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-rw-r--r--arch/arm/mm/copypage-xscale.c131
1 files changed, 131 insertions, 0 deletions
diff --git a/arch/arm/mm/copypage-xscale.c b/arch/arm/mm/copypage-xscale.c
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1/*
2 * linux/arch/arm/lib/copypage-xscale.S
3 *
4 * Copyright (C) 1995-2005 Russell King
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 *
10 * This handles the mini data cache, as found on SA11x0 and XScale
11 * processors. When we copy a user page page, we map it in such a way
12 * that accesses to this page will not touch the main data cache, but
13 * will be cached in the mini data cache. This prevents us thrashing
14 * the main data cache on page faults.
15 */
16#include <linux/init.h>
17#include <linux/mm.h>
18
19#include <asm/page.h>
20#include <asm/pgtable.h>
21#include <asm/tlbflush.h>
22
23/*
24 * 0xffff8000 to 0xffffffff is reserved for any ARM architecture
25 * specific hacks for copying pages efficiently.
26 */
27#define COPYPAGE_MINICACHE 0xffff8000
28
29#define minicache_pgprot __pgprot(L_PTE_PRESENT | L_PTE_YOUNG | \
30 L_PTE_CACHEABLE)
31
32#define TOP_PTE(x) pte_offset_kernel(top_pmd, x)
33
34static DEFINE_SPINLOCK(minicache_lock);
35
36/*
37 * XScale mini-dcache optimised copy_user_page
38 *
39 * We flush the destination cache lines just before we write the data into the
40 * corresponding address. Since the Dcache is read-allocate, this removes the
41 * Dcache aliasing issue. The writes will be forwarded to the write buffer,
42 * and merged as appropriate.
43 */
44static void __attribute__((naked))
45mc_copy_user_page(void *from, void *to)
46{
47 /*
48 * Strangely enough, best performance is achieved
49 * when prefetching destination as well. (NP)
50 */
51 asm volatile(
52 "stmfd sp!, {r4, r5, lr} \n\
53 mov lr, %2 \n\
54 pld [r0, #0] \n\
55 pld [r0, #32] \n\
56 pld [r1, #0] \n\
57 pld [r1, #32] \n\
581: pld [r0, #64] \n\
59 pld [r0, #96] \n\
60 pld [r1, #64] \n\
61 pld [r1, #96] \n\
622: ldrd r2, [r0], #8 \n\
63 ldrd r4, [r0], #8 \n\
64 mov ip, r1 \n\
65 strd r2, [r1], #8 \n\
66 ldrd r2, [r0], #8 \n\
67 strd r4, [r1], #8 \n\
68 ldrd r4, [r0], #8 \n\
69 strd r2, [r1], #8 \n\
70 strd r4, [r1], #8 \n\
71 mcr p15, 0, ip, c7, c10, 1 @ clean D line\n\
72 ldrd r2, [r0], #8 \n\
73 mcr p15, 0, ip, c7, c6, 1 @ invalidate D line\n\
74 ldrd r4, [r0], #8 \n\
75 mov ip, r1 \n\
76 strd r2, [r1], #8 \n\
77 ldrd r2, [r0], #8 \n\
78 strd r4, [r1], #8 \n\
79 ldrd r4, [r0], #8 \n\
80 strd r2, [r1], #8 \n\
81 strd r4, [r1], #8 \n\
82 mcr p15, 0, ip, c7, c10, 1 @ clean D line\n\
83 subs lr, lr, #1 \n\
84 mcr p15, 0, ip, c7, c6, 1 @ invalidate D line\n\
85 bgt 1b \n\
86 beq 2b \n\
87 ldmfd sp!, {r4, r5, pc} "
88 :
89 : "r" (from), "r" (to), "I" (PAGE_SIZE / 64 - 1));
90}
91
92void xscale_mc_copy_user_page(void *kto, const void *kfrom, unsigned long vaddr)
93{
94 spin_lock(&minicache_lock);
95
96 set_pte(TOP_PTE(COPYPAGE_MINICACHE), pfn_pte(__pa(kfrom) >> PAGE_SHIFT, minicache_pgprot));
97 flush_tlb_kernel_page(COPYPAGE_MINICACHE);
98
99 mc_copy_user_page((void *)COPYPAGE_MINICACHE, kto);
100
101 spin_unlock(&minicache_lock);
102}
103
104/*
105 * XScale optimised clear_user_page
106 */
107void __attribute__((naked))
108xscale_mc_clear_user_page(void *kaddr, unsigned long vaddr)
109{
110 asm volatile(
111 "mov r1, %0 \n\
112 mov r2, #0 \n\
113 mov r3, #0 \n\
1141: mov ip, r0 \n\
115 strd r2, [r0], #8 \n\
116 strd r2, [r0], #8 \n\
117 strd r2, [r0], #8 \n\
118 strd r2, [r0], #8 \n\
119 mcr p15, 0, ip, c7, c10, 1 @ clean D line\n\
120 subs r1, r1, #1 \n\
121 mcr p15, 0, ip, c7, c6, 1 @ invalidate D line\n\
122 bne 1b \n\
123 mov pc, lr"
124 :
125 : "I" (PAGE_SIZE / 32));
126}
127
128struct cpu_user_fns xscale_mc_user_fns __initdata = {
129 .cpu_clear_user_page = xscale_mc_clear_user_page,
130 .cpu_copy_user_page = xscale_mc_copy_user_page,
131};