xref: /openbmc/linux/arch/parisc/kernel/traps.c (revision d3964221)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  *  linux/arch/parisc/traps.c
4  *
5  *  Copyright (C) 1991, 1992  Linus Torvalds
6  *  Copyright (C) 1999, 2000  Philipp Rumpf <prumpf@tux.org>
7  */
8 
9 /*
10  * 'Traps.c' handles hardware traps and faults after we have saved some
11  * state in 'asm.s'.
12  */
13 
14 #include <linux/sched.h>
15 #include <linux/sched/debug.h>
16 #include <linux/kernel.h>
17 #include <linux/string.h>
18 #include <linux/errno.h>
19 #include <linux/ptrace.h>
20 #include <linux/timer.h>
21 #include <linux/delay.h>
22 #include <linux/mm.h>
23 #include <linux/module.h>
24 #include <linux/smp.h>
25 #include <linux/spinlock.h>
26 #include <linux/init.h>
27 #include <linux/interrupt.h>
28 #include <linux/console.h>
29 #include <linux/bug.h>
30 #include <linux/ratelimit.h>
31 #include <linux/uaccess.h>
32 
33 #include <asm/assembly.h>
34 #include <asm/io.h>
35 #include <asm/irq.h>
36 #include <asm/traps.h>
37 #include <asm/unaligned.h>
38 #include <linux/atomic.h>
39 #include <asm/smp.h>
40 #include <asm/pdc.h>
41 #include <asm/pdc_chassis.h>
42 #include <asm/unwind.h>
43 #include <asm/tlbflush.h>
44 #include <asm/cacheflush.h>
45 
46 #include "../math-emu/math-emu.h"	/* for handle_fpe() */
47 
48 static void parisc_show_stack(struct task_struct *task, unsigned long *sp,
49 	struct pt_regs *regs);
50 
51 static int printbinary(char *buf, unsigned long x, int nbits)
52 {
53 	unsigned long mask = 1UL << (nbits - 1);
54 	while (mask != 0) {
55 		*buf++ = (mask & x ? '1' : '0');
56 		mask >>= 1;
57 	}
58 	*buf = '\0';
59 
60 	return nbits;
61 }
62 
63 #ifdef CONFIG_64BIT
64 #define RFMT "%016lx"
65 #else
66 #define RFMT "%08lx"
67 #endif
68 #define FFMT "%016llx"	/* fpregs are 64-bit always */
69 
70 #define PRINTREGS(lvl,r,f,fmt,x)	\
71 	printk("%s%s%02d-%02d  " fmt " " fmt " " fmt " " fmt "\n",	\
72 		lvl, f, (x), (x+3), (r)[(x)+0], (r)[(x)+1],		\
73 		(r)[(x)+2], (r)[(x)+3])
74 
75 static void print_gr(char *level, struct pt_regs *regs)
76 {
77 	int i;
78 	char buf[64];
79 
80 	printk("%s\n", level);
81 	printk("%s     YZrvWESTHLNXBCVMcbcbcbcbOGFRQPDI\n", level);
82 	printbinary(buf, regs->gr[0], 32);
83 	printk("%sPSW: %s %s\n", level, buf, print_tainted());
84 
85 	for (i = 0; i < 32; i += 4)
86 		PRINTREGS(level, regs->gr, "r", RFMT, i);
87 }
88 
89 static void print_fr(char *level, struct pt_regs *regs)
90 {
91 	int i;
92 	char buf[64];
93 	struct { u32 sw[2]; } s;
94 
95 	/* FR are 64bit everywhere. Need to use asm to get the content
96 	 * of fpsr/fper1, and we assume that we won't have a FP Identify
97 	 * in our way, otherwise we're screwed.
98 	 * The fldd is used to restore the T-bit if there was one, as the
99 	 * store clears it anyway.
