linux/crypto/async_tx/async_xor.c
Dan Williams a06d568f7c async_xor: dma_map destination DMA_BIDIRECTIONAL
Mapping the destination multiple times is a misuse of the dma-api.
Since the destination may be reused as a source, ensure that it is only
mapped once and that it is mapped bidirectionally.  This appears to add
ugliness on the unmap side in that it always reads back the destination
address from the descriptor, but gcc can determine that dma_unmap is a
nop and not emit the code that calculates its arguments.

Cc: <stable@kernel.org>
Cc: Saeed Bishara <saeed@marvell.com>
Acked-by: Yuri Tikhonov <yur@emcraft.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2008-12-08 13:46:00 -07:00

329 lines
9.7 KiB
C

/*
* xor offload engine api
*
* Copyright © 2006, Intel Corporation.
*
* Dan Williams <dan.j.williams@intel.com>
*
* with architecture considerations by:
* Neil Brown <neilb@suse.de>
* Jeff Garzik <jeff@garzik.org>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope 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.,
* 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
*
*/
#include <linux/kernel.h>
#include <linux/interrupt.h>
#include <linux/mm.h>
#include <linux/dma-mapping.h>
#include <linux/raid/xor.h>
#include <linux/async_tx.h>
/* do_async_xor - dma map the pages and perform the xor with an engine.
* This routine is marked __always_inline so it can be compiled away
* when CONFIG_DMA_ENGINE=n
*/
static __always_inline struct dma_async_tx_descriptor *
do_async_xor(struct dma_chan *chan, struct page *dest, struct page **src_list,
unsigned int offset, int src_cnt, size_t len,
enum async_tx_flags flags,
struct dma_async_tx_descriptor *depend_tx,
dma_async_tx_callback cb_fn, void *cb_param)
{
struct dma_device *dma = chan->device;
dma_addr_t *dma_src = (dma_addr_t *) src_list;
struct dma_async_tx_descriptor *tx = NULL;
int src_off = 0;
int i;
dma_async_tx_callback _cb_fn;
void *_cb_param;
enum async_tx_flags async_flags;
enum dma_ctrl_flags dma_flags;
int xor_src_cnt;
dma_addr_t dma_dest;
/* map the dest bidrectional in case it is re-used as a source */
dma_dest = dma_map_page(dma->dev, dest, offset, len, DMA_BIDIRECTIONAL);
for (i = 0; i < src_cnt; i++) {
/* only map the dest once */
if (unlikely(src_list[i] == dest)) {
dma_src[i] = dma_dest;
continue;
}
dma_src[i] = dma_map_page(dma->dev, src_list[i], offset,
len, DMA_TO_DEVICE);
}
while (src_cnt) {
async_flags = flags;
dma_flags = 0;
xor_src_cnt = min(src_cnt, dma->max_xor);
/* if we are submitting additional xors, leave the chain open,
* clear the callback parameters, and leave the destination
* buffer mapped
*/
if (src_cnt > xor_src_cnt) {
async_flags &= ~ASYNC_TX_ACK;
dma_flags = DMA_COMPL_SKIP_DEST_UNMAP;
_cb_fn = NULL;
_cb_param = NULL;
} else {
_cb_fn = cb_fn;
_cb_param = cb_param;
}
if (_cb_fn)
dma_flags |= DMA_PREP_INTERRUPT;
/* Since we have clobbered the src_list we are committed
* to doing this asynchronously. Drivers force forward progress
* in case they can not provide a descriptor
*/
tx = dma->device_prep_dma_xor(chan, dma_dest, &dma_src[src_off],
xor_src_cnt, len, dma_flags);
if (unlikely(!tx))
async_tx_quiesce(&depend_tx);
/* spin wait for the preceeding transactions to complete */
while (unlikely(!tx)) {
dma_async_issue_pending(chan);
tx = dma->device_prep_dma_xor(chan, dma_dest,
&dma_src[src_off],
