Message-ID: <521DDC3E.8020503@hitachi.com>
Date: Wed, 28 Aug 2013 20:17:18 +0900
From: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Organization: Hitachi, Ltd., Japan
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To: Namhyung Kim <namhyung@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>, Namhyung Kim <namhyung.kim@lge.com>,
        Hyeoncheol Lee <cheol.lee@lge.com>,
        LKML <linux-kernel@vger.kernel.org>,
        Srikar Dronamraju <srikar@linux.vnet.ibm.com>,
        Oleg Nesterov <oleg@redhat.com>,
        "zhangwei(Jovi)" <jovi.zhangwei@huawei.com>,
        Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Subject: Re: Re: [PATCH 13/13] tracing/uprobes: Add support for full argument
 access methods
References: <1377593336-16828-1-git-send-email-namhyung@kernel.org> <1377593336-16828-14-git-send-email-namhyung@kernel.org> <521C9385.8070201@hitachi.com> <87d2oyv0cr.fsf@sejong.aot.lge.com>
In-Reply-To: <87d2oyv0cr.fsf@sejong.aot.lge.com>
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(2013/08/28 14:41), Namhyung Kim wrote:
> On Tue, 27 Aug 2013 20:54:45 +0900, Masami Hiramatsu wrote:
>> (2013/08/27 17:48), Namhyung Kim wrote:
>>> @@ -315,13 +316,18 @@ static int parse_probe_vars(char *arg, const struct fetch_type *t,
>>>  			ret = -EINVAL;
>>>  	} else if (strncmp(arg, "stack", 5) == 0) {
>>>  		if (arg[5] == '\0') {
>>> -			if (strcmp(t->name, DEFAULT_FETCH_TYPE_STR) == 0)
>>> -				f->fn = fetch_stack_address;
>>> -			else
>>> -				ret = -EINVAL;
>>> +			if (strcmp(t->name, DEFAULT_FETCH_TYPE_STR))
>>> +				return -EINVAL;
>>> +
>>> +			if (is_kprobe)
>>> +				f->fn = fetch_kernel_stack_address;
>>> +			else {
>>> +				f->fn = t->fetch[FETCH_MTD_stack];
>>> +				f->data = (void *)0;
>>> +			}
>>
>> No, the 'stack' means the address of the stack frame. Perhaps you might make a
>> new function to retrieve it from pt_regs.
> 
> Hmm.. right.  How about this?
> 
> 
> static __kprobes void fetch_user_stack_address(struct pt_regs *regs,
> 					  void *dummy, void *dest, void *priv)
> {
> 	*(unsigned long *)dest = user_stack_pointer(regs);
> }
> 
> 
> ...
> 
> 			if (is_kprobe)
> 				f->fn = fetch_kernel_stack_address;
> 			else
> 				f->fn = fetch_user_stack_address;

Yeah, this looks good for me ;)

Thank you!


-- 
Masami HIRAMATSU
IT Management Research Dept. Linux Technology Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: masami.hiramatsu.pt@hitachi.com


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