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Commit de5506e1 authored by Chris Leech's avatar Chris Leech Committed by David S. Miller
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[I/OAT]: Utility functions for offloading sk_buff to iovec copies 



Provides for pinning user space pages in memory, copying to iovecs,
and copying from sk_buffs including fragmented and chained sk_buffs.

Signed-off-by: default avatarChris Leech <christopher.leech@intel.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent db217334

drivers/dma/Makefile

+2 −1
Original line number Diff line number Diff line 
obj-y += dmaengine.o

obj-$(CONFIG_DMA_ENGINE) += dmaengine.o

obj-$(CONFIG_NET_DMA) += iovlock.o

obj-$(CONFIG_INTEL_IOATDMA) += ioatdma.o

drivers/dma/iovlock.c

0 → 100644
+301 −0
Original line number Diff line number Diff line 
/*

 * Copyright(c) 2004 - 2006 Intel Corporation. All rights reserved.

 * Portions based on net/core/datagram.c and copyrighted by their authors.

 *

 * This program is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License as published by the Free

 * Software Foundation; either version 2 of the License, or (at your option)

 * any later version.

 *

 * This program is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for

 * more details.

 *

 * You should have received a copy of the GNU General Public License along with

 * this program; if not, write to the Free Software Foundation, Inc., 59

 * Temple Place - Suite 330, Boston, MA  02111-1307, USA.

 *

 * The full GNU General Public License is included in this distribution in the

 * file called COPYING.

 */



/*

 * This code allows the net stack to make use of a DMA engine for

 * skb to iovec copies.

 */



#include <linux/dmaengine.h>

#include <linux/pagemap.h>

#include <net/tcp.h> /* for memcpy_toiovec */

#include <asm/io.h>

#include <asm/uaccess.h>



int num_pages_spanned(struct iovec *iov)

{

	return

	((PAGE_ALIGN((unsigned long)iov->iov_base + iov->iov_len) -

	((unsigned long)iov->iov_base & PAGE_MASK)) >> PAGE_SHIFT);

}



/*

 * Pin down all the iovec pages needed for len bytes.

 * Return a struct dma_pinned_list to keep track of pages pinned down.

 *

 * We are allocating a single chunk of memory, and then carving it up into

 * 3 sections, the latter 2 whose size depends on the number of iovecs and the

 * total number of pages, respectively.

 */

struct dma_pinned_list *dma_pin_iovec_pages(struct iovec *iov, size_t len)

{

	struct dma_pinned_list *local_list;

	struct page **pages;

	int i;

	int ret;

	int nr_iovecs = 0;

	int iovec_len_used = 0;

	int iovec_pages_used = 0;

	long err;



	/* don't pin down non-user-based iovecs */

	if (segment_eq(get_fs(), KERNEL_DS))

		return NULL;



	/* determine how many iovecs/pages there are, up front */

	do {

		iovec_len_used += iov[nr_iovecs].iov_len;

		iovec_pages_used += num_pages_spanned(&iov[nr_iovecs]);

		nr_iovecs++;

	} while (iovec_len_used < len);



	/* single kmalloc for pinned list, page_list[], and the page arrays */

	local_list = kmalloc(sizeof(*local_list)

		+ (nr_iovecs * sizeof (struct dma_page_list))

		+ (iovec_pages_used * sizeof (struct page*)), GFP_KERNEL);

	if (!local_list) {

		err = -ENOMEM;

		goto out;

	}



	/* list of pages starts right after the page list array */

	pages = (struct page **) &local_list->page_list[nr_iovecs];



	for (i = 0; i < nr_iovecs; i++) {

		struct dma_page_list *page_list = &local_list->page_list[i];



		len -= iov[i].iov_len;



		if (!access_ok(VERIFY_WRITE, iov[i].iov_base, iov[i].iov_len)) {

			err = -EFAULT;

			goto unpin;

		}



		page_list->nr_pages = num_pages_spanned(&iov[i]);

		page_list->base_address = iov[i].iov_base;



		page_list->pages = pages;

		pages += page_list->nr_pages;



		/* pin pages down */

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

		ret = get_user_pages(

			current,

			current->mm,

			(unsigned long) iov[i].iov_base,

			page_list->nr_pages,

			1,	/* write */

			0,	/* force */

			page_list->pages,

			NULL);

