unsigned long *)dst = 0;
210 
211 #if !defined(__LITTLE_ENDIAN__)
212 			dst += 2;
213 #endif
214 			if (ma->from(dst, srcu, 2))
215 				goto fetch_fault;
216 			sign_extend(2, dst);
217 			ret = 0;
218 			break;
219 		}
220 		break;
221 
222 	case 9: /* mov.w @(disp,PC),Rn */
223 		srcu = (unsigned char __user *)regs->pc;
224 		srcu += 4;
225 		srcu += (instruction & 0x00FF) << 1;
226 		dst = (unsigned char *)rn;
227 		*(unsigned long *)dst = 0;
228 
229 #if !defined(__LITTLE_ENDIAN__)
230 		dst += 2;
231 #endif
232 
233 		if (ma->from(dst, srcu, 2))
234 			goto fetch_fault;
235 		sign_extend(2, dst);
236 		ret = 0;
237 		break;
238 
239 	case 0xd: /* mov.l @(disp,PC),Rn */
240 		srcu = (unsigned char __user *)(regs->pc & ~0x3);
241 		srcu += 4;
242 		srcu += (instruction & 0x00FF) << 2;
243 		dst = (unsigned char *)rn;
244 		*(unsigned long *)dst = 0;
245 
246 		if (ma->from(dst, srcu, 4))
247 			goto fetch_fault;
248 		ret = 0;
249 		break;
250 	}
251 	return ret;
252 
253  fetch_fault:
254 	/* Argh. Address not only misaligned but also non-existent.
255 	 * Raise an EFAULT and see if it's trapped
256 	 */
257 	die_if_no_fixup("Fault in unaligned fixup", regs, 0);
258 	return -EFAULT;
259 }
260 
261 /*
262  * emulate the instruction in the delay slot
263  * - fetches the instruction from PC+2
264  */
265 static inline int handle_delayslot(struct pt_regs *regs,
266 				   insn_size_t old_instruction,
267 				   struct mem_access *ma)
268 {
269 	insn_size_t instruction;
270 	void __user *addr = (void __user *)(regs->pc +
271 		instruction_size(old_instruction));
272 
273 	if (copy_from_user(&instruction, addr, sizeof(instruction))) {
274 		/* the instruction-fetch faulted */
275 		if (user_mode(regs))
276 			return -EFAULT;
277 
278 		/* kernel */
279 		die("delay-slot-insn faulting in handle_unaligned_delayslot",
280 		    regs, 0);
281 	}
282 
283 	return handle_unaligned_ins(instruction, regs, ma);
284 }
285 
286 /*
287  * handle an instruction that does an unaligned memory access
288  * - have to be careful of branch delay-slot instructions that fault
289  *  SH3:
290  *   - if the branch would be taken PC points to the branch
291  *   - if the branch would not be taken, PC points to delay-slot
292  *  SH4:
293  *   - PC always points to delayed branch
294  * - return 0 if handled, -EFAULT if failed (may not return if in kernel)
295  */
296 
297 /* Macros to determine offset from current PC for branch instructions */
298 /* Explicit type coercion is used to force sign extension where needed */
299 #define SH_PC_8BIT_OFFSET(instr) ((((signed char)(instr))*2) + 4)
300 #define SH_PC_12BIT_OFFSET(instr) ((((signed short)(instr<<4))>>3) + 4)
301 
302 int handle_unaligned_access(insn_size_t instruction, struct pt_regs *regs,
303 			    struct mem_access *ma, int expected,
304 			    unsigned long address)
305 {
306 	u_int rm;
307 	int ret, index;
308 
309 	/*
310 	 * XXX: We can't handle mixed 16/32-bit instructions yet
311 	 */
312 	if (instruction_size(instruction) != 2)
313 		return -EINVAL;
314 
315 	index = (instruction>>8)&15;	/* 0x0F00 */
316 	rm = regs->regs[index];
317 
318 	/*
319 	 * Log the unexpected fixups, and then pass them on to perf.
320 	 *
321 	 * We intentionally don't report the expected cases to perf as
322 	 * otherwise the trapped I/O case will skew the results too much
323 	 * to be useful.
