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trap.c revision 1.35
      1 /*	$NetBSD: trap.c,v 1.35 2006/07/19 21:11:45 ad Exp $	*/
      2 
      3 /*
      4  * Copyright 2001 Wasabi Systems, Inc.
      5  * All rights reserved.
      6  *
      7  * Written by Eduardo Horvath and Simon Burge for Wasabi Systems, Inc.
      8  *
      9  * Redistribution and use in source and binary forms, with or without
     10  * modification, are permitted provided that the following conditions
     11  * are met:
     12  * 1. Redistributions of source code must retain the above copyright
     13  *    notice, this list of conditions and the following disclaimer.
     14  * 2. Redistributions in binary form must reproduce the above copyright
     15  *    notice, this list of conditions and the following disclaimer in the
     16  *    documentation and/or other materials provided with the distribution.
     17  * 3. All advertising materials mentioning features or use of this software
     18  *    must display the following acknowledgement:
     19  *      This product includes software developed for the NetBSD Project by
     20  *      Wasabi Systems, Inc.
     21  * 4. The name of Wasabi Systems, Inc. may not be used to endorse
     22  *    or promote products derived from this software without specific prior
     23  *    written permission.
     24  *
     25  * THIS SOFTWARE IS PROVIDED BY WASABI SYSTEMS, INC. ``AS IS'' AND
     26  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     27  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     28  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL WASABI SYSTEMS, INC
     29  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     30  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     31  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     32  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     33  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     34  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     35  * POSSIBILITY OF SUCH DAMAGE.
     36  */
     37 
     38 /*
     39  * Copyright (C) 1995, 1996 Wolfgang Solfrank.
     40  * Copyright (C) 1995, 1996 TooLs GmbH.
     41  * All rights reserved.
     42  *
     43  * Redistribution and use in source and binary forms, with or without
     44  * modification, are permitted provided that the following conditions
     45  * are met:
     46  * 1. Redistributions of source code must retain the above copyright
     47  *    notice, this list of conditions and the following disclaimer.
     48  * 2. Redistributions in binary form must reproduce the above copyright
     49  *    notice, this list of conditions and the following disclaimer in the
     50  *    documentation and/or other materials provided with the distribution.
     51  * 3. All advertising materials mentioning features or use of this software
     52  *    must display the following acknowledgement:
     53  *	This product includes software developed by TooLs GmbH.
     54  * 4. The name of TooLs GmbH may not be used to endorse or promote products
     55  *    derived from this software without specific prior written permission.
     56  *
     57  * THIS SOFTWARE IS PROVIDED BY TOOLS GMBH ``AS IS'' AND ANY EXPRESS OR
     58  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
     59  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     60  * IN NO EVENT SHALL TOOLS GMBH BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     61  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
     62  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
