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_file(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