[PATCH] ARM: Fix Xscale copy_page implementation
The ARM copypage changes in 2.6.12-rc4-git1 removed the preempt locking
from the copypage functions which broke the XScale implementation.
This patch fixes the locking on XScale and removes the now unneeded
minicache code.
Signed-off-by: Russell King <rmk@arm.linux.org.uk>
Checked-by: Richard Purdie
diff --git a/arch/arm/mm/copypage-xscale.c b/arch/arm/mm/copypage-xscale.c
new file mode 100644
index 0000000..42a6ee2
--- /dev/null
+++ b/arch/arm/mm/copypage-xscale.c
@@ -0,0 +1,131 @@
+/*
+ * linux/arch/arm/lib/copypage-xscale.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 COPYPAGE_MINICACHE 0xffff8000
+
+#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);
+
+/*
+ * XScale 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.
+ */
+static void __attribute__((naked))
+mc_copy_user_page(void *from, void *to)
+{
+ /*
+ * Strangely enough, best performance is achieved
+ * when prefetching destination as well. (NP)
+ */
+ asm volatile(
+ "stmfd sp!, {r4, r5, lr} \n\
+ mov lr, %2 \n\
+ pld [r0, #0] \n\
+ pld [r0, #32] \n\
+ pld [r1, #0] \n\
+ pld [r1, #32] \n\
+1: pld [r0, #64] \n\
+ pld [r0, #96] \n\
+ pld [r1, #64] \n\
+ pld [r1, #96] \n\
+2: ldrd r2, [r0], #8 \n\
+ ldrd r4, [r0], #8 \n\
+ mov ip, r1 \n\
+ strd r2, [r1], #8 \n\
+ ldrd r2, [r0], #8 \n\
+ strd r4, [r1], #8 \n\
+ ldrd r4, [r0], #8 \n\
+ strd r2, [r1], #8 \n\
+ strd r4, [r1], #8 \n\
+ mcr p15, 0, ip, c7, c10, 1 @ clean D line\n\
+ ldrd r2, [r0], #8 \n\
+ mcr p15, 0, ip, c7, c6, 1 @ invalidate D line\n\
+ ldrd r4, [r0], #8 \n\
+ mov ip, r1 \n\
+ strd r2, [r1], #8 \n\
+ ldrd r2, [r0], #8 \n\
+ strd r4, [r1], #8 \n\
+ ldrd r4, [r0], #8 \n\
+ strd r2, [r1], #8 \n\
+ strd r4, [r1], #8 \n\
+ mcr p15, 0, ip, c7, c10, 1 @ clean D line\n\
+ subs lr, lr, #1 \n\
+ mcr p15, 0, ip, c7, c6, 1 @ invalidate D line\n\
+ bgt 1b \n\
+ beq 2b \n\
+ ldmfd sp!, {r4, r5, pc} "
+ :
+ : "r" (from), "r" (to), "I" (PAGE_SIZE / 64 - 1));
+}
+
+void xscale_mc_copy_user_page(void *kto, const void *kfrom, unsigned long vaddr)
+{
+ spin_lock(&minicache_lock);
+
+ set_pte(TOP_PTE(COPYPAGE_MINICACHE), pfn_pte(__pa(kfrom) >> PAGE_SHIFT, minicache_pgprot));
+ flush_tlb_kernel_page(COPYPAGE_MINICACHE);
+
+ mc_copy_user_page((void *)COPYPAGE_MINICACHE, kto);
+
+ spin_unlock(&minicache_lock);
+}
+
+/*
+ * XScale optimised clear_user_page
+ */
+void __attribute__((naked))
+xscale_mc_clear_user_page(void *kaddr, unsigned long vaddr)
+{
+ asm volatile(
+ "mov r1, %0 \n\
+ mov r2, #0 \n\
+ mov r3, #0 \n\
+1: mov ip, r0 \n\
+ strd r2, [r0], #8 \n\
+ strd r2, [r0], #8 \n\
+ strd r2, [r0], #8 \n\
+ strd r2, [r0], #8 \n\
+ mcr p15, 0, ip, c7, c10, 1 @ clean D line\n\
+ subs r1, r1, #1 \n\
+ mcr p15, 0, ip, c7, c6, 1 @ invalidate D line\n\
+ bne 1b \n\
+ mov pc, lr"
+ :
+ : "I" (PAGE_SIZE / 32));
+}
+
+struct cpu_user_fns xscale_mc_user_fns __initdata = {
+ .cpu_clear_user_page = xscale_mc_clear_user_page,
+ .cpu_copy_user_page = xscale_mc_copy_user_page,
+};