     63  * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
     64  * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
     65  * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
     66  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     67  */
     68 
     69 #include <sys/cdefs.h>
     70 __KERNEL_RCSID(0, "$NetBSD: trap.c,v 1.35 2006/07/19 21:11:45 ad Exp $");
     71 
     72 #include "opt_altivec.h"
     73 #include "opt_ddb.h"
     74 
     75 #include <sys/param.h>
     76 #include <sys/proc.h>
     77 #include <sys/reboot.h>
     78 #include <sys/syscall.h>
     79 #include <sys/systm.h>
     80 #include <sys/user.h>
     81 #include <sys/pool.h>
     82 #include <sys/sa.h>
     83 #include <sys/savar.h>
     84 #include <sys/userret.h>
     85 #include <sys/kauth.h>
     86 
     87 #include <uvm/uvm_extern.h>
     88 
     89 #include <dev/cons.h>
     90 
     91 #include <machine/cpu.h>
     92 #include <machine/db_machdep.h>
     93 #include <machine/fpu.h>
     94 #include <machine/frame.h>
     95 #include <machine/pcb.h>
     96 #include <machine/psl.h>
     97 #include <machine/trap.h>
     98 
     99 #include <powerpc/spr.h>
    100 #include <powerpc/ibm4xx/pmap.h>
    101 #include <powerpc/ibm4xx/tlb.h>
    102 #include <powerpc/fpu/fpu_extern.h>
    103 
    104 /* These definitions should probably be somewhere else			XXX */
    105 #define	FIRSTARG	3		/* first argument is in reg 3 */
    106 #define	NARGREG		8		/* 8 args are in registers */
    107 #define	MOREARGS(sp)	((caddr_t)((int)(sp) + 8)) /* more args go here */
    108 
    109 static int fix_unaligned __P((struct lwp *l, struct trapframe *frame));
    110 
    111 void trap __P((struct trapframe *));	/* Called from locore / trap_subr */
    112 /* Why are these not defined in a header? */
    113 int badaddr __P((void *, size_t));
    114 int badaddr_read __P((void *, size_t, int *));
    115 int ctx_setup __P((int, int));
    116 
    117 #ifdef DEBUG
    118 #define TDB_ALL	0x1
    119 int trapdebug = /* TDB_ALL */ 0;
    120 #define	DBPRINTF(x, y)	if (trapdebug & (x)) printf y
    121 #else
    122 #define DBPRINTF(x, y)
    123 #endif
    124 
    125 void
    126 trap(struct trapframe *frame)
    127 {
    128 	struct lwp *l = curlwp;
    129 	struct proc *p = l ? l->l_proc : NULL;
    130 	int type = frame->exc;
    131 	int ftype, rv;
    132 	ksiginfo_t ksi;
    133 
    134 	KASSERT(l == 0 || (l->l_stat == LSONPROC));
    135 
    136 	if (frame->srr1 & PSL_PR) {
    137 		LWP_CACHE_CREDS(l, p);
    138 		type |= EXC_USER;
    139 	}
    140 
    141 	ftype = VM_PROT_READ;
    142 
    143 	DBPRINTF(TDB_ALL, ("trap(%x) at %lx from frame %p &frame %p\n",
    144 	    type, frame->srr0, frame, &frame));
    145 
    146 	switch (type) {
    147 	case EXC_DEBUG|EXC_USER:
    148 		{
    149 			int srr2, srr3;
    150 
    151 			__asm volatile("mfspr %0,0x3f0" :
    152 			    "=r" (rv), "=r" (srr2), "=r" (srr3) :);
    153 			printf("debug reg is %x srr2 %x srr3 %x\n", rv, srr2,
    154 			    srr3);
    155 			/* XXX fall through or break here?! */
    156 		}
    157 		/*
    158 		 * DEBUG intr -- probably single-step.
    159 		 */
    160 	case EXC_TRC|EXC_USER:
    161 		frame->srr1 &= ~PSL_SE;
    162 		KSI_INIT_TRAP(&ksi);
    163 		ksi.ksi_signo = SIGTRAP;
    164 		ksi.ksi_trap = EXC_TRC;
    165 		ksi.ksi_addr = (void *)frame->srr0;
    166 		KERNEL_PROC_LOCK(l);
    167 		trapsignal(l, &ksi);
    168 		KERNEL_PROC_UNLOCK(l);
    169 		break;
    170 
    171 	/*
    172 	 * If we could not find and install appropriate TLB entry, fall through.
