copyinstr.c revision 1.12 
1/*	$NetBSD: copyinstr.c,v 1.12 2020/03/05 01:13:00 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 1.12 2020/03/05 01:13:00 rin Exp $");
40
41#include <sys/param.h>
42#include <uvm/uvm_extern.h>
43#include <machine/pcb.h>
44
45int
46copyinstr(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		"mfpid %1;"			/* Save old PID */
79		"sync; isync;"
80
81		"1: "
82		"mtpid %4; sync;"		/* Load user ctx */
83		"lbz %2,0(%5); addi %5,%5,1;"	/* Load byte */
84		"sync; isync;"
85		"mtpid %1;sync;"
86		"stb %2,0(%6); dcbst 0,%6; addi %6,%6,1;"
87						/* Store kernel byte */
88		"sync; isync;"
89		"or. %2,%2,%2;"
90		"bdnzf 2,1b;"			/* while(ctr-- && !zero) */
91		"mtpid %1; mtmsr %0;"		/* Restore PID, MSR */
92		"sync; isync;"
93		"mfctr %3;"			/* Restore resid */
94		: "=&r" (msr), "=&r" (pid), "=&r" (data), "+r" (resid)
95		: "r" (ctx), "b" (udaddr), "b" (kaddr));
96
97	curpcb->pcb_onfault = NULL;
98	if (done)
99		*done = len - resid;
100	if (resid == 0 && (char)data != '\0')
101		return ENAMETOOLONG;
102	else
103		return 0;
104}
105