324 	 */
325 	if (!expected) {
326 		unaligned_fixups_notify(current, instruction, regs);
327 		perf_sw_event(PERF_COUNT_SW_ALIGNMENT_FAULTS, 1,
328 			      regs, address);
329 	}
330 
331 	ret = -EFAULT;
332 	switch (instruction&0xF000) {
333 	case 0x0000:
334 		if (instruction==0x000B) {
335 			/* rts */
336 			ret = handle_delayslot(regs, instruction, ma);
337 			if (ret==0)
338 				regs->pc = regs->pr;
339 		}
340 		else if ((instruction&0x00FF)==0x0023) {
341 			/* braf @Rm */
342 			ret = handle_delayslot(regs, instruction, ma);
343 			if (ret==0)
344 				regs->pc += rm + 4;
345 		}
346 		else if ((instruction&0x00FF)==0x0003) {
347 			/* bsrf @Rm */
348 			ret = handle_delayslot(regs, instruction, ma);
349 			if (ret==0) {
350 				regs->pr = regs->pc + 4;
351 				regs->pc += rm + 4;
352 			}
353 		}
354 		else {
355 			/* mov.[bwl] to/from memory via r0+rn */
356 			goto simple;
357 		}
358 		break;
359 
360 	case 0x1000: /* mov.l Rm,@(disp,Rn) */
361 		goto simple;
362 
363 	case 0x2000: /* mov.[bwl] to memory, possibly with pre-decrement */
364 		goto simple;
365 
366 	case 0x4000:
367 		if ((instruction&0x00FF)==0x002B) {
368 			/* jmp @Rm */
369 			ret = handle_delayslot(regs, instruction, ma);
370 			if (ret==0)
371 				regs->pc = rm;
372 		}
373 		else if ((instruction&0x00FF)==0x000B) {
374 			/* jsr @Rm */
375 			ret = handle_delayslot(regs, instruction, ma);
376 			if (ret==0) {
377 				regs->pr = regs->pc + 4;
378 				regs->pc = rm;
379 			}
380 		}
381 		else {
382 			/* mov.[bwl] to/from memory via r0+rn */
383 			goto simple;
384 		}
385 		break;
386 
387 	case 0x5000: /* mov.l @(disp,Rm),Rn */
388 		goto simple;
389 
390 	case 0x6000: /* mov.[bwl] from memory, possibly with post-increment */
391 		goto simple;
392 
393 	case 0x8000: /* bf lab, bf/s lab, bt lab, bt/s lab */
394 		switch (instruction&0x0F00) {
395 		case 0x0100: /* mov.w R0,@(disp,Rm) */
396 			goto simple;
397 		case 0x0500: /* mov.w @(disp,Rm),R0 */
398 			goto simple;
399 		case 0x0B00: /* bf   lab - no delayslot*/
400 			ret = 0;
401 			break;
402 		case 0x0F00: /* bf/s lab */
403 			ret = handle_delayslot(regs, instruction, ma);
404 			if (ret==0) {
405 #if defined(CONFIG_CPU_SH4) || defined(CONFIG_SH7705_CACHE_32KB)
406 				if ((regs->sr & 0x00000001) != 0)
407 					regs->pc += 4; /* next after slot */
408 				else
409 #endif
410 					regs->pc += SH_PC_8BIT_OFFSET(instruction);
411 			}
412 			break;
413 		case 0x0900: /* bt   lab - no delayslot */
414 			ret = 0;
415 			break;
416 		case 0x0D00: /* bt/s lab */
417 			ret = handle_delayslot(regs, instruction, ma);
418 			if (ret==0) {
419 #if defined(CONFIG_CPU_SH4) || defined(CONFIG_SH7705_CACHE_32KB)
420 				if ((regs->sr & 0x00000001) == 0)
421 					regs->pc += 4; /* next after slot */
422 				else
423 #endif
424 					regs->pc += SH_PC_8BIT_OFFSET(instruction);
425 			}
426 			break;
427 		}
428 		break;
429 
430 	case 0x9000: /* mov.w @(disp,Rm),Rn */
431 		goto simple;
432 
433 	case 0xA000: /* bra label */
434 		ret = handle_delayslot(regs, instruction, ma);
435 		if (ret==0)
436 			regs->pc += SH_PC_12BIT_OFFSET(instruction);
437 		break;
438 
439 	case 0xB000: /* bsr label */
440 		ret = handle_delayslot(regs, instruction, ma);
441 		if (ret==0) {
442 			regs->pr = regs->pc + 4;
443 			regs->pc += SH_PC_12BIT_OFFSET(instruction);
444 		}
445 		break;
446 
447 	case 0xD000: /* mov.l @(disp,Rm),Rn */
448 		goto simple;
449 	}
450 	return ret;
451 
452 	/* handle non-delay-slot instruction */
453  simple:
454 	ret = handle_unaligned_ins(instruction, regs, ma);
455 	if (ret==0)
456 		regs->pc += instruction_size(instruction);
457 	return ret;
458 }
459 
460 /*
461  * Handle various address error exceptions:
462  *  - instruction address error:
463  *       misaligned PC
464  *       PC >= 0x80000000 in user mode
465  *  - data address error (read and write)
466  *       misaligned data access
467  *       access to >= 0x80000000 is user mode
468  * Unfortuntaly we can't distinguish between instruction address error
469  * and data address errors caused by read accesses.
