| 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 |