diff options
Diffstat (limited to 'arch/arm/mm/copypage-v4mc.c')
| -rw-r--r-- | arch/arm/mm/copypage-v4mc.c | 111 |
1 files changed, 111 insertions, 0 deletions
diff --git a/arch/arm/mm/copypage-v4mc.c b/arch/arm/mm/copypage-v4mc.c new file mode 100644 index 00000000000..fc69dccdace --- /dev/null +++ b/arch/arm/mm/copypage-v4mc.c @@ -0,0 +1,111 @@ +/* + * linux/arch/arm/lib/copypage-armv4mc.S + * + * Copyright (C) 1995-2005 Russell King + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + * This handles the mini data cache, as found on SA11x0 and XScale + * processors. When we copy a user page page, we map it in such a way + * that accesses to this page will not touch the main data cache, but + * will be cached in the mini data cache. This prevents us thrashing + * the main data cache on page faults. + */ +#include <linux/init.h> +#include <linux/mm.h> + +#include <asm/page.h> +#include <asm/pgtable.h> +#include <asm/tlbflush.h> + +/* + * 0xffff8000 to 0xffffffff is reserved for any ARM architecture + * specific hacks for copying pages efficiently. + */ +#define minicache_pgprot __pgprot(L_PTE_PRESENT | L_PTE_YOUNG | \ + L_PTE_CACHEABLE) + +#define TOP_PTE(x) pte_offset_kernel(top_pmd, x) + +static DEFINE_SPINLOCK(minicache_lock); + +/* + * ARMv4 mini-dcache optimised copy_user_page + * + * We flush the destination cache lines just before we write the data into the + * corresponding address. Since the Dcache is read-allocate, this removes the + * Dcache aliasing issue. The writes will be forwarded to the write buffer, + * and merged as appropriate. + * + * Note: We rely on all ARMv4 processors implementing the "invalidate D line" + * instruction. If your processor does not supply this, you have to write your + * own copy_user_page that does the right thing. + */ +static void __attribute__((naked)) +mc_copy_user_page(void *from, void *to) +{ + asm volatile( + "stmfd sp!, {r4, lr} @ 2\n\ + mov r4, %2 @ 1\n\ + ldmia %0!, {r2, r3, ip, lr} @ 4\n\ +1: mcr p15, 0, %1, c7, c6, 1 @ 1 invalidate D line\n\ + stmia %1!, {r2, r3, ip, lr} @ 4\n\ + ldmia %0!, {r2, r3, ip, lr} @ 4+1\n\ + stmia %1!, {r2, r3, ip, lr} @ 4\n\ + ldmia %0!, {r2, r3, ip, lr} @ 4\n\ + mcr p15, 0, %1, c7, c6, 1 @ 1 invalidate D line\n\ + stmia %1!, {r2, r3, ip, lr} @ 4\n\ + ldmia %0!, {r2, r3, ip, lr} @ 4\n\ + subs r4, r4, #1 @ 1\n\ + stmia %1!, {r2, r3, ip, lr} @ 4\n\ + ldmneia %0!, {r2, r3, ip, lr} @ 4\n\ + bne 1b @ 1\n\ + ldmfd sp!, {r4, pc} @ 3" + : + : "r" (from), "r" (to), "I" (PAGE_SIZE / 64)); +} + +void v4_mc_copy_user_page(void *kto, const void *kfrom, unsigned long vaddr) +{ + spin_lock(&minicache_lock); + + set_pte(TOP_PTE(0xffff8000), pfn_pte(__pa(kfrom) >> PAGE_SHIFT, minicache_pgprot)); + flush_tlb_kernel_page(0xffff8000); + + mc_copy_user_page((void *)0xffff8000, kto); + + spin_unlock(&minicache_lock); +} + +/* + * ARMv4 optimised clear_user_page + */ +void __attribute__((naked)) +v4_mc_clear_user_page(void *kaddr, unsigned long vaddr) +{ + asm volatile( + "str lr, [sp, #-4]!\n\ + mov r1, %0 @ 1\n\ + mov r2, #0 @ 1\n\ + mov r3, #0 @ 1\n\ + mov ip, #0 @ 1\n\ + mov lr, #0 @ 1\n\ +1: mcr p15, 0, r0, c7, c6, 1 @ 1 invalidate D line\n\ + stmia r0!, {r2, r3, ip, lr} @ 4\n\ + stmia r0!, {r2, r3, ip, lr} @ 4\n\ + mcr p15, 0, r0, c7, c6, 1 @ 1 invalidate D line\n\ + stmia r0!, {r2, r3, ip, lr} @ 4\n\ + stmia r0!, {r2, r3, ip, lr} @ 4\n\ + subs r1, r1, #1 @ 1\n\ + bne 1b @ 1\n\ + ldr pc, [sp], #4" + : + : "I" (PAGE_SIZE / 64)); +} + +struct cpu_user_fns v4_mc_user_fns __initdata = { + .cpu_clear_user_page = v4_mc_clear_user_page, + .cpu_copy_user_page = v4_mc_copy_user_page, +}; |