qib_user_pages.c

/*
 * Copyright (c) 2006, 2007, 2008, 2009 QLogic Corporation. All rights reserved.
 * Copyright (c) 2003, 2004, 2005, 2006 PathScale, Inc. All rights reserved.
 *
 * This software is available to you under a choice of one of two
 * licenses.  You may choose to be licensed under the terms of the GNU
 * General Public License (GPL) Version 2, available from the file
 * COPYING in the main directory of this source tree, or the
 * OpenIB.org BSD license below:
 *
 *     Redistribution and use in source and binary forms, with or
 *     without modification, are permitted provided that the following
 *     conditions are met:
 *
 *      - Redistributions of source code must retain the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer.
 *
 *      - Redistributions in binary form must reproduce the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer in the documentation and/or other materials
 *        provided with the distribution.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

#include <linux/mm.h>
#include <linux/device.h>

#include "qib.h"

static void __qib_release_user_pages(struct page **p, size_t num_pages,
				     int dirty)
{
	size_t i;

	for (i = 0; i < num_pages; i++) {
		if (dirty)
			set_page_dirty_lock(p[i]);
		put_page(p[i]);
	}
}

/*
 * Call with current->mm->mmap_sem held.
 */
static int __qib_get_user_pages(unsigned long start_page, size_t num_pages,
				struct page **p, struct vm_area_struct **vma)
{
	unsigned long lock_limit;
	size_t got;
	int ret;

	lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;

	if (num_pages > lock_limit && !capable(CAP_IPC_LOCK)) {
		ret = -ENOMEM;
		goto bail;
	}

	for (got = 0; got < num_pages; got += ret) {
		ret = get_user_pages(current, current->mm,
				     start_page + got * PAGE_SIZE,
				     num_pages - got, 1, 1,
				     p + got, vma);
		if (ret < 0)
			goto bail_release;
	}

	current->mm->locked_vm += num_pages;

	ret = 0;
	goto bail;

bail_release:
	__qib_release_user_pages(p, got, 0);
bail:
	return ret;
}

/**
 * qib_map_page - a safety wrapper around pci_map_page()
 *
 * A dma_addr of all 0's is interpreted by the chip as "disabled".
 * Unfortunately, it can also be a valid dma_addr returned on some
 * architectures.
 *
 * The powerpc iommu assigns dma_addrs in ascending order, so we don't
 * have to bother with retries or mapping a dummy page to insure we
 * don't just get the same mapping again.
 *
 * I'm sure we won't be so lucky with other iommu's, so FIXME.
 */
dma_addr_t qib_map_page(struct pci_dev *hwdev, struct page *page,
			unsigned long offset, size_t size, int direction)
{
	dma_addr_t phys;

	phys = pci_map_page(hwdev, page, offset, size, direction);

	if (phys == 0) {
		pci_unmap_page(hwdev, phys, size, direction);
		phys = pci_map_page(hwdev, page, offset, size, direction);
		/*
		 * FIXME: If we get 0 again, we should keep this page,
		 * map another, then free the 0 page.
		 */
	}

	return phys;
}

/**
 * qib_get_user_pages - lock user pages into memory
 * @start_page: the start page
 * @num_pages: the number of pages
 * @p: the output page structures
 *
 * This function takes a given start page (page aligned user virtual
 * address) and pins it and the following specified number of pages.  For
 * now, num_pages is always 1, but that will probably change at some point
 * (because caller is doing expected sends on a single virtually contiguous
 * buffer, so we can do all pages at once).
 */
int qib_get_user_pages(unsigned long start_page, size_t num_pages,
		       struct page **p)
{
	int ret;

	down_write(&current->mm->mmap_sem);

	ret = __qib_get_user_pages(start_page, num_pages, p, NULL);

	up_write(&current->mm->mmap_sem);

	return ret;
}

void qib_release_user_pages(struct page **p, size_t num_pages)
{
	if (current->mm) /* during close after signal, mm can be NULL */
		down_write(&current->mm->mmap_sem);

	__qib_release_user_pages(p, num_pages, 1);

	if (current->mm) {
		current->mm->locked_vm -= num_pages;
		up_write(&current->mm->mmap_sem);
	}
}