[ARM] clearpage: provide our own clear_user_highpage()

For similar reasons as copy_user_page(), we want to avoid the
additional kmap_atomic if it's unnecessary.

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

1 files changed, 9 insertions, 14 deletions

diff --git a/arch/arm/mm/copypage-v6.c b/arch/arm/mm/copypage-v6.c
index 2ea75d0f5048..4127a7bddfe5 100644
--- a/arch/arm/mm/copypage-v6.c
+++ b/arch/arm/mm/copypage-v6.c
@@ -49,9 +49,11 @@ static void v6_copy_user_highpage_nonaliasing(struct page *to,
  * Clear the user page.  No aliasing to deal with so we can just
  * attack the kernel's existing mapping of this page.
  */
-static void v6_clear_user_page_nonaliasing(void *kaddr, unsigned long vaddr)
+static void v6_clear_user_highpage_nonaliasing(struct page *page, unsigned long vaddr)
 {
+        void *kaddr = kmap_atomic(page, KM_USER0);
         clear_page(kaddr);
+        kunmap_atomic(kaddr, KM_USER0);
 }
 
 /*
@@ -107,20 +109,13 @@ static void v6_copy_user_highpage_aliasing(struct page *to,
  * so remap the kernel page into the same cache colour as the user
  * page.
  */
-static void v6_clear_user_page_aliasing(void *kaddr, unsigned long vaddr)
+static void v6_clear_user_highpage_aliasing(struct page *page, unsigned long vaddr)
 {
         unsigned int offset = CACHE_COLOUR(vaddr);
         unsigned long to = to_address + (offset << PAGE_SHIFT);
 
-        /*
-         * Discard data in the kernel mapping for the new page
-         * FIXME: needs this MCRR to be supported.
-         */
-        __asm__("mcrr   p15, 0, %1, %0, c6      @ 0xec401f06"
-           :
-           : "r" (kaddr),
-             "r" ((unsigned long)kaddr + PAGE_SIZE - L1_CACHE_BYTES)
-           : "cc");
+        /* FIXME: not highmem safe */
+        discard_old_kernel_data(page_address(page));
 
         /*
          * Now clear the page using the same cache colour as
@@ -128,7 +123,7 @@ static void v6_clear_user_page_aliasing(void *kaddr, unsigned long vaddr)
          */
         spin_lock(&v6_lock);
 
-        set_pte_ext(TOP_PTE(to_address) + offset, pfn_pte(__pa(kaddr) >> PAGE_SHIFT, PAGE_KERNEL), 0);
+        set_pte_ext(TOP_PTE(to_address) + offset, pfn_pte(page_to_pfn(page), PAGE_KERNEL), 0);
         flush_tlb_kernel_page(to);
         clear_page((void *)to);
 
@@ -136,14 +131,14 @@ static void v6_clear_user_page_aliasing(void *kaddr, unsigned long vaddr)
 }
 
 struct cpu_user_fns v6_user_fns __initdata = {
-        .cpu_clear_user_page    = v6_clear_user_page_nonaliasing,
+        .cpu_clear_user_highpage = v6_clear_user_highpage_nonaliasing,
         .cpu_copy_user_highpage = v6_copy_user_highpage_nonaliasing,
 };
 
 static int __init v6_userpage_init(void)
 {
         if (cache_is_vipt_aliasing()) {
-                cpu_user.cpu_clear_user_page = v6_clear_user_page_aliasing;
+                cpu_user.cpu_clear_user_highpage = v6_clear_user_highpage_aliasing;
                 cpu_user.cpu_copy_user_highpage = v6_copy_user_highpage_aliasing;
         }