IO memory support can be indicated by an iteratee with the
SG_MITRE_SUPPORTS_IOMEM flag. If an unmappable sgl gets into a miter
without this support, the kernel will BUGON.
For supported cases, the sg_miter code will set the ioaddr pointer and
leave addr NULL.
sg_copy_buffer is changed to support IO memory by simply calling
the appropriate memcpy when required.
Signed-off-by: Logan Gunthorpe <logang@xxxxxxxxxxxx>
Signed-off-by: Stephen Bates <sbates@xxxxxxxxxxxx>
---
include/linux/scatterlist.h | 3 +++
lib/scatterlist.c | 35 +++++++++++++++++++++++++++++------
2 files changed, 32 insertions(+), 6 deletions(-)
diff --git a/include/linux/scatterlist.h b/include/linux/scatterlist.h
index 8cb662c..2c54c6c 100644
--- a/include/linux/scatterlist.h
+++ b/include/linux/scatterlist.h
@@ -447,11 +447,14 @@ static inline dma_addr_t sg_page_iter_dma_address(struct sg_page_iter *piter)
#define SG_MITER_ATOMIC (1 << 0) /* use kmap_atomic */
#define SG_MITER_TO_SG (1 << 1) /* flush back to phys on unmap */
#define SG_MITER_FROM_SG (1 << 2) /* nop */
+#define SG_MITRE_SUPPORTS_IOMEM (1 << 3) /* io memory is supported by
+ * the iteratee */
struct sg_mapping_iter {
/* the following three fields can be accessed directly */
struct page *page; /* currently mapped page */
void *addr; /* pointer to the mapped area */
+ void __iomem *ioaddr; /* address to io memory */
size_t length; /* length of the mapped area */
size_t consumed; /* number of consumed bytes */
struct sg_page_iter piter; /* page iterator */
diff --git a/lib/scatterlist.c b/lib/scatterlist.c
index 6bc33e0..1ec768e 100644
--- a/lib/scatterlist.c
+++ b/lib/scatterlist.c
@@ -601,6 +601,8 @@ EXPORT_SYMBOL(sg_miter_skip);
*/
bool sg_miter_next(struct sg_mapping_iter *miter)
{
+ pfn_t pfn = miter->piter.sg->__pfn;
+
sg_miter_stop(miter);
/*
@@ -610,9 +612,20 @@ bool sg_miter_next(struct sg_mapping_iter *miter)
if (!sg_miter_get_next_page(miter))
return false;
- miter->page = sg_page_iter_page(&miter->piter);
miter->consumed = miter->length = miter->__remaining;
+ if (!(miter->__flags & SG_MITRE_SUPPORTS_IOMEM)) {
+ BUG_ON(!pfn_t_is_always_mappable(pfn));
+ } else if (pfn_t_is_iomem(pfn)) {
+ miter->ioaddr = ioremap(pfn_t_to_phys(pfn), PAGE_SIZE);
+ miter->addr = NULL;
+ return true;
+ }
+
+ miter->ioaddr = NULL;
+ miter->page = pfn_t_to_page(pfn);
+ BUG_ON(!miter->page);
+
if (miter->__flags & SG_MITER_ATOMIC)
miter->addr = kmap_atomic(miter->page) + miter->__offset;
else
@@ -660,6 +673,9 @@ void sg_miter_stop(struct sg_mapping_iter *miter)
miter->length = 0;
miter->consumed = 0;
}
+
+ if (miter->ioaddr)
+ iounmap(miter->ioaddr);
}
EXPORT_SYMBOL(sg_miter_stop);
@@ -681,7 +697,7 @@ size_t sg_copy_buffer(struct scatterlist *sgl, unsigned int nents, void *buf,
{
unsigned int offset = 0;
struct sg_mapping_iter miter;
- unsigned int sg_flags = SG_MITER_ATOMIC;
+ unsigned int sg_flags = SG_MITER_ATOMIC | SG_MITRE_SUPPORTS_IOMEM;
if (to_buffer)
sg_flags |= SG_MITER_FROM_SG;
@@ -698,10 +714,17 @@ size_t sg_copy_buffer(struct scatterlist *sgl, unsigned int nents, void *buf,
len = min(miter.length, buflen - offset);
- if (to_buffer)
- memcpy(buf + offset, miter.addr, len);
- else
- memcpy(miter.addr, buf + offset, len);
+ if (miter.addr) {
+ if (to_buffer)
+ memcpy(buf + offset, miter.addr, len);
+ else
+ memcpy(miter.addr, buf + offset, len);
+ } else if (miter.ioaddr) {
+ if (to_buffer)
+ memcpy_fromio(buf + offset, miter.addr, len);
+ else
+ memcpy_toio(miter.addr, buf + offset, len);
+ }
offset += len;
}
--
2.1.4
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