ARC: mm: do_page_fault refactor #3: tidyup vma access permission code

The coding pattern to NOT intialize variables at declaration time but
rather near code which makes us eof them makes it much easier to grok
the overall logic, specially when the init is not simply 0 or 1

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

diff --git a/arch/arc/mm/fault.c b/arch/arc/mm/fault.c
index a3a292c58e50be7482ddea1ff5a796e6c0930c53..8c7c81ce7f6a873d0d283b41d19c24c0c293af17 100644 (file)
--- a/arch/arc/mm/fault.c
+++ b/arch/arc/mm/fault.c
@@ -64,9 +64,9 @@ void do_page_fault(unsigned long address, struct pt_regs *regs)
        struct task_struct *tsk = current;
        struct mm_struct *mm = tsk->mm;
        int si_code = SEGV_MAPERR;
+       unsigned int write = 0, exec = 0, mask;
        vm_fault_t fault;
-       int write = regs->ecr_cause & ECR_C_PROTV_STORE;  /* ST/EX */
-       unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
+       unsigned int flags;
 
        /*
         * NOTE! We MUST NOT take any locks for this case. We may
@@ -88,8 +88,18 @@ void do_page_fault(unsigned long address, struct pt_regs *regs)
        if (faulthandler_disabled() || !mm)
                goto no_context;
 
+       if (regs->ecr_cause & ECR_C_PROTV_STORE)        /* ST/EX */
+               write = 1;
+       else if ((regs->ecr_vec == ECR_V_PROTV) &&
+                (regs->ecr_cause == ECR_C_PROTV_INST_FETCH))
+               exec = 1;
+
+       flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
        if (user_mode(regs))
                flags |= FAULT_FLAG_USER;
+       if (write)
+               flags |= FAULT_FLAG_WRITE;
+
 retry:
        down_read(&mm->mmap_sem);
 
@@ -102,24 +112,17 @@ retry:
        }
 
        /*
-        * Ok, we have a good vm_area for this memory access, so
-        * we can handle it..
+        * vm_area is good, now check permissions for this memory access
         */
-       si_code = SEGV_ACCERR;
-
-       /* Handle protection violation, execute on heap or stack */
-
-       if ((regs->ecr_vec == ECR_V_PROTV) &&
-           (regs->ecr_cause == ECR_C_PROTV_INST_FETCH))
+       mask = VM_READ;
+       if (write)
+               mask = VM_WRITE;
+       if (exec)
+               mask = VM_EXEC;
+
+       if (!(vma->vm_flags & mask)) {
+               si_code = SEGV_ACCERR;
                goto bad_area;
-
-       if (write) {
-               if (!(vma->vm_flags & VM_WRITE))
-                       goto bad_area;
-               flags |= FAULT_FLAG_WRITE;
-       } else {
-               if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
-                       goto bad_area;
        }
 
        /*