x86/irqwork: Get rid of duplicated tracing interrupt code

Two NOP5s are a reasonable tradeoff to avoid duplicated code and the
requirement to switch the IDT.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/20170828064957.064746737@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/include/asm/hw_irq.h

@@ -48,13 +48,13 @@ extern asmlinkage void call_function_single_interrupt(void);
 
 #ifdef CONFIG_TRACING
 /* Interrupt handlers registered during init_IRQ */
-extern void trace_irq_work_interrupt(void);
 extern void trace_thermal_interrupt(void);
 extern void trace_reschedule_interrupt(void);
 extern void trace_threshold_interrupt(void);
 extern void trace_deferred_error_interrupt(void);
 extern void trace_call_function_interrupt(void);
 extern void trace_call_function_single_interrupt(void);
+#define trace_irq_work_interrupt irq_work_interrupt
 #define trace_error_interrupt error_interrupt
 #define trace_spurious_interrupt spurious_interrupt
 #define trace_x86_platform_ipi	x86_platform_ipi

arch/x86/kernel/irq_work.c

@@ -11,24 +11,12 @@
 #include <asm/trace/irq_vectors.h>
 #include <linux/interrupt.h>
 
-static inline void __smp_irq_work_interrupt(void)
-{
-	inc_irq_stat(apic_irq_work_irqs);
-	irq_work_run();
-}
-
 __visible void __irq_entry smp_irq_work_interrupt(struct pt_regs *regs)
-{
-	ipi_entering_ack_irq();
-	__smp_irq_work_interrupt();
-	exiting_irq();
-}
-
-__visible void __irq_entry smp_trace_irq_work_interrupt(struct pt_regs *regs)
 {
 	ipi_entering_ack_irq();
 	trace_irq_work_entry(IRQ_WORK_VECTOR);
-	__smp_irq_work_interrupt();
+	inc_irq_stat(apic_irq_work_irqs);
+	irq_work_run();
 	trace_irq_work_exit(IRQ_WORK_VECTOR);
 	exiting_irq();
 }