linux-kernel - Re: [PATCH] trace: add the MMIO-tracer to the tracer menu

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Date:	Fri, 24 Oct 2008 20:08:11 +0300
From:	Pekka Paalanen <pq@....fi>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	Steven Rostedt <rostedt@...dmis.org>,
	Peter Zijlstra <peterz@...radead.org>,
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] trace: add the MMIO-tracer to the tracer menu

On Fri, 24 Oct 2008 07:56:05 -0400 (EDT)
Steven Rostedt <rostedt@...dmis.org> wrote:

> 
> On Fri, 24 Oct 2008, Ingo Molnar wrote:
> > >  #
> > >  # IO delay types:
> > > Index: linux-2.6/kernel/trace/Kconfig
> > > ===================================================================
> > > --- linux-2.6.orig/kernel/trace/Kconfig
> > > +++ linux-2.6/kernel/trace/Kconfig
> > > @@ -194,4 +194,32 @@ config FTRACE_STARTUP_TEST
> > >  	  functioning properly. It will do tests on all the configured
> > >  	  tracers of ftrace.
> > >  
> > > +config MMIOTRACE_HOOKS
> > > +	bool
> > > +
> > > +config MMIOTRACE
> > > +	bool "Memory mapped IO tracing"
> > > +	depends on HAVE_MMIOTRACE_SUPPORT && DEBUG_KERNEL && PCI
> > > +	select TRACING
> > > +	select MMIOTRACE_HOOKS
> > 
> > change makes sense, but isnt MMIOTRACE_HOOKS basically overlapping 
> > HAVE_MMIOTRACE_SUPPORT? So i think we could get rid of MMIOTRACE_HOOKS 
> > altogether and just use HAVE_MMIOTRACE_SUPPORT.
> 
> And doing this will remove the need about my question on depends on X86.

Yes, we can remove MMIOTRACE_HOOKS and replace it with just MMIOTRACE.
MMIOTRACE_HOOKS is a remnant from the time when I thought that
something else could also use the kmmio facilities.

Here's a compile-tested patch against current Ingo's tip/master.

>From d4b97cd777c3382b784a9504281feccc9f2c4036 Mon Sep 17 00:00:00 2001
From: Pekka Paalanen <pq@....fi>
Date: Fri, 24 Oct 2008 18:59:56 +0300
Subject: [PATCH] mmiotrace: Remove unneeded CONFIG_MMIOTRACE_HOOKS.

Signed-off-by: Pekka Paalanen <pq@....fi>
---
 arch/x86/Kconfig.debug |    4 ----
 arch/x86/mm/Makefile   |    3 +--
 arch/x86/mm/fault.c    |    2 +-
 3 files changed, 2 insertions(+), 7 deletions(-)

diff --git a/arch/x86/Kconfig.debug b/arch/x86/Kconfig.debug
index fc58b86..01649e1 100644
--- a/arch/x86/Kconfig.debug
+++ b/arch/x86/Kconfig.debug
@@ -175,14 +175,10 @@ config IOMMU_LEAK
 	  Add a simple leak tracer to the IOMMU code. This is useful when you
 	  are debugging a buggy device driver that leaks IOMMU mappings.
 
-config MMIOTRACE_HOOKS
-	bool
-
 config MMIOTRACE
 	bool "Memory mapped IO tracing"
 	depends on DEBUG_KERNEL && PCI
 	select TRACING
-	select MMIOTRACE_HOOKS
 	help
 	  Mmiotrace traces Memory Mapped I/O access and is meant for
 	  debugging and reverse engineering. It is called from the ioremap
diff --git a/arch/x86/mm/Makefile b/arch/x86/mm/Makefile
index f4edb6e..617537f 100644
--- a/arch/x86/mm/Makefile
+++ b/arch/x86/mm/Makefile
@@ -10,9 +10,8 @@ obj-$(CONFIG_HIGHMEM)		+= highmem_32.o
 
 obj-$(CONFIG_KMEMCHECK)		+= kmemcheck/
 
-obj-$(CONFIG_MMIOTRACE_HOOKS)	+= kmmio.o
 obj-$(CONFIG_MMIOTRACE)		+= mmiotrace.o
-mmiotrace-y			:= pf_in.o mmio-mod.o
+mmiotrace-y			:= kmmio.o pf_in.o mmio-mod.o
 obj-$(CONFIG_MMIOTRACE_TEST)	+= testmmiotrace.o
 
 obj-$(CONFIG_NUMA)		+= numa_$(BITS).o
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index ed9ee30..63e9f7c 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -55,7 +55,7 @@
 
 static inline int kmmio_fault(struct pt_regs *regs, unsigned long addr)
 {
-#ifdef CONFIG_MMIOTRACE_HOOKS
+#ifdef CONFIG_MMIOTRACE
 	if (unlikely(is_kmmio_active()))
 		if (kmmio_handler(regs, addr) == 1)
 			return -1;
-- 
1.5.6.4


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