470  */
471 asmlinkage void do_address_error(struct pt_regs *regs,
472 				 unsigned long writeaccess,
473 				 unsigned long address)
474 {
475 	unsigned long error_code = 0;
476 	mm_segment_t oldfs;
477 	insn_size_t instruction;
478 	int tmp;
479 
480 	/* Intentional ifdef */
481 #ifdef CONFIG_CPU_HAS_SR_RB
482 	error_code = lookup_exception_vector();
483 #endif
484 
485 	oldfs = get_fs();
486 
487 	if (user_mode(regs)) {
488 		int si_code = BUS_ADRERR;
489 		unsigned int user_action;
490 
491 		local_irq_enable();
492 		inc_unaligned_user_access();
493 
494 		set_fs(USER_DS);
495 		if (copy_from_user(&instruction, (insn_size_t *)(regs->pc & ~1),
496 				   sizeof(instruction))) {
497 			set_fs(oldfs);
498 			goto uspace_segv;
499 		}
500 		set_fs(oldfs);
501 
502 		/* shout about userspace fixups */
503 		unaligned_fixups_notify(current, instruction, regs);
504 
505 		user_action = unaligned_user_action();
506 		if (user_action & UM_FIXUP)
507 			goto fixup;
508 		if (user_action & UM_SIGNAL)
509 			goto uspace_segv;
510 		else {
511 			/* ignore */
512 			regs->pc += instruction_size(instruction);
513 			return;
514 		}
515 
516 fixup:
517 		/* bad PC is not something we can fix */
518 		if (regs->pc & 1) {
519 			si_code = BUS_ADRALN;
520 			goto uspace_segv;
521 		}
522 
523 		set_fs(USER_DS);
524 		tmp = handle_unaligned_access(instruction, regs,
525 					      &user_mem_access, 0,
526 					      address);
527 		set_fs(oldfs);
528 
529 		if (tmp == 0)
530 			return; /* sorted */
531 uspace_segv:
532 		printk(KERN_NOTICE "Sending SIGBUS to \"%s\" due to unaligned "
533 		       "access (PC %lx PR %lx)\n", current->comm, regs->pc,
534 		       regs->pr);
535 
536 		force_sig_fault(SIGBUS, si_code, (void __user *)address);
537 	} else {
538 		inc_unaligned_kernel_access();
539 
540 		if (regs->pc & 1)
541 			die("unaligned program counter", regs, error_code);
542 
543 		set_fs(KERNEL_DS);
544 		if (copy_from_user(&instruction, (void __user *)(regs->pc),
545 				   sizeof(instruction))) {
546 			/* Argh. Fault on the instruction itself.
547 			   This should never happen non-SMP
548 			*/
549 			set_fs(oldfs);
550 			die("insn faulting in do_address_error", regs, 0);
551 		}
552 
553 		unaligned_fixups_notify(current, instruction, regs);
554 
555 		handle_unaligned_access(instruction, regs, &user_mem_access,
556 					0, address);
557 		set_fs(oldfs);
558 	}
559 }
560 
561 #ifdef CONFIG_SH_DSP
562 /*
563  *	SH-DSP support gerg@snapgear.com.
