Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 2feb1b31 authored by Thomas Gleixner's avatar Thomas Gleixner Committed by Ingo Molnar
Browse files

x86/tracing: Introduce a static key for exception tracing 



Switching the IDT just for avoiding tracepoints creates a completely
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: default avatarThomas 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/20170828064956.593094539@linutronix.de


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent f7eaf6e0

arch/x86/include/asm/trace/common.h

0 → 100644
+15 −0
Original line number Original line Diff line number Diff line 
#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

arch/x86/include/asm/trace/exceptions.h

+1 −3
Original line number Original line Diff line number Diff line
@@ -5,9 +5,7 @@ 
#define _TRACE_PAGE_FAULT_H

#define _TRACE_PAGE_FAULT_H





#include <linux/tracepoint.h>

#include <linux/tracepoint.h>



#include <asm/trace/common.h>

extern int trace_irq_vector_regfunc(void);

extern void trace_irq_vector_unregfunc(void);





DECLARE_EVENT_CLASS(x86_exceptions,

DECLARE_EVENT_CLASS(x86_exceptions,

arch/x86/include/asm/trace/irq_vectors.h

+1 −3
Original line number Original line Diff line number Diff line
@@ -5,9 +5,7 @@ 
#define _TRACE_IRQ_VECTORS_H

#define _TRACE_IRQ_VECTORS_H





#include <linux/tracepoint.h>

#include <linux/tracepoint.h>



#include <asm/trace/common.h>

extern int trace_irq_vector_regfunc(void);

extern void trace_irq_vector_unregfunc(void);





DECLARE_EVENT_CLASS(x86_irq_vector,

DECLARE_EVENT_CLASS(x86_irq_vector,

arch/x86/kernel/tracepoint.c

+8 −1
Original line number Original line Diff line number Diff line
@@ -4,9 +4,11 @@ 
 * Copyright (C) 2013 Seiji Aguchi <seiji.aguchi@hds.com>

 * Copyright (C) 2013 Seiji Aguchi <seiji.aguchi@hds.com>

 *

 *

 */

 */

#include <linux/jump_label.h>

#include <linux/atomic.h>



#include <asm/hw_irq.h>

#include <asm/hw_irq.h>

#include <asm/desc.h>

#include <asm/desc.h>

#include <linux/atomic.h>





atomic_t trace_idt_ctr = ATOMIC_INIT(0);

atomic_t trace_idt_ctr = ATOMIC_INIT(0);

struct desc_ptr trace_idt_descr = { NR_VECTORS * 16 - 1,

struct desc_ptr trace_idt_descr = { NR_VECTORS * 16 - 1,
@@ -15,6 +17,7 @@ struct desc_ptr trace_idt_descr = { NR_VECTORS * 16 - 1, 
/* No need to be aligned, but done to keep all IDTs defined the same way. */

/* 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;

gate_desc trace_idt_table[NR_VECTORS] __page_aligned_bss;





DEFINE_STATIC_KEY_FALSE(trace_irqvectors_key);

static int trace_irq_vector_refcount;

static int trace_irq_vector_refcount;

static DEFINE_MUTEX(irq_vector_mutex);

static DEFINE_MUTEX(irq_vector_mutex);
@@ -36,6 +39,8 @@ static void switch_idt(void *arg) 




int trace_irq_vector_regfunc(void)

int trace_irq_vector_regfunc(void)

{

{

	static_branch_inc(&trace_irqvectors_key);



	mutex_lock(&irq_vector_mutex);

	mutex_lock(&irq_vector_mutex);

	if (!trace_irq_vector_refcount) {

	if (!trace_irq_vector_refcount) {

		set_trace_idt_ctr(1);

		set_trace_idt_ctr(1);
@@ -49,6 +54,8 @@ int trace_irq_vector_regfunc(void) 




void trace_irq_vector_unregfunc(void)

void trace_irq_vector_unregfunc(void)

{

{

	static_branch_dec(&trace_irqvectors_key);



	mutex_lock(&irq_vector_mutex);

	mutex_lock(&irq_vector_mutex);

	trace_irq_vector_refcount--;

	trace_irq_vector_refcount--;

	if (!trace_irq_vector_refcount) {

	if (!trace_irq_vector_refcount) {