100 	 * PA2.0 book says "thou shall not use fstw on FPSR/FPERs" - T-Bone */
101 	asm volatile ("fstd %%fr0,0(%1)	\n\t"
102 		      "fldd 0(%1),%%fr0	\n\t"
103 		      : "=m" (s) : "r" (&s) : "r0");
104 
105 	printk("%s\n", level);
106 	printk("%s      VZOUICununcqcqcqcqcqcrmunTDVZOUI\n", level);
107 	printbinary(buf, s.sw[0], 32);
108 	printk("%sFPSR: %s\n", level, buf);
109 	printk("%sFPER1: %08x\n", level, s.sw[1]);
110 
111 	/* here we'll print fr0 again, tho it'll be meaningless */
112 	for (i = 0; i < 32; i += 4)
113 		PRINTREGS(level, regs->fr, "fr", FFMT, i);
114 }
115 
116 void show_regs(struct pt_regs *regs)
117 {
118 	int i, user;
119 	char *level;
120 	unsigned long cr30, cr31;
121 
122 	user = user_mode(regs);
123 	level = user ? KERN_DEBUG : KERN_CRIT;
124 
125 	show_regs_print_info(level);
126 
127 	print_gr(level, regs);
128 
129 	for (i = 0; i < 8; i += 4)
130 		PRINTREGS(level, regs->sr, "sr", RFMT, i);
131 
132 	if (user)
133 		print_fr(level, regs);
134 
135 	cr30 = mfctl(30);
136 	cr31 = mfctl(31);
137 	printk("%s\n", level);
138 	printk("%sIASQ: " RFMT " " RFMT " IAOQ: " RFMT " " RFMT "\n",
139 	       level, regs->iasq[0], regs->iasq[1], regs->iaoq[0], regs->iaoq[1]);
140 	printk("%s IIR: %08lx    ISR: " RFMT "  IOR: " RFMT "\n",
141 	       level, regs->iir, regs->isr, regs->ior);
142 	printk("%s CPU: %8d   CR30: " RFMT " CR31: " RFMT "\n",
143 	       level, current_thread_info()->cpu, cr30, cr31);
144 	printk("%s ORIG_R28: " RFMT "\n", level, regs->orig_r28);
145 
146 	if (user) {
147 		printk("%s IAOQ[0]: " RFMT "\n", level, regs->iaoq[0]);
148 		printk("%s IAOQ[1]: " RFMT "\n", level, regs->iaoq[1]);
149 		printk("%s RP(r2): " RFMT "\n", level, regs->gr[2]);
150 	} else {
151 		printk("%s IAOQ[0]: %pS\n", level, (void *) regs->iaoq[0]);
152 		printk("%s IAOQ[1]: %pS\n", level, (void *) regs->iaoq[1]);
153 		printk("%s RP(r2): %pS\n", level, (void *) regs->gr[2]);
154 
155 		parisc_show_stack(current, NULL, regs);
156 	}
157 }
158 
159 static DEFINE_RATELIMIT_STATE(_hppa_rs,
160 	DEFAULT_RATELIMIT_INTERVAL, DEFAULT_RATELIMIT_BURST);
161 
162 #define parisc_printk_ratelimited(critical, regs, fmt, ...)	{	      \
163 	if ((critical || show_unhandled_signals) && __ratelimit(&_hppa_rs)) { \
164 		printk(fmt, ##__VA_ARGS__);				      \
165 		show_regs(regs);					      \
166 	}								      \
167 }
168 
169 
170 static void do_show_stack(struct unwind_frame_info *info)
171 {
172 	int i = 1;
173 
174 	printk(KERN_CRIT "Backtrace:\n");
175 	while (i <= 16) {
176 		if (unwind_once(info) < 0 || info->ip == 0)
177 			break;
178 
179 		if (__kernel_text_address(info->ip)) {
180 			printk(KERN_CRIT " [<" RFMT ">] %pS\n",
181 				info->ip, (void *) info->ip);
182 			i++;
183 		}
184 	}
185 	printk(KERN_CRIT "\n");
186 }
187 
188 static void parisc_show_stack(struct task_struct *task, unsigned long *sp,
189 	struct pt_regs *regs)
190 {
191 	struct unwind_frame_info info;
192 	struct task_struct *t;
193 
194 	t = task ? task : current;
195 	if (regs) {
196 		unwind_frame_init(&info, t, regs);
