[PATCH] ARM: Move copy/clear user_page locking into implementation

Move the locking for copy_user_page() and clear_user_page() into
the implementations which require locking.  For simple memcpy/
memset based implementations, the locking is extra overhead which
is not necessary, and prevents preemption occuring.

Signed-off-by: Russell King <rmk@arm.linux.org.uk>

diff --git a/arch/arm/mm/copypage-v4mc.S b/arch/arm/mm/copypage-v4mc.S
deleted file mode 100644 (file)
index 305af3d..0000000
--- a/arch/arm/mm/copypage-v4mc.S
+++ /dev/null
@@ -1,80 +0,0 @@
-/*
- *  linux/arch/arm/lib/copy_page-armv4mc.S
- *
- *  Copyright (C) 1995-2001 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.
- *
- *  ASM optimised string functions
- */
-#include <linux/linkage.h>
-#include <linux/init.h>
-#include <asm/constants.h>
-
-       .text
-       .align  5
-/*
- * 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.
- */
-ENTRY(v4_mc_copy_user_page)
-       stmfd   sp!, {r4, lr}                   @ 2
-       mov     r4, r0
-       mov     r0, r1
-       bl      map_page_minicache
-       mov     r1, #PAGE_SZ/64                 @ 1
-       ldmia   r0!, {r2, r3, ip, lr}           @ 4
-1:     mcr     p15, 0, r4, c7, c6, 1           @ 1   invalidate D line
-       stmia   r4!, {r2, r3, ip, lr}           @ 4
-       ldmia   r0!, {r2, r3, ip, lr}           @ 4+1
-       stmia   r4!, {r2, r3, ip, lr}           @ 4
-       ldmia   r0!, {r2, r3, ip, lr}           @ 4
-       mcr     p15, 0, r4, c7, c6, 1           @ 1   invalidate D line
-       stmia   r4!, {r2, r3, ip, lr}           @ 4
-       ldmia   r0!, {r2, r3, ip, lr}           @ 4
-       subs    r1, r1, #1                      @ 1
-       stmia   r4!, {r2, r3, ip, lr}           @ 4
-       ldmneia r0!, {r2, r3, ip, lr}           @ 4
-       bne     1b                              @ 1
-       ldmfd   sp!, {r4, pc}                   @ 3
-
-       .align  5
-/*
- * ARMv4 optimised clear_user_page
- *
- * Same story as above.
- */
-ENTRY(v4_mc_clear_user_page)
-       str     lr, [sp, #-4]!
-       mov     r1, #PAGE_SZ/64                 @ 1
-       mov     r2, #0                          @ 1
-       mov     r3, #0                          @ 1
-       mov     ip, #0                          @ 1
-       mov     lr, #0                          @ 1
-1:     mcr     p15, 0, r0, c7, c6, 1           @ 1   invalidate D line
-       stmia   r0!, {r2, r3, ip, lr}           @ 4
-       stmia   r0!, {r2, r3, ip, lr}           @ 4
-       mcr     p15, 0, r0, c7, c6, 1           @ 1   invalidate D line
-       stmia   r0!, {r2, r3, ip, lr}           @ 4
-       stmia   r0!, {r2, r3, ip, lr}           @ 4
-       subs    r1, r1, #1                      @ 1
-       bne     1b                              @ 1
-       ldr     pc, [sp], #4
-
-       __INITDATA
-
-       .type   v4_mc_user_fns, #object
-ENTRY(v4_mc_user_fns)
-       .long   v4_mc_clear_user_page
-       .long   v4_mc_copy_user_page
-       .size   v4_mc_user_fns, . - v4_mc_user_fns

diff --git a/arch/arm/mm/copypage-v4mc.c b/arch/arm/mm/copypage-v4mc.c
new file mode 100644 (file)
index 0000000..16384a7
--- /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(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);
+}
+
+/*
+ * 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,
+};

diff --git a/include/asm-arm/page.h b/include/asm-arm/page.h
index d26d157..019c45d 100644 (file)
--- a/include/asm-arm/page.h
+++ b/include/asm-arm/page.h
@@ -114,19 +114,8 @@ extern void __cpu_copy_user_page(void *to, const void *from,
                                 unsigned long user);
 #endif
 
-#define clear_user_page(addr,vaddr,pg)                 \
-       do {                                            \
-               preempt_disable();                      \
-               __cpu_clear_user_page(addr, vaddr);     \
-               preempt_enable();                       \
-       } while (0)
-
-#define copy_user_page(to,from,vaddr,pg)               \
-       do {                                            \
-               preempt_disable();                      \
-               __cpu_copy_user_page(to, from, vaddr);  \
-               preempt_enable();                       \
-       } while (0)
+#define clear_user_page(addr,vaddr,pg)  __cpu_clear_user_page(addr, vaddr)
+#define copy_user_page(to,from,vaddr,pg) __cpu_copy_user_page(to, from, vaddr)
 
 #define clear_page(page)       memzero((void *)(page), PAGE_SIZE)
 extern void copy_page(void *to, const void *from);