copyinstr.c revision 1.24 
1/*	$NetBSD: copyinstr.c,v 1.24 2022/10/05 08:18:00 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 1.24 2022/10/05 08:18:00 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
46int
47copyinstr(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, tmp, 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		"mfmsr	%[msr];"		/* Save MSR */
77		"li	%[tmp],0x20;"		/* Disable IMMU */
78		"andc	%[tmp],%[msr],%[tmp];"
79		"mtmsr	%[tmp];"
80		"isync;"
81		MFPID(%[pid])			/* Save old PID */
82
83	"1:"	MTPID(%[ctx])			/* Load user ctx */
84		"isync;"
85		"lbz	%[tmp],0(%[uaddr]);"	/* Load byte */
86		"addi	%[uaddr],%[uaddr],1;"
87		"sync;"
88
89		MTPID(%[pid])
90		"isync;"
91		"stb	%[tmp],0(%[kaddr]);"	/* Store kernel byte */
92		"addi	%[kaddr],%[kaddr],1;"
93		"or.	%[tmp],%[tmp],%[tmp];"
94		"sync;"
95		"bdnzf	eq,1b;"			/* while(ctr-- && !zero) */
96
97		"mtmsr	%[msr];"		/* Restore MSR */
98		"isync;"
99		"mfctr	%[resid];"		/* Restore resid */
100
101		: [msr] "=&r" (msr), [pid] "=&r" (pid), [tmp] "=&r" (tmp),
102		  [resid] "+r" (resid)
103		: [ctx] "r" (ctx), [uaddr] "b" (uaddr), [kaddr] "b" (kaddr)
104		: "cr0", "ctr");
105
106	curpcb->pcb_onfault = NULL;
107	if (done)
108		*done = len - resid;
109	if (resid == 0 && (char)tmp != '\0')
110		return ENAMETOOLONG;
111	else
112		return 0;
113}
114