197 		goto show_stack;
198 	}
199 
200 	if (t == current) {
201 		unsigned long sp;
202 
203 HERE:
204 		asm volatile ("copy %%r30, %0" : "=r"(sp));
205 		{
206 			struct pt_regs r;
207 
208 			memset(&r, 0, sizeof(struct pt_regs));
209 			r.iaoq[0] = (unsigned long)&&HERE;
210 			r.gr[2] = (unsigned long)__builtin_return_address(0);
211 			r.gr[30] = sp;
212 
213 			unwind_frame_init(&info, current, &r);
214 		}
215 	} else {
216 		unwind_frame_init_from_blocked_task(&info, t);
217 	}
218 
219 show_stack:
220 	do_show_stack(&info);
221 }
222 
223 void show_stack(struct task_struct *t, unsigned long *sp)
224 {
225 	return parisc_show_stack(t, sp, NULL);
226 }
227 
228 int is_valid_bugaddr(unsigned long iaoq)
229 {
230 	return 1;
231 }
232 
233 void die_if_kernel(char *str, struct pt_regs *regs, long err)
234 {
235 	if (user_mode(regs)) {
236 		if (err == 0)
237 			return; /* STFU */
238 
239 		parisc_printk_ratelimited(1, regs,
240 			KERN_CRIT "%s (pid %d): %s (code %ld) at " RFMT "\n",
241 			current->comm, task_pid_nr(current), str, err, regs->iaoq[0]);
242 
243 		return;
244 	}
245 
246 	oops_in_progress = 1;
247 
248 	oops_enter();
249 
250 	/* Amuse the user in a SPARC fashion */
251 	if (err) printk(KERN_CRIT
252 			"      _______________________________ \n"
253 			"     < Your System ate a SPARC! Gah! >\n"
254 			"      ------------------------------- \n"
255 			"             \\   ^__^\n"
256 			"                 (__)\\       )\\/\\\n"
257 			"                  U  ||----w |\n"
258 			"                     ||     ||\n");
259 
260 	/* unlock the pdc lock if necessary */
261 	pdc_emergency_unlock();
262 
263 	/* maybe the kernel hasn't booted very far yet and hasn't been able
264 	 * to initialize the serial or STI console. In that case we should
265 	 * re-enable the pdc console, so that the user will be able to
266 	 * identify the problem. */
267 	if (!console_drivers)
268 		pdc_console_restart();
269 
270 	if (err)
271 		printk(KERN_CRIT "%s (pid %d): %s (code %ld)\n",
272 			current->comm, task_pid_nr(current), str, err);
273 
274 	/* Wot's wrong wif bein' racy? */
275 	if (current->thread.flags & PARISC_KERNEL_DEATH) {
276 		printk(KERN_CRIT "%s() recursion detected.\n", __func__);
277 		local_irq_enable();
278 		while (1);
279 	}
280 	current->thread.flags |= PARISC_KERNEL_DEATH;
281 
282 	show_regs(regs);
283 	dump_stack();
284 	add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
285 
286 	if (in_interrupt())
287 		panic("Fatal exception in interrupt");
288 
289 	if (panic_on_oops)
290 		panic("Fatal exception");
291 
292 	oops_exit();
293 	do_exit(SIGSEGV);
294 }
295 
296 /* gdb uses break 4,8 */
297 #define GDB_BREAK_INSN 0x10004
298 static void handle_gdb_break(struct pt_regs *regs, int wot)
299 {
300 	struct siginfo si;
301 
302 	si.si_signo = SIGTRAP;
303 	si.si_errno = 0;
304 	si.si_code = wot;
305 	si.si_addr = (void __user *) (regs->iaoq[0] & ~3);
306 	force_sig_info(SIGTRAP, &si, current);
307 }
308 
309 static void handle_break(struct pt_regs *regs)
310 {
311 	unsigned iir = regs->iir;
