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>

1 files changed, 29 insertions, 31 deletions

diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index b481341c9369..6ff771559af3 100644
--- 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)                              \