[PATCH 03/13] [RFC] ipath copy routines

[Roland Dreier]

Copy routines for ipath driver

---

 drivers/infiniband/hw/ipath/ipath_copy.c     |  666 ++++++++++++++++++++++++++
 drivers/infiniband/hw/ipath/ipath_dwordcpy.S |   62 ++
 2 files changed, 728 insertions(+), 0 deletions(-)
 create mode 100644 drivers/infiniband/hw/ipath/ipath_copy.c
 create mode 100644 drivers/infiniband/hw/ipath/ipath_dwordcpy.S

99f636a78e0d759ab663a7abb29e6a71b32a552d
diff --git a/drivers/infiniband/hw/ipath/ipath_copy.c b/drivers/infiniband/hw/ipath/ipath_copy.c
new file mode 100644
index 0000000..26211ad
--- /dev/null
+++ b/drivers/infiniband/hw/ipath/ipath_copy.c
@@ -0,0 +1,666 @@
+/*
+ * Copyright (c) 2003, 2004, 2005. 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.
+ *
+ * Patent licenses, if any, provided herein do not apply to
+ * combinations of this program with other software, or any other
+ * product whatsoever.
+ *
+ * $Id: ipath_copy.c 4365 2005-12-10 00:04:16Z rjwalsh $
+ */
+
+/*
+ * This file provides support for doing sk_buff buffer swapping between
+ * the low level driver eager buffers, and the network layer.  It's part
+ * of the core driver, rather than the ether driver, because it relies
+ * on variables and functions in the core driver.  It exports a single
+ * entry point for use in the ipath_ether module.
+ */
+
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/types.h>
+#include <asm/io.h>
+#include <asm/byteorder.h>
+#include <asm/bitops.h>
+#include <linux/skbuff.h>
+#include <linux/netdevice.h>
+
+#include <linux/crc32.h>	/* we can generate our own crc's for testing */
+
+#include "ipath_kernel.h"
+#include "ips_common.h"
+#include "ipath_layer.h"
+
+#define TRUE 1
+#define FALSE 0
+
+/*
+ * Allocate a PIO send buffer, initialize the header and copy it out.
+ */
+static int layer_send_getpiobuf(struct copy_data_s *cdp)
+{
+	int whichpb;
+	uint32_t device = cdp->device;
+	uint32_t extra_bytes;
+	uint32_t len, nwords;
+	uint32_t *piobuf;
+
+	whichpb = ipath_getpiobuf(device);
+	if (whichpb < 0) {
+		cdp->error = whichpb;
+		return whichpb;
+	}
+
+	/*
+	 * Compute the max amount of data that can fit into a PIO buffer.
+	 * buffer size - header size - trigger qword length & flags - CRC
+	 */
+	len = devdata[device].ipath_ibmaxlen -
+	    sizeof(ether_header_typ) - 8 - (SIZE_OF_CRC << 2);
+	if (len > (cdp->len + cdp->extra))
+		len = (cdp->len + cdp->extra);
+	/* Compute word aligment (i.e., (len & 3) ? 4 - (len & 3) : 0) */
+	extra_bytes = (4 - len) & 3;
+	nwords = (sizeof(ether_header_typ) + len + extra_bytes) >> 2;
+	cdp->hdr->lrh[2] = htons(nwords + SIZE_OF_CRC);
+	cdp->hdr->bth[0] = htonl((OPCODE_ITH4X << 24) + (extra_bytes << 20) +
+				 IPS_DEFAULT_P_KEY);
+	cdp->hdr->sub_opcode = OPCODE_ENCAP;
+
+	cdp->hdr->bth[2] = 0;
+	/* Generate an interrupt on the receive side for the last fragment. */
+	cdp->hdr->iph.pkt_flags = ((cdp->len+cdp->extra) == len) ? INFINIPATH_KPF_INTR : 0;
+	cdp->hdr->iph.chksum =
+	    (uint16_t) IPS_LRH_BTH +
+	    (uint16_t) (nwords + SIZE_OF_CRC) -
+	    (uint16_t) ((cdp->hdr->iph.ver_port_tid_offset >> 16) & 0xFFFF) -
+	    (uint16_t) (cdp->hdr->iph.ver_port_tid_offset & 0xFFFF) -
+	    (uint16_t) cdp->hdr->iph.pkt_flags;
+
+	piobuf = (uint32_t *) (((char *)(devdata[device].ipath_kregbase)) +
+			       devdata[device].ipath_piobufbase +
+			       whichpb * devdata[device].ipath_palign);
+	_IPATH_VDBG("send %d (%x %x %x %x %x %x %x)\n", nwords,
+		    cdp->hdr->lrh[0],
+		    cdp->hdr->lrh[1],
+		    cdp->hdr->lrh[2],
+		    cdp->hdr->lrh[3],
+		    cdp->hdr->bth[0], cdp->hdr->bth[1], cdp->hdr->bth[2]);
+	/*
+	 * Write len to control qword, no flags.