312 
313 	if (unlikely(iir == PARISC_BUG_BREAK_INSN && !user_mode(regs))) {
314 		/* check if a BUG() or WARN() trapped here.  */
315 		enum bug_trap_type tt;
316 		tt = report_bug(regs->iaoq[0] & ~3, regs);
317 		if (tt == BUG_TRAP_TYPE_WARN) {
318 			regs->iaoq[0] += 4;
319 			regs->iaoq[1] += 4;
320 			return; /* return to next instruction when WARN_ON().  */
321 		}
322 		die_if_kernel("Unknown kernel breakpoint", regs,
323 			(tt == BUG_TRAP_TYPE_NONE) ? 9 : 0);
324 	}
325 
326 	if (unlikely(iir != GDB_BREAK_INSN))
327 		parisc_printk_ratelimited(0, regs,
328 			KERN_DEBUG "break %d,%d: pid=%d command='%s'\n",
329 			iir & 31, (iir>>13) & ((1<<13)-1),
330 			task_pid_nr(current), current->comm);
331 
332 	/* send standard GDB signal */
333 	handle_gdb_break(regs, TRAP_BRKPT);
334 }
335 
336 static void default_trap(int code, struct pt_regs *regs)
337 {
338 	printk(KERN_ERR "Trap %d on CPU %d\n", code, smp_processor_id());
339 	show_regs(regs);
340 }
341 
342 void (*cpu_lpmc) (int code, struct pt_regs *regs) __read_mostly = default_trap;
343 
344 
345 void transfer_pim_to_trap_frame(struct pt_regs *regs)
346 {
347     register int i;
348     extern unsigned int hpmc_pim_data[];
349     struct pdc_hpmc_pim_11 *pim_narrow;
350     struct pdc_hpmc_pim_20 *pim_wide;
351 
352     if (boot_cpu_data.cpu_type >= pcxu) {
353 
354 	pim_wide = (struct pdc_hpmc_pim_20 *)hpmc_pim_data;
355 
356 	/*
357 	 * Note: The following code will probably generate a
358 	 * bunch of truncation error warnings from the compiler.
359 	 * Could be handled with an ifdef, but perhaps there
360 	 * is a better way.
361 	 */
362 
363 	regs->gr[0] = pim_wide->cr[22];
364 
365 	for (i = 1; i < 32; i++)
366 	    regs->gr[i] = pim_wide->gr[i];
367 
368 	for (i = 0; i < 32; i++)
369 	    regs->fr[i] = pim_wide->fr[i];
370 
371 	for (i = 0; i < 8; i++)
372 	    regs->sr[i] = pim_wide->sr[i];
373 
374 	regs->iasq[0] = pim_wide->cr[17];
375 	regs->iasq[1] = pim_wide->iasq_back;
376 	regs->iaoq[0] = pim_wide->cr[18];
377 	regs->iaoq[1] = pim_wide->iaoq_back;
378 
379 	regs->sar  = pim_wide->cr[11];
380 	regs->iir  = pim_wide->cr[19];
381 	regs->isr  = pim_wide->cr[20];
382 	regs->ior  = pim_wide->cr[21];
383     }
384     else {
385 	pim_narrow = (struct pdc_hpmc_pim_11 *)hpmc_pim_data;
386 
387 	regs->gr[0] = pim_narrow->cr[22];
388 
389 	for (i = 1; i < 32; i++)
390 	    regs->gr[i] = pim_narrow->gr[i];
391 
392 	for (i = 0; i < 32; i++)
393 	    regs->fr[i] = pim_narrow->fr[i];
394 
395 	for (i = 0; i < 8; i++)
396 	    regs->sr[i] = pim_narrow->sr[i];
397 
398 	regs->iasq[0] = pim_narrow->cr[17];
399 	regs->iasq[1] = pim_narrow->iasq_back;
400 	regs->iaoq[0] = pim_narrow->cr[18];
401 	regs->iaoq[1] = pim_narrow->iaoq_back;
402 
403 	regs->sar  = pim_narrow->cr[11];
404 	regs->iir  = pim_narrow->cr[19];
405 	regs->isr  = pim_narrow->cr[20];
406 	regs->ior  = pim_narrow->cr[21];
407     }
408 
409     /*
410      * The following fields only have meaning if we came through
411      * another path. So just zero them here.
