Initial source

1 files changed, 171 insertions, 0 deletions

diff --git a/scsi/adapters/scsi_user_dma.c b/scsi/adapters/scsi_user_dma.c
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+++ b/scsi/adapters/scsi_user_dma.c
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+/* 
+ * 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 <mach/std_types.h>
+#include <scsi/adapters/scsi_user_dma.h>
+
+#include <kern/assert.h>
+
+#include <vm/vm_kern.h>
+#include <mach/vm_param.h>	/* round_page() */
+
+/* bp -> pmap */
+#include <sys/buf.h>
+#include <sys/proc.h>
+
+/*
+ * 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*/