From f07a4c844da9f0ecae5bbee1ab94be56505f26f7 Mon Sep 17 00:00:00 2001 From: Thomas Bushnell Date: Tue, 25 Feb 1997 21:28:37 +0000 Subject: Initial source --- scsi/adapters/scsi_user_dma.c | 171 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 171 insertions(+) create mode 100644 scsi/adapters/scsi_user_dma.c (limited to 'scsi/adapters/scsi_user_dma.c') diff --git a/scsi/adapters/scsi_user_dma.c b/scsi/adapters/scsi_user_dma.c new file mode 100644 index 0000000..5fb98d6 --- /dev/null +++ b/scsi/adapters/scsi_user_dma.c @@ -0,0 +1,171 @@ +/* + * Mach Operating System + * Copyright (c) 1991,1990 Carnegie Mellon University + * All Rights Reserved. + * + * Permission to use, copy, modify and distribute this software and its + * documentation is hereby granted, provided that both the copyright + * notice and this permission notice appear in all copies of the + * software, derivative works or modified versions, and any portions + * thereof, and that both notices appear in supporting documentation. + * + * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS + * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR + * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. + * + * Carnegie Mellon requests users of this software to return to + * + * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU + * School of Computer Science + * Carnegie Mellon University + * Pittsburgh PA 15213-3890 + * + * any improvements or extensions that they make and grant Carnegie the + * rights to redistribute these changes. + */ +/* + * File: scsi_user_dma.c + * Author: Alessandro Forin, Carnegie Mellon University + * Date: 4/91 + * + * Mach 2.5 compat file, to handle case of DMA to user space + * [e.g. fsck and other raw device accesses] + */ + +#ifdef MACH_KERNEL +/* We do not need this in 3.0 */ +#else /*MACH_KERNEL*/ + +#include +#include + +#include + +#include +#include /* round_page() */ + +/* bp -> pmap */ +#include +#include + +/* + * Initialization, called once per device + */ +fdma_init(fdma, size) + fdma_t fdma; + vm_size_t size; +{ + vm_offset_t addr; + + size = round_page(size); + addr = kmem_alloc_pageable(kernel_map, size); + if (addr == 0) panic("fdma_init"); + + fdma->kernel_virtual = addr; + fdma->max_data = size; + fdma->user_virtual = -1; + +} + +/* + * Remap a buffer from user space to kernel space. + * Note that physio() has already validated + * and wired the user's address range. + */ +fdma_map(fdma, bp) + fdma_t fdma; + struct buf *bp; +{ + pmap_t pmap; + vm_offset_t user_addr; + vm_size_t size; + vm_offset_t kernel_addr; + vm_offset_t off; + vm_prot_t prot; + + /* + * If this is not to user space, or no data xfer is + * involved, no need to do anything. + */ + user_addr = (vm_offset_t)bp->b_un.b_addr; + if (!(bp->b_flags & B_PHYS) || (user_addr == 0)) { + fdma->user_virtual = -1; + return; + } + /* + * We are going to clobber the buffer pointer, so + * remember what it was to restore it later. + */ + fdma->user_virtual = user_addr; + + /* + * Account for initial offset into phys page + */ + off = user_addr - trunc_page(user_addr); + + /* + * Check xfer size makes sense, note how many pages we'll remap + */ + size = bp->b_bcount + off; + assert((size <= fdma->max_data)); + fdma->xfer_size_rnd = round_page(size); + + pmap = bp->b_proc->task->map->pmap; + + /* + * Use minimal protection possible + */ + prot = VM_PROT_READ; + if (bp->b_flags & B_READ) + prot |= VM_PROT_WRITE; + + /* + * Loop through all phys pages, taking them from the + * user pmap (they are wired) and inserting them into + * the kernel pmap. + */ + user_addr -= off; + kernel_addr = fdma->kernel_virtual; + bp->b_un.b_addr = (char *)kernel_addr + off; + + for (size = fdma->xfer_size_rnd; size; size -= PAGE_SIZE) { + register vm_offset_t phys; + + phys = pmap_extract(pmap, user_addr); + pmap_enter(kernel_pmap, kernel_addr, phys, prot, TRUE); + user_addr += PAGE_SIZE; + kernel_addr += PAGE_SIZE; + } +} + +/* + * Called at end of xfer, to restore the buffer + */ +fdma_unmap(fdma, bp) + fdma_t fdma; + struct buf *bp; +{ + register vm_offset_t end_addr; + + /* + * Check we actually did remap it + */ + if (fdma->user_virtual == -1) + return; + + /* + * Restore the buffer + */ + bp->b_un.b_addr = (char *)fdma->user_virtual; + fdma->user_virtual = -1; + + /* + * Eliminate the mapping, pmap module might mess up + * the pv list otherwise. Some might actually tolerate it. + */ + end_addr = fdma->kernel_virtual + fdma->xfer_size_rnd; + pmap_remove(kernel_pmap, fdma->kernel_virtual, end_addr); + +} + +#endif /*MACH_KERNEL*/ -- cgit v1.2.3