412      */
413 
414     regs->ksp = 0;
415     regs->kpc = 0;
416     regs->orig_r28 = 0;
417 }
418 
419 
420 /*
421  * This routine is called as a last resort when everything else
422  * has gone clearly wrong. We get called for faults in kernel space,
423  * and HPMC's.
424  */
425 void parisc_terminate(char *msg, struct pt_regs *regs, int code, unsigned long offset)
426 {
427 	static DEFINE_SPINLOCK(terminate_lock);
428 
429 	oops_in_progress = 1;
430 
431 	set_eiem(0);
432 	local_irq_disable();
433 	spin_lock(&terminate_lock);
434 
435 	/* unlock the pdc lock if necessary */
436 	pdc_emergency_unlock();
437 
438 	/* restart pdc console if necessary */
439 	if (!console_drivers)
440 		pdc_console_restart();
441 
442 	/* Not all paths will gutter the processor... */
443 	switch(code){
444 
445 	case 1:
446 		transfer_pim_to_trap_frame(regs);
447 		break;
448 
449 	default:
450 		/* Fall through */
451 		break;
452 
453 	}
454 
455 	{
456 		/* show_stack(NULL, (unsigned long *)regs->gr[30]); */
457 		struct unwind_frame_info info;
458 		unwind_frame_init(&info, current, regs);
459 		do_show_stack(&info);
460 	}
461 
462 	printk("\n");
463 	pr_crit("%s: Code=%d (%s) regs=%p (Addr=" RFMT ")\n",
464 		msg, code, trap_name(code), regs, offset);
465 	show_regs(regs);
466 
467 	spin_unlock(&terminate_lock);
468 
469 	/* put soft power button back under hardware control;
470 	 * if the user had pressed it once at any time, the
471 	 * system will shut down immediately right here. */
472 	pdc_soft_power_button(0);
473 
474 	/* Call kernel panic() so reboot timeouts work properly
475 	 * FIXME: This function should be on the list of
476 	 * panic notifiers, and we should call panic
477 	 * directly from the location that we wish.
478 	 * e.g. We should not call panic from
479 	 * parisc_terminate, but rather the oter way around.
480 	 * This hack works, prints the panic message twice,
481 	 * and it enables reboot timers!
482 	 */
483 	panic(msg);
484 }
485 
486 void notrace handle_interruption(int code, struct pt_regs *regs)
487 {
488 	unsigned long fault_address = 0;
489 	unsigned long fault_space = 0;
490 	struct siginfo si;
491 
492 	if (code == 1)
493 	    pdc_console_restart();  /* switch back to pdc if HPMC */
494 	else
495 	    local_irq_enable();
496 
497 	/* Security check:
498 	 * If the priority level is still user, and the
499 	 * faulting space is not equal to the active space
500 	 * then the user is attempting something in a space
501 	 * that does not belong to them. Kill the process.
502 	 *
503 	 * This is normally the situation when the user
504 	 * attempts to jump into the kernel space at the
505 	 * wrong offset, be it at the gateway page or a
506 	 * random location.
507 	 *
508 	 * We cannot normally signal the process because it
509 	 * could *be* on the gateway page, and processes
510 	 * executing on the gateway page can't have signals
511 	 * delivered.
512 	 *
513 	 * We merely readjust the address into the users
514 	 * space, at a destination address of zero, and
515 	 * allow processing to continue.
