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 #include <linux/highmem.h>
19
20 #include <asm/pgtable.h>
21 #include <asm/tlbflush.h>
22 #include <asm/cacheflush.h>
23
24 #include "mm.h"
25
26 /*
27 * 0xffff8000 to 0xffffffff is reserved for any ARM architecture
28 * specific hacks for copying pages efficiently.
29 */
30 #define COPYPAGE_MINICACHE 0xffff8000
31
32 #define minicache_pgprot __pgprot(L_PTE_PRESENT | L_PTE_YOUNG | \
33 L_PTE_MT_MINICACHE)
34
35 static DEFINE_SPINLOCK(minicache_lock);
36
37 /*
38 * XScale mini-dcache optimised copy_user_highpage
39 *
40 * We flush the destination cache lines just before we write the data into the
41 * corresponding address. Since the Dcache is read-allocate, this removes the
42 * Dcache aliasing issue. The writes will be forwarded to the write buffer,
43 * and merged as appropriate.
44 */
45 static void __naked
mc_copy_user_page(void * from,void * to)46 mc_copy_user_page(void *from, void *to)
47 {
48 /*
49 * Strangely enough, best performance is achieved
50 * when prefetching destination as well. (NP)
51 */
52 asm volatile(
53 "stmfd sp!, {r4, r5, lr} \n\
54 mov lr, %2 \n\
55 pld [r0, #0] \n\
56 pld [r0, #32] \n\
57 pld [r1, #0] \n\
58 pld [r1, #32] \n\
59 1: pld [r0, #64] \n\
60 pld [r0, #96] \n\
61 pld [r1, #64] \n\
62 pld [r1, #96] \n\
63 2: ldrd r2, [r0], #8 \n\
64 ldrd r4, [r0], #8 \n\
65 mov ip, r1 \n\
66 strd r2, [r1], #8 \n\
67 ldrd r2, [r0], #8 \n\
68 strd r4, [r1], #8 \n\
69 ldrd r4, [r0], #8 \n\
70 strd r2, [r1], #8 \n\
71 strd r4, [r1], #8 \n\
72 mcr p15, 0, ip, c7, c10, 1 @ clean D line\n\
73 ldrd r2, [r0], #8 \n\
74 mcr p15, 0, ip, c7, c6, 1 @ invalidate D line\n\
75 ldrd r4, [r0], #8 \n\
76 mov ip, r1 \n\
77 strd r2, [r1], #8 \n\
78 ldrd r2, [r0], #8 \n\
79 strd r4, [r1], #8 \n\
80 ldrd r4, [r0], #8 \n\
81 strd r2, [r1], #8 \n\
82 strd r4, [r1], #8 \n\
83 mcr p15, 0, ip, c7, c10, 1 @ clean D line\n\
84 subs lr, lr, #1 \n\
85 mcr p15, 0, ip, c7, c6, 1 @ invalidate D line\n\
86 bgt 1b \n\
87 beq 2b \n\
88 ldmfd sp!, {r4, r5, pc} "
89 :
90 : "r" (from), "r" (to), "I" (PAGE_SIZE / 64 - 1));
91 }
92
xscale_mc_copy_user_highpage(struct page * to,struct page * from,unsigned long vaddr,struct vm_area_struct * vma)93 void xscale_mc_copy_user_highpage(struct page *to, struct page *from,
94 unsigned long vaddr, struct vm_area_struct *vma)
95 {
96 void *kto = kmap_atomic(to, KM_USER1);
97
98 if (!test_and_set_bit(PG_dcache_clean, &from->flags))
99 __flush_dcache_page(page_mapping(from), from);
100
101 spin_lock(&minicache_lock);
102
103 set_pte_ext(TOP_PTE(COPYPAGE_MINICACHE), pfn_pte(page_to_pfn(from), minicache_pgprot), 0);
104 flush_tlb_kernel_page(COPYPAGE_MINICACHE);
105
106 mc_copy_user_page((void *)COPYPAGE_MINICACHE, kto);
107
108 spin_unlock(&minicache_lock);
109
110 kunmap_atomic(kto, KM_USER1);
111 }
112
113 /*
114 * XScale optimised clear_user_page
115 */
116 void
xscale_mc_clear_user_highpage(struct page * page,unsigned long vaddr)117 xscale_mc_clear_user_highpage(struct page *page, unsigned long vaddr)
118 {
119 void *ptr, *kaddr = kmap_atomic(page, KM_USER0);
120 asm volatile(
121 "mov r1, %2 \n\
122 mov r2, #0 \n\
123 mov r3, #0 \n\
124 1: mov ip, %0 \n\
125 strd r2, [%0], #8 \n\
126 strd r2, [%0], #8 \n\
127 strd r2, [%0], #8 \n\
128 strd r2, [%0], #8 \n\
129 mcr p15, 0, ip, c7, c10, 1 @ clean D line\n\
130 subs r1, r1, #1 \n\
131 mcr p15, 0, ip, c7, c6, 1 @ invalidate D line\n\
132 bne 1b"
133 : "=r" (ptr)
134 : "0" (kaddr), "I" (PAGE_SIZE / 32)
135 : "r1", "r2", "r3", "ip");
136 kunmap_atomic(kaddr, KM_USER0);
137 }
138
139 struct cpu_user_fns xscale_mc_user_fns __initdata = {
140 .cpu_clear_user_highpage = xscale_mc_clear_user_highpage,
141 .cpu_copy_user_highpage = xscale_mc_copy_user_highpage,
142 };
143