powerpc/mm: Move/simplify faulthandler_disabled() and !mm check

Do the check before we re-enable interrupts and clean the code
up a bit.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
index 6f3a243..7928445 100644 (file)
--- a/arch/powerpc/mm/fault.c
+++ b/arch/powerpc/mm/fault.c
@@ -355,24 +355,23 @@ static int __do_page_fault(struct pt_regs *regs, unsigned long address,
        if (unlikely(!is_user && bad_kernel_fault(is_exec, error_code, address)))
                return SIGSEGV;
 
+       /*
+        * If we're in an interrupt, have no user context or are running
+        * in a region with pagefaults disabled then we must not take the fault
+        */
+       if (unlikely(faulthandler_disabled() || !mm)) {
+               if (is_user)
+                       printk_ratelimited(KERN_ERR "Page fault in user mode"
+                                          " with faulthandler_disabled()=%d"
+                                          " mm=%p\n",
+                                          faulthandler_disabled(), mm);
+               return bad_area_nosemaphore(regs, address);
+       }
+
        /* We restore the interrupt state now */
        if (!arch_irq_disabled_regs(regs))
                local_irq_enable();
 
-       if (faulthandler_disabled() || mm == NULL) {
-               if (!is_user)
-                       return SIGSEGV;
-
-               /* faulthandler_disabled() in user mode is really bad,
-                  as is current->mm == NULL. */
-               printk(KERN_EMERG "Page fault in user mode with "
-                      "faulthandler_disabled() = %d mm = %p\n",
-                      faulthandler_disabled(), mm);
-               printk(KERN_EMERG "NIP = %lx  MSR = %lx\n",
-                      regs->nip, regs->msr);
-               die("Weird page fault", regs, SIGSEGV);
-       }
-
        perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
 
        /*