Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1765812Ab3DEA4K (ORCPT ); Thu, 4 Apr 2013 20:56:10 -0400 Received: from LGEMRELSE7Q.lge.com ([156.147.1.151]:56052 "EHLO LGEMRELSE7Q.lge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1765795Ab3DEA4I (ORCPT ); Thu, 4 Apr 2013 20:56:08 -0400 X-AuditID: 9c930197-b7b50ae00000018c-6a-515e212373eb Date: Fri, 5 Apr 2013 09:56:28 +0900 From: Joonsoo Kim To: Oskar Andero Cc: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, masami.hiramatsu.pt@hitachi.com, davem@davemloft.net, anil.s.keshavamurthy@intel.com, ananth@in.ibm.com, radovan.lekanovic@sonymobile.com, bjorn.davidsson@sonymobile.com, Toby Collett Subject: Re: [PATCH v2 1/4] kprobes: delay blacklist symbol lookup until we actually need it Message-ID: <20130405005628.GA13624@lge.com> References: <1365079889-21525-1-git-send-email-oskar.andero@sonymobile.com> <1365079889-21525-2-git-send-email-oskar.andero@sonymobile.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1365079889-21525-2-git-send-email-oskar.andero@sonymobile.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-Brightmail-Tracker: AAAAAA== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6100 Lines: 186 Hello, Oskar. On Thu, Apr 04, 2013 at 02:51:26PM +0200, Oskar Andero 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. > > Cc: Masami Hiramatsu > Cc: David S. Miller > Reviewed-by: Radovan Lekanovic > Signed-off-by: Toby Collett > Signed-off-by: Oskar Andero > --- > kernel/kprobes.c | 98 ++++++++++++++++++++++++++++++++++---------------------- > 1 file changed, 60 insertions(+), 38 deletions(-) > > diff --git a/kernel/kprobes.c b/kernel/kprobes.c > index e35be53..0a270e5 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 +103,60 @@ 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; > + > + 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; > + } > + > + 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; You need smp_wmb() before assigning 'kprobe_blacklist_initialized = 1'. This guarantee that who see kprobe_blacklist_initialized = 1 will get updated data of kprobe_blacklist. Please refer my previous patch once more :) And How about define kprobe_blacklist_initialized as boolean? Thanks. > + > +out: > + mutex_unlock(&kprobe_mutex); > +} > + > #ifdef __ARCH_WANT_KPROBES_INSN_SLOT > /* > * kprobe->ainsn.insn points to the copy of the instruction to be > @@ -1331,6 +1386,9 @@ 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 (unlikely(!kprobe_blacklist_initialized)) > + init_kprobe_blacklist(); > /* > * If there exists a kprobe_blacklist, verify and > * fail any probe registration in the prohibited area > @@ -1816,6 +1874,8 @@ int __kprobes register_kretprobe(struct kretprobe *rp) > void *addr; > > if (kretprobe_blacklist_size) { > + if (unlikely(!kprobe_blacklist_initialized)) > + init_kprobe_blacklist(); > addr = kprobe_addr(&rp->kp); > if (IS_ERR(addr)) > return PTR_ERR(addr); > @@ -2065,11 +2125,6 @@ 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 +2134,6 @@ 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 */ > -- > 1.8.1.5 > > -- > 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/ -- 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/