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 /*
19 prefetch(x) attempts to pre-emptively get the memory pointed to
20 by address "x" into the CPU L1 cache.
21 prefetch(x) should not cause any kind of exception, prefetch(0) is
22 specifically ok.
23
24 prefetch() should be defined by the architecture, if not, the
25 #define below provides a no-op define.
26
27 There are 3 prefetch() macros:
28
29 prefetch(x) - prefetches the cacheline at "x" for read
30 prefetchw(x) - prefetches the cacheline at "x" for write
31 spin_lock_prefetch(x) - prefetches the spinlock *x for taking
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 ARCH_HAS_SPINLOCK_PREFETCH
47 #define spin_lock_prefetch(x) prefetchw(x)
48 #endif
49
50 #ifndef PREFETCH_STRIDE
51 #define PREFETCH_STRIDE (4*L1_CACHE_BYTES)
52 #endif
53
54 static inline void prefetch_range(void *addr, size_t len)
55 {
56 #ifdef ARCH_HAS_PREFETCH
57 char *cp;
58 char *end = addr + len;
59
60 for (cp = addr; cp < end; cp += PREFETCH_STRIDE)
61 prefetch(cp);
62 #endif
63 }
64
65 #endif