1 /* 2 * Copyright (c) 1988 University of Utah. 3 * Copyright (c) 1982, 1986, 1990, 1993 4 * The Regents of the University of California. 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 $Hdr: mem.c 1.14 90/10/12$ 13 * 14 * @(#)mem.c 8.1 (Berkeley) 06/10/93 15 */ 16 17 /* 18 * Memory special file 19 */ 20 21 #include <sys/param.h> 22 #include <sys/conf.h> 23 #include <sys/buf.h> 24 #include <sys/systm.h> 25 #include <sys/malloc.h> 26 27 #include <machine/cpu.h> 28 29 #include <vm/vm_param.h> 30 #include <vm/lock.h> 31 #include <vm/vm_prot.h> 32 #include <vm/pmap.h> 33 34 /*ARGSUSED*/ 35 mmrw(dev, uio, flags) 36 dev_t dev; 37 struct uio *uio; 38 int flags; 39 { 40 register int o; 41 register u_int c, v; 42 register struct iovec *iov; 43 int error = 0; 44 caddr_t zbuf = NULL; 45 int kernloc; 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(kernel_pmap, (vm_offset_t)vmmap, 68 trunc_page(v), uio->uio_rw == UIO_READ ? 69 VM_PROT_READ : VM_PROT_WRITE, 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(kernel_pmap, (vm_offset_t)vmmap, 76 (vm_offset_t)&vmmap[NBPG]); 77 continue; 78 79 /* minor device 1 is kernel memory */ 80 case 1: 81 kernloc = uio->uio_offset; 82 c = min(iov->iov_len, MAXPHYS); 83 if (!kernacc((caddr_t)kernloc, c, 84 uio->uio_rw == UIO_READ ? B_READ : B_WRITE)) 85 return (EFAULT); 86 error = uiomove((caddr_t)kernloc, (int)c, uio); 87 continue; 88 89 /* minor device 2 is EOF/RATHOLE */ 90 case 2: 91 if (uio->uio_rw == UIO_WRITE) 92 uio->uio_resid = 0; 93 return (0); 94 95 /* minor device 12 (/dev/zero) is source of nulls on read, rathole on write */ 96 case 12: 97 if (uio->uio_rw == UIO_WRITE) { 98 c = iov->iov_len; 99 break; 100 } 101 if (zbuf == NULL) { 102 zbuf = (caddr_t) 103 malloc(CLBYTES, M_TEMP, M_WAITOK); 104 bzero(zbuf, CLBYTES); 105 } 106 c = min(iov->iov_len, CLBYTES); 107 error = uiomove(zbuf, (int)c, uio); 108 continue; 109 110 default: 111 return (ENXIO); 112 } 113 if (error) 114 break; 115 iov->iov_base += c; 116 iov->iov_len -= c; 117 uio->uio_offset += c; 118 uio->uio_resid -= c; 119 } 120 if (zbuf) 121 free(zbuf, M_TEMP); 122 return (error); 123 } 124