1 /* 2 * Copyright (c) 1988 University of Utah. 3 * Copyright (c) 1982, 1986, 1990 The Regents of the University of California. 4 * All rights reserved. 5 * 6 * This code is derived from software contributed to Berkeley by 7 * the Systems Programming Group of the University of Utah Computer 8 * Science Department. 9 * 10 * %sccs.include.redist.c% 11 * 12 * from: Utah $Hdr: mem.c 1.13 89/10/08$ 13 * 14 * @(#)mem.c 7.4 (Berkeley) 04/20/91 15 */ 16 17 /* 18 * Memory special file 19 */ 20 21 #include "param.h" 22 #include "conf.h" 23 #include "buf.h" 24 #include "systm.h" 25 #include "malloc.h" 26 27 #include "../include/cpu.h" 28 29 #include "vm/vm_param.h" 30 #include "vm/lock.h" 31 #include "vm/vm_statistics.h" 32 #include "vm/pmap.h" 33 #include "vm/vm_prot.h" 34 35 /*ARGSUSED*/ 36 mmrw(dev, uio, flags) 37 dev_t dev; 38 struct uio *uio; 39 int flags; 40 { 41 register int o; 42 register u_int c, v; 43 register struct iovec *iov; 44 int error = 0; 45 caddr_t zbuf = NULL; 46 extern u_int lowram; 47 48 while (uio->uio_resid > 0 && error == 0) { 49 iov = uio->uio_iov; 50 if (iov->iov_len == 0) { 51 uio->uio_iov++; 52 uio->uio_iovcnt--; 53 if (uio->uio_iovcnt < 0) 54 panic("mmrw"); 55 continue; 56 } 57 switch (minor(dev)) { 58 59 /* minor device 0 is physical memory */ 60 case 0: 61 v = uio->uio_offset; 62 #ifndef DEBUG 63 /* allow reads only in RAM (except for DEBUG) */ 64 if (v >= 0xFFFFFFFC || v < lowram) 65 return (EFAULT); 66 #endif 67 pmap_enter(pmap_kernel(), vmmap, v, 68 uio->uio_rw == UIO_READ ? VM_PROT_READ : VM_PROT_WRITE, 69 TRUE); 70 o = (int)uio->uio_offset & PGOFSET; 71 c = (u_int)(NBPG - ((int)iov->iov_base & PGOFSET)); 72 c = MIN(c, (u_int)(NBPG - o)); 73 c = MIN(c, (u_int)iov->iov_len); 74 error = uiomove((caddr_t)&vmmap[o], (int)c, uio); 75 pmap_remove(pmap_kernel(), vmmap, &vmmap[NBPG]); 76 continue; 77 78 /* minor device 1 is kernel memory */ 79 case 1: 80 c = MIN(iov->iov_len, MAXPHYS); 81 if (!kernacc((caddr_t)uio->uio_offset, c, 82 uio->uio_rw == UIO_READ ? B_READ : B_WRITE)) 83 return (EFAULT); 84 error = uiomove((caddr_t)uio->uio_offset, (int)c, uio); 85 continue; 86 87 /* minor device 2 is EOF/RATHOLE */ 88 case 2: 89 if (uio->uio_rw == UIO_WRITE) 90 uio->uio_resid = 0; 91 return (0); 92 93 /* minor device 12 (/dev/zero) is source of nulls on read, rathole on write */ 94 case 12: 95 if (uio->uio_rw == UIO_WRITE) { 96 c = iov->iov_len; 97 break; 98 } 99 if (zbuf == NULL) { 100 zbuf = (caddr_t) 101 malloc(CLBYTES, M_TEMP, M_WAITOK); 102 bzero(zbuf, CLBYTES); 103 } 104 c = MIN(iov->iov_len, CLBYTES); 105 error = uiomove(zbuf, (int)c, uio); 106 continue; 107 108 default: 109 return (ENXIO); 110 } 111 if (error) 112 break; 113 iov->iov_base += c; 114 iov->iov_len -= c; 115 uio->uio_offset += c; 116 uio->uio_resid -= c; 117 } 118 if (zbuf) 119 free(zbuf, M_TEMP); 120 return (error); 121 } 122