3 files changed, 33 insertions, 84 deletions

diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c
index a94d75fef598..a917e3dd3666 100644
--- a/arch/arm/kernel/signal.c
+++ b/arch/arm/kernel/signal.c
@@ -139,93 +139,33 @@ struct iwmmxt_sigframe {
         unsigned long   storage[0x98/4];
 };
 
-static int page_present(struct mm_struct *mm, void __user *uptr, int wr)
-{
-        unsigned long addr = (unsigned long)uptr;
-        pgd_t *pgd = pgd_offset(mm, addr);
-        if (pgd_present(*pgd)) {
-                pmd_t *pmd = pmd_offset(pgd, addr);
-                if (pmd_present(*pmd)) {
-                        pte_t *pte = pte_offset_map(pmd, addr);
-                        return (pte_present(*pte) && (!wr || pte_write(*pte)));
-                }
-        }
-        return 0;
-}
-
-static int copy_locked(void __user *uptr, void *kptr, size_t size, int write,
-                       void (*copyfn)(void *, void __user *))
-{
-        unsigned char v, __user *userptr = uptr;
-        int err = 0;
-
-        do {
-                struct mm_struct *mm;
-
-                if (write) {
-                        __put_user_error(0, userptr, err);
-                        __put_user_error(0, userptr + size - 1, err);
-                } else {
-                        __get_user_error(v, userptr, err);
-                        __get_user_error(v, userptr + size - 1, err);
-                }
-
-                if (err)
-                        break;
-
-                mm = current->mm;
-                spin_lock(&mm->page_table_lock);
-                if (page_present(mm, userptr, write) &&
-                    page_present(mm, userptr + size - 1, write)) {
-                        copyfn(kptr, uptr);
-                } else
-                        err = 1;
-                spin_unlock(&mm->page_table_lock);
-        } while (err);
-
-        return err;
-}
-
 static int preserve_iwmmxt_context(struct iwmmxt_sigframe *frame)
 {
-        int err = 0;
+        char kbuf[sizeof(*frame) + 8];
+        struct iwmmxt_sigframe *kframe;
 
         /* the iWMMXt context must be 64 bit aligned */
-        WARN_ON((unsigned long)frame & 7);
-
-        __put_user_error(IWMMXT_MAGIC0, &frame->magic0, err);
-        __put_user_error(IWMMXT_MAGIC1, &frame->magic1, err);
-
-        /*
-         * iwmmxt_task_copy() doesn't check user permissions.
-         * Let's do a dummy write on the upper boundary to ensure
-         * access to user mem is OK all way up.
-         */
-        err |= copy_locked(&frame->storage, current_thread_info(),
-                           sizeof(frame->storage), 1, iwmmxt_task_copy);
-        return err;
+        kframe = (struct iwmmxt_sigframe *)((unsigned long)(kbuf + 8) & ~7);
+        kframe->magic0 = IWMMXT_MAGIC0;
+        kframe->magic1 = IWMMXT_MAGIC1;
+        iwmmxt_task_copy(current_thread_info(), &kframe->storage);
+        return __copy_to_user(frame, kframe, sizeof(*frame));
 }
 
 static int restore_iwmmxt_context(struct iwmmxt_sigframe *frame)
 {
-        unsigned long magic0, magic1;
-        int err = 0;
+        char kbuf[sizeof(*frame) + 8];
+        struct iwmmxt_sigframe *kframe;
 
