[RFC][PATCH 7/7] x86/debug: Move cond_local_irq_enable() block into exc_debug_user()

[Peter Zijlstra]

Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org>
---
 arch/x86/kernel/traps.c |   65 +++++++++++++++++++++++-------------------------
 1 file changed, 32 insertions(+), 33 deletions(-)

--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -783,41 +783,15 @@ static __always_inline unsigned long deb
  *
  * May run on IST stack.
  */
-static void handle_debug(struct pt_regs *regs, unsigned long dr6)
+static bool notify_debug(struct pt_regs *regs, unsigned long dr6)
 {
-       struct task_struct *tsk = current;
-
        /* Store the virtualized DR6 value */
-       tsk->thread.debugreg6 = dr6;
-
-       if (notify_die(DIE_DEBUG, "debug", regs, (long)&dr6, 0,
-                      SIGTRAP) == NOTIFY_STOP) {
-               return;
-       }
-
-       /* It's safe to allow irq's after DR6 has been saved */
-       cond_local_irq_enable(regs);
+       current->thread.debugreg6 = dr6;
 
-       if (v8086_mode(regs)) {
-               handle_vm86_trap((struct kernel_vm86_regs *) regs, 0,
-                                X86_TRAP_DB);
-               goto out;
-       }
-
-       /*
-        * Reload dr6, the notifier might have changed it.
-        */
-       dr6 = tsk->thread.debugreg6;
-       /*
-        * If dr6 has no reason to give us about the origin of this trap,
-        * then it's very likely the result of an icebp/int01 trap.
-        * User wants a sigtrap for that.
-        */
-       if (dr6 & (DR_STEP | DR_TRAP_BITS) || !dr6)
-               send_sigtrap(regs, 0, get_si_code(dr6));
+       if (notify_die(DIE_DEBUG, "debug", regs, (long)&dr6, 0, SIGTRAP) == 
NOTIFY_STOP)
+               return true;
 
-out:
-       cond_local_irq_disable(regs);
+       return false;
 }
 
 static __always_inline void exc_debug_kernel(struct pt_regs *regs,
@@ -872,7 +846,7 @@ static __always_inline void exc_debug_ke
        if (!dr6)
                goto out;
 
-       handle_debug(regs, dr6);
+       notify_debug(regs, dr6);
 
 out:
        instrumentation_end();
@@ -902,8 +876,33 @@ static __always_inline void exc_debug_us
        irqentry_enter_from_user_mode(regs);
        instrumentation_begin();
 
-       handle_debug(regs, dr6);
+       if (notify_debug(regs, dr6))
+               goto out;
+
+       /*
+        * Reload dr6, the notifier might have changed it.
+        */
+       dr6 = current->thread.debugreg6;
+
+       /* It's safe to allow irq's after DR6 has been saved */
+       local_irq_enable();
+
+       if (v8086_mode(regs)) {
+               handle_vm86_trap((struct kernel_vm86_regs *)regs, 0, 
X86_TRAP_DB);
+               goto out_irq;
+       }
 
+       /*
+        * If dr6 has no reason to give us about the origin of this trap,
+        * then it's very likely the result of an icebp/int01 trap.
+        * User wants a sigtrap for that.
+        */
+       if (dr6 & (DR_STEP | DR_TRAP_BITS) || !dr6)
+               send_sigtrap(regs, 0, get_si_code(dr6));
+
+out_irq:
+       local_irq_disable();
+out:
        instrumentation_end();
        irqentry_exit_to_user_mode(regs);
 }