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      1 /*
      2  * CDDL HEADER START
      3  *
      4  * The contents of this file are subject to the terms of the
      5  * Common Development and Distribution License, Version 1.0 only
      6  * (the "License").  You may not use this file except in compliance
      7  * with the License.
      8  *
      9  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
     10  * or http://www.opensolaris.org/os/licensing.
     11  * See the License for the specific language governing permissions
     12  * and limitations under the License.
     13  *
     14  * When distributing Covered Code, include this CDDL HEADER in each
     15  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
     16  * If applicable, add the following below this CDDL HEADER, with the
     17  * fields enclosed by brackets "[]" replaced with your own identifying
     18  * information: Portions Copyright [yyyy] [name of copyright owner]
     19  *
     20  * CDDL HEADER END
     21  */
     22 /*
     23  * Copyright 2005 Sun Microsystems, Inc.  All rights reserved.
     24  * Use is subject to license terms.
     25  */
     26 
     27 #pragma ident	"%Z%%M%	%I%	%E% SMI"
     28 
     29 #include <sys/types.h>
     30 #include <sys/errno.h>
     31 #include <sys/proc.h>
     32 #include <sys/procfs.h>
     33 #include <sys/sysmacros.h>
     34 #include <sys/uio.h>
     35 #include <sys/cmn_err.h>
     36 
     37 #if defined(__sparc)
     38 #include <sys/stack.h>
     39 #endif
     40 
     41 #define	STACK_BUF_SIZE	64	/* power of 2 */
     42 
     43 int
     44 prusrio(proc_t *p, enum uio_rw rw, struct uio *uiop, int old)
     45 {
     46 	/* longlong-aligned short buffer */
     47 	longlong_t buffer[STACK_BUF_SIZE / sizeof (longlong_t)];
     48 	int error = 0;
     49 	void *bp;
     50 	int allocated;
     51 	ssize_t total = uiop->uio_resid;
     52 	uintptr_t addr;
     53 	size_t len;
     54 
     55 	/* for short reads/writes, use the on-stack buffer */
     56 	if (uiop->uio_resid <= STACK_BUF_SIZE) {
     57 		bp = buffer;
     58 		allocated = 0;
     59 	} else {
     60 		bp = kmem_alloc(PAGESIZE, KM_SLEEP);
     61 		allocated = 1;
     62 	}
     63 
     64 #if defined(__sparc)
     65 	if (p == curproc)
     66 		(void) flush_user_windows_to_stack(NULL);
     67 #endif
     68 
     69 	switch (rw) {
     70 	case UIO_READ:
     71 		while (uiop->uio_resid != 0) {
     72 			addr = uiop->uio_offset;
     73 			len = MIN(uiop->uio_resid,
     74 			    PAGESIZE - (addr & PAGEOFFSET));
     75 
     76 			if ((error = uread(p, bp, len, addr)) != 0 ||
     77 			    (error = uiomove(bp, len, UIO_READ, uiop)) != 0)
     78 				break;
     79 		}
     80 
     81 		/*
     82 		 * ENXIO indicates that a page didn't exist. If the I/O was
     83 		 * truncated, return success; otherwise convert the error into
     84 		 * EIO. When obeying new /proc semantics, we don't return an
     85 		 * error for a read that begins at an invalid address.
     86 		 */
     87 		if (error == ENXIO) {
     88 			if (total != uiop->uio_resid || !old)
     89 				error = 0;
     90 			else
     91 				error = EIO;
     92 		}
     93 		break;
     94 	case UIO_WRITE:
     95 		while (uiop->uio_resid != 0) {
     96 			addr = uiop->uio_offset;
     97 			len = MIN(uiop->uio_resid,
     98 			    PAGESIZE - (addr & PAGEOFFSET));
     99 
    100 			if ((error = uiomove(bp, len, UIO_WRITE, uiop)) != 0)
    101 				break;
    102 			if ((error = uwrite(p, bp, len, addr)) != 0) {
    103 				uiop->uio_resid += len;
    104 				uiop->uio_loffset -= len;
    105 				break;
    106 			}
    107 		}
    108 
    109 		/*
    110 		 * ENXIO indicates that a page didn't exist. If the I/O was
    111 		 * truncated, return success; otherwise convert the error
    112 		 * into EIO.
    113 		 */
    114 		if (error == ENXIO) {
    115 			if (total != uiop->uio_resid)
    116 				error = 0;
    117 			else
    118 				error = EIO;
    119 		}
    120 		break;
    121 	default:
    122 		panic("prusrio: rw=%d neither UIO_READ not UIO_WRITE", rw);
    123 		/*NOTREACHED*/
    124 	}
    125 
    126 	if (allocated)
    127 		kmem_free(bp, PAGESIZE);
    128 
    129 	return (error);
    130 }
    131