cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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scatterlist.h (4262B)

      1/* SPDX-License-Identifier: GPL-2.0 */
      2#ifndef SCATTERLIST_H
      3#define SCATTERLIST_H
      4#include <linux/kernel.h>
      5
      6struct scatterlist {
      7	unsigned long	page_link;
      8	unsigned int	offset;
      9	unsigned int	length;
     10	dma_addr_t	dma_address;
     11};
     12
     13/* Scatterlist helpers, stolen from linux/scatterlist.h */
     14#define sg_is_chain(sg)		((sg)->page_link & 0x01)
     15#define sg_is_last(sg)		((sg)->page_link & 0x02)
     16#define sg_chain_ptr(sg)	\
     17	((struct scatterlist *) ((sg)->page_link & ~0x03))
     18
     19/**
     20 * sg_assign_page - Assign a given page to an SG entry
     21 * @sg:		    SG entry
     22 * @page:	    The page
     23 *
     24 * Description:
     25 *   Assign page to sg entry. Also see sg_set_page(), the most commonly used
     26 *   variant.
     27 *
     28 **/
     29static inline void sg_assign_page(struct scatterlist *sg, struct page *page)
     30{
     31	unsigned long page_link = sg->page_link & 0x3;
     32
     33	/*
     34	 * In order for the low bit stealing approach to work, pages
     35	 * must be aligned at a 32-bit boundary as a minimum.
     36	 */
     37	BUG_ON((unsigned long) page & 0x03);
     38#ifdef CONFIG_DEBUG_SG
     39	BUG_ON(sg_is_chain(sg));
     40#endif
     41	sg->page_link = page_link | (unsigned long) page;
     42}
     43
     44/**
     45 * sg_set_page - Set sg entry to point at given page
     46 * @sg:		 SG entry
     47 * @page:	 The page
     48 * @len:	 Length of data
     49 * @offset:	 Offset into page
     50 *
     51 * Description:
     52 *   Use this function to set an sg entry pointing at a page, never assign
     53 *   the page directly. We encode sg table information in the lower bits
     54 *   of the page pointer. See sg_page() for looking up the page belonging
     55 *   to an sg entry.
     56 *
     57 **/
     58static inline void sg_set_page(struct scatterlist *sg, struct page *page,
     59			       unsigned int len, unsigned int offset)
     60{
     61	sg_assign_page(sg, page);
     62	sg->offset = offset;
     63	sg->length = len;
     64}
     65
     66static inline struct page *sg_page(struct scatterlist *sg)
     67{
     68#ifdef CONFIG_DEBUG_SG
     69	BUG_ON(sg_is_chain(sg));
     70#endif
     71	return (struct page *)((sg)->page_link & ~0x3);
     72}
     73
     74/*
     75 * Loop over each sg element, following the pointer to a new list if necessary
     76 */
     77#define for_each_sg(sglist, sg, nr, __i)	\
     78	for (__i = 0, sg = (sglist); __i < (nr); __i++, sg = sg_next(sg))
     79
     80/**
     81 * sg_chain - Chain two sglists together
     82 * @prv:	First scatterlist
     83 * @prv_nents:	Number of entries in prv
     84 * @sgl:	Second scatterlist
     85 *
     86 * Description:
     87 *   Links @prv@ and @sgl@ together, to form a longer scatterlist.
     88 *
     89 **/
     90static inline void sg_chain(struct scatterlist *prv, unsigned int prv_nents,
     91			    struct scatterlist *sgl)
     92{
     93	/*
     94	 * offset and length are unused for chain entry.  Clear them.
     95	 */
     96	prv[prv_nents - 1].offset = 0;
     97	prv[prv_nents - 1].length = 0;
     98
     99	/*
    100	 * Set lowest bit to indicate a link pointer, and make sure to clear
    101	 * the termination bit if it happens to be set.
    102	 */
    103	prv[prv_nents - 1].page_link = ((unsigned long) sgl | 0x01) & ~0x02;
    104}
    105
    106/**
    107 * sg_mark_end - Mark the end of the scatterlist
    108 * @sg:		 SG entryScatterlist
    109 *
    110 * Description:
    111 *   Marks the passed in sg entry as the termination point for the sg
    112 *   table. A call to sg_next() on this entry will return NULL.
    113 *
    114 **/
    115static inline void sg_mark_end(struct scatterlist *sg)
    116{
    117	/*
    118	 * Set termination bit, clear potential chain bit
    119	 */
    120	sg->page_link |= 0x02;
    121	sg->page_link &= ~0x01;
    122}
    123
    124/**
    125 * sg_unmark_end - Undo setting the end of the scatterlist
    126 * @sg:		 SG entryScatterlist
    127 *
    128 * Description:
    129 *   Removes the termination marker from the given entry of the scatterlist.
    130 *
    131 **/
    132static inline void sg_unmark_end(struct scatterlist *sg)
    133{
    134	sg->page_link &= ~0x02;
    135}
    136
    137static inline struct scatterlist *sg_next(struct scatterlist *sg)
    138{
    139	if (sg_is_last(sg))
    140		return NULL;
    141
    142	sg++;
    143	if (unlikely(sg_is_chain(sg)))
    144		sg = sg_chain_ptr(sg);
    145
    146	return sg;
    147}
    148
    149static inline void sg_init_table(struct scatterlist *sgl, unsigned int nents)
    150{
    151	memset(sgl, 0, sizeof(*sgl) * nents);
    152	sg_mark_end(&sgl[nents - 1]);
    153}
    154
    155static inline dma_addr_t sg_phys(struct scatterlist *sg)
    156{
    157	return page_to_phys(sg_page(sg)) + sg->offset;
    158}
    159
    160static inline void sg_set_buf(struct scatterlist *sg, const void *buf,
    161			      unsigned int buflen)
    162{
    163	sg_set_page(sg, virt_to_page(buf), buflen, offset_in_page(buf));
    164}
    165
    166static inline void sg_init_one(struct scatterlist *sg,
    167			       const void *buf, unsigned int buflen)
    168{
    169	sg_init_table(sg, 1);
    170	sg_set_buf(sg, buf, buflen);
    171}
    172#endif /* SCATTERLIST_H */