__pfn_t has flags for sg_chain and sg_last, use it to replace the (struct page *) entry in struct scatterlist.
Signed-off-by: Dan Williams <[email protected]> --- include/linux/mm.h | 9 +++ include/linux/scatterlist.h | 111 ++++++++++++++++++++++++++++++------------- samples/kfifo/dma-example.c | 8 ++- 3 files changed, 91 insertions(+), 37 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index c4683ea2fcab..348f69467f54 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -992,6 +992,15 @@ static inline __pfn_t page_to_pfn_t(struct page *page) return pfn; } +static inline __pfn_t nth_pfn(__pfn_t pfn, unsigned int n) +{ + __pfn_t ret; + + ret.val = (__pfn_t_to_pfn(pfn) + n) << PAGE_SHIFT + | (pfn.val & PFN_MASK); + return ret; +} + /* * Some inline functions in vmstat.h depend on page_zone() */ diff --git a/include/linux/scatterlist.h b/include/linux/scatterlist.h index 698e906ca730..c612599bb155 100644 --- a/include/linux/scatterlist.h +++ b/include/linux/scatterlist.h @@ -11,7 +11,7 @@ struct scatterlist { #ifdef CONFIG_DEBUG_SG unsigned long sg_magic; #endif - unsigned long page_link; + __pfn_t pfn; unsigned int offset; unsigned int length; dma_addr_t dma_address; @@ -44,14 +44,14 @@ struct sg_table { /* * Notes on SG table design. * - * We use the unsigned long page_link field in the scatterlist struct to place + * We use the __pfn_t pfn field in the scatterlist struct to place * the page pointer AND encode information about the sg table as well. The two * lower bits are reserved for this information. * - * If bit 0 is set, then the page_link contains a pointer to the next sg + * If PFN_SG_CHAIN is set, then the pfn contains a pointer to the next sg * table list. Otherwise the next entry is at sg + 1. * - * If bit 1 is set, then this sg entry is the last element in a list. + * If PFN_SG_LAST is set, then this sg entry is the last element in a list. * * See sg_next(). * @@ -64,10 +64,31 @@ struct sg_table { * a valid sg entry, or whether it points to the start of a new scatterlist. * Those low bits are there for everyone! (thanks mason :-) */ -#define sg_is_chain(sg) ((sg)->page_link & 0x01) -#define sg_is_last(sg) ((sg)->page_link & 0x02) -#define sg_chain_ptr(sg) \ - ((struct scatterlist *) ((sg)->page_link & ~0x03)) +static inline bool sg_is_chain(struct scatterlist *sg) +{ + return (sg->pfn.val & PFN_SG_CHAIN) == PFN_SG_CHAIN; +} + +static inline bool sg_is_last(struct scatterlist *sg) +{ + return (sg->pfn.val & PFN_SG_LAST) == PFN_SG_LAST; +} + +static inline struct scatterlist *sg_chain_ptr(struct scatterlist *sg) +{ + return (struct scatterlist *) (sg->pfn.val + & ~(PFN_SG_CHAIN | PFN_SG_LAST)); +} + +static inline void sg_assign_pfn(struct scatterlist *sg, __pfn_t pfn) +{ +#ifdef CONFIG_DEBUG_SG + BUG_ON(sg->sg_magic != SG_MAGIC); + BUG_ON(sg_is_chain(sg)); +#endif + pfn.val &= ~PFN_SG_LAST; + sg->pfn.val = (sg->pfn.val & PFN_SG_LAST) | pfn.val; +} /** * sg_assign_page - Assign a given page to an SG entry @@ -81,18 +102,20 @@ struct sg_table { **/ static inline void sg_assign_page(struct scatterlist *sg, struct page *page) { - unsigned long page_link = sg->page_link & 0x3; + __pfn_t pfn = page_to_pfn_t(page); - /* - * In order for the low bit stealing approach to work, pages - * must be aligned at a 32-bit boundary as a minimum. - */ - BUG_ON((unsigned long) page & 0x03); -#ifdef CONFIG_DEBUG_SG - BUG_ON(sg->sg_magic != SG_MAGIC); - BUG_ON(sg_is_chain(sg)); -#endif - sg->page_link = page_link | (unsigned long) page; + /* check that a __pfn_t has enough bits to encode a page */ + BUG_ON(pfn.val & (PFN_SG_LAST | PFN_SG_CHAIN)); + + sg_assign_pfn(sg, pfn); +} + +static inline void sg_set_pfn(struct scatterlist *sg, __pfn_t pfn, + unsigned int len, unsigned int offset) +{ + sg_assign_pfn(sg, pfn); + sg->offset = offset; + sg->length = len; } /** @@ -112,18 +135,34 @@ static inline void sg_assign_page(struct scatterlist *sg, struct page *page) static inline void sg_set_page(struct scatterlist *sg, struct page *page, unsigned int len, unsigned int