516 	 */
517 	if (((unsigned long)regs->iaoq[0] & 3) &&
518 	    ((unsigned long)regs->iasq[0] != (unsigned long)regs->sr[7])) {
519 		/* Kill the user process later */
520 		regs->iaoq[0] = 0 | 3;
521 		regs->iaoq[1] = regs->iaoq[0] + 4;
522 		regs->iasq[0] = regs->iasq[1] = regs->sr[7];
523 		regs->gr[0] &= ~PSW_B;
524 		return;
525 	}
526 
527 #if 0
528 	printk(KERN_CRIT "Interruption # %d\n", code);
529 #endif
530 
531 	switch(code) {
532 
533 	case  1:
534 		/* High-priority machine check (HPMC) */
535 
536 		/* set up a new led state on systems shipped with a LED State panel */
537 		pdc_chassis_send_status(PDC_CHASSIS_DIRECT_HPMC);
538 
539 		parisc_terminate("High Priority Machine Check (HPMC)",
540 				regs, code, 0);
541 		/* NOT REACHED */
542 
543 	case  2:
544 		/* Power failure interrupt */
545 		printk(KERN_CRIT "Power failure interrupt !\n");
546 		return;
547 
548 	case  3:
549 		/* Recovery counter trap */
550 		regs->gr[0] &= ~PSW_R;
551 		if (user_space(regs))
552 			handle_gdb_break(regs, TRAP_TRACE);
553 		/* else this must be the start of a syscall - just let it run */
554 		return;
555 
556 	case  5:
557 		/* Low-priority machine check */
558 		pdc_chassis_send_status(PDC_CHASSIS_DIRECT_LPMC);
559 
560 		flush_cache_all();
561 		flush_tlb_all();
562 		cpu_lpmc(5, regs);
563 		return;
564 
565 	case  6:
566 		/* Instruction TLB miss fault/Instruction page fault */
567 		fault_address = regs->iaoq[0];
568 		fault_space   = regs->iasq[0];
569 		break;
570 
571 	case  8:
572 		/* Illegal instruction trap */
573 		die_if_kernel("Illegal instruction", regs, code);
574 		si.si_code = ILL_ILLOPC;
575 		goto give_sigill;
576 
577 	case  9:
578 		/* Break instruction trap */
579 		handle_break(regs);
580 		return;
581 
582 	case 10:
583 		/* Privileged operation trap */
584 		die_if_kernel("Privileged operation", regs, code);
585 		si.si_code = ILL_PRVOPC;
586 		goto give_sigill;
587 
588 	case 11:
589 		/* Privileged register trap */
590 		if ((regs->iir & 0xffdfffe0) == 0x034008a0) {
591 
592 			/* This is a MFCTL cr26/cr27 to gr instruction.
593 			 * PCXS traps on this, so we need to emulate it.
594 			 */
595 
596 			if (regs->iir & 0x00200000)
597 				regs->gr[regs->iir & 0x1f] = mfctl(27);
598 			else
599 				regs->gr[regs->iir & 0x1f] = mfctl(26);
600 
601 			regs->iaoq[0] = regs->iaoq[1];
602 			regs->iaoq[1] += 4;
603 			regs->iasq[0] = regs->iasq[1];
604 			return;
605 		}
606 
607 		die_if_kernel("Privileged register usage", regs, code);
608 		si.si_code = ILL_PRVREG;
609 	give_sigill:
610 		si.si_signo = SIGILL;
611 		si.si_errno = 0;
612 		si.si_addr = (void __user *) regs->iaoq[0];
613 		force_sig_info(SIGILL, &si, current);
614 		return;
615 
616 	case 12:
617 		/* Overflow Trap, let the userland signal handler do the cleanup */
618 		si.si_signo = SIGFPE;
619 		si.si_code = FPE_INTOVF;
620 		si.si_addr = (void __user *) regs->iaoq[0];
621 		force_sig_info(SIGFPE, &si, current);
622 		return;
623 
624 	case 13:
625 		/* Conditional Trap
626 		   The condition succeeds in an instruction which traps
627 		   on condition  */
628 		if(user_mode(regs)){
629 			si.si_signo = SIGFPE;
630 			/* Set to zero, and let the userspace app figure it out from
631 			   the insn pointed to by si_addr */
632 			si.si_code = 0;
633 			si.si_addr = (void __user *) regs->iaoq[0];
634 			force_sig_info(SIGFPE, &si, current);
635 			return;
636 		}
637 		/* The kernel doesn't want to handle condition codes */
638 		break;
639 
640 	case 14:
641 		/* Assist Exception Trap, i.e. floating point exception. */
642 		die_if_kernel("Floating point exception", regs, 0); /* quiet */
643 		__inc_irq_stat(irq_fpassist_count);
644 		handle_fpe(regs);
645 		return;
646 
647 	case 15:
648 		/* Data TLB miss fault/Data page fault */
649 		/* Fall through */
650 	case 16:
651 		/* Non-access instruction TLB miss fault */
652 		/* The instruction TLB entry needed for the target address of the FIC
653 		   is absent, and hardware can't find it, so we get to cleanup */
654 		/* Fall through */
655 	case 17:
656 		/* Non-access data TLB miss fault/Non-access data page fault */
657 		/* FIXME:
