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 18 struct 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 55 static 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 66 static 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