offset) { - sg_assign_page(sg, page); - sg->offset = offset; - sg->length = len; + sg_set_pfn(sg, page_to_pfn_t(page), len, offset); +} + +static inline bool sg_has_page(struct scatterlist *sg) +{ + return __pfn_t_has_page(sg->pfn); } static inline struct page *sg_page(struct scatterlist *sg) { + __pfn_t pfn = sg->pfn; + struct page *page; + + WARN_ONCE(!sg_has_page(sg), "scatterlist references unmapped memory\n"); + #ifdef CONFIG_DEBUG_SG BUG_ON(sg->sg_magic != SG_MAGIC); BUG_ON(sg_is_chain(sg)); #endif - return (struct page *)((sg)->page_link & ~0x3); + + page = __pfn_t_to_page(pfn); + + return page; +} + +static inline unsigned long sg_pfn(struct scatterlist *sg) +{ + return __pfn_t_to_pfn(sg->pfn); } /** @@ -171,7 +210,8 @@ static inline void sg_chain(struct scatterlist *prv, unsigned int prv_nents, * Set lowest bit to indicate a link pointer, and make sure to clear * the termination bit if it happens to be set. */ - prv[prv_nents - 1].page_link = ((unsigned long) sgl | 0x01) & ~0x02; + prv[prv_nents - 1].pfn.val = ((unsigned long) sgl | PFN_SG_CHAIN) + & ~PFN_SG_LAST; } /** @@ -191,8 +231,8 @@ static inline void sg_mark_end(struct scatterlist *sg) /* * Set termination bit, clear potential chain bit */ - sg->page_link |= 0x02; - sg->page_link &= ~0x01; + sg->pfn.val |= PFN_SG_LAST; + sg->pfn.val &= ~PFN_SG_CHAIN; } /** @@ -208,7 +248,7 @@ static inline void sg_unmark_end(struct scatterlist *sg) #ifdef CONFIG_DEBUG_SG BUG_ON(sg->sg_magic != SG_MAGIC); #endif - sg->page_link &= ~0x02; + sg->pfn.val &= ~PFN_SG_LAST; } /** @@ -216,14 +256,13 @@ static inline void sg_unmark_end(struct scatterlist *sg) * @sg: SG entry * * Description: - * This calls page_to_phys() on the page in this sg entry, and adds the - * sg offset. The caller must know that it is legal to call page_to_phys() - * on the sg page. + * This calls __pfn_t_to_phys() on the pfn in this sg entry, and adds the + * sg offset. * **/ static inline dma_addr_t sg_phys(struct scatterlist *sg) { - return page_to_phys(sg_page(sg)) + sg->offset; + return __pfn_t_to_phys(sg->pfn) + sg->offset; } /** @@ -281,7 +320,7 @@ size_t sg_pcopy_to_buffer(struct scatterlist *sgl, unsigned int nents, #define SG_MAX_SINGLE_ALLOC (PAGE_SIZE / sizeof(struct scatterlist)) /* - * sg page iterator + * sg page / pfn iterator * * Iterates over sg entries page-by-page. On each successful iteration, * you can call sg_page_iter_page(@piter) and sg_page_iter_dma_address(@piter) @@ -304,13 +343,19 @@ bool __sg_page_iter_next(struct sg_page_iter *piter); void __sg_page_iter_start(struct sg_page_iter *piter, struct scatterlist *sglist, unsigned int nents, unsigned long pgoffset); + +static inline __pfn_t sg_page_iter_pfn(struct sg_page_iter *piter) +{ + return nth_pfn(piter->sg->pfn, piter->sg_pgoffset); +} + /** * sg_page_iter_page - get the current page held by the page iterator * @piter: page iterator holding the page */ static inline struct page *sg_page_iter_page(struct sg_page_iter *piter) { - return nth_page(sg_page(piter->sg), piter->sg_pgoffset); + return __pfn_t_to_page(sg_page_iter_pfn(piter)); } /** diff --git a/samples/kfifo/dma-example.c b/samples/kfifo/dma-example.c index aa243db93f01..3eeff9a56e0e 100644 --- a/samples/kfifo/dma-example.c +++ b/samples/kfifo/dma-example.c @@ -75,8 +75,8 @@ static int __init example_init(void) for (i = 0; i < nents; i++) { printk(KERN_INFO "sg[%d] -> " - "page_link 0x%.8lx offset 0x%.8x length 0x%.8x\n", - i, sg[i].page_link, sg[i].offset, sg[i].length); + "pfn_data 0x%.8lx offset 0x%.8x length 0x%.8x\n", + i, sg[i].pfn.data, sg[i].offset, sg[i].length); if (sg_is_last(&sg[i])) break; @@ -104,8 +104,8 @@ static int __init example_init(void) for (i = 0; i < nents; i++) { printk(KERN_INFO "sg[%d] -> " - "page_link 0x%.8lx offset 0x%.8x length 0x%.8x\n", - i, sg[i].page_link, sg[i].offset, sg[i].length); + "pfn_data 0x%.8lx offset 0x%.8x length 0x%.8x\n", + i, sg[i].pfn.data, sg[i].offset, sg[i].length); if (sg_is_last(&sg[i])) break; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