+	 * +1 is for the qword padding of pbc.
+	 */
+	*((uint64_t *) piobuf) = (uint64_t) (nwords + 1);
+	piobuf += 2;
+	ipath_dwordcpy(piobuf, (uint32_t *) cdp->hdr,
+		       sizeof(ether_header_typ) >> 2);
+	cdp->csum_pio = &((ether_header_typ *) piobuf)->csum;
+	cdp->to = piobuf + (sizeof(ether_header_typ) >> 2);
+	cdp->flen = nwords - (sizeof(ether_header_typ) >> 2);
+	cdp->hdr->frag_num++;
+	return 0;
+}
+
+/*
+ * Copy data out of one or a chain of sk_buffs, into the PIO buffer.
+ * Fragment an sk_buff into multiple IB packets if the amount of data is
+ * more than a single eager send.
+ * Offset and len are in bytes.
+ * Note that this function is recursive!
+ */
+static void copy_bits(const struct sk_buff *skb, unsigned int offset,
+		      unsigned int len, struct copy_data_s *cdp)
+{
+	unsigned int start = skb_headlen(skb);
+	unsigned int i, copy;
+	uint32_t n;
+	u8 *p;
+
+	/* Copy header. */
+	if ((int)(copy = start - offset) > 0) {
+		if (copy > len)
+			copy = len;
+		p = skb->data + offset;
+		offset += copy;
+		len -= copy;
+		/*
+		 * If the alignment buffer is not empty, fill it and write
+		 * it out.
+		 */
+		if (cdp->extra) {
+			if (cdp->extra == 4)
+				goto extra_copy_bits_done;
+
+			while (copy != 0) {
+				cdp->u.buf[cdp->extra] = *p++;
+				copy--;
+				cdp->offset++;
+				cdp->len--;
+
+				if (++cdp->extra == 4) {
+extra_copy_bits_done:
+					if (cdp->flen == 0
+					    && layer_send_getpiobuf(cdp) < 0)
+						return;
+					*cdp->to++ = cdp->u.w;
+					cdp->extra = 0;
+					cdp->flen -= 1;
+					break;
+				}
+			}
+		}
+		while (copy >= 4) {
+			if (cdp->flen == 0 && layer_send_getpiobuf(cdp) < 0)
+				return;
+			n = copy >> 2;
+			if (n > cdp->flen)
+				n = cdp->flen;
+			ipath_dwordcpy(cdp->to, (uint32_t *) p, n);
+			cdp->to += n;
+			cdp->flen -= n;
+			n <<= 2;
+			p += n;
+			cdp->offset += n;
+			cdp->len -= n;
+			copy -= n;
+		}
+		/*
+		 * Either cdp->extra is zero or copy is zero which means that
+		 * the loop here can't cause the alignment buffer to fill up.
