sh: Fix fatal oops in copy_user_page() on sh4a (SH7780).

We had a pretty interesting oops happening, where copy_user_page()
was down()'ing p3map_sem[] with a bogus offset (particularly, an
offset that hadn't been initialized with sema_init(), due to the
mismatch between cpu_data->dcache.n_aliases and what was assumed
based off of the old CACHE_ALIAS value).

Luckily, spinlock debugging caught this for us, and so we drop
the old hardcoded CACHE_ALIAS for sh4 completely and rely on the
run-time probed cpu_data->dcache.alias_mask. This in turn gets
the p3map_sem[] index right, and everything works again.

While we're at it, also convert to 4-level page tables..

Signed-off-by: Paul Mundt <lethal@linux-sh.org>

1 files changed, 14 insertions, 10 deletions

diff --git a/arch/sh/mm/pg-sh4.c b/arch/sh/mm/pg-sh4.c
index c776b60fc250..07371ed7a313 100644
--- a/arch/sh/mm/pg-sh4.c
+++ b/arch/sh/mm/pg-sh4.c
@@ -2,7 +2,7 @@
  * arch/sh/mm/pg-sh4.c
  *
  * Copyright (C) 1999, 2000, 2002  Niibe Yutaka
- * Copyright (C) 2002  Paul Mundt
+ * Copyright (C) 2002 - 2005  Paul Mundt
  *
  * Released under the terms of the GNU GPL v2.0.
  */
@@ -23,6 +23,8 @@
 
 extern struct semaphore p3map_sem[];
 
+#define CACHE_ALIAS (cpu_data->dcache.alias_mask)
+
 /*
  * clear_user_page
  * @to: P1 address
@@ -35,14 +37,15 @@ void clear_user_page(void *to, unsigned long address, struct page *page)
         if (((address ^ (unsigned long)to) & CACHE_ALIAS) == 0)
                 clear_page(to);
         else {
-                pgprot_t pgprot = __pgprot(_PAGE_PRESENT | 
+                pgprot_t pgprot = __pgprot(_PAGE_PRESENT |
                                            _PAGE_RW | _PAGE_CACHABLE |
-                                           _PAGE_DIRTY | _PAGE_ACCESSED | 
+                                           _PAGE_DIRTY | _PAGE_ACCESSED |
                                            _PAGE_HW_SHARED | _PAGE_FLAGS_HARD);
                 unsigned long phys_addr = PHYSADDR(to);
                 unsigned long p3_addr = P3SEG + (address & CACHE_ALIAS);
-                pgd_t *dir = pgd_offset_k(p3_addr);
-                pmd_t *pmd = pmd_offset(dir, p3_addr);
+                pgd_t *pgd = pgd_offset_k(p3_addr);
+                pud_t *pud = pud_offset(pgd, p3_addr);
+                pmd_t *pmd = pmd_offset(pud, p3_addr);
                 pte_t *pte = pte_offset_kernel(pmd, p3_addr);
                 pte_t entry;
                 unsigned long flags;
@@ -67,21 +70,22 @@ void clear_user_page(void *to, unsigned long address, struct page *page)
  * @address: U0 address to be mapped
  * @page: page (virt_to_page(to))
  */
-void copy_user_page(void *to, void *from, unsigned long address, 
+void copy_user_page(void *to, void *from, unsigned long address,
                     struct page *page)
 {
         __set_bit(PG_mapped, &page->flags);
         if (((address ^ (unsigned long)to) & CACHE_ALIAS) == 0)
                 copy_page(to, from);
         else {
-                pgprot_t pgprot = __pgprot(_PAGE_PRESENT | 
+                pgprot_t pgprot = __pgprot(_PAGE_PRESENT |
                                            _PAGE_RW | _PAGE_CACHABLE |
-                                           _PAGE_DIRTY | _PAGE_ACCESSED | 
+                                           _PAGE_DIRTY | _PAGE_ACCESSED |
                                            _PAGE_HW_SHARED | _PAGE_FLAGS_HARD);
                 unsigned long phys_addr = PHYSADDR(to);
                 unsigned long p3_addr = P3SEG + (address & CACHE_ALIAS);
-                pgd_t *dir = pgd_offset_k(p3_addr);
-                pmd_t *pmd = pmd_offset(dir, p3_addr);
+                pgd_t *pgd = pgd_offset_k(p3_addr);
+                pud_t *pud = pud_offset(pgd, p3_addr);
+                pmd_t *pmd = pmd_offset(pud, p3_addr);
                 pte_t *pte = pte_offset_kernel(pmd, p3_addr);
                 pte_t entry;
                 unsigned long flags;