564  */
565 int is_dsp_inst(struct pt_regs *regs)
566 {
567 	unsigned short inst = 0;
568 
569 	/*
570 	 * Safe guard if DSP mode is already enabled or we're lacking
571 	 * the DSP altogether.
572 	 */
573 	if (!(current_cpu_data.flags & CPU_HAS_DSP) || (regs->sr & SR_DSP))
574 		return 0;
575 
576 	get_user(inst, ((unsigned short *) regs->pc));
577 
578 	inst &= 0xf000;
579 
580 	/* Check for any type of DSP or support instruction */
581 	if ((inst == 0xf000) || (inst == 0x4000))
582 		return 1;
583 
584 	return 0;
585 }
586 #else
587 #define is_dsp_inst(regs)	(0)
588 #endif /* CONFIG_SH_DSP */
589 
590 #ifdef CONFIG_CPU_SH2A
591 asmlinkage void do_divide_error(unsigned long r4)
592 {
593 	int code;
594 
595 	switch (r4) {
596 	case TRAP_DIVZERO_ERROR:
597 		code = FPE_INTDIV;
598 		break;
599 	case TRAP_DIVOVF_ERROR:
600 		code = FPE_INTOVF;
601 		break;
602 	default:
603 		/* Let gcc know unhandled cases don't make it past here */
604 		return;
605 	}
606 	force_sig_fault(SIGFPE, code, NULL);
607 }
608 #endif
609 
610 asmlinkage void do_reserved_inst(void)
611 {
612 	struct pt_regs *regs = current_pt_regs();
613 	unsigned long error_code;
614 
615 #ifdef CONFIG_SH_FPU_EMU
616 	unsigned short inst = 0;
617 	int err;
618 
619 	get_user(inst, (unsigned short*)regs->pc);
620 
621 	err = do_fpu_inst(inst, regs);
622 	if (!err) {
623 		regs->pc += instruction_size(inst);
624 		return;
625 	}
626 	/* not a FPU inst. */
627 #endif
628 
629 #ifdef CONFIG_SH_DSP
630 	/* Check if it's a DSP instruction */
631 	if (is_dsp_inst(regs)) {
632 		/* Enable DSP mode, and restart instruction. */
633 		regs->sr |= SR_DSP;
634 		/* Save DSP mode */
635 		current->thread.dsp_status.status |= SR_DSP;
636 		return;
637 	}
638 #endif
639 
640 	error_code = lookup_exception_vector();
641 
642 	local_irq_enable();
643 	force_sig(SIGILL);
644 	die_if_no_fixup("reserved instruction", regs, error_code);
645 }
646 
647 #ifdef CONFIG_SH_FPU_EMU
648 static int emulate_branch(unsigned short inst, struct pt_regs *regs)
649 {
650 	/*
651 	 * bfs: 8fxx: PC+=d*2+4;
652 	 * bts: 8dxx: PC+=d*2+4;
653 	 * bra: axxx: PC+=D*2+4;
654 	 * bsr: bxxx: PC+=D*2+4  after PR=PC+4;
655 	 * braf:0x23: PC+=Rn*2+4;
656 	 * bsrf:0x03: PC+=Rn*2+4 after PR=PC+4;
657 	 * jmp: 4x2b: PC=Rn;
658 	 * jsr: 4x0b: PC=Rn      after PR=PC+4;
659 	 * rts: 000b: PC=PR;
660 	 */
661 	if (((inst & 0xf000) == 0xb000)  ||	/* bsr */
662 	    ((inst & 0xf0ff) == 0x0003)  ||	/* bsrf */
663 	    ((inst & 0xf0ff) == 0x400b))	/* jsr */
664 		regs->pr = regs->pc + 4;
665 
666 	if ((inst & 0xfd00) == 0x8d00) {	/* bfs, bts */
667 		regs->pc += SH_PC_8BIT_OFFSET(inst);
668 		return 0;
669 	}
670 
671 	if ((inst & 0xe000) == 0xa000) {	/* bra, bsr */
672 		regs->pc += SH_PC_12BIT_OFFSET(inst);
673 		return 0;
674 	}
675 
676 	if ((inst & 0xf0df) == 0x0003) {	/* braf, bsrf */
677 		regs->pc += regs->regs[(inst & 0x0f00) >> 8] + 4;
678 		return 0;
679 	}
680 
681 	if ((inst & 0xf0df) == 0x400b) {	/* jmp, jsr */
682 		regs->pc = regs->regs[(inst & 0x0f00) >> 8];
