Messages in this thread | | | Subject | Re: [PATCH -mm] kprobes: kprobe-booster for ia64 | From | Shaohua Li <> | Date | Mon, 10 Mar 2008 11:43:20 +0800 |
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On Sat, 2008-03-08 at 00:01 +0800, Masami Hiramatsu wrote: > From: Masami Hiramatsu <mhiramat@redhat.com> >
> + > +/* > + * In this function, we check whether the target bundle modifies IP > or > + * it triggers an exception. If so, it cannot be boostable. > + */ > +static int __kprobes can_boost(bundle_t *bundle, uint slot, > + unsigned long bundle_addr) > +{ > + unsigned int template = bundle->quad0.template; > + > + do { > + if (search_exception_tables(bundle_addr + slot) || > + __is_ia64_break_inst(bundle, slot)) > + return 0; /* exception may occur in this > bundle*/ > + } while ((++slot) < 3); > + template &= 0x1e; > + if (template >= 0x10 /* including B unit */ || > + template == 0x04 /* including X unit */ || > + template == 0x06) /* undefined */ > + return 0; > + > + return 1; > +} > + > +/* Prepare long jump bundle and disables other boosters if need */ > +static void __kprobes prepare_booster(struct kprobe *p) > +{ > + unsigned long addr = (unsigned long)p->addr & ~0xFULL; > + unsigned int slot = addr & 0xf; slot = (unsigned long)p->addr & 0xf ?
> + struct kprobe *other_kp; > + > + if (can_boost(&p->ainsn.insn[0].bundle, slot, addr)) { > + set_brl_inst(&p->ainsn.insn[1].bundle, (bundle_t > *)addr + 1); > + p->ainsn.inst_flag |= INST_FLAG_BOOSTABLE; > + } > + > + /* disables boosters in previous slots */ > + for (; addr < (unsigned long)p->addr; addr++) { > + other_kp = get_kprobe((void *)addr); > + if (other_kp) > + other_kp->ainsn.inst_flag &= > ~INST_FLAG_BOOSTABLE; > + } > +} > + There is no lock to protect the flag. If one cpu invokes other_kp and the other cpu is changing the flag, what's the result?
Thanks, Shaohua
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