xor_src_cnt, len,
dma_flags);
}
async_tx_submit(chan, tx, async_flags, depend_tx, _cb_fn,
_cb_param);
depend_tx = tx;
flags |= ASYNC_TX_DEP_ACK;
if (src_cnt > xor_src_cnt) {
/* drop completed sources */
src_cnt -= xor_src_cnt;
src_off += xor_src_cnt;
/* use the intermediate result a source */
dma_src[--src_off] = dma_dest;
src_cnt++;
} else
break;
}
return tx;
}
static void
do_sync_xor(struct page *dest, struct page **src_list, unsigned int offset,
int src_cnt, size_t len, enum async_tx_flags flags,
dma_async_tx_callback cb_fn, void *cb_param)
{
int i;
int xor_src_cnt;
int src_off = 0;
void *dest_buf;
void **srcs = (void **) src_list;
/* reuse the 'src_list' array to convert to buffer pointers */
for (i = 0; i < src_cnt; i++)
srcs[i] = page_address(src_list[i]) + offset;
/* set destination address */
dest_buf = page_address(dest) + offset;
if (flags & ASYNC_TX_XOR_ZERO_DST)
memset(dest_buf, 0, len);
while (src_cnt > 0) {
/* process up to 'MAX_XOR_BLOCKS' sources */
xor_src_cnt = min(src_cnt, MAX_XOR_BLOCKS);
xor_blocks(xor_src_cnt, len, dest_buf, &srcs[src_off]);
/* drop completed sources */
src_cnt -= xor_src_cnt;
src_off += xor_src_cnt;
}
async_tx_sync_epilog(cb_fn, cb_param);
}
/**
* async_xor - attempt to xor a set of blocks with a dma engine.
* xor_blocks always uses the dest as a source so the ASYNC_TX_XOR_ZERO_DST
* flag must be set to not include dest data in the calculation. The
* assumption with dma eninges is that they only use the destination
* buffer as a source when it is explicity specified in the source list.
* @dest: destination page
* @src_list: array of source pages (if the dest is also a source it must be
* at index zero). The contents of this array may be overwritten.
* @offset: offset in pages to start transaction
* @src_cnt: number of source pages
* @len: length in bytes
* @flags: ASYNC_TX_XOR_ZERO_DST, ASYNC_TX_XOR_DROP_DEST,
* ASYNC_TX_ACK, ASYNC_TX_DEP_ACK
* @depend_tx: xor depends on the result of this transaction.
* @cb_fn: function to call when the xor completes
* @cb_param: parameter to pass to the callback routine
*/
struct dma_async_tx_descriptor *
async_xor(struct page *dest, struct page **src_list, unsigned int offset,
int src_cnt, size_t len, enum async_tx_flags flags,
struct dma_async_tx_descriptor *depend_tx,
dma_async_tx_callback cb_fn, void *cb_param)
{
struct dma_chan *chan = async_tx_find_channel(depend_tx, DMA_XOR,
&dest, 1, src_list,
src_cnt, len);
BUG_ON(src_cnt <= 1);
if (chan) {
/* run the xor asynchronously */
pr_debug("%s (async): len: %zu\n", __func__, len);
return do_async_xor(chan, dest, src_list, offset, src_cnt, len,
flags, depend_tx, cb_fn, cb_param);
} else {
/* run the xor synchronously */
pr_debug("%s (sync): len: %zu\n", __func__, len);
/* in the sync case the dest is an implied source
* (assumes the dest is the first source)
*/
if (flags & ASYNC_TX_XOR_DROP_DST) {
src_cnt--;
src_list++;
}
/* wait for any prerequisite operations */
async_tx_quiesce(&depend_tx);
do_sync_xor(dest, src_list, offset, src_cnt, len,
flags, cb_fn, cb_param);
return NULL;
}
}
EXPORT_SYMBOL_GPL(async_xor);
static int page_is_zero(struct page *p, unsigned int offset, size_t len)
{
char *a = page_address(p) + offset;
return ((*(u32 *) a) == 0 &&
memcmp(a, a + 4, len - 4) == 0);
}
/**
* async_xor_zero_sum - attempt a xor parity check with a dma engine.