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



		if (ret != page_list->nr_pages) {

			err = -ENOMEM;

			goto unpin;

		}



		local_list->nr_iovecs = i + 1;

	}



	return local_list;



unpin:

	dma_unpin_iovec_pages(local_list);

out:

	return ERR_PTR(err);

}



void dma_unpin_iovec_pages(struct dma_pinned_list *pinned_list)

{

	int i, j;



	if (!pinned_list)

		return;



	for (i = 0; i < pinned_list->nr_iovecs; i++) {

		struct dma_page_list *page_list = &pinned_list->page_list[i];

		for (j = 0; j < page_list->nr_pages; j++) {

			set_page_dirty_lock(page_list->pages[j]);

			page_cache_release(page_list->pages[j]);

		}

	}



	kfree(pinned_list);

}



static dma_cookie_t dma_memcpy_to_kernel_iovec(struct dma_chan *chan, struct

	iovec *iov, unsigned char *kdata, size_t len)

{

	dma_cookie_t dma_cookie = 0;



	while (len > 0) {

		if (iov->iov_len) {

			int copy = min_t(unsigned int, iov->iov_len, len);

			dma_cookie = dma_async_memcpy_buf_to_buf(

					chan,

					iov->iov_base,

					kdata,

					copy);

			kdata += copy;

			len -= copy;

			iov->iov_len -= copy;

			iov->iov_base += copy;

		}

		iov++;

	}



	return dma_cookie;

}



/*

 * We have already pinned down the pages we will be using in the iovecs.

 * Each entry in iov array has corresponding entry in pinned_list->page_list.

 * Using array indexing to keep iov[] and page_list[] in sync.

 * Initial elements in iov array's iov->iov_len will be 0 if already copied into

 *   by another call.

 * iov array length remaining guaranteed to be bigger than len.

 */

dma_cookie_t dma_memcpy_to_iovec(struct dma_chan *chan, struct iovec *iov,

	struct dma_pinned_list *pinned_list, unsigned char *kdata, size_t len)

{

	int iov_byte_offset;

	int copy;

	dma_cookie_t dma_cookie = 0;

	int iovec_idx;

	int page_idx;



	if (!chan)

		return memcpy_toiovec(iov, kdata, len);



	/* -> kernel copies (e.g. smbfs) */

	if (!pinned_list)

		return dma_memcpy_to_kernel_iovec(chan, iov, kdata, len);



	iovec_idx = 0;

	while (iovec_idx < pinned_list->nr_iovecs) {

		struct dma_page_list *page_list;



		/* skip already used-up iovecs */

		while (!iov[iovec_idx].iov_len)

			iovec_idx++;



		page_list = &pinned_list->page_list[iovec_idx];



		iov_byte_offset = ((unsigned long)iov[iovec_idx].iov_base & ~PAGE_MASK);

		page_idx = (((unsigned long)iov[iovec_idx].iov_base & PAGE_MASK)

			 - ((unsigned long)page_list->base_address & PAGE_MASK)) >> PAGE_SHIFT;



		/* break up copies to not cross page boundary */

		while (iov[iovec_idx].iov_len) {

			copy = min_t(int, PAGE_SIZE - iov_byte_offset, len);

			copy = min_t(int, copy, iov[iovec_idx].iov_len);



			dma_cookie = dma_async_memcpy_buf_to_pg(chan,

					page_list->pages[page_idx],

					iov_byte_offset,

					kdata,

					copy);



			len -= copy;

			iov[iovec_idx].iov_len -= copy;

			iov[iovec_idx].iov_base += copy;



			if (!len)

				return dma_cookie;



			kdata += copy;

			iov_byte_offset = 0;

			page_idx++;

		}

		iovec_idx++;

	}



	/* really bad if we ever run out of iovecs */

	BUG();

	return -EFAULT;

}



dma_cookie_t dma_memcpy_pg_to_iovec(struct dma_chan *chan, struct iovec *iov,

	struct dma_pinned_list *pinned_list, struct page *page,

	unsigned int offset, size_t len)