658 			 Still need to add slow path emulation code here!
659 			 If the insn used a non-shadow register, then the tlb
660 			 handlers could not have their side-effect (e.g. probe
661 			 writing to a target register) emulated since rfir would
662 			 erase the changes to said register. Instead we have to
663 			 setup everything, call this function we are in, and emulate
664 			 by hand. Technically we need to emulate:
665 			 fdc,fdce,pdc,"fic,4f",prober,probeir,probew, probeiw
666 		*/
667 		fault_address = regs->ior;
668 		fault_space = regs->isr;
669 		break;
670 
671 	case 18:
672 		/* PCXS only -- later cpu's split this into types 26,27 & 28 */
673 		/* Check for unaligned access */
674 		if (check_unaligned(regs)) {
675 			handle_unaligned(regs);
676 			return;
677 		}
678 		/* Fall Through */
679 	case 26:
680 		/* PCXL: Data memory access rights trap */
681 		fault_address = regs->ior;
682 		fault_space   = regs->isr;
683 		break;
684 
685 	case 19:
686 		/* Data memory break trap */
687 		regs->gr[0] |= PSW_X; /* So we can single-step over the trap */
688 		/* fall thru */
689 	case 21:
690 		/* Page reference trap */
691 		handle_gdb_break(regs, TRAP_HWBKPT);
692 		return;
693 
694 	case 25:
695 		/* Taken branch trap */
696 		regs->gr[0] &= ~PSW_T;
697 		if (user_space(regs))
698 			handle_gdb_break(regs, TRAP_BRANCH);
699 		/* else this must be the start of a syscall - just let it
700 		 * run.
701 		 */
702 		return;
703 
704 	case  7:
705 		/* Instruction access rights */
706 		/* PCXL: Instruction memory protection trap */
707 
708 		/*
709 		 * This could be caused by either: 1) a process attempting
710 		 * to execute within a vma that does not have execute
711 		 * permission, or 2) an access rights violation caused by a
712 		 * flush only translation set up by ptep_get_and_clear().
713 		 * So we check the vma permissions to differentiate the two.
714 		 * If the vma indicates we have execute permission, then
715 		 * the cause is the latter one. In this case, we need to
716 		 * call do_page_fault() to fix the problem.
717 		 */
718 
719 		if (user_mode(regs)) {
720 			struct vm_area_struct *vma;
721 
722 			down_read(&current->mm->mmap_sem);
723 			vma = find_vma(current->mm,regs->iaoq[0]);
724 			if (vma && (regs->iaoq[0] >= vma->vm_start)
725 				&& (vma->vm_flags & VM_EXEC)) {
726 
727 				fault_address = regs->iaoq[0];
728 				fault_space = regs->iasq[0];
729 
730 				up_read(&current->mm->mmap_sem);
731 				break; /* call do_page_fault() */
732 			}
733 			up_read(&current->mm->mmap_sem);
734 		}
735 		/* Fall Through */
736 	case 27:
737 		/* Data memory protection ID trap */
738 		if (code == 27 && !user_mode(regs) &&
739 			fixup_exception(regs))
740 			return;
741 
742 		die_if_kernel("Protection id trap", regs, code);
743 		si.si_code = SEGV_MAPERR;
744 		si.si_signo = SIGSEGV;
745 		si.si_errno = 0;
746 		if (code == 7)
747 		    si.si_addr = (void __user *) regs->iaoq[0];
748 		else
749 		    si.si_addr = (void __user *) regs->ior;
750 		force_sig_info(SIGSEGV, &si, current);
751 		return;
752 
753 	case 28:
