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 2 prefetch() macros: 29 30 prefetch(x) - prefetches the cacheline at "x" for read 31 prefetchw(x) - prefetches the cacheline at "x" for write 32 33 there is also PREFETCH_STRIDE which is the architecure-preferred 34 "lookahead" size for prefetching streamed operations. 35 36 */ 37 38 #ifndef ARCH_HAS_PREFETCH 39 #define prefetch(x) __builtin_prefetch(x) 40 #endif 41 42 #ifndef ARCH_HAS_PREFETCHW 43 #define prefetchw(x) __builtin_prefetch(x,1) 44 #endif 45 46 #ifndef PREFETCH_STRIDE 47 #define PREFETCH_STRIDE (4*L1_CACHE_BYTES) 48 #endif 49 50 static inline void prefetch_range(void *addr, size_t len) 51 { 52 #ifdef ARCH_HAS_PREFETCH 53 char *cp; 54 char *end = addr + len; 55 56 for (cp = addr; cp < end; cp += PREFETCH_STRIDE) 57 prefetch(cp); 58 #endif 59 } 60 61 static inline void prefetch_page_address(struct page *page) 62 { 63 #if defined(WANT_PAGE_VIRTUAL) || defined(HASHED_PAGE_VIRTUAL) 64 prefetch(page); 65 #endif 66 } 67 68 #endif 69