From mboxrd@z Thu Jan  1 00:00:00 1970
From: dave.long@linaro.org (David Long)
Date: Mon, 21 Mar 2016 09:33:51 -0400
Subject: [PATCH v11 8/9] arm64: Add kernel return probes support
 (kretprobes)
In-Reply-To: <50399556C9727B4D88A595C8584AAB37B4E504AA@GSjpTKYDCembx32.service.hitachi.net>
References: <1457501543-24197-1-git-send-email-dave.long@linaro.org>
 <1457501543-24197-9-git-send-email-dave.long@linaro.org>
 <50399556C9727B4D88A595C8584AAB37B4E50431@GSjpTKYDCembx32.service.hitachi.net>
 <50399556C9727B4D88A595C8584AAB37B4E504AA@GSjpTKYDCembx32.service.hitachi.net>
Message-ID: <56EFF83F.7040906@linaro.org>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

On 03/17/2016 08:58 AM, ???? / HIRAMATU?MASAMI wrote:
>> From: ???? / HIRAMATU?MASAMI [mailto:masami.hiramatsu.pt at hitachi.com]
>>
>> Hi,
>>
>>> From: Sandeepa Prabhu <sandeepa.s.prabhu@gmail.com>
>>>
>>> The pre-handler of this special 'trampoline' kprobe executes the return
>>> probe handler functions and restores original return address in ELR_EL1.
>>> This way the saved pt_regs still hold the original register context to be
>>> carried back to the probed kernel function.
>>
>> This patch seems not well separated.
>>
>>> diff --git a/arch/arm64/kernel/kprobes.c b/arch/arm64/kernel/kprobes.c
>>> index bd3f233..13d3333 100644
>>> --- a/arch/arm64/kernel/kprobes.c
>>> +++ b/arch/arm64/kernel/kprobes.c
>>
>> [snip]
>>
>>> +void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
>>> +				      struct pt_regs *regs)
>>> +{
>>> +	ri->ret_addr = (kprobe_opcode_t *)regs->regs[30];
>>> +
>>> +	/* replace return addr (x30) with trampoline */
>>> +	regs->regs[30] = (long)&kretprobe_trampoline;
>>
>> So, where is the kretprobe_trampoline? It seems that function is
>> defined in other patch.
>>
>>> +}
>>> +
>>> +int __kprobes arch_trampoline_kprobe(struct kprobe *p)
>>> +{
>>> +	return 0;
>>> }
>>
>> And what this function is for??
>
> Ah, sorry, this was my fault. Yes, this function is required.
> But this implementation also means there is an asm-based trampoline
> function which should be included in this patch.
>
> David, could you tell me the repository which I can get the latest
> version of this series? I'd like to see the whole code of kprobes/arm64.
>
> Thank you,
>

It can be found in:

http://git.linaro.org/people/dave.long/linux.git

...in the kprobes64-v11 branch.

Thanks,
-dl