Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756536AbZCFST7 (ORCPT ); Fri, 6 Mar 2009 13:19:59 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752667AbZCFSTt (ORCPT ); Fri, 6 Mar 2009 13:19:49 -0500 Received: from mx2.mail.elte.hu ([157.181.151.9]:48992 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754282AbZCFSTt (ORCPT ); Fri, 6 Mar 2009 13:19:49 -0500 Date: Fri, 6 Mar 2009 19:18:57 +0100 From: Ingo Molnar To: Mathieu Desnoyers Cc: Masami Hiramatsu , Andrew Morton , Nick Piggin , Steven Rostedt , Andi Kleen , Linux Kernel Mailing List , Thomas Gleixner , Peter Zijlstra , Frederic Weisbecker , Linus Torvalds , Arjan van de Ven , Rusty Russell , "H. Peter Anvin" Subject: Re: [PATCH -tip 4/4] Atomic text_poke() with fixmap Message-ID: <20090306181857.GA26642@elte.hu> References: <49B1428A.9050500@redhat.com> <49B14352.2040705@redhat.com> <20090306181356.GD14236@Krystal> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090306181356.GD14236@Krystal> User-Agent: Mutt/1.5.18 (2008-05-17) X-ELTE-VirusStatus: clean 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=3.2.3 -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: 2737 Lines: 76 * Mathieu Desnoyers wrote: > * Masami Hiramatsu (mhiramat@redhat.com) wrote: > > Use fixmaps instead of vmap/vunmap in text_poke() for avoiding page allocation > > and delayed unmapping. > > > > At the result of above change, text_poke() becomes atomic and can be called > > from stop_machine() etc. > > > > Signed-off-by: Masami Hiramatsu > > Acked-by: Mathieu Desnoyers > > Cc: Ingo Molnar > > --- > > arch/x86/include/asm/fixmap.h | 2 ++ > > arch/x86/kernel/alternative.c | 24 +++++++++++++++--------- > > 2 files changed, 17 insertions(+), 9 deletions(-) > > > > Index: linux-2.6-tip/arch/x86/kernel/alternative.c > > =================================================================== > > --- linux-2.6-tip.orig/arch/x86/kernel/alternative.c > > +++ linux-2.6-tip/arch/x86/kernel/alternative.c > > @@ -13,7 +13,9 @@ > > #include > > #include > > #include > > +#include > > #include > > +#include > > > > #define MAX_PATCH_LEN (255-1) > > > > @@ -505,15 +507,16 @@ void *text_poke_early(void *addr, const > > * It means the size must be writable atomically and the address must be aligned > > * in a way that permits an atomic write. It also makes sure we fit on a single > > * page. > > + * > > + * Note: Must be called under text_mutex. > > */ > > void *__kprobes text_poke(void *addr, const void *opcode, size_t len) > > { > > + unsigned long flags; > > char *vaddr; > > - int nr_pages = 2; > > struct page *pages[2]; > > int i; > > > > - might_sleep(); > > if (!core_kernel_text((unsigned long)addr)) { > > pages[0] = vmalloc_to_page(addr); > > pages[1] = vmalloc_to_page(addr + PAGE_SIZE); > > @@ -523,14 +526,17 @@ void *__kprobes text_poke(void *addr, co > > pages[1] = virt_to_page(addr + PAGE_SIZE); > > } > > BUG_ON(!pages[0]); > > - if (!pages[1]) > > - nr_pages = 1; > > - vaddr = vmap(pages, nr_pages, VM_MAP, PAGE_KERNEL); > > - BUG_ON(!vaddr); > > - local_irq_disable(); > > + set_fixmap(FIX_TEXT_POKE0, page_to_phys(pages[0])); > > Can the set_fixmap/clear_fixmap/local_flush_tlb be called > within local_irq_save ? If yes, that would be better, > especially for the SMP alternatives code, which would rely on > interrupt disabling in text_poke for consistency (the mutex is > not needed there). yes, it is atomic. 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/