    173 	 */
    174 
    175 	case EXC_DSI:
    176 		/* FALLTHROUGH */
    177 	case EXC_DTMISS:
    178 		{
    179 			struct vm_map *map;
    180 			vaddr_t va;
    181 			struct faultbuf *fb = NULL;
    182 
    183 			KERNEL_LOCK(LK_CANRECURSE|LK_EXCLUSIVE);
    184 			va = frame->dar;
    185 			if (frame->tf_xtra[TF_PID] == KERNEL_PID) {
    186 				map = kernel_map;
    187 			} else {
    188 				map = &p->p_vmspace->vm_map;
    189 				if (l->l_flag & L_SA) {
    190 					l->l_savp->savp_faultaddr = va;
    191 					l->l_flag |= L_SA_PAGEFAULT;
    192 				}
    193 			}
    194 
    195 			if (frame->tf_xtra[TF_ESR] & (ESR_DST|ESR_DIZ))
    196 				ftype = VM_PROT_WRITE;
    197 
    198 			DBPRINTF(TDB_ALL,
    199 			    ("trap(EXC_DSI) at %lx %s fault on %p esr %x\n",
    200 			    frame->srr0,
    201 			    (ftype & VM_PROT_WRITE) ? "write" : "read",
    202 			    (void *)va, frame->tf_xtra[TF_ESR]));
    203 			rv = uvm_fault(map, trunc_page(va), ftype);
    204 			KERNEL_UNLOCK();
    205 			if (map != kernel_map)
    206 				l->l_flag &= ~L_SA_PAGEFAULT;
    207 			if (rv == 0)
    208 				goto done;
    209 			if ((fb = l->l_addr->u_pcb.pcb_onfault) != NULL) {
    210 				frame->tf_xtra[TF_PID] = KERNEL_PID;
    211 				frame->srr0 = fb->fb_pc;
    212 				frame->srr1 |= PSL_IR; /* Re-enable IMMU */
    213 				frame->fixreg[1] = fb->fb_sp;
    214 				frame->fixreg[2] = fb->fb_r2;
    215 				frame->fixreg[3] = 1; /* Return TRUE */
    216 				frame->cr = fb->fb_cr;
    217 				memcpy(&frame->fixreg[13], fb->fb_fixreg,
    218 				    sizeof(fb->fb_fixreg));
    219 				goto done;
    220 			}
    221 		}
    222 		goto brain_damage;
    223 
    224 	case EXC_DSI|EXC_USER:
    225 		/* FALLTHROUGH */
    226 	case EXC_DTMISS|EXC_USER:
    227 		KERNEL_PROC_LOCK(l);
    228 
    229 		if (frame->tf_xtra[TF_ESR] & (ESR_DST|ESR_DIZ))
    230 			ftype = VM_PROT_WRITE;
    231 
    232 		DBPRINTF(TDB_ALL,
    233 		    ("trap(EXC_DSI|EXC_USER) at %lx %s fault on %lx %x\n",
    234 		    frame->srr0, (ftype & VM_PROT_WRITE) ? "write" : "read",
    235 		    frame->dar, frame->tf_xtra[TF_ESR]));
    236 		KASSERT(l == curlwp && (l->l_stat == LSONPROC));
    237 		if (l->l_flag & L_SA) {
    238 			l->l_savp->savp_faultaddr = (vaddr_t)frame->dar;
    239 			l->l_flag |= L_SA_PAGEFAULT;
    240 		}
    241 		rv = uvm_fault(&p->p_vmspace->vm_map, trunc_page(frame->dar),
    242 		    ftype);
    243 		if (rv == 0) {
    244 			l->l_flag &= ~L_SA_PAGEFAULT;
    245 			KERNEL_PROC_UNLOCK(l);
    246 			break;
    247 		}
    248 		KSI_INIT_TRAP(&ksi);
    249 		ksi.ksi_signo = SIGSEGV;
    250 		ksi.ksi_trap = EXC_DSI;
    251 		ksi.ksi_addr = (void *)frame->dar;
    252 		if (rv == ENOMEM) {
    253 			printf("UVM: pid %d (%s) lid %d, uid %d killed: "
    254 			    "out of swap\n",
    255 			    p->p_pid, p->p_comm, l->l_lid,
    256 			    p->p_cred ?
