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 <ana...@in.ibm.com>
> Cc: Anil S Keshavamurthy <anil.s.keshavamur...@intel.com>
> Cc: "David S. Miller" <da...@davemloft.net>
> Cc: Masami Hiramatsu <masami.hiramatsu...@hitachi.com>
> Signed-off-by: Joonsoo Kim <iamjoonsoo....@lge.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...@hitachi.com
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