+		 */
+		while (copy != 0) {
+			cdp->u.buf[cdp->extra++] = *p++;
+			copy--;
+			cdp->offset++;
+			cdp->len--;
+
+		}
+		if (len == 0)
+			return;
+	}
+
+	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
+		skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
+		unsigned int end;
+
+		end = start + frag->size;
+		if ((int)(copy = end - offset) > 0) {
+			u8 *vaddr;
+
+			if (copy > len)
+				copy = len;
+			vaddr = kmap_skb_frag(frag);
+			p = vaddr + frag->page_offset + offset - start;
+			offset += copy;
+			len -= copy;
+			/*
+			 * If the alignment buffer is not empty, fill
+			 * it and write it out.
+			 */
+			if (cdp->extra) {
+				if (cdp->extra == 4)
+					goto extra1_copy_bits_done;
+
+				while (copy != 0) {
+					cdp->u.buf[cdp->extra] = *p++;
+					copy--;
+					cdp->offset++;
+					cdp->len--;
+
+					if (++cdp->extra == 4) {
+extra1_copy_bits_done:
+						if (cdp->flen == 0
+						    && layer_send_getpiobuf(cdp)
+						    < 0)
+							return;
+						*cdp->to++ = cdp->u.w;
+						cdp->extra = 0;
+						cdp->flen -= 1;
+						break;
+					}
+				}
+			}
+			while (copy >= 4) {
+				if (cdp->flen == 0
+				    && layer_send_getpiobuf(cdp) < 0)
+					return;
+				n = copy >> 2;
+				if (n > cdp->flen)
+					n = cdp->flen;
+				ipath_dwordcpy(cdp->to, (uint32_t *) p, n);
+				cdp->to += n;
+				cdp->flen -= n;
+				n <<= 2;
+				p += n;
+				cdp->offset += n;
+				cdp->len -= n;
+				copy -= n;
+			}
+			/*
+			 * Either cdp->extra is zero or copy is zero
+			 * which means that the loop here can't cause
+			 * the alignment buffer to fill up.
+			 */
+			while (copy != 0) {
+				cdp->u.buf[cdp->extra++] = *p++;
+				copy--;
+				cdp->offset++;
+				cdp->len--;
+			}
+			kunmap_skb_frag(vaddr);
+
+			if (len == 0)
+				return;
+		}
+		start = end;
+	}
+
+	if (skb_shinfo(skb)->frag_list) {
+		struct sk_buff *list = skb_shinfo(skb)->frag_list;
+
+		for (; list; list = list->next) {
+			unsigned int end;
+
+			end = start + list->len;
+			if ((int)(copy = end - offset) > 0) {
+				if (copy > len)
+					copy = len;
+				copy_bits(list, offset - start, copy, cdp);
+				if (cdp->error || (len -= copy) == 0)
+					return;
+			}
+			start = end;
+		}
+	}
+	if (len)
+		cdp->error = -EFAULT;
+}
+
+/*
+ * Copy data out of one or a chain of sk_buffs, into the PIO buffer, generating
+ * the checksum as we go.
+ * Fragment an sk_buff into multiple IB packets if the amount of data is
+ * more than a single eager send.
+ * Offset and len are in bytes.
+ * Note that this function is recursive!
+ */
+static void copy_and_csum_bits(const struct sk_buff *skb, unsigned int offset,
+			       unsigned int len, struct copy_data_s *cdp)
+{
+	unsigned int start = skb_headlen(skb);
+	unsigned int i, copy;
+	unsigned int csum2;
+	uint32_t n;
+	u8 *p;
+
+	/* Copy header. */
+	if ((int)(copy = start - offset) > 0) {
+		if (copy > len)
+			copy = len;
+		p = skb->data + offset;
+		offset += copy;
+		len -= copy;
+		if (!cdp->checksum_calc) {
+			cdp->checksum_calc = TRUE;
+
+			csum2 = csum_partial(p, copy, 0);
+			cdp->csum = csum_block_add(cdp->csum, csum2, cdp->pos);
+			cdp->pos += copy;
+		}
+		/*
+		 * If the alignment buffer is not empty, fill it and
+		 * write it out.