683 		return 0;
684 	}
685 
686 	if ((inst & 0xffff) == 0x000b) {	/* rts */
687 		regs->pc = regs->pr;
688 		return 0;
689 	}
690 
691 	return 1;
692 }
693 #endif
694 
695 asmlinkage void do_illegal_slot_inst(void)
696 {
697 	struct pt_regs *regs = current_pt_regs();
698 	unsigned long inst;
699 
700 	if (kprobe_handle_illslot(regs->pc) == 0)
701 		return;
702 
703 #ifdef CONFIG_SH_FPU_EMU
704 	get_user(inst, (unsigned short *)regs->pc + 1);
705 	if (!do_fpu_inst(inst, regs)) {
706 		get_user(inst, (unsigned short *)regs->pc);
707 		if (!emulate_branch(inst, regs))
708 			return;
709 		/* fault in branch.*/
710 	}
711 	/* not a FPU inst. */
712 #endif
713 
714 	inst = lookup_exception_vector();
715 
716 	local_irq_enable();
717 	force_sig(SIGILL);
718 	die_if_no_fixup("illegal slot instruction", regs, inst);
719 }
720 
721 asmlinkage void do_exception_error(void)
722 {
723 	long ex;
724 
725 	ex = lookup_exception_vector();
726 	die_if_kernel("exception", current_pt_regs(), ex);
727 }
728 
729 void per_cpu_trap_init(void)
730 {
731 	extern void *vbr_base;
732 
733 	/* NOTE: The VBR value should be at P1
734 	   (or P2, virtural "fixed" address space).
735 	   It's definitely should not in physical address.  */
736 
737 	asm volatile("ldc	%0, vbr"
738 		     : /* no output */
739 		     : "r" (&vbr_base)
740 		     : "memory");
741 
742 	/* disable exception blocking now when the vbr has been setup */
743 	clear_bl_bit();
744 }
745 
746 void *set_exception_table_vec(unsigned int vec, void *handler)
747 {
748 	extern void *exception_handling_table[];
749 	void *old_handler;
750 
751 	old_handler = exception_handling_table[vec];
752 	exception_handling_table[vec] = handler;
753 	return old_handler;
754 }
755 
756 void __init trap_init(void)
757 {
758 	set_exception_table_vec(TRAP_RESERVED_INST, do_reserved_inst);
759 	set_exception_table_vec(TRAP_ILLEGAL_SLOT_INST, do_illegal_slot_inst);
760 
761 #if defined(CONFIG_CPU_SH4) && !defined(CONFIG_SH_FPU) || \
762     defined(CONFIG_SH_FPU_EMU)
763 	/*
764 	 * For SH-4 lacking an FPU, treat floating point instructions as
765 	 * reserved. They'll be handled in the math-emu case, or faulted on
766 	 * otherwise.
767 	 */
768 	set_exception_table_evt(0x800, do_reserved_inst);
769 	set_exception_table_evt(0x820, do_illegal_slot_inst);
770 #elif defined(CONFIG_SH_FPU)
771 	set_exception_table_evt(0x800, fpu_state_restore_trap_handler);
772 	set_exception_table_evt(0x820, fpu_state_restore_trap_handler);
773 #endif
774 
775 #ifdef CONFIG_CPU_SH2
776 	set_exception_table_vec(TRAP_ADDRESS_ERROR, address_error_trap_handler);
777 #endif
778 #ifdef CONFIG_CPU_SH2A
779 	set_exception_table_vec(TRAP_DIVZERO_ERROR, do_divide_error);
780 	set_exception_table_vec(TRAP_DIVOVF_ERROR, do_divide_error);
781 #ifdef CONFIG_SH_FPU
782 	set_exception_table_vec(TRAP_FPU_ERROR, fpu_error_trap_handler);
783 #endif
784 #endif
785 
786 #ifdef TRAP_UBC
787 	set_exception_table_vec(TRAP_UBC, breakpoint_trap_handler);
788 #endif
789 }
790