* @dest: destination page used if the xor is performed synchronously
* @src_list: array of source pages. The dest page must be listed as a source
* at index zero. The contents of this array may be overwritten.
* @offset: offset in pages to start transaction
* @src_cnt: number of source pages
* @len: length in bytes
* @result: 0 if sum == 0 else non-zero
* @flags: ASYNC_TX_ACK, ASYNC_TX_DEP_ACK
* @depend_tx: xor depends on the result of this transaction.
* @cb_fn: function to call when the xor completes
* @cb_param: parameter to pass to the callback routine
*/
struct dma_async_tx_descriptor *
async_xor_zero_sum(struct page *dest, struct page **src_list,
unsigned int offset, int src_cnt, size_t len,
u32 *result, enum async_tx_flags flags,
struct dma_async_tx_descriptor *depend_tx,
dma_async_tx_callback cb_fn, void *cb_param)
{
struct dma_chan *chan = async_tx_find_channel(depend_tx, DMA_ZERO_SUM,
&dest, 1, src_list,
src_cnt, len);
struct dma_device *device = chan ? chan->device : NULL;
struct dma_async_tx_descriptor *tx = NULL;
BUG_ON(src_cnt <= 1);
if (device && src_cnt <= device->max_xor) {
dma_addr_t *dma_src = (dma_addr_t *) src_list;
unsigned long dma_prep_flags = cb_fn ? DMA_PREP_INTERRUPT : 0;
int i;
pr_debug("%s: (async) len: %zu\n", __func__, len);
for (i = 0; i < src_cnt; i++)
dma_src[i] = dma_map_page(device->dev, src_list[i],
offset, len, DMA_TO_DEVICE);
tx = device->device_prep_dma_zero_sum(chan, dma_src, src_cnt,
len, result,
dma_prep_flags);
if (unlikely(!tx)) {
async_tx_quiesce(&depend_tx);
while (!tx) {
dma_async_issue_pending(chan);
tx = device->device_prep_dma_zero_sum(chan,
dma_src, src_cnt, len, result,
dma_prep_flags);
}
}
async_tx_submit(chan, tx, flags, depend_tx, cb_fn, cb_param);
} else {
unsigned long xor_flags = flags;
pr_debug("%s: (sync) len: %zu\n", __func__, len);
xor_flags |= ASYNC_TX_XOR_DROP_DST;
xor_flags &= ~ASYNC_TX_ACK;
tx = async_xor(dest, src_list, offset, src_cnt, len, xor_flags,
depend_tx, NULL, NULL);
async_tx_quiesce(&tx);
*result = page_is_zero(dest, offset, len) ? 0 : 1;
async_tx_sync_epilog(cb_fn, cb_param);
}
return tx;
}
EXPORT_SYMBOL_GPL(async_xor_zero_sum);
static int __init async_xor_init(void)
{
#ifdef CONFIG_DMA_ENGINE
/* To conserve stack space the input src_list (array of page pointers)
* is reused to hold the array of dma addresses passed to the driver.
* This conversion is only possible when dma_addr_t is less than the
* the size of a pointer. HIGHMEM64G is known to violate this
* assumption.
*/
BUILD_BUG_ON(sizeof(dma_addr_t) > sizeof(struct page *));
#endif
return 0;
}
static void __exit async_xor_exit(void)
{
do { } while (0);
}
module_init(async_xor_init);
module_exit(async_xor_exit);
MODULE_AUTHOR("Intel Corporation");
MODULE_DESCRIPTION("asynchronous xor/xor-zero-sum api");
MODULE_LICENSE("GPL");