From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757654AbYFZFrR (ORCPT ); Thu, 26 Jun 2008 01:47:17 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753389AbYFZFrF (ORCPT ); Thu, 26 Jun 2008 01:47:05 -0400 Received: from ozlabs.org ([203.10.76.45]:36386 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751467AbYFZFrE (ORCPT ); Thu, 26 Jun 2008 01:47:04 -0400 From: Rusty Russell To: Arjan van de Ven Subject: Re: [PATCH] modules: Take a shortcut for checking if an address is in a module Date: Thu, 26 Jun 2008 15:46:58 +1000 User-Agent: KMail/1.9.9 Cc: mingo@elte.hu, linux-kernel@vger.kernel.org References: <20080610130519.21bc66f3@infradead.org> <20080611081847.0b22079c@infradead.org> <200806121020.58881.rusty@rustcorp.com.au> In-Reply-To: <200806121020.58881.rusty@rustcorp.com.au> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200806261546.58919.rusty@rustcorp.com.au> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thursday 12 June 2008 10:20:58 Rusty Russell wrote: > Or, we could actually make those as variables and update them in module.c > itself. No arch changes required, and pretty easy to understand. And since you didn't reply, here's the patch. modules: Take a shortcut for checking if an address is in a module This patch keeps track of the boundaries of module allocation, in order to speed up module_text_address(). Inspired by Arjan's version, which required arch-specific defines: Various pieces of the kernel (lockdep, latencytop, etc) tend to store backtraces, sometimes at a relatively high frequency. In itself this isn't a big performance deal (after all you're using diagnostics features), but there have been some complaints from people who have over 100 modules loaded that this is a tad too slow. This is due to the new backtracer code which looks at every slot on the stack to see if it's a kernel/module text address, so that's 1024 slots. 1024 times 100 modules... that's a lot of list walking. Signed-off-by: Rusty Russell --- kernel/module.c | 24 ++++++++++++++++++++++-- 1 file changed, 22 insertions(+), 2 deletions(-) diff --git a/kernel/module.c b/kernel/module.c --- a/kernel/module.c +++ b/kernel/module.c @@ -69,6 +69,9 @@ static DECLARE_WAIT_QUEUE_HEAD(module_wq static DECLARE_WAIT_QUEUE_HEAD(module_wq); static BLOCKING_NOTIFIER_HEAD(module_notify_list); + +/* Bounds of module allocation, for speeding __module_text_address */ +static unsigned long module_addr_min = -1UL, module_addr_max = 0; int register_module_notifier(struct notifier_block * nb) { @@ -1770,6 +1773,20 @@ static inline void add_kallsyms(struct m } #endif /* CONFIG_KALLSYMS */ +static void *module_alloc_update_bounds(unsigned long size) +{ + void *ret = module_alloc(size); + + if (ret) { + /* Update module bounds. */ + if ((unsigned long)ret < module_addr_min) + module_addr_min = (unsigned long)ret; + if ((unsigned long)ret + size > module_addr_max) + module_addr_max = (unsigned long)ret + size; + } + return ret; +} + /* Allocate and load the module: note that size of section 0 is always zero, and we rely on this for optional sections. */ static struct module *load_module(void __user *umod, @@ -1971,7 +1988,7 @@ static struct module *load_module(void _ layout_sections(mod, hdr, sechdrs, secstrings); /* Do the allocs. */ - ptr = module_alloc(mod->core_size); + ptr = module_alloc_update_bounds(mod->core_size); if (!ptr) { err = -ENOMEM; goto free_percpu; @@ -1979,7 +1996,7 @@ static struct module *load_module(void _ memset(ptr, 0, mod->core_size); mod->module_core = ptr; - ptr = module_alloc(mod->init_size); + ptr = module_alloc_update_bounds(mod->init_size); if (!ptr && mod->init_size) { err = -ENOMEM; goto free_core; @@ -2636,6 +2653,9 @@ struct module *__module_text_address(uns { struct module *mod; + if (addr < module_addr_min || addr > module_addr_max) + return NULL; + list_for_each_entry(mod, &modules, list) if (within(addr, mod->module_init, mod->init_text_size) || within(addr, mod->module_core, mod->core_text_size))