sh: pmd rework.

Remove extra bits from the pmd structure and store a kernel logical
address rather than a physical address. This allows it to be directly
dereferenced. Another piece of wierdness inherited from x86.

Signed-off-by: Stuart Menefy <stuart.menefy@st.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

1 files changed, 40 insertions, 0 deletions

diff --git a/arch/sh/mm/fault.c b/arch/sh/mm/fault.c
index 43bed2cb00e3..128907ef7fcd 100644
--- a/arch/sh/mm/fault.c
+++ b/arch/sh/mm/fault.c
@@ -46,6 +46,45 @@ asmlinkage void __kprobes do_page_fault(struct pt_regs *regs,
         mm = tsk->mm;
         si_code = SEGV_MAPERR;
 
+        if (unlikely(address >= TASK_SIZE)) {
+                /*
+                 * Synchronize this task's top level page-table
+                 * with the 'reference' page table.
+                 *
+                 * Do _not_ use "tsk" here. We might be inside
+                 * an interrupt in the middle of a task switch..
+                 */
+                int offset = pgd_index(address);
+                pgd_t *pgd, *pgd_k;
+                pud_t *pud, *pud_k;
+                pmd_t *pmd, *pmd_k;
+
+                pgd = get_TTB() + offset;
+                pgd_k = swapper_pg_dir + offset;
+
+                /* This will never happen with the folded page table. */
+                if (!pgd_present(*pgd)) {
+                        if (!pgd_present(*pgd_k))
+                                goto bad_area_nosemaphore;
+                        set_pgd(pgd, *pgd_k);
+                        return;
+                }
+
+                pud = pud_offset(pgd, address);
+                pud_k = pud_offset(pgd_k, address);
+                if (pud_present(*pud) || !pud_present(*pud_k))
+                        goto bad_area_nosemaphore;
+                set_pud(pud, *pud_k);
+
+                pmd = pmd_offset(pud, address);
+                pmd_k = pmd_offset(pud_k, address);
+                if (pmd_present(*pmd) || !pmd_present(*pmd_k))
+                        goto bad_area_nosemaphore;
+                set_pmd(pmd, *pmd_k);
+
+                return;
+        }
+
         /*
          * If we're in an interrupt or have no user
          * context, we must not take the fault..
@@ -109,6 +148,7 @@ survive:
 bad_area:
         up_read(&mm->mmap_sem);
 
+bad_area_nosemaphore:
         if (user_mode(regs)) {
                 info.si_signo = SIGSEGV;
                 info.si_errno = 0;