LXR linux/include/linux/prefetch.h

   1/* SPDX-License-Identifier: GPL-2.0 */
   2/*
   3 *  Generic cache management functions. Everything is arch-specific,  
   4 *  but this header exists to make sure the defines/functions can be
   5 *  used in a generic way.
   6 *
   7 *  2000-11-13  Arjan van de Ven   <arjan@fenrus.demon.nl>
   8 *
   9 */
  10
  11#ifndef _LINUX_PREFETCH_H
  12#define _LINUX_PREFETCH_H
  13
  14#include <linux/types.h>
  15#include <asm/processor.h>
  16#include <asm/cache.h>
  17
  18struct page;
  19/*
  20        prefetch(x) attempts to pre-emptively get the memory pointed to
  21        by address "x" into the CPU L1 cache. 
  22        prefetch(x) should not cause any kind of exception, prefetch(0) is
  23        specifically ok.
  24
  25        prefetch() should be defined by the architecture, if not, the 
  26        #define below provides a no-op define.  
  27        
  28        There are 3 prefetch() macros:
  29        
  30        prefetch(x)     - prefetches the cacheline at "x" for read
  31        prefetchw(x)    - prefetches the cacheline at "x" for write
  32        spin_lock_prefetch(x) - prefetches the spinlock *x for taking
  33        
  34        there is also PREFETCH_STRIDE which is the architecure-preferred 
  35        "lookahead" size for prefetching streamed operations.
  36        
  37*/
  38
  39#ifndef ARCH_HAS_PREFETCH
  40#define prefetch(x) __builtin_prefetch(x)
  41#endif
  42
  43#ifndef ARCH_HAS_PREFETCHW
  44#define prefetchw(x) __builtin_prefetch(x,1)
  45#endif
  46
  47#ifndef ARCH_HAS_SPINLOCK_PREFETCH
  48#define spin_lock_prefetch(x) prefetchw(x)
  49#endif
  50
  51#ifndef PREFETCH_STRIDE
  52#define PREFETCH_STRIDE (4*L1_CACHE_BYTES)
  53#endif
  54
  55static inline void prefetch_range(void *addr, size_t len)
  56{
  57#ifdef ARCH_HAS_PREFETCH
  58        char *cp;
  59        char *end = addr + len;
  60
  61        for (cp = addr; cp < end; cp += PREFETCH_STRIDE)
  62                prefetch(cp);
  63#endif
  64}
  65
  66static inline void prefetch_page_address(struct page *page)
  67{
  68#if defined(WANT_PAGE_VIRTUAL) || defined(HASHED_PAGE_VIRTUAL)
  69        prefetch(page);
  70#endif
  71}
  72
  73#endif
  74