    257 			    kauth_cred_geteuid(p->p_cred) : -1);
    258 			ksi.ksi_signo = SIGKILL;
    259 		}
    260 		trapsignal(l, &ksi);
    261 		l->l_flag &= ~L_SA_PAGEFAULT;
    262 		KERNEL_PROC_UNLOCK(l);
    263 		break;
    264 
    265 	case EXC_ITMISS|EXC_USER:
    266 	case EXC_ISI|EXC_USER:
    267 		KERNEL_PROC_LOCK(l);
    268 		if (l->l_flag & L_SA) {
    269 			l->l_savp->savp_faultaddr = (vaddr_t)frame->srr0;
    270 			l->l_flag |= L_SA_PAGEFAULT;
    271 		}
    272 		ftype = VM_PROT_EXECUTE;
    273 		DBPRINTF(TDB_ALL,
    274 		    ("trap(EXC_ISI|EXC_USER) at %lx execute fault tf %p\n",
    275 		    frame->srr0, frame));
    276 		rv = uvm_fault(&p->p_vmspace->vm_map, trunc_page(frame->srr0),
    277 		    ftype);
    278 		if (rv == 0) {
    279 			l->l_flag &= ~L_SA_PAGEFAULT;
    280 			KERNEL_PROC_UNLOCK(l);
    281 			break;
    282 		}
    283 		KSI_INIT_TRAP(&ksi);
    284 		ksi.ksi_signo = SIGSEGV;
    285 		ksi.ksi_trap = EXC_ISI;
    286 		ksi.ksi_addr = (void *)frame->srr0;
    287 		ksi.ksi_code = (rv == EACCES ? SEGV_ACCERR : SEGV_MAPERR);
    288 		trapsignal(l, &ksi);
    289 		l->l_flag &= ~L_SA_PAGEFAULT;
    290 		KERNEL_PROC_UNLOCK(l);
    291 		break;
    292 
    293 	case EXC_AST|EXC_USER:
    294 		curcpu()->ci_astpending = 0;	/* we are about to do it */
    295 		KERNEL_PROC_LOCK(l);
    296 		uvmexp.softs++;
    297 		if (p->p_flag & P_OWEUPC) {
    298 			p->p_flag &= ~P_OWEUPC;
    299 			ADDUPROF(p);
    300 		}
    301 		/* Check whether we are being preempted. */
    302 		if (curcpu()->ci_want_resched)
    303 			preempt(0);
    304 		KERNEL_PROC_UNLOCK(l);
    305 		break;
    306 
    307 
    308 	case EXC_ALI|EXC_USER:
    309 		KERNEL_PROC_LOCK(l);
    310 		if (fix_unaligned(l, frame) != 0) {
    311 			KSI_INIT_TRAP(&ksi);
    312 			ksi.ksi_signo = SIGBUS;
    313 			ksi.ksi_trap = EXC_ALI;
    314 			ksi.ksi_addr = (void *)frame->dar;
    315 			trapsignal(l, &ksi);
    316 		} else
    317 			frame->srr0 += 4;
    318 		KERNEL_PROC_UNLOCK(l);
    319 		break;
    320 
    321 	case EXC_PGM|EXC_USER:
    322 		/*
    323 		 * Illegal insn:
    324 		 *
    325 		 * let's try to see if it's FPU and can be emulated.
    326 		 */
    327 		uvmexp.traps++;
    328 		if (!(l->l_addr->u_pcb.pcb_flags & PCB_FPU)) {
    329 			memset(&l->l_addr->u_pcb.pcb_fpu, 0,
    330 				sizeof l->l_addr->u_pcb.pcb_fpu);
    331 			l->l_addr->u_pcb.pcb_flags |= PCB_FPU;
    332 		}
    333 
    334 		if ((rv = fpu_emulate(frame,
    335 			(struct fpreg *)&l->l_addr->u_pcb.pcb_fpu))) {
    336 			KSI_INIT_TRAP(&ksi);
    337 			ksi.ksi_signo = rv;
    338 			ksi.ksi_trap = EXC_PGM;
    339 			ksi.ksi_addr = (void *)frame->srr0;
    340 			KERNEL_PROC_LOCK(l);
    341 			trapsignal(l, &ksi);
    342 			KERNEL_PROC_UNLOCK(l);
    343 		}
    344 		break;
    345 
    346 	case EXC_MCHK:
    347 		{
    348 			struct faultbuf *fb;
    349 
    350 			if ((fb = l->l_addr->u_pcb.pcb_onfault) != NULL) {
    351 				frame->tf_xtra[TF_PID] = KERNEL_PID;
    352 				frame->srr0 = fb->fb_pc;
    353 				frame->srr1 |= PSL_IR; /* Re-enable IMMU */
    354 				frame->fixreg[1] = fb->fb_sp;
    355 				frame->fixreg[2] = fb->fb_r2;
    356 				frame->fixreg[3] = 1; /* Return TRUE */
    357 				frame->cr = fb->fb_cr;
    358 				memcpy(&frame->fixreg[13], fb->fb_fixreg,
    359 				    sizeof(fb->fb_fixreg));