754 		/* Unaligned data reference trap */
755 		handle_unaligned(regs);
756 		return;
757 
758 	default:
759 		if (user_mode(regs)) {
760 			parisc_printk_ratelimited(0, regs, KERN_DEBUG
761 				"handle_interruption() pid=%d command='%s'\n",
762 				task_pid_nr(current), current->comm);
763 			/* SIGBUS, for lack of a better one. */
764 			si.si_signo = SIGBUS;
765 			si.si_code = BUS_OBJERR;
766 			si.si_errno = 0;
767 			si.si_addr = (void __user *) regs->ior;
768 			force_sig_info(SIGBUS, &si, current);
769 			return;
770 		}
771 		pdc_chassis_send_status(PDC_CHASSIS_DIRECT_PANIC);
772 
773 		parisc_terminate("Unexpected interruption", regs, code, 0);
774 		/* NOT REACHED */
775 	}
776 
777 	if (user_mode(regs)) {
778 	    if ((fault_space >> SPACEID_SHIFT) != (regs->sr[7] >> SPACEID_SHIFT)) {
779 		parisc_printk_ratelimited(0, regs, KERN_DEBUG
780 				"User fault %d on space 0x%08lx, pid=%d command='%s'\n",
781 				code, fault_space,
782 				task_pid_nr(current), current->comm);
783 		si.si_signo = SIGSEGV;
784 		si.si_errno = 0;
785 		si.si_code = SEGV_MAPERR;
786 		si.si_addr = (void __user *) regs->ior;
787 		force_sig_info(SIGSEGV, &si, current);
788 		return;
789 	    }
790 	}
791 	else {
792 
793 	    /*
794 	     * The kernel should never fault on its own address space,
795 	     * unless pagefault_disable() was called before.
796 	     */
797 
798 	    if (fault_space == 0 && !faulthandler_disabled())
799 	    {
800 		/* Clean up and return if in exception table. */
801 		if (fixup_exception(regs))
802 			return;
803 		pdc_chassis_send_status(PDC_CHASSIS_DIRECT_PANIC);
804 		parisc_terminate("Kernel Fault", regs, code, fault_address);
805 	    }
806 	}
807 
808 	do_page_fault(regs, code, fault_address);
809 }
810 
811 
812 void __init initialize_ivt(const void *iva)
813 {
814 	extern u32 os_hpmc_size;
815 	extern const u32 os_hpmc[];
816 
817 	int i;
818 	u32 check = 0;
819 	u32 *ivap;
820 	u32 *hpmcp;
821 	u32 length, instr;
822 
823 	if (strcmp((const char *)iva, "cows can fly"))
824 		panic("IVT invalid");
825 
826 	ivap = (u32 *)iva;
827 
828 	for (i = 0; i < 8; i++)
829 	    *ivap++ = 0;
830 
831 	/*
832 	 * Use PDC_INSTR firmware function to get instruction that invokes
833 	 * PDCE_CHECK in HPMC handler.  See programming note at page 1-31 of
834 	 * the PA 1.1 Firmware Architecture document.
835 	 */
836 	if (pdc_instr(&instr) == PDC_OK)
837 		ivap[0] = instr;
838 
839 	/* Compute Checksum for HPMC handler */
840 	length = os_hpmc_size;
841 	ivap[7] = length;
842 
843 	hpmcp = (u32 *)os_hpmc;
844 
845 	for (i=0; i<length/4; i++)
846 	    check += *hpmcp++;
847 
848 	for (i=0; i<8; i++)
849 	    check += ivap[i];
850 
851 	ivap[5] = -check;
852 }
853 
854 
855 /* early_trap_init() is called before we set up kernel mappings and
856  * write-protect the kernel */
857 void  __init early_trap_init(void)
858 {
859 	extern const void fault_vector_20;
860 
861 #ifndef CONFIG_64BIT
862 	extern const void fault_vector_11;
863 	initialize_ivt(&fault_vector_11);
864 #endif
865 
866 	initialize_ivt(&fault_vector_20);
867 }
868 
869 void __init trap_init(void)
870 {
871 }
872