[PATCH] mm: i386 sh sh64 ready for split ptlock

Use pte_offset_map_lock, instead of pte_offset_map (or inappropriate
pte_offset_kernel) and mm-wide page_table_lock, in sundry arch places.

The i386 vm86 mark_screen_rdonly: yes, there was and is an assumption that the
screen fits inside the one page table, as indeed it does.

The sh __do_page_fault: which handles both kernel faults (without lock) and
user mm faults (locked - though it set_pte without locking before).

The sh64 flush_cache_range and helpers: which wrongly thought callers held
page_table_lock before (only its tlb_start_vma did, and no longer does so);
moved the flush loop down, and adjusted the large versus small range decision
to consider a range which spans page tables as large.

Signed-off-by: Hugh Dickins <hugh@veritas.com>
Acked-by: Paul Mundt <lethal@linux-sh.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 7 insertions, 10 deletions

diff --git a/arch/i386/kernel/vm86.c b/arch/i386/kernel/vm86.c
index 16b485009622..fc1993564f98 100644
--- a/arch/i386/kernel/vm86.c
+++ b/arch/i386/kernel/vm86.c
@@ -134,17 +134,16 @@ struct pt_regs * fastcall save_v86_state(struct kernel_vm86_regs * regs)
         return ret;
 }
 
-static void mark_screen_rdonly(struct task_struct * tsk)
+static void mark_screen_rdonly(struct mm_struct *mm)
 {
         pgd_t *pgd;
         pud_t *pud;
         pmd_t *pmd;
-        pte_t *pte, *mapped;
+        pte_t *pte;
+        spinlock_t *ptl;
         int i;
 
-        preempt_disable();
-        spin_lock(&tsk->mm->page_table_lock);
-        pgd = pgd_offset(tsk->mm, 0xA0000);
+        pgd = pgd_offset(mm, 0xA0000);
         if (pgd_none_or_clear_bad(pgd))
                 goto out;
         pud = pud_offset(pgd, 0xA0000);
@@ -153,16 +152,14 @@ static void mark_screen_rdonly(struct task_struct * tsk)
         pmd = pmd_offset(pud, 0xA0000);
         if (pmd_none_or_clear_bad(pmd))
                 goto out;
-        pte = mapped = pte_offset_map(pmd, 0xA0000);
+        pte = pte_offset_map_lock(mm, pmd, 0xA0000, &ptl);
         for (i = 0; i < 32; i++) {
                 if (pte_present(*pte))
                         set_pte(pte, pte_wrprotect(*pte));
                 pte++;
         }
-        pte_unmap(mapped);
+        pte_unmap_unlock(pte, ptl);
 out:
-        spin_unlock(&tsk->mm->page_table_lock);
-        preempt_enable();
         flush_tlb();
 }
 
@@ -306,7 +303,7 @@ static void do_sys_vm86(struct kernel_vm86_struct *info, struct task_struct *tsk
 
         tsk->thread.screen_bitmap = info->screen_bitmap;
         if (info->flags & VM86_SCREEN_BITMAP)
-                mark_screen_rdonly(tsk);
+                mark_screen_rdonly(tsk->mm);
         __asm__ __volatile__(
                 "xorl %%eax,%%eax; movl %%eax,%%fs; movl %%eax,%%gs\n\t"
                 "movl %0,%%esp\n\t"