    360 				goto done;
    361 			}
    362 		}
    363 		goto brain_damage;
    364 	default:
    365  brain_damage:
    366 		printf("trap type 0x%x at 0x%lx\n", type, frame->srr0);
    367 #ifdef DDB
    368 		if (kdb_trap(type, frame))
    369 			goto done;
    370 #endif
    371 #ifdef TRAP_PANICWAIT
    372 		printf("Press a key to panic.\n");
    373 		cngetc();
    374 #endif
    375 		panic("trap");
    376 	}
    377 
    378 	/* Invoke MI userret code */
    379 	mi_userret(l);
    380 
    381 	curcpu()->ci_schedstate.spc_curpriority = l->l_priority = l->l_usrpri;
    382  done:
    383 	return;
    384 }
    385 
    386 int
    387 ctx_setup(int ctx, int srr1)
    388 {
    389 	volatile struct pmap *pm;
    390 
    391 	/* Update PID if we're returning to user mode. */
    392 	if (srr1 & PSL_PR) {
    393 		pm = curproc->p_vmspace->vm_map.pmap;
    394 		if (!pm->pm_ctx) {
    395 			ctx_alloc(__UNVOLATILE(pm));
    396 		}
    397 		ctx = pm->pm_ctx;
    398 		if (srr1 & PSL_SE) {
    399 			int dbreg, mask = 0x48000000;
    400 				/*
    401 				 * Set the Internal Debug and
    402 				 * Instruction Completion bits of
    403 				 * the DBCR0 register.
    404 				 *
    405 				 * XXX this is also used by jtag debuggers...
    406 				 */
    407 			__asm volatile("mfspr %0,0x3f2;"
    408 			    "or %0,%0,%1;"
    409 			    "mtspr 0x3f2,%0;" :
    410 			    "=&r" (dbreg) : "r" (mask));
    411 		}
    412 	}
    413 	else if (!ctx) {
    414 		ctx = KERNEL_PID;
    415 	}
    416 	return (ctx);
    417 }
    418 
    419 /*
    420  * Used by copyin()/copyout()
    421  */
    422 extern vaddr_t vmaprange __P((struct proc *, vaddr_t, vsize_t, int));
    423 extern void vunmaprange __P((vaddr_t, vsize_t));
    424 static int bigcopyin __P((const void *, void *, size_t ));
    425 static int bigcopyout __P((const void *, void *, size_t ));
    426 
    427 int
    428 copyin(const void *udaddr, void *kaddr, size_t len)
    429 {
    430 	struct pmap *pm = curproc->p_vmspace->vm_map.pmap;
    431 	int msr, pid, tmp, ctx;
    432 	struct faultbuf env;
    433 
    434 	/* For bigger buffers use the faster copy */
    435 	if (len > 256)
    436 		return (bigcopyin(udaddr, kaddr, len));
    437 
    438 	if (setfault(&env)) {
    439 		curpcb->pcb_onfault = 0;
    440 		return EFAULT;
    441 	}
    442 
    443 	if (!(ctx = pm->pm_ctx)) {
    444 		/* No context -- assign it one */
    445 		ctx_alloc(pm);
    446 		ctx = pm->pm_ctx;
    447 	}
    448 
    449 	__asm volatile("addi %6,%6,1; mtctr %6;"	/* Set up counter */
    450 		"mfmsr %0;"			/* Save MSR */
    451 		"li %1,0x20; "
    452 		"andc %1,%0,%1; mtmsr %1;"	/* Disable IMMU */
    453 		"mfpid %1;"			/* Save old PID */
    454 		"sync; isync;"
    455 
    456 		"1: bdz 2f;"			/* while len */
    457 		"mtpid %3; sync;"		/* Load user ctx */
    458 		"lbz %2,0(%4); addi %4,%4,1;"	/* Load byte */
    459 		"sync; isync;"
    460 		"mtpid %1;sync;"
    461 		"stb %2,0(%5); dcbf 0,%5; addi %5,%5,1;" /* Store kernel byte */
    462 		"sync; isync;"
    463 		"b 1b;"				/* repeat */
    464 
    465 		"2: mtpid %1; mtmsr %0;"	/* Restore PID and MSR */
    466 		"sync; isync;"
    467 		: "=&r" (msr), "=&r" (pid), "=&r" (tmp)
    468 		: "r" (ctx), "b" (udaddr), "b" (kaddr), "b" (len));
    469 
    470 	curpcb->pcb_onfault = 0;
    471 	return 0;
