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copyinstr.c revision 1.14 
      1 /*	$NetBSD: copyinstr.c,v 1.14 2020/06/19 07:31:59 rin 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 #include <sys/cdefs.h>
     39 __KERNEL_RCSID(0, "$NetBSD: copyinstr.c,v 1.14 2020/06/19 07:31:59 rin Exp $");
     40 
     41 #include <sys/param.h>
     42 #include <uvm/uvm_extern.h>
     43 #include <machine/pcb.h>
     44 
     45 int
     46 copyinstr(const void *udaddr, void *kaddr, size_t len, size_t *done)
     47 {
     48 	struct pmap *pm = curproc->p_vmspace->vm_map.pmap;
     49 	size_t resid;
     50 	int rv, msr, pid, data, ctx;
     51 	struct faultbuf env;
     52 
     53 	if (__predict_false(len == 0)) {
     54 		if (done)
     55 			*done = 0;
     56 		return 0;
     57 	}
     58 
     59 	if ((rv = setfault(&env))) {
     60 		curpcb->pcb_onfault = NULL;
     61 		if (done)
     62 			*done = 0;
     63 		return rv;
     64 	}
     65 
     66 	if (!(ctx = pm->pm_ctx)) {
     67 		/* No context -- assign it one */
     68 		ctx_alloc(pm);
     69 		ctx = pm->pm_ctx;
     70 	}
     71 
     72 	resid = len;
     73 	__asm volatile(
     74 		"mtctr %3;"			/* Set up counter */
     75 		"mfmsr %0;"			/* Save MSR */
     76 		"li %1,0x20;"
     77 		"andc %1,%0,%1; mtmsr %1;"	/* Disable IMMU */
     78 		"isync;"
     79 		"mfpid %1;"			/* Save old PID */
     80 
     81 		"1: "
     82 		"mtpid %4; isync;"		/* Load user ctx */
     83 		"lbz %2,0(%5); addi %5,%5,1;"	/* Load byte */
     84 		"sync;"
     85 		"mtpid %1; isync;"
     86 		"stb %2,0(%6); dcbst 0,%6; addi %6,%6,1;"
     87 						/* Store kernel byte */
     88 		"or. %2,%2,%2;"
     89 		"sync;"
     90 		"bdnzf 2,1b;"			/* while(ctr-- && !zero) */
     91 
     92 		"mtpid %1; mtmsr %0;"		/* Restore PID, MSR */
     93 		"isync;"
     94 		"mfctr %3;"			/* Restore resid */
     95 		: "=&r" (msr), "=&r" (pid), "=&r" (data), "+r" (resid)
     96 		: "r" (ctx), "b" (udaddr), "b" (kaddr));
     97 
     98 	curpcb->pcb_onfault = NULL;
     99 	if (done)
    100 		*done = len - resid;
    101 	if (resid == 0 && (char)data != '\0')
    102 		return ENAMETOOLONG;
    103 	else
    104 		return 0;
    105 }
    106