Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761547Ab3DBKts (ORCPT ); Tue, 2 Apr 2013 06:49:48 -0400 Received: from mail7.hitachi.co.jp ([133.145.228.42]:39889 "EHLO mail7.hitachi.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1761120Ab3DBKtq (ORCPT ); Tue, 2 Apr 2013 06:49:46 -0400 Message-ID: <515AB7C6.2030807@hitachi.com> Date: Tue, 02 Apr 2013 19:49:42 +0900 From: Masami Hiramatsu Organization: Hitachi, Ltd., Japan User-Agent: Mozilla/5.0 (Windows NT 5.2; rv:13.0) Gecko/20120614 Thunderbird/13.0.1 MIME-Version: 1.0 To: Joonsoo Kim , oskar.andero@sonymobile.com, toby.collett@sonymobile.com Cc: linux-kernel@vger.kernel.org, Ananth N Mavinakayanahalli , Anil S Keshavamurthy , "David S. Miller" Subject: Re: [PATCH] kprobe: initialize kprobe_blacklist when it is used firstly References: <1364799356-15768-1-git-send-email-iamjoonsoo.kim@lge.com> In-Reply-To: <1364799356-15768-1-git-send-email-iamjoonsoo.kim@lge.com> Content-Type: text/plain; charset=ISO-2022-JP Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5061 Lines: 162 Hi, (2013/04/01 15:55), Joonsoo Kim wrote: > Currently, initializing kprobe_blacklist is done during boot process. > It takes 230 ms on our android platform and this is significant amount > for our use case. We can disable CONFIG_KPROBES for production kernel, > but it is hassle. This kprobe functionality is not commonly used, > so we don't need to pay this cost at all times. With this rationale, > change code to initialize kprobe_blacklist when it is used firstly. I saw similar patch from Oskar and Toby, and I decided to wait until his blacklist separating work. I'd like to ask Oskar how the patch is going first. Thank you, > > Cc: Ananth N Mavinakayanahalli > Cc: Anil S Keshavamurthy > Cc: "David S. Miller" > Cc: Masami Hiramatsu > Signed-off-by: Joonsoo Kim > --- > I fotgot to add lkml. > Sorry for noise. > > diff --git a/kernel/kprobes.c b/kernel/kprobes.c > index e35be53..5e90092 100644 > --- a/kernel/kprobes.c > +++ b/kernel/kprobes.c > @@ -101,6 +101,7 @@ static struct kprobe_blackpoint kprobe_blacklist[] = { > {"mcount",}, /* mcount can be called from everywhere */ > {NULL} /* Terminator */ > }; > +static bool kprobe_blacklist_initialized; > > #ifdef __ARCH_WANT_KPROBES_INSN_SLOT > /* > @@ -1324,6 +1325,49 @@ out: > return ret; > } > > +static void __kprobes init_kprobe_blacklist(void) > +{ > + unsigned long offset = 0, size = 0; > + char *modname, namebuf[128]; > + const char *symbol_name; > + void *addr; > + struct kprobe_blackpoint *kb; > + > + mutex_lock(&kprobe_mutex); > + if (kprobe_blacklist_initialized) > + goto out; > + > + /* > + * Lookup and populate the kprobe_blacklist. > + * > + * Unlike the kretprobe blacklist, we'll need to determine > + * the range of addresses that belong to the said functions, > + * since a kprobe need not necessarily be at the beginning > + * of a function. > + */ > + for (kb = kprobe_blacklist; kb->name != NULL; kb++) { > + kprobe_lookup_name(kb->name, addr); > + if (!addr) > + continue; > + > + kb->start_addr = (unsigned long)addr; > + symbol_name = kallsyms_lookup(kb->start_addr, > + &size, &offset, &modname, namebuf); > + if (!symbol_name) > + kb->range = 0; > + else > + kb->range = size; > + } > + > + /* This guarantee that who see initilized will > + * get a updated data of kprobe_blacklist */ > + smp_wmb(); > + kprobe_blacklist_initialized = true; > + > +out: > + mutex_unlock(&kprobe_mutex); > +} > + > static int __kprobes in_kprobes_functions(unsigned long addr) > { > struct kprobe_blackpoint *kb; > @@ -1331,6 +1375,7 @@ static int __kprobes in_kprobes_functions(unsigned long addr) > if (addr >= (unsigned long)__kprobes_text_start && > addr < (unsigned long)__kprobes_text_end) > return -EINVAL; > + > /* > * If there exists a kprobe_blacklist, verify and > * fail any probe registration in the prohibited area > @@ -1476,6 +1521,9 @@ int __kprobes register_kprobe(struct kprobe *p) > struct module *probed_mod; > kprobe_opcode_t *addr; > > + if (unlikely(!kprobe_blacklist_initialized)) > + init_kprobe_blacklist(); > + > /* Adjust probe address from symbol */ > addr = kprobe_addr(p); > if (IS_ERR(addr)) > @@ -2065,11 +2113,6 @@ static struct notifier_block kprobe_module_nb = { > static int __init init_kprobes(void) > { > int i, err = 0; > - unsigned long offset = 0, size = 0; > - char *modname, namebuf[128]; > - const char *symbol_name; > - void *addr; > - struct kprobe_blackpoint *kb; > > /* FIXME allocate the probe table, currently defined statically */ > /* initialize all list heads */ > @@ -2079,28 +2122,6 @@ static int __init init_kprobes(void) > raw_spin_lock_init(&(kretprobe_table_locks[i].lock)); > } > > - /* > - * Lookup and populate the kprobe_blacklist. > - * > - * Unlike the kretprobe blacklist, we'll need to determine > - * the range of addresses that belong to the said functions, > - * since a kprobe need not necessarily be at the beginning > - * of a function. > - */ > - for (kb = kprobe_blacklist; kb->name != NULL; kb++) { > - kprobe_lookup_name(kb->name, addr); > - if (!addr) > - continue; > - > - kb->start_addr = (unsigned long)addr; > - symbol_name = kallsyms_lookup(kb->start_addr, > - &size, &offset, &modname, namebuf); > - if (!symbol_name) > - kb->range = 0; > - else > - kb->range = size; > - } > - > if (kretprobe_blacklist_size) { > /* lookup the function address from its name */ > for (i = 0; kretprobe_blacklist[i].name != NULL; i++) { > -- Masami HIRAMATSU IT Management Research Dept. Linux Technology Center Hitachi, Ltd., Yokohama Research Laboratory E-mail: masami.hiramatsu.pt@hitachi.com -- 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/