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copyinstr.c revision 1.18 
      1 /*	$NetBSD: copyinstr.c,v 1.18 2022/10/03 23:41:28 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 1.18 2022/10/03 23:41:28 rin Exp $");
     40 
     41 #include <sys/param.h>
     42 #include <uvm/uvm_extern.h>
     43 #include <powerpc/ibm4xx/spr.h>
     44 #include <machine/pcb.h>
     45 
     46 int
     47 copyinstr(const void *uaddr, void *kaddr, size_t len, size_t *done)
     48 {
     49 	struct pmap *pm = curproc->p_vmspace->vm_map.pmap;
     50 	size_t resid;
     51 	int rv, msr, pid, data, ctx;
     52 	struct faultbuf env;
     53 
     54 	if (__predict_false(len == 0)) {
     55 		if (done)
     56 			*done = 0;
     57 		return 0;
     58 	}
     59 
     60 	if ((rv = setfault(&env))) {
     61 		curpcb->pcb_onfault = NULL;
     62 		if (done)
     63 			*done = 0;
     64 		return rv;
     65 	}
     66 
     67 	if (!(ctx = pm->pm_ctx)) {
     68 		/* No context -- assign it one */
     69 		ctx_alloc(pm);
     70 		ctx = pm->pm_ctx;
     71 	}
     72 
     73 	resid = len;
     74 	__asm volatile(
     75 		"mtctr %[resid];"		/* Set up counter */
     76 
     77 		"mfmsr %[msr];"			/* Save MSR */
     78 
     79 		"li %[pid],0x20;"		/* Disable IMMU */
     80 		"andc %[pid],%[msr],%[pid];"
     81 		"mtmsr %[pid];"
     82 		"isync;"
     83 
     84 		MFPID(%[pid])			/* Save old PID */
     85 
     86 	"1:"	MTPID(%[ctx])			/* Load user ctx */
     87 		"isync;"
     88 		"lbz %[data],0(%[uaddr]);"	/* Load byte */
     89 		"addi %[uaddr],%[uaddr],1;"
     90 		"sync;"
     91 
     92 		MTPID(%[pid])
     93 		"isync;"
     94 		"stb %[data],0(%[kaddr]);"	/* Store kernel byte */
     95 		"dcbst 0,%[kaddr];"
     96 		"addi %[kaddr],%[kaddr],1;"
     97 		"or. %[data],%[data],%[data];"
     98 		"sync;"
     99 
    100 		"bdnzf eq,1b;"			/* while(ctr-- && !zero) */
    101 
    102 		MTPID(%[pid])			/* Restore PID, MSR */
    103 		"mtmsr %[msr];"
    104 		"isync;"
    105 
    106 		"mfctr %[resid];"		/* Restore resid */
    107 
    108 		: [msr] "=&r" (msr), [pid] "=&r" (pid), [data] "=&r" (data),
    109 		  [resid] "+r" (resid)
    110 		: [ctx] "r" (ctx), [uaddr] "b" (uaddr), [kaddr] "b" (kaddr)
    111 		: "cr0", "ctr");
    112 
    113 	curpcb->pcb_onfault = NULL;
    114 	if (done)
    115 		*done = len - resid;
    116 	if (resid == 0 && (char)data != '\0')
    117 		return ENAMETOOLONG;
    118 	else
    119 		return 0;
    120 }
    121