From: wangnan0@huawei•com (Wang Nan)
To: linux-arm-kernel@lists•infradead.org
Subject: [RFC PATCH] kprobes: arm: enable OPTPROBES for arm 32
Date: Fri, 8 Aug 2014 09:25:24 +0800 [thread overview]
Message-ID: <53E42704.3090909@huawei.com> (raw)
In-Reply-To: <53E323D1.8020209@hitachi.com>
On 2014/8/7 14:59, Masami Hiramatsu wrote:
> (2014/08/06 15:24), Wang Nan wrote:
>>>> +
>>>> +static void
>>>> +optimized_callback(struct optimized_kprobe *op, struct pt_regs *regs)
>>>> +{
>>>> + unsigned long flags;
>>>> +
>>>> + regs->ARM_pc = (unsigned long)op->kp.addr;
>>>> + regs->ARM_ORIG_r0 = ~0UL;
>>>> +
>>>> +
>>>> + local_irq_save(flags);
>>>> + /*
>>>> + * This is possible if op is under delayed unoptimizing.
>>>> + * We need simulate the replaced instruction.
>>>> + */
>>>> + if (kprobe_disabled(&op->kp)) {
>>>> + struct kprobe *p = &op->kp;
>>>> + op->kp.ainsn.insn_singlestep(p->opcode, &p->ainsn, regs);
>>>> + } else {
>>>> + kprobe_handler(regs);
>>>> + }
>>>
>>> You don't need brace "{}" for one statement.
>>> By the way, why don't you call opt_pre_handler()?
>>>
>>
>> I use kprobe_handler because it handles instruction emulation.
>>
>> In addition, I'm not very sure whether skipping the complex checks
>> in kprobe_handler() is safe or not.
>
> That seems to do same thing on x86. Then you should do something like
> the optimized_callback() on x86 as below.
>
> static void
> optimized_callback(struct optimized_kprobe *op, struct pt_regs *regs)
> {
> struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
> unsigned long flags;
>
> local_irq_save(flags);
> if (kprobe_running()) {
> kprobes_inc_nmissed_count(&op->kp);
In this case we still need a singlestep, right?
> } else {
> /* Save skipped registers */
> regs->ARM_pc = (unsigned long)op->kp.addr;
> regs->ARM_ORIG_r0 = ~0UL;
>
> __this_cpu_write(current_kprobe, &op->kp);
> kcb->kprobe_status = KPROBE_HIT_ACTIVE;
> opt_pre_handler(&op->kp, regs);
> __this_cpu_write(current_kprobe, NULL);
> op->kp.ainsn.insn_singlestep(op->kp.opcode, &op->kp.ainsn, regs);
> }
> local_irq_restore(flags);
> }
>
> Thank you,
>
next prev parent reply other threads:[~2014-08-08 1:25 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-08-05 7:28 [RFC PATCH] kprobes: arm: enable OPTPROBES for arm 32 Wang Nan
2014-08-06 4:44 ` Masami Hiramatsu
2014-08-06 6:24 ` Wang Nan
2014-08-07 6:59 ` Masami Hiramatsu
2014-08-08 1:25 ` Wang Nan [this message]
2014-08-08 2:07 ` Masami Hiramatsu
2014-08-06 13:36 ` Jon Medhurst (Tixy)
2014-08-06 13:40 ` Wang Nan
2014-08-06 14:23 ` Jon Medhurst (Tixy)
2014-08-06 22:57 ` Russell King - ARM Linux
2014-08-06 22:55 ` Russell King - ARM Linux
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