-        /* the iWMMXt context is 64 bit aligned */
-        WARN_ON((unsigned long)frame & 7);
-
-        /*
-         * Validate iWMMXt context signature.
-         * Also, iwmmxt_task_restore() doesn't check user permissions.
-         * Let's do a dummy write on the upper boundary to ensure
-         * access to user mem is OK all way up.
-         */
-        __get_user_error(magic0, &frame->magic0, err);
-        __get_user_error(magic1, &frame->magic1, err);
-        if (!err && magic0 == IWMMXT_MAGIC0 && magic1 == IWMMXT_MAGIC1)
-                err = copy_locked(&frame->storage, current_thread_info(),
-                                  sizeof(frame->storage), 0, iwmmxt_task_restore);
-        return err;
+        /* the iWMMXt context must be 64 bit aligned */
+        kframe = (struct iwmmxt_sigframe *)((unsigned long)(kbuf + 8) & ~7);
+        if (__copy_from_user(kframe, frame, sizeof(*frame)))
+                return -1;
+        if (kframe->magic0 != IWMMXT_MAGIC0 ||
+            kframe->magic1 != IWMMXT_MAGIC1)
+                return -1;
+        iwmmxt_task_restore(current_thread_info(), &kframe->storage);
+        return 0;
 }
 
 #endif
diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c
index baa09601a64e..66e5a0516f23 100644
--- a/arch/arm/kernel/traps.c
+++ b/arch/arm/kernel/traps.c
@@ -483,29 +483,33 @@ asmlinkage int arm_syscall(int no, struct pt_regs *regs)
                 unsigned long addr = regs->ARM_r2;
                 struct mm_struct *mm = current->mm;
                 pgd_t *pgd; pmd_t *pmd; pte_t *pte;
+                spinlock_t *ptl;
 
                 regs->ARM_cpsr &= ~PSR_C_BIT;
-                spin_lock(&mm->page_table_lock);
+                down_read(&mm->mmap_sem);
                 pgd = pgd_offset(mm, addr);
                 if (!pgd_present(*pgd))
                         goto bad_access;
                 pmd = pmd_offset(pgd, addr);
                 if (!pmd_present(*pmd))
                         goto bad_access;
-                pte = pte_offset_map(pmd, addr);
-                if (!pte_present(*pte) || !pte_write(*pte))
+                pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
+                if (!pte_present(*pte) || !pte_write(*pte)) {
+                        pte_unmap_unlock(pte, ptl);
                         goto bad_access;
+                }
                 val = *(unsigned long *)addr;
                 val -= regs->ARM_r0;
                 if (val == 0) {
                         *(unsigned long *)addr = regs->ARM_r1;
                         regs->ARM_cpsr |= PSR_C_BIT;
                 }
-                spin_unlock(&mm->page_table_lock);
+                pte_unmap_unlock(pte, ptl);
+                up_read(&mm->mmap_sem);
                 return val;
 
                 bad_access:
-                spin_unlock(&mm->page_table_lock);
+                up_read(&mm->mmap_sem);
                 /* simulate a write access fault */
                 do_DataAbort(addr, 15 + (1 << 11), regs);
                 return -1;
diff --git a/arch/arm/mm/fault-armv.c b/arch/arm/mm/fault-armv.c
index be4ab3d73c91..7fc1b35a6746 100644
--- a/arch/arm/mm/fault-armv.c
+++ b/arch/arm/mm/fault-armv.c
@@ -26,6 +26,11 @@ static unsigned long shared_pte_mask = L_PTE_CACHEABLE;
 /*
  * We take the easy way out of this problem - we make the
  * PTE uncacheable.  However, we leave the write buffer on.
+ *
+ * Note that the pte lock held when calling update_mmu_cache must also
+ * guard the pte (somewhere else in the same mm) that we modify here.
+ * Therefore those configurations which might call adjust_pte (those
+ * without CONFIG_CPU_CACHE_VIPT) cannot support split page_table_lock.
  */
 static int adjust_pte(struct vm_area_struct *vma, unsigned long address)
 {
@@ -127,7 +132,7 @@ void __flush_dcache_page(struct address_space *mapping, struct page *page);
  *  2. If we have multiple shared mappings of the same space in
  *     an object, we need to deal with the cache aliasing issues.
  *
- * Note that the page_table_lock will be held.
+ * Note that the pte lock will be held.
  */
 void update_mmu_cache(struct vm_area_struct *vma, unsigned long addr, pte_t pte)
 {