avr32: Cover the kernel page tables in the user PGDs

Expand the per-process PGDs so that they cover the kernel virtual
memory area as well. This simplifies the TLB miss handler fastpath
since it doesn't have to check for kernel addresses anymore.

If a TLB miss happens on a kernel address and a second-level page
table can't be found, we check swapper_pg_dir and copy the PGD entry
into the user PGD if it can be found there.

Signed-off-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com>

1 files changed, 10 insertions, 4 deletions

diff --git a/include/asm-avr32/pgalloc.h b/include/asm-avr32/pgalloc.h
index 5b768fc2388e..e9636d1f383f 100644
--- a/include/asm-avr32/pgalloc.h
+++ b/include/asm-avr32/pgalloc.h
@@ -9,8 +9,6 @@
 #define __ASM_AVR32_PGALLOC_H
 
 #include <linux/mm.h>
-#include <linux/sched.h>
-#include <linux/slab.h>
 
 static inline void pmd_populate_kernel(struct mm_struct *mm,
                                        pmd_t *pmd, pte_t *pte)
@@ -30,12 +28,20 @@ static inline void pmd_populate(struct mm_struct *mm, pmd_t *pmd,
  */
 static inline pgd_t *pgd_alloc(struct mm_struct *mm)
 {
-        return kcalloc(USER_PTRS_PER_PGD, sizeof(pgd_t), GFP_KERNEL);
+        pgd_t *pgd;
+
+        pgd = (pgd_t *)get_zeroed_page(GFP_KERNEL | __GFP_REPEAT);
+        if (likely(pgd))
+                memcpy(pgd + USER_PTRS_PER_PGD,
+                        swapper_pg_dir + USER_PTRS_PER_PGD,
+                        (PTRS_PER_PGD - USER_PTRS_PER_PGD) * sizeof(pgd_t));
+
+        return pgd;
 }
 
 static inline void pgd_free(struct mm_struct *mm, pgd_t *pgd)
 {
-        kfree(pgd);
+        free_page((unsigned long)pgd);
 }
 
 static inline pte_t *pte_alloc_one_kernel(struct mm_struct *mm,