{

	int iov_byte_offset;

	int copy;

	dma_cookie_t dma_cookie = 0;

	int iovec_idx;

	int page_idx;

	int err;



	/* this needs as-yet-unimplemented buf-to-buff, so punt. */

	/* TODO: use dma for this */

	if (!chan || !pinned_list) {

		u8 *vaddr = kmap(page);

		err = memcpy_toiovec(iov, vaddr + offset, len);

		kunmap(page);

		return err;

	}



	iovec_idx = 0;

	while (iovec_idx < pinned_list->nr_iovecs) {

		struct dma_page_list *page_list;



		/* skip already used-up iovecs */

		while (!iov[iovec_idx].iov_len)

			iovec_idx++;



		page_list = &pinned_list->page_list[iovec_idx];



		iov_byte_offset = ((unsigned long)iov[iovec_idx].iov_base & ~PAGE_MASK);

		page_idx = (((unsigned long)iov[iovec_idx].iov_base & PAGE_MASK)

			 - ((unsigned long)page_list->base_address & PAGE_MASK)) >> PAGE_SHIFT;



		/* break up copies to not cross page boundary */

		while (iov[iovec_idx].iov_len) {

			copy = min_t(int, PAGE_SIZE - iov_byte_offset, len);

			copy = min_t(int, copy, iov[iovec_idx].iov_len);



			dma_cookie = dma_async_memcpy_pg_to_pg(chan,

					page_list->pages[page_idx],

					iov_byte_offset,

					page,

					offset,

					copy);



			len -= copy;

			iov[iovec_idx].iov_len -= copy;

			iov[iovec_idx].iov_base += copy;



			if (!len)

				return dma_cookie;



			offset += copy;

			iov_byte_offset = 0;

			page_idx++;

		}

		iovec_idx++;

	}



	/* really bad if we ever run out of iovecs */

	BUG();

	return -EFAULT;

}

include/linux/dmaengine.h

+22 −0
Original line number Diff line number Diff line
@@ -333,5 +333,27 @@ static inline enum dma_status dma_async_is_complete(dma_cookie_t cookie, 
int dma_async_device_register(struct dma_device *device);

void dma_async_device_unregister(struct dma_device *device);



/* --- Helper iov-locking functions --- */



struct dma_page_list {

	char *base_address;

	int nr_pages;

	struct page **pages;

};



struct dma_pinned_list {

	int nr_iovecs;

	struct dma_page_list page_list[0];

};



struct dma_pinned_list *dma_pin_iovec_pages(struct iovec *iov, size_t len);

void dma_unpin_iovec_pages(struct dma_pinned_list* pinned_list);



dma_cookie_t dma_memcpy_to_iovec(struct dma_chan *chan, struct iovec *iov,

	struct dma_pinned_list *pinned_list, unsigned char *kdata, size_t len);

dma_cookie_t dma_memcpy_pg_to_iovec(struct dma_chan *chan, struct iovec *iov,

	struct dma_pinned_list *pinned_list, struct page *page,

	unsigned int offset, size_t len);



#endif /* CONFIG_DMA_ENGINE */

#endif /* DMAENGINE_H */

include/net/netdma.h

+6 −0
Original line number Diff line number Diff line
@@ -23,6 +23,7 @@ 
#include <linux/config.h>

#ifdef CONFIG_NET_DMA

#include <linux/dmaengine.h>

#include <linux/skbuff.h>



static inline struct dma_chan *get_softnet_dma(void)

{
@@ -34,5 +35,10 @@ static inline struct dma_chan *get_softnet_dma(void) 
	rcu_read_unlock();

	return chan;

}



int dma_skb_copy_datagram_iovec(struct dma_chan* chan,

		const struct sk_buff *skb, int offset, struct iovec *to,

		size_t len, struct dma_pinned_list *pinned_list);



#endif /* CONFIG_NET_DMA */

#endif /* NETDMA_H */

net/core/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -16,3 +16,4 @@ obj-$(CONFIG_NET_DIVERT) += dv.o 
obj-$(CONFIG_NET_PKTGEN) += pktgen.o

obj-$(CONFIG_WIRELESS_EXT) += wireless.o

obj-$(CONFIG_NETPOLL) += netpoll.o

obj-$(CONFIG_NET_DMA) += user_dma.o