+		 */
+		if (cdp->extra) {
+			if (cdp->extra == 4)
+				goto extra_copy_and_csum_bits_done;
+
+			while (copy != 0) {
+				cdp->u.buf[cdp->extra] = *p++;
+				copy--;
+				cdp->offset++;
+				cdp->len--;
+				if (++cdp->extra == 4) {
+extra_copy_and_csum_bits_done:
+					if (cdp->flen == 0
+					    && layer_send_getpiobuf(cdp) < 0)
+						return;
+					/*
+					 * write the checksum before
+					 * the last PIO write.
+					 */
+					if (cdp->flen == 1) {
+						*cdp->csum_pio =
+						    csum_fold(cdp->csum);
+						mb();
+					}
+					*cdp->to++ = cdp->u.w;
+					cdp->extra = 0;
+					cdp->flen -= 1;
+					break;
+				}
+			}
+		}
+
+		while (copy >= 4) {
+			if (cdp->flen == 0 && layer_send_getpiobuf(cdp) < 0)
+				return;
+
+			n = copy >> 2;
+			if (n > cdp->flen)
+				n = cdp->flen;
+			/* write the checksum before the last PIO write. */
+			if (cdp->flen == n) {
+				*cdp->csum_pio = csum_fold(cdp->csum);
+				mb();
+			}
+			ipath_dwordcpy(cdp->to, (uint32_t *) p, n);
+			cdp->to += n;
+			cdp->flen -= n;
+			n <<= 2;
+			p += n;
+			cdp->offset += n;
+			cdp->len -= n;
+			copy -= n;
+		}
+		/*
+		 * Either cdp->extra is zero or copy is zero which means that
+		 * the loop here can't cause the alignment buffer to fill up.
+		 */
+		while (copy != 0) {
+			cdp->u.buf[cdp->extra++] = *p++;
+			copy--;
+			cdp->offset++;
+			cdp->len--;
+		}
+
+		cdp->checksum_calc = FALSE;
+
+		if (len == 0)
+			return;
+	}
+
+	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
+		skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
+		unsigned int end;
+
+		end = start + frag->size;
+		if ((int)(copy = end - offset) > 0) {
+			u8 *vaddr;
+
+			if (copy > len)
+				copy = len;
+			vaddr = kmap_skb_frag(frag);
+			p = vaddr + frag->page_offset + offset - start;
+			offset += copy;
+			len -= copy;
+
+			if (!cdp->checksum_calc) {
+				cdp->checksum_calc = TRUE;
+
+				csum2 = csum_partial(p, copy, 0);
+				cdp->csum = csum_block_add(cdp->csum, csum2,
+							   cdp->pos);
+				cdp->pos += copy;
+			}
+			/*
+			 * If the alignment buffer is not empty, fill
+			 * it and write it out.
+			 */
+			if (cdp->extra) {
+				if (cdp->extra == 4)
+					goto extra1_copy_and_csum_bits_done;
+				while (copy != 0) {
+					cdp->u.buf[cdp->extra] = *p++;
+					copy--;
+					cdp->offset++;
+					cdp->len--;
+
+					if (++cdp->extra == 4) {
+extra1_copy_and_csum_bits_done:
+						if (cdp->flen == 0
+						    && layer_send_getpiobuf(cdp)
+						    < 0) {
+							kunmap_skb_frag(vaddr);
+							return;
+						}
+						/*
+						 * write the checksum
+						 * before the last PIO
+						 * write.
+						 */
+						if (cdp->flen == 1) {
+							*cdp->csum_pio =
+							    csum_fold(cdp->
+								      csum);
+							mb();
+						}
+						*cdp->to++ = cdp->u.w;
+						cdp->extra = 0;
+						cdp->flen -= 1;
+						break;
+					}
+				}
+			}
+			while (copy >= 4) {
+				if (cdp->flen == 0
+				    && layer_send_getpiobuf(cdp) < 0) {
+					kunmap_skb_frag(vaddr);
+					return;
+				}
+				n = copy >> 2;
+				if (n > cdp->flen)
+					n = cdp->flen;
+				/*
+				 * write the checksum before the last
+				 * PIO write.
