[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

1 files changed, 131 insertions, 0 deletions

diff --git a/arch/arm/mm/copypage-xscale.c b/arch/arm/mm/copypage-xscale.c
new file mode 100644
index 000000000000..42a6ee255ce0
--- /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,
+};