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Date: Tue, 2 Apr 2013 14:16:43 +0200
From: <oskar.andero@...ymobile.com>
To: Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
CC: Joonsoo Kim <iamjoonsoo.kim@....com>,
"Collett, Toby" <Toby.Collett@...ymobile.com>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
Ananth N Mavinakayanahalli <ananth@...ibm.com>,
Anil S Keshavamurthy <anil.s.keshavamurthy@...el.com>,
"David S. Miller" <davem@...emloft.net>
Subject: Re: [PATCH] kprobe: initialize kprobe_blacklist when it is used
firstly
On 12:49 Tue 02 Apr , Masami Hiramatsu wrote:
> 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.
>
I am currently preparing a series of 4 patches including the move of
blacklist initialization (same as Joonsoo's patch) and separation of
architecture specific blackpoints.
The patches are dependent, so I appreciate if you wait a bit.
You can expect the series at latest tomorrow.
-Oskar
> >
> > Cc: Ananth N Mavinakayanahalli <ananth@...ibm.com>
> > Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@...el.com>
> > Cc: "David S. Miller" <davem@...emloft.net>
> > Cc: Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
> > Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@....com>
> > ---
> > 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@...achi.com
>
>
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