From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751607AbZBPPcQ (ORCPT ); Mon, 16 Feb 2009 10:32:16 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753703AbZBPPbw (ORCPT ); Mon, 16 Feb 2009 10:31:52 -0500 Received: from mx2.suse.de ([195.135.220.15]:52023 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753534AbZBPPbu (ORCPT ); Mon, 16 Feb 2009 10:31:50 -0500 Date: Mon, 16 Feb 2009 16:31:45 +0100 From: Nick Piggin To: Masami Hiramatsu Cc: Mathieu Desnoyers , Peter Zijlstra , akpm , linux-kernel , Ingo Molnar , Ananth N Mavinakayanahalli , Jim Keniston Subject: Re: irq-disabled vs vmap vs text_poke Message-ID: <20090216153145.GB19182@wotan.suse.de> References: <1234529407.6519.28.camel@twins> <20090213141839.GA31922@Krystal> <4995A0B7.1030705@redhat.com> <20090213165555.GA4684@Krystal> <4995B88C.2090900@redhat.com> <20090213185725.GC7124@Krystal> <4995E925.3080506@redhat.com> <4999808B.5080505@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4999808B.5080505@redhat.com> User-Agent: Mutt/1.5.9i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Feb 16, 2009 at 10:04:43AM -0500, Masami Hiramatsu wrote: > >>>>>BTW, what about using map_vm_area() in text_poke() instead of vmap()? > >>>>>Since text_poke() just maps text pages to alias pages temporarily, > >>>>>I think we don't need to use delayed vunmap(). [...] > Here is the patch which replace v(un)map with (un)map_vm_area. I don't quite understand the point of this... delayed vunmap() is just an implementation detail of vmap subsystem. Callers should not have to care. > Signed-off-by: Masami Hiramatsu > --- > arch/x86/include/asm/alternative.h | 1 + > arch/x86/kernel/alternative.c | 25 ++++++++++++++++++++----- > init/main.c | 3 +++ > 3 files changed, 24 insertions(+), 5 deletions(-) > > Index: linux-2.6/arch/x86/include/asm/alternative.h > =================================================================== > --- linux-2.6.orig/arch/x86/include/asm/alternative.h > +++ linux-2.6/arch/x86/include/asm/alternative.h > @@ -177,6 +177,7 @@ extern void add_nops(void *insns, unsign > * The _early version expects the memory to already be RW. > */ > > +extern void text_poke_init(void); > extern void *text_poke(void *addr, const void *opcode, size_t len); > extern void *text_poke_early(void *addr, const void *opcode, size_t len); > > Index: linux-2.6/arch/x86/kernel/alternative.c > =================================================================== > --- linux-2.6.orig/arch/x86/kernel/alternative.c > +++ linux-2.6/arch/x86/kernel/alternative.c > @@ -485,6 +485,16 @@ void *text_poke_early(void *addr, const > return addr; > } > > +static struct vm_struct *text_poke_area[2]; > +static DEFINE_SPINLOCK(text_poke_lock); > + > +void __init text_poke_init(void) > +{ > + text_poke_area[0] = get_vm_area(PAGE_SIZE, VM_ALLOC); > + text_poke_area[1] = get_vm_area(2 * PAGE_SIZE, VM_ALLOC); > + BUG_ON(!text_poke_area[0] || !text_poke_area[1]); > +} > + > /** > * text_poke - Update instructions on a live kernel > * @addr: address to modify > @@ -501,8 +511,9 @@ void *__kprobes text_poke(void *addr, co > unsigned long flags; > char *vaddr; > int nr_pages = 2; > - struct page *pages[2]; > - int i; > + struct page *pages[2], **pgp = pages; > + int i, ret; > + struct vm_struct *vma; > > if (!core_kernel_text((unsigned long)addr)) { > pages[0] = vmalloc_to_page(addr); > @@ -515,12 +526,16 @@ void *__kprobes text_poke(void *addr, co > BUG_ON(!pages[0]); > if (!pages[1]) > nr_pages = 1; > - vaddr = vmap(pages, nr_pages, VM_MAP, PAGE_KERNEL); > - BUG_ON(!vaddr); > + spin_lock(&text_poke_lock); > + vma = text_poke_area[nr_pages-1]; > + ret = map_vm_area(vma, PAGE_KERNEL, &pgp); > + BUG_ON(ret); > + vaddr = vma->addr; > local_irq_save(flags); > memcpy(&vaddr[(unsigned long)addr & ~PAGE_MASK], opcode, len); > local_irq_restore(flags); > - vunmap(vaddr); > + unmap_kernel_range((unsigned long)vma->addr, (unsigned > long)vma->size); > + spin_unlock(&text_poke_lock); > sync_core(); > /* Could also do a CLFLUSH here to speed up CPU recovery; but > that causes hangs on some VIA CPUs. */ > Index: linux-2.6/init/main.c > =================================================================== > --- linux-2.6.orig/init/main.c > +++ linux-2.6/init/main.c > @@ -676,6 +676,9 @@ asmlinkage void __init start_kernel(void > taskstats_init_early(); > delayacct_init(); > > +#ifdef CONFIG_X86 > + text_poke_init(); > +#endif > check_bugs(); > > acpi_early_init(); /* before LAPIC and SMP init */ > > -- > Masami Hiramatsu > > Software Engineer > Hitachi Computer Products (America) Inc. > Software Solutions Division > > e-mail: mhiramat@redhat.com