    472 }
    473 
    474 static int
    475 bigcopyin(const void *udaddr, void *kaddr, size_t len)
    476 {
    477 	const char *up;
    478 	char *kp = kaddr;
    479 	struct lwp *l = curlwp;
    480 	struct proc *p;
    481 	int error;
    482 
    483 	if (!l) {
    484 		return EFAULT;
    485 	}
    486 
    487 	p = l->l_proc;
    488 
    489 	/*
    490 	 * Stolen from physio():
    491 	 */
    492 	PHOLD(l);
    493 	error = uvm_vslock(p, __UNCONST(udaddr), len, VM_PROT_READ);
    494 	if (error) {
    495 		PRELE(l);
    496 		return EFAULT;
    497 	}
    498 	up = (char *)vmaprange(p, (vaddr_t)udaddr, len, VM_PROT_READ);
    499 
    500 	memcpy(kp, up, len);
    501 	vunmaprange((vaddr_t)up, len);
    502 	uvm_vsunlock(p, __UNCONST(udaddr), len);
    503 	PRELE(l);
    504 
    505 	return 0;
    506 }
    507 
    508 int
    509 copyout(const void *kaddr, void *udaddr, size_t len)
    510 {
    511 	struct pmap *pm = curproc->p_vmspace->vm_map.pmap;
    512 	int msr, pid, tmp, ctx;
    513 	struct faultbuf env;
    514 
    515 	/* For big copies use more efficient routine */
    516 	if (len > 256)
    517 		return (bigcopyout(kaddr, udaddr, len));
    518 
    519 	if (setfault(&env)) {
    520 		curpcb->pcb_onfault = 0;
    521 		return EFAULT;
    522 	}
    523 
    524 	if (!(ctx = pm->pm_ctx)) {
    525 		/* No context -- assign it one */
    526 		ctx_alloc(pm);
    527 		ctx = pm->pm_ctx;
    528 	}
    529 
    530 	__asm volatile("addi %6,%6,1; mtctr %6;"	/* Set up counter */
    531 		"mfmsr %0;"			/* Save MSR */
    532 		"li %1,0x20; "
    533 		"andc %1,%0,%1; mtmsr %1;"	/* Disable IMMU */
    534 		"mfpid %1;"			/* Save old PID */
    535 		"sync; isync;"
    536 
    537 		"1: bdz 2f;"			/* while len */
    538 		"mtpid %1;sync;"
    539 		"lbz %2,0(%5); addi %5,%5,1;"	/* Load kernel byte */
    540 		"sync; isync;"
    541 		"mtpid %3; sync;"		/* Load user ctx */
    542 		"stb %2,0(%4);  dcbf 0,%4; addi %4,%4,1;" /* Store user byte */
    543 		"sync; isync;"
    544 		"b 1b;"				/* repeat */
    545 
    546 		"2: mtpid %1; mtmsr %0;"	/* Restore PID and MSR */
    547 		"sync; isync;"
    548 		: "=&r" (msr), "=&r" (pid), "=&r" (tmp)
    549 		: "r" (ctx), "b" (udaddr), "b" (kaddr), "b" (len));
    550 
    551 	curpcb->pcb_onfault = 0;
    552 	return 0;
    553 }
    554 
    555 static int
    556 bigcopyout(const void *kaddr, void *udaddr, size_t len)
    557 {
    558 	char *up;
    559 	const char *kp = (const char *)kaddr;
    560 	struct lwp *l = curlwp;
    561 	struct proc *p;
    562 	int error;
    563 
    564 	if (!l) {
    565 		return EFAULT;
    566 	}
    567 
    568 	p = l->l_proc;
    569 
    570 	/*
    571 	 * Stolen from physio():
    572 	 */
    573 	PHOLD(l);
    574 	error = uvm_vslock(p, udaddr, len, VM_PROT_WRITE);
    575 	if (error) {
    576 		PRELE(l);
    577 		return EFAULT;
    578 	}
    579 	up = (char *)vmaprange(p, (vaddr_t)udaddr, len,
    580 	    VM_PROT_READ | VM_PROT_WRITE);
    581 
    582 	memcpy(up, kp, len);
    583 	vunmaprange((vaddr_t)up, len);
    584 	uvm_vsunlock(p, udaddr, len);
    585 	PRELE(l);
    586 
    587 	return 0;
    588 }
    589 
    590 /*
    591  * kcopy(const void *src, void *dst, size_t len);
    592  *
    593  * Copy len bytes from src to dst, aborting if we encounter a fatal
    594  * page fault.
