Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756390AbZJALUT (ORCPT ); Thu, 1 Oct 2009 07:20:19 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756379AbZJALUT (ORCPT ); Thu, 1 Oct 2009 07:20:19 -0400 Received: from mx2.mail.elte.hu ([157.181.151.9]:50704 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756370AbZJALUR (ORCPT ); Thu, 1 Oct 2009 07:20:17 -0400 Date: Thu, 1 Oct 2009 13:20:03 +0200 From: Ingo Molnar To: Jason Baron Cc: linux-kernel@vger.kernel.org, mathieu.desnoyers@polymtl.ca, tglx@linutronix.de, rostedt@goodmis.org, ak@suse.de, roland@redhat.com, rth@redhat.com, mhiramat@redhat.com Subject: Re: [PATCH 1/4] jump label - make init_kernel_text() global Message-ID: <20091001112003.GA2962@elte.hu> References: <77d69d0f3c8e1f98a4c2392ea4e4f6c25ed177f4.1253831946.git.jbaron@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <77d69d0f3c8e1f98a4c2392ea4e4f6c25ed177f4.1253831946.git.jbaron@redhat.com> User-Agent: Mutt/1.5.18 (2008-05-17) X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.5 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2749 Lines: 74 * Jason Baron wrote: > allow usage of init_kernel_text - we need this in jump labeling to > avoid attemtpting to patch code that has been freed as in the __init > sections s/attemtpting/attempting > Signed-off-by: Jason Baron > --- > include/linux/kernel.h | 1 + > kernel/extable.c | 2 +- > 2 files changed, 2 insertions(+), 1 deletions(-) > > diff --git a/include/linux/kernel.h b/include/linux/kernel.h > index f61039e..9d3419f 100644 > --- a/include/linux/kernel.h > +++ b/include/linux/kernel.h > @@ -295,6 +295,7 @@ extern int get_option(char **str, int *pint); > extern char *get_options(const char *str, int nints, int *ints); > extern unsigned long long memparse(const char *ptr, char **retptr); > > +extern int init_kernel_text(unsigned long addr); > extern int core_kernel_text(unsigned long addr); > extern int __kernel_text_address(unsigned long addr); > extern int kernel_text_address(unsigned long addr); > diff --git a/kernel/extable.c b/kernel/extable.c > index 7f8f263..f6893ad 100644 > --- a/kernel/extable.c > +++ b/kernel/extable.c > @@ -52,7 +52,7 @@ const struct exception_table_entry *search_exception_tables(unsigned long addr) > return e; > } > > -static inline int init_kernel_text(unsigned long addr) > +int init_kernel_text(unsigned long addr) > { > if (addr >= (unsigned long)_sinittext && > addr <= (unsigned long)_einittext) i'm confused. Later on jump_label_update() does: + if (!(system_state == SYSTEM_RUNNING && + (init_kernel_text(iter->code)))) + jump_label_transform(iter, type); which is: + if (system_state != SYSTEM_RUNNING || + !init_kernel_text(iter->code))) + jump_label_transform(iter, type); What is the logic behind that? System going into SYSTEM_RUNNING does not coincide with free_initmem() precisely. Also, do we ever want to patch init-text tracepoints? I think we want to stay away from them as much as possible. It appears to me that what we want here is a straight: if (kernel_text(iter->code)) jump_label_transform(iter, type); Also, maybe a WARN_ONCE(!kernel_text()) - we should never even attempt to transform non-patchable code. If yes then we want to know about that in a noisy way and not skip it silently. Ingo -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/