+				 */
+				if (cdp->flen == n) {
+					*cdp->csum_pio = csum_fold(cdp->csum);
+					mb();
+				}
+				ipath_dwordcpy(cdp->to, (uint32_t *) p, n);
+				cdp->to += n;
+				cdp->flen -= n;
+				n <<= 2;
+				p += n;
+				cdp->offset += n;
+				cdp->len -= n;
+				copy -= n;
+			}
+			/*
+			 * Either cdp->extra is zero or copy is zero
+			 * which means that the loop here can't cause
+			 * the alignment buffer to fill up.
+			 */
+			while (copy != 0) {
+				cdp->u.buf[cdp->extra++] = *p++;
+				copy--;
+				cdp->offset++;
+				cdp->len--;
+			}
+			kunmap_skb_frag(vaddr);
+
+			cdp->checksum_calc = FALSE;
+
+			if (len == 0)
+				return;
+		}
+		start = end;
+	}
+
+	if (skb_shinfo(skb)->frag_list) {
+		struct sk_buff *list = skb_shinfo(skb)->frag_list;
+
+		for (; list; list = list->next) {
+			unsigned int end;
+
+			end = start + list->len;
+			if ((int)(copy = end - offset) > 0) {
+				if (copy > len)
+					copy = len;
+				copy_and_csum_bits(list, offset - start, copy, cdp);
+				if (cdp->error || (len -= copy) == 0)
+					return;
+				offset += copy;
+			}
+			start = end;
+		}
+	}
+	if (len)
+		cdp->error = -EFAULT;
+}
+
+/*
+ * Note that the header should have the unchanging parts
+ * initialized but the rest of the header is computed as needed in
+ * order to break up skb data buffers larger than the hardware MTU.
+ * In other words, the Linux network stack MTU can be larger than the
+ * hardware MTU.
+ */
+int ipath_layer_send_skb(struct copy_data_s *cdata)
+{
+	int ret = 0;
+	uint16_t vlsllnh;
+	int device = cdata->device;
+
+	if (device >= infinipath_max) {
+		_IPATH_INFO("Invalid unit %u, failing\n", device);
+		return -EINVAL;
+	}
+	if (!(devdata[device].ipath_flags & IPATH_RCVHDRSZ_SET)) {
+		_IPATH_INFO("send while not open\n");
+		ret = -EINVAL;
+	} else
+	    if ((devdata[device].ipath_flags & (IPATH_LINKUNK | IPATH_LINKDOWN))
+		|| devdata[device].ipath_lid == 0) {
+		/* lid check is for when sma hasn't yet configured */
+		ret = -ENETDOWN;
+		_IPATH_VDBG("send while not ready, mylid=%u, flags=0x%x\n",
+			    devdata[device].ipath_lid,
+			    devdata[device].ipath_flags);
+	}
+	vlsllnh = *((uint16_t *) cdata->hdr);
+	if (vlsllnh != htons(IPS_LRH_BTH)) {
+		_IPATH_DBG("Warning: lrh[0] wrong (%x, not %x); not sending\n",
+			   vlsllnh, htons(IPS_LRH_BTH));
+		ret = -EINVAL;
+	}
+	if (ret)
+		goto done;
+
+	cdata->error = 0;	/* clear last calls error  */
+
+	if (cdata->skb->ip_summed == CHECKSUM_HW) {
+		unsigned int csstart = cdata->skb->h.raw - cdata->skb->data;
+
+		/*
+		 * Computing the checksum is a bit tricky since if we fragment
+		 * the packet, the fragment that should contain the checksum
+		 * will have already been sent.  The solution is to
+		 * store the checksum in the header of the last fragment
+		 * just before we write the last data word which triggers
+		 * the last fragment to be sent.  The receiver will
+		 * check the header "tag" field, see that there is a
+		 * checksum, and store the checksum back into the packet.
