xref: /openbmc/linux/arch/arm/mm/copypage-xscale.c (revision b34e08d5)
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 #define minicache_pgprot __pgprot(L_PTE_PRESENT | L_PTE_YOUNG | \
27 				  L_PTE_MT_MINICACHE)
28 
29 static DEFINE_RAW_SPINLOCK(minicache_lock);
30 
31 /*
32  * XScale mini-dcache optimised copy_user_highpage
33  *
34  * We flush the destination cache lines just before we write the data into the
35  * corresponding address.  Since the Dcache is read-allocate, this removes the
36  * Dcache aliasing issue.  The writes will be forwarded to the write buffer,
37  * and merged as appropriate.
38  */
39 static void __naked
40 mc_copy_user_page(void *from, void *to)
41 {
42 	/*
43 	 * Strangely enough, best performance is achieved
44 	 * when prefetching destination as well.  (NP)
45 	 */
46 	asm volatile(
47 	"stmfd	sp!, {r4, r5, lr}		\n\
48 	mov	lr, %2				\n\
49 	pld	[r0, #0]			\n\
50 	pld	[r0, #32]			\n\
51 	pld	[r1, #0]			\n\
52 	pld	[r1, #32]			\n\
53 1:	pld	[r0, #64]			\n\
54 	pld	[r0, #96]			\n\
55 	pld	[r1, #64]			\n\
56 	pld	[r1, #96]			\n\
57 2:	ldrd	r2, [r0], #8			\n\
58 	ldrd	r4, [r0], #8			\n\
59 	mov	ip, r1				\n\
60 	strd	r2, [r1], #8			\n\
61 	ldrd	r2, [r0], #8			\n\
62 	strd	r4, [r1], #8			\n\
63 	ldrd	r4, [r0], #8			\n\
64 	strd	r2, [r1], #8			\n\
65 	strd	r4, [r1], #8			\n\
66 	mcr	p15, 0, ip, c7, c10, 1		@ clean D line\n\
67 	ldrd	r2, [r0], #8			\n\
68 	mcr	p15, 0, ip, c7, c6, 1		@ invalidate D line\n\
69 	ldrd	r4, [r0], #8			\n\
70 	mov	ip, r1				\n\
71 	strd	r2, [r1], #8			\n\
72 	ldrd	r2, [r0], #8			\n\
73 	strd	r4, [r1], #8			\n\
74 	ldrd	r4, [r0], #8			\n\
75 	strd	r2, [r1], #8			\n\
76 	strd	r4, [r1], #8			\n\
77 	mcr	p15, 0, ip, c7, c10, 1		@ clean D line\n\
78 	subs	lr, lr, #1			\n\
79 	mcr	p15, 0, ip, c7, c6, 1		@ invalidate D line\n\
80 	bgt	1b				\n\
81 	beq	2b				\n\
82 	ldmfd	sp!, {r4, r5, pc}		"
83 	:
84 	: "r" (from), "r" (to), "I" (PAGE_SIZE / 64 - 1));
85 }
86 
87 void xscale_mc_copy_user_highpage(struct page *to, struct page *from,
88 	unsigned long vaddr, struct vm_area_struct *vma)
89 {
90 	void *kto = kmap_atomic(to);
91 
92 	if (!test_and_set_bit(PG_dcache_clean, &from->flags))
93 		__flush_dcache_page(page_mapping(from), from);
94 
95 	raw_spin_lock(&minicache_lock);
96 
97 	set_top_pte(COPYPAGE_MINICACHE, mk_pte(from, minicache_pgprot));
98 
99 	mc_copy_user_page((void *)COPYPAGE_MINICACHE, kto);
100 
101 	raw_spin_unlock(&minicache_lock);
102 
103 	kunmap_atomic(kto);
104 }
105 
106 /*
107  * XScale optimised clear_user_page
108  */
109 void
110 xscale_mc_clear_user_highpage(struct page *page, unsigned long vaddr)
111 {
112 	void *ptr, *kaddr = kmap_atomic(page);
113 	asm volatile(
114 	"mov	r1, %2				\n\
115 	mov	r2, #0				\n\
116 	mov	r3, #0				\n\
117 1:	mov	ip, %0				\n\
118 	strd	r2, [%0], #8			\n\
119 	strd	r2, [%0], #8			\n\
120 	strd	r2, [%0], #8			\n\
121 	strd	r2, [%0], #8			\n\
122 	mcr	p15, 0, ip, c7, c10, 1		@ clean D line\n\
123 	subs	r1, r1, #1			\n\
124 	mcr	p15, 0, ip, c7, c6, 1		@ invalidate D line\n\
125 	bne	1b"
126 	: "=r" (ptr)
127 	: "0" (kaddr), "I" (PAGE_SIZE / 32)
128 	: "r1", "r2", "r3", "ip");
129 	kunmap_atomic(kaddr);
130 }
131 
132 struct cpu_user_fns xscale_mc_user_fns __initdata = {
133 	.cpu_clear_user_highpage = xscale_mc_clear_user_highpage,
134 	.cpu_copy_user_highpage	= xscale_mc_copy_user_highpage,
135 };
136