1 /* 2 * Copyright (c) 1988 University of Utah. 3 * Copyright (c) 1992, 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 and Ralph Campbell. 9 * 10 * %sccs.include.redist.c% 11 * 12 * from: Utah $Hdr: mem.c 1.14 90/10/12$ 13 * 14 * @(#)mem.c 8.2 (Berkeley) 03/28/94 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 u_long v; 41 register u_int c; 42 register struct iovec *iov; 43 int error = 0; 44 caddr_t zbuf = NULL; 45 extern vm_offset_t avail_end; 46 47 while (uio->uio_resid > 0 && error == 0) { 48 iov = uio->uio_iov; 49 if (iov->iov_len == 0) { 50 uio->uio_iov++; 51 uio->uio_iovcnt--; 52 if (uio->uio_iovcnt < 0) 53 panic("mmrw"); 54 continue; 55 } 56 switch (minor(dev)) { 57 58 /* minor device 0 is physical memory */ 59 case 0: 60 v = (u_long)uio->uio_offset; 61 c = iov->iov_len; 62 if (v + c <= btoc(physmem)) 63 v += MACH_CACHED_MEMORY_ADDR; 64 else 65 return (EFAULT); 66 error = uiomove((caddr_t)v, (int)c, uio); 67 continue; 68 69 /* minor device 1 is kernel memory */ 70 case 1: 71 v = (u_long)uio->uio_offset; 72 if (v < MACH_CACHED_MEMORY_ADDR) 73 return (EFAULT); 74 c = iov->iov_len; 75 if (v + c <= MACH_PHYS_TO_CACHED(avail_end) || 76 v >= MACH_KSEG2_ADDR && kernacc((caddr_t)v, c, 77 uio->uio_rw == UIO_READ ? B_READ : B_WRITE)) { 78 error = uiomove((caddr_t)v, (int)c, uio); 79 continue; 80 } 81 return (EFAULT); 82 83 /* minor device 2 is EOF/RATHOLE */ 84 case 2: 85 if (uio->uio_rw == UIO_WRITE) 86 uio->uio_resid = 0; 87 return (0); 88 89 /* minor device 12 (/dev/zero) is source of nulls on read, rathole on write */ 90 case 12: 91 if (uio->uio_rw == UIO_WRITE) { 92 c = iov->iov_len; 93 break; 94 } 95 if (zbuf == NULL) { 96 zbuf = (caddr_t) 97 malloc(CLBYTES, M_TEMP, M_WAITOK); 98 bzero(zbuf, CLBYTES); 99 } 100 c = min(iov->iov_len, CLBYTES); 101 error = uiomove(zbuf, (int)c, uio); 102 continue; 103 104 default: 105 return (ENXIO); 106 } 107 if (error) 108 break; 109 iov->iov_base += c; 110 iov->iov_len -= c; 111 uio->uio_offset += c; 112 uio->uio_resid -= c; 113 } 114 if (zbuf) 115 free(zbuf, M_TEMP); 116 return (error); 117 } 118