+		 *
+		 * Save the offset of the two byte checksum.
+		 * Note that we have to add 2 to account for the two
+		 * bytes of the ethernet address we stripped from the
+		 * packet and put in the header.
+		 */
+		cdata->hdr->csum_offset = csstart + cdata->skb->csum + 2;
+
+		if (cdata->offset < csstart)
+			copy_bits(cdata->skb, cdata->offset,
+				  csstart - cdata->offset, cdata);
+
+		if (cdata->error) {
+			return (cdata->error);
+
+		}
+
+		if (cdata->offset < cdata->skb->len)
+			copy_and_csum_bits(cdata->skb, cdata->offset,
+					   cdata->skb->len - cdata->offset,
+					   cdata);
+
+		if (cdata->error) {
+			return (cdata->error);
+		}
+
+		if (cdata->extra) {
+			while (cdata->extra < 4)
+				cdata->u.buf[cdata->extra++] = 0;
+			if (cdata->flen != 0
+			    || layer_send_getpiobuf(cdata) >= 0) {
+				/*
+				 * write the checksum before the last
+				 * PIO write.
+				 */
+				*cdata->csum_pio = csum_fold(cdata->csum);
+				mb();
+				*cdata->to = cdata->u.w;
+			}
+		}
+	} else {
+		copy_bits(cdata->skb, cdata->offset,
+			  cdata->skb->len - cdata->offset, cdata);
+
+		if (cdata->error) {
+			return (cdata->error);
+		}
+
+		if (cdata->extra) {
+			while (cdata->extra < 4)
+				cdata->u.buf[cdata->extra++] = 0;
+			if (cdata->flen != 0
+			    || layer_send_getpiobuf(cdata) >= 0)
+				*cdata->to = cdata->u.w;
+		}
+	}
+
+	if (cdata->error) {
+		ret = cdata->error;
+		if (cdata->error != -EBUSY)
+			/* just means no PIO buffers available */
+			_IPATH_UNIT_ERROR(device,
+					  "layer_send copy_bits failed with error %d\n",
+					  -ret);
+	}
+
+	ipath_stats.sps_ether_spkts++;	/* another ether packet sent */
+
+done:
+	return ret;
+}
+
+EXPORT_SYMBOL(ipath_layer_send_skb);
diff --git a/drivers/infiniband/hw/ipath/ipath_dwordcpy.S b/drivers/infiniband/hw/ipath/ipath_dwordcpy.S
new file mode 100644
index 0000000..fdd8ec7
--- /dev/null
+++ b/drivers/infiniband/hw/ipath/ipath_dwordcpy.S
@@ -0,0 +1,62 @@
+/*
+ * Copyright (c) 2003, 2004, 2005. 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.
+ *
+ * Patent licenses, if any, provided herein do not apply to
+ * combinations of this program with other software, or any other
+ * product whatsoever.
+ *
+ * $Id: ipath_dwordcpy.S 4365 2005-12-10 00:04:16Z rjwalsh $
+ */
+	
+/*
+ * ipath_dwordcpy - Copy a memory block, primarily for writing to the
+ * InfiniPath PIO buffers, which only support dword multiple writes, and
+ * thus can not use memcpy().  For this reason, we use nothing smaller than
+ * dword writes.
+ * It is also used as a fast copy routine in some places that have been
+ * measured to win over memcpy, and the performance delta matters.
+ *
+ * Count is number of dwords; might not be a qword multiple.
+*/
+
+ 	.globl ipath_dwordcpy
+/* rdi	destination, rsi source, rdx count */
+ipath_dwordcpy:
+	movl %edx,%ecx
+	shrl $1,%ecx
+	andl $1,%edx	
+	cld
+	rep 
+	movsq 
+	movl %edx,%ecx
+	rep
+	movsd
+	ret
-- 
0.99.9n
-
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