Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933679Ab3CHGsl (ORCPT ); Fri, 8 Mar 2013 01:48:41 -0500 Received: from mail7.hitachi.co.jp ([133.145.228.42]:37343 "EHLO mail7.hitachi.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750988Ab3CHGsk (ORCPT ); Fri, 8 Mar 2013 01:48:40 -0500 Message-ID: <513989C2.7000909@hitachi.com> Date: Fri, 08 Mar 2013 15:48:34 +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: oskar.andero@sonymobile.com Cc: linux-kernel@vger.kernel.org, davem@davemloft.net, anil.s.keshavamurthy@intel.com, ananth@in.ibm.com, radovan.lekanovic@sonymobile.com, Toby Collett Subject: Re: [PATCH] delay blacklist symbol lookup until we actually need it References: <1362660318-30603-1-git-send-email-oskar.andero@sonymobile.com> In-Reply-To: <1362660318-30603-1-git-send-email-oskar.andero@sonymobile.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: 5631 Lines: 174 (2013/03/07 21:45), oskar.andero@sonymobile.com wrote: > From: Toby Collett > > The symbol lookup can take a long time and kprobes is > initialised very early in boot, so delay symbol lookup > until the blacklist is first used. I like this idea, but the implementation may have to be changed if we split blacklist into common/arch as the previous thread. I'd like to see the update series of patches including that changes. Thank you, > > Reviewed-by: Radovan Lekanovic > Signed-off-by: Toby Collett > Signed-off-by: Oskar Andero > --- > kernel/kprobes.c | 91 +++++++++++++++++++++++++++++++---------------------- > 1 files changed, 53 insertions(+), 38 deletions(-) > > diff --git a/kernel/kprobes.c b/kernel/kprobes.c > index e35be53..71a6bee 100644 > --- a/kernel/kprobes.c > +++ b/kernel/kprobes.c > @@ -68,6 +68,7 @@ > #endif > > static int kprobes_initialized; > +static int kprobe_blacklist_initialized; > static struct hlist_head kprobe_table[KPROBE_TABLE_SIZE]; > static struct hlist_head kretprobe_inst_table[KPROBE_TABLE_SIZE]; > > @@ -102,6 +103,53 @@ static struct kprobe_blackpoint kprobe_blacklist[] = { > {NULL} /* Terminator */ > }; > > +/* it can take some time ( > 100ms ) to initialise the > + * blacklist so we delay this until we actually need it > + */ > +static void init_kprobe_blacklist(void) > +{ > + int i; > + unsigned long offset = 0, size = 0; > + char *modname, namebuf[128]; > + const char *symbol_name; > + void *addr; > + struct kprobe_blackpoint *kb; > + > + /* > + * 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++) { > + kprobe_lookup_name(kretprobe_blacklist[i].name, > + kretprobe_blacklist[i].addr); > + if (!kretprobe_blacklist[i].addr) > + printk("kretprobe: lookup failed: %s\n", > + kretprobe_blacklist[i].name); > + } > + } > + kprobe_blacklist_initialized = 1; > +} > + > #ifdef __ARCH_WANT_KPROBES_INSN_SLOT > /* > * kprobe->ainsn.insn points to the copy of the instruction to be > @@ -1331,6 +1379,9 @@ 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 (!kprobe_blacklist_initialized) > + init_kprobe_blacklist(); > /* > * If there exists a kprobe_blacklist, verify and > * fail any probe registration in the prohibited area > @@ -1816,6 +1867,8 @@ int __kprobes register_kretprobe(struct kretprobe *rp) > void *addr; > > if (kretprobe_blacklist_size) { > + if (!kprobe_blacklist_initialized) > + init_kprobe_blacklist(); > addr = kprobe_addr(&rp->kp); > if (IS_ERR(addr)) > return PTR_ERR(addr); > @@ -2065,11 +2118,6 @@ 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 */ > @@ -2079,39 +2127,6 @@ 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++) { > - kprobe_lookup_name(kretprobe_blacklist[i].name, > - kretprobe_blacklist[i].addr); > - if (!kretprobe_blacklist[i].addr) > - printk("kretprobe: lookup failed: %s\n", > - kretprobe_blacklist[i].name); > - } > - } > - > #if defined(CONFIG_OPTPROBES) > #if defined(__ARCH_WANT_KPROBES_INSN_SLOT) > /* Init kprobe_optinsn_slots */ > -- 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/