x86: do_page_fault small unification

Copy the prefetch of map_sem from X86_64 and move the check
notify_page_fault (soon to be kprobe_handle_fault) out of
the unlikely if() statement.

This makes the X86_32|64 pagefault handlers closer to each
other.

Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 7 insertions, 9 deletions

diff --git a/arch/x86/mm/fault_32.c b/arch/x86/mm/fault_32.c
index 36cb67e02b04..52c13d2e011e 100644
--- a/arch/x86/mm/fault_32.c
+++ b/arch/x86/mm/fault_32.c
@@ -295,13 +295,18 @@ void __kprobes do_page_fault(struct pt_regs *regs, unsigned long error_code)
          */
         trace_hardirqs_fixup();
 
+        tsk = current;
+        mm = tsk->mm;
+        prefetchw(&mm->mmap_sem);
+
         /* get the address */
         address = read_cr2();
 
-        tsk = current;
-
         si_code = SEGV_MAPERR;
 
+        if (notify_page_fault(regs))
+                return;
+
         /*
          * We fault-in kernel-space virtual memory on-demand. The
          * 'reference' page table is init_mm.pgd.
@@ -319,8 +324,6 @@ void __kprobes do_page_fault(struct pt_regs *regs, unsigned long error_code)
                 if (!(error_code & (PF_RSVD|PF_USER|PF_PROT)) &&
                     vmalloc_fault(address) >= 0)
                         return;
-                if (notify_page_fault(regs))
-                        return;
                 /*
                  * Don't take the mm semaphore here. If we fixup a prefetch
                  * fault we could otherwise deadlock.
@@ -328,16 +331,11 @@ void __kprobes do_page_fault(struct pt_regs *regs, unsigned long error_code)
                 goto bad_area_nosemaphore;
         }
 
-        if (notify_page_fault(regs))
-                return;
-
         /* It's safe to allow irq's after cr2 has been saved and the vmalloc
            fault has been handled. */
         if (regs->flags & (X86_EFLAGS_IF|VM_MASK))
                 local_irq_enable();
 
-        mm = tsk->mm;
-
         /*
          * If we're in an interrupt, have no user context or are running in an
          * atomic region then we must not take the fault.