[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: Chris Leech --- drivers/dma/Makefile | 3 drivers/dma/iovlock.c | 301 +++++++++++++++++++++++++++++++++++++++++++++ include/linux/dmaengine.h | 22 +++ include/net/netdma.h | 6 + net/core/Makefile | 1 net/core/user_dma.c | 127 +++++++++++++++++++ 6 files changed, 459 insertions(+), 1 deletions(-) diff --git a/drivers/dma/Makefile b/drivers/dma/Makefile index c8a5f56..bdcfdbd 100644 --- a/drivers/dma/Makefile +++ b/drivers/dma/Makefile @@ -1,2 +1,3 @@ -obj-y += dmaengine.o +obj-$(CONFIG_DMA_ENGINE) += dmaengine.o +obj-$(CONFIG_NET_DMA) += iovlock.o obj-$(CONFIG_INTEL_IOATDMA) += ioatdma.o diff --git a/drivers/dma/iovlock.c b/drivers/dma/iovlock.c new file mode 100644 index 0000000..5ed327e --- /dev/null +++ b/drivers/dma/iovlock.c @@ -0,0 +1,301 @@ +/* + * 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 +#include +#include /* for memcpy_toiovec */ +#include +#include + +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(¤t->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(¤t->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; +} diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h index 3078154..78b236c 100644 --- a/include/linux/dmaengine.h +++ b/include/linux/dmaengine.h @@ -333,5 +333,27 @@ static inline enum dma_status dma_async_ 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 */ diff --git a/include/net/netdma.h b/include/net/netdma.h index cbfe89d..19760eb 100644 --- a/include/net/netdma.h +++ b/include/net/netdma.h @@ -23,6 +23,7 @@ #include #ifdef CONFIG_NET_DMA #include +#include static inline struct dma_chan *get_softnet_dma(void) { @@ -34,5 +35,10 @@ static inline struct dma_chan *get_softn 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 */ diff --git a/net/core/Makefile b/net/core/Makefile index 79fe12c..e9bd246 100644 --- a/net/core/Makefile +++ b/net/core/Makefile @@ -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 diff --git a/net/core/user_dma.c b/net/core/user_dma.c new file mode 100644 index 0000000..9eee91b --- /dev/null +++ b/net/core/user_dma.c @@ -0,0 +1,127 @@ +/* + * 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 +#include +#include /* for BUG_TRAP */ +#include + +/** + * dma_skb_copy_datagram_iovec - Copy a datagram to an iovec. + * @skb - buffer to copy + * @offset - offset in the buffer to start copying from + * @iovec - io vector to copy to + * @len - amount of data to copy from buffer to iovec + * @pinned_list - locked iovec buffer data + * + * Note: the iovec is modified during the copy. + */ +int dma_skb_copy_datagram_iovec(struct dma_chan *chan, + struct sk_buff *skb, int offset, struct iovec *to, + size_t len, struct dma_pinned_list *pinned_list) +{ + int start = skb_headlen(skb); + int i, copy = start - offset; + dma_cookie_t cookie = 0; + + /* Copy header. */ + if (copy > 0) { + if (copy > len) + copy = len; + cookie = dma_memcpy_to_iovec(chan, to, pinned_list, + skb->data + offset, copy); + if (cookie < 0) + goto fault; + len -= copy; + if (len == 0) + goto end; + offset += copy; + } + + /* Copy paged appendix. Hmm... why does this look so complicated? */ + for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) { + int end; + + BUG_TRAP(start <= offset + len); + + end = start + skb_shinfo(skb)->frags[i].size; + copy = end - offset; + if ((copy = end - offset) > 0) { + skb_frag_t *frag = &skb_shinfo(skb)->frags[i]; + struct page *page = frag->page; + + if (copy > len) + copy = len; + + cookie = dma_memcpy_pg_to_iovec(chan, to, pinned_list, page, + frag->page_offset + offset - start, copy); + if (cookie < 0) + goto fault; + len -= copy; + if (len == 0) + goto end; + offset += copy; + } + start = end; + } + + if (skb_shinfo(skb)->frag_list) { + struct sk_buff *list = skb_shinfo(skb)->frag_list; + + for (; list; list = list->next) { + int end; + + BUG_TRAP(start <= offset + len); + + end = start + list->len; + copy = end - offset; + if (copy > 0) { + if (copy > len) + copy = len; + cookie = dma_skb_copy_datagram_iovec(chan, list, + offset - start, to, copy, + pinned_list); + if (cookie < 0) + goto fault; + len -= copy; + if (len == 0) + goto end; + offset += copy; + } + start = end; + } + } + +end: + if (!len) { + skb->dma_cookie = cookie; + return cookie; + } + +fault: + return -EFAULT; +}