On 08:44 Thu 04 Apr , Masami Hiramatsu wrote:
> (2013/04/03 17:28), oskar.and...@sonymobile.com wrote:
> >
> > +/* 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();
>
> Joonsoo reminds me that these calling points are not protected by
> kprobe_mutex,
> thus we have to do something for avoiding concurrent initialization.
>
> Perhaps, the easiest way is to protect init_kprobe_blacklist() by kprobe_mutex
> and check kprobe_blacklist_initialized again in the top of that.
Yes, you are right. I had a second look at Joonsoo's patch and I will
add a similar mutex for v2.
-Oskar
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