x86: Unspaghettize do_trap()

Cleanup the label maze in this function. Having a
seperate function to first handle the traps that don't
generate a signal makes it easier to convert into
more readable conditional paths.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1348577479-2564-1-git-send-email-fweisbec@gmail.com
[ Fixed 32-bit build failure. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index b481341..6ff7715 100644 (file)
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -107,30 +107,45 @@ static inline void preempt_conditional_cli(struct pt_regs *regs)
        dec_preempt_count();
 }
 
-static void __kprobes
-do_trap(int trapnr, int signr, char *str, struct pt_regs *regs,
-       long error_code, siginfo_t *info)
+static int __kprobes
+do_trap_no_signal(struct task_struct *tsk, int trapnr, char *str,
+                 struct pt_regs *regs, long error_code)
 {
-       struct task_struct *tsk = current;
-
 #ifdef CONFIG_X86_32
        if (regs->flags & X86_VM_MASK) {
                /*
-                * traps 0, 1, 3, 4, and 5 should be forwarded to vm86.
+                * Traps 0, 1, 3, 4, and 5 should be forwarded to vm86.
                 * On nmi (interrupt 2), do_trap should not be called.
                 */
-               if (trapnr < X86_TRAP_UD)
-                       goto vm86_trap;
-               goto trap_signal;
+               if (trapnr < X86_TRAP_UD) {
+                       if (!handle_vm86_trap((struct kernel_vm86_regs *) regs,
+                                               error_code, trapnr))
+                               return 0;
+               }
+               return -1;
        }
 #endif
+       if (!user_mode(regs)) {
+               if (!fixup_exception(regs)) {
+                       tsk->thread.error_code = error_code;
+                       tsk->thread.trap_nr = trapnr;
+                       die(str, regs, error_code);
+               }
+               return 0;
+       }
 
-       if (!user_mode(regs))
-               goto kernel_trap;
+       return -1;
+}
 
-#ifdef CONFIG_X86_32
-trap_signal:
-#endif
+static void __kprobes
+do_trap(int trapnr, int signr, char *str, struct pt_regs *regs,
+       long error_code, siginfo_t *info)
+{
+       struct task_struct *tsk = current;
+
+
+       if (!do_trap_no_signal(tsk, trapnr, str, regs, error_code))
+               return;
        /*
         * We want error_code and trap_nr set for userspace faults and
         * kernelspace faults which result in die(), but not
@@ -158,23 +173,6 @@ trap_signal:
                force_sig_info(signr, info, tsk);
        else
                force_sig(signr, tsk);
-       return;
-
-kernel_trap:
-       if (!fixup_exception(regs)) {
-               tsk->thread.error_code = error_code;
-               tsk->thread.trap_nr = trapnr;
-               die(str, regs, error_code);
-       }
-       return;
-
-#ifdef CONFIG_X86_32
-vm86_trap:
-       if (handle_vm86_trap((struct kernel_vm86_regs *) regs,
-                                               error_code, trapnr))
-               goto trap_signal;
-       return;
-#endif
 }
 
 #define DO_ERROR(trapnr, signr, str, name)                             \