    595  *
    596  * kcopy() _must_ save and restore the old fault handler since it is
    597  * called by uiomove(), which may be in the path of servicing a non-fatal
    598  * page fault.
    599  */
    600 int
    601 kcopy(const void *src, void *dst, size_t len)
    602 {
    603 	struct faultbuf env, *oldfault;
    604 
    605 	oldfault = curpcb->pcb_onfault;
    606 	if (setfault(&env)) {
    607 		curpcb->pcb_onfault = oldfault;
    608 		return EFAULT;
    609 	}
    610 
    611 	memcpy(dst, src, len);
    612 
    613 	curpcb->pcb_onfault = oldfault;
    614 	return 0;
    615 }
    616 
    617 int
    618 badaddr(void *addr, size_t size)
    619 {
    620 
    621 	return badaddr_read(addr, size, NULL);
    622 }
    623 
    624 int
    625 badaddr_read(void *addr, size_t size, int *rptr)
    626 {
    627 	struct faultbuf env;
    628 	int x;
    629 
    630 	/* Get rid of any stale machine checks that have been waiting.  */
    631 	__asm volatile ("sync; isync");
    632 
    633 	if (setfault(&env)) {
    634 		curpcb->pcb_onfault = 0;
    635 		__asm volatile ("sync");
    636 		return 1;
    637 	}
    638 
    639 	__asm volatile ("sync");
    640 
    641 	switch (size) {
    642 	case 1:
    643 		x = *(volatile int8_t *)addr;
    644 		break;
    645 	case 2:
    646 		x = *(volatile int16_t *)addr;
    647 		break;
    648 	case 4:
    649 		x = *(volatile int32_t *)addr;
    650 		break;
    651 	default:
    652 		panic("badaddr: invalid size (%d)", size);
    653 	}
    654 
    655 	/* Make sure we took the machine check, if we caused one. */
    656 	__asm volatile ("sync; isync");
    657 
    658 	curpcb->pcb_onfault = 0;
    659 	__asm volatile ("sync");	/* To be sure. */
    660 
    661 	/* Use the value to avoid reorder. */
    662 	if (rptr)
    663 		*rptr = x;
    664 
    665 	return 0;
    666 }
    667 
    668 /*
    669  * For now, this only deals with the particular unaligned access case
    670  * that gcc tends to generate.  Eventually it should handle all of the
    671  * possibilities that can happen on a 32-bit PowerPC in big-endian mode.
    672  */
    673 
    674 static int
    675 fix_unaligned(struct lwp *l, struct trapframe *frame)
    676 {
    677 
    678 	return -1;
    679 }
    680 
    681 /*
    682  * Start a new LWP
    683  */
    684 void
    685 startlwp(arg)
    686 	void *arg;
    687 {
    688 	int err;
    689 	ucontext_t *uc = arg;
    690 	struct lwp *l = curlwp;
    691 
    692 	err = cpu_setmcontext(l, &uc->uc_mcontext, uc->uc_flags);
    693 #if DIAGNOSTIC
    694 	if (err) {
    695 		printf("Error %d from cpu_setmcontext.", err);
    696 	}
    697 #endif
    698 	pool_put(&lwp_uc_pool, uc);
    699 
    700 	upcallret(l);
    701 }
    702 
    703 /*
    704  * XXX This is a terrible name.
    705  */
    706 void
    707 upcallret(l)
    708 	struct lwp *l;
    709 {
    710 
    711 	/* Invoke MI userret code */
    712 	mi_userret(l);
    713 
    714 	curcpu()->ci_schedstate.spc_curpriority = l->l_priority = l->l_usrpri;
    715 }
    716