From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751340AbdH1HFM (ORCPT ); Mon, 28 Aug 2017 03:05:12 -0400 Received: from Galois.linutronix.de ([146.0.238.70]:45714 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750838AbdH1GxR (ORCPT ); Mon, 28 Aug 2017 02:53:17 -0400 Message-Id: <20170828064956.593094539@linutronix.de> User-Agent: quilt/0.63-1 Date: Mon, 28 Aug 2017 08:47:21 +0200 From: Thomas Gleixner To: LKML Cc: Ingo Molnar , Peter Anvin , Peter Zijlstra , Andy Lutomirski , Borislav Petkov , Steven Rostedt Subject: [patch V3 06/44] x86/tracing: Introduce a static key for exception tracing References: <20170828064715.802987421@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Content-Disposition: inline; filename=x86-tracing--Introduce-a-static-key-for-exception-tracing.patch Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Switching the IDT just for avoiding tracepoints creates a complete impenetrable macro/inline/ifdef mess. There is no point in avoiding tracepoints for most of the traps/exceptions. For the more expensive tracepoints, like pagefaults, this can be handled with an explicit static key. Preparatory patch to remove the tracing idt. Signed-off-by: Thomas Gleixner --- arch/x86/include/asm/trace/common.h | 15 +++++++++++++++ arch/x86/include/asm/trace/exceptions.h | 4 +--- arch/x86/include/asm/trace/irq_vectors.h | 4 +--- arch/x86/kernel/tracepoint.c | 9 ++++++++- 4 files changed, 25 insertions(+), 7 deletions(-) --- /dev/null +++ b/arch/x86/include/asm/trace/common.h @@ -0,0 +1,15 @@ +#ifndef _ASM_TRACE_COMMON_H +#define _ASM_TRACE_COMMON_H + +extern int trace_irq_vector_regfunc(void); +extern void trace_irq_vector_unregfunc(void); + +#ifdef CONFIG_TRACING +DECLARE_STATIC_KEY_FALSE(trace_irqvectors_key); +#define trace_irqvectors_enabled() \ + static_branch_unlikely(&trace_irqvectors_key) +#else +static inline bool trace_irqvectors_enabled(void) { return false; } +#endif + +#endif --- a/arch/x86/include/asm/trace/exceptions.h +++ b/arch/x86/include/asm/trace/exceptions.h @@ -5,9 +5,7 @@ #define _TRACE_PAGE_FAULT_H #include - -extern int trace_irq_vector_regfunc(void); -extern void trace_irq_vector_unregfunc(void); +#include DECLARE_EVENT_CLASS(x86_exceptions, --- a/arch/x86/include/asm/trace/irq_vectors.h +++ b/arch/x86/include/asm/trace/irq_vectors.h @@ -5,9 +5,7 @@ #define _TRACE_IRQ_VECTORS_H #include - -extern int trace_irq_vector_regfunc(void); -extern void trace_irq_vector_unregfunc(void); +#include DECLARE_EVENT_CLASS(x86_irq_vector, --- a/arch/x86/kernel/tracepoint.c +++ b/arch/x86/kernel/tracepoint.c @@ -4,9 +4,11 @@ * Copyright (C) 2013 Seiji Aguchi * */ +#include +#include + #include #include -#include atomic_t trace_idt_ctr = ATOMIC_INIT(0); struct desc_ptr trace_idt_descr = { NR_VECTORS * 16 - 1, @@ -15,6 +17,7 @@ struct desc_ptr trace_idt_descr = { NR_V /* No need to be aligned, but done to keep all IDTs defined the same way. */ gate_desc trace_idt_table[NR_VECTORS] __page_aligned_bss; +DEFINE_STATIC_KEY_FALSE(trace_irqvectors_key); static int trace_irq_vector_refcount; static DEFINE_MUTEX(irq_vector_mutex); @@ -36,6 +39,8 @@ static void switch_idt(void *arg) int trace_irq_vector_regfunc(void) { + static_branch_inc(&trace_irqvectors_key); + mutex_lock(&irq_vector_mutex); if (!trace_irq_vector_refcount) { set_trace_idt_ctr(1); @@ -49,6 +54,8 @@ int trace_irq_vector_regfunc(void) void trace_irq_vector_unregfunc(void) { + static_branch_dec(&trace_irqvectors_key); + mutex_lock(&irq_vector_mutex); trace_irq_vector_refcount--; if (!trace_irq_vector_refcount) {