Re: [PATCH] arm64: kprobe: Enable OPTPROBE for arm64

From: "liuqi (BA)" <liuqi115@huawei.com>
To: Linuxarm <linuxarm@huawei.com>,
	"Song Bao Hua (Barry Song)" <song.bao.hua@hisilicon.com>,
	Masami Hiramatsu <mhiramat@kernel.org>
Cc: "catalin.marinas@arm.com" <catalin.marinas@arm.com>,
	"will@kernel.org" <will@kernel.org>,
	"naveen.n.rao@linux.ibm.com" <naveen.n.rao@linux.ibm.com>,
	"anil.s.keshavamurthy@intel.com" <anil.s.keshavamurthy@intel.com>,
	"davem@davemloft.net" <davem@davemloft.net>,
	"linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>,
	"Zengtao (B)" <prime.zeng@hisilicon.com>,
	"robin.murphy@arm.com" <robin.murphy@arm.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] arm64: kprobe: Enable OPTPROBE for arm64
Date: Mon, 2 Aug 2021 20:02:47 +0800	[thread overview]
Message-ID: <ddb44b9b-cc18-8f49-e82c-b1ae00546962@huawei.com> (raw)
In-Reply-To: <2f32fff3-6b58-583f-8e85-06ec1553d3f4@huawei.com>

On 2021/8/2 11:52, liuqi (BA) wrote:
[...]

>> This might be the direction to go later. Anyway, "Rome wasn't built
>> in a day", for this stage, we might focus on optprobe for the case
>> of non-randomized module region :-).
>>
>> BTW, @liuqi, if users set "nokaslr" in bootargs, will your optprobe
>> always work and not fall back to normal kprobe even we remove the
>> dependency on RANDOMIZED_MODULE_REGION_FULL?
>>
> Hi Barry,
> 
> I do some tests on Hip08 platform, using nokaslr in booting cmdline and 
> remove dependency on RANDOMIZED_MODULE_REGION_FULL, optprobe seems work.
> Here is the log:
> 
> estuary:/$ uname -a
> Linux (none) 5.13.0-rc4+ #37 SMP PREEMPT Mon Aug 2 08:13:37 CST 2021 
> aarch64 GNU/Linux
> estuary:/$ zcat /proc/config.gz | grep RANDOMIZE_MODULE_REGION
> CONFIG_RANDOMIZE_MODULE_REGION_FULL=y
> estuary:/$ zcat /proc/config.gz | grep OPTPROBE
> CONFIG_OPTPROBES=y
> CONFIG_HAVE_OPTPROBES=y
> estuary:/$ cat /proc/cmdline
> console=ttyAMA0,115200 earlycon=pl011,0x9000000 kpti=off nokaslr
> estuary:/$ cat /sys/bus/platform/devices/hello_driver/kprobe_test
> [   61.304143] do_empty returned 0 and took 200 ns to execute
> [   61.304662] do_empty returned 0 and took 110 ns to execute
> [   61.305196] do_empty returned 0 and took 100 ns to execute
> [   61.305745] do_empty returned 0 and took 90 ns to execute
> [   61.306262] do_empty returned 0 and took 90 ns to execute
> [   61.306781] do_empty returned 0 and took 90 ns to execute
> [   61.307286] do_empty returned 0 and took 90 ns to execute
> [   61.307798] do_empty returned 0 and took 90 ns to execute
> [   61.308314] do_empty returned 0 and took 90 ns to execute
> [   61.308828] do_empty returned 0 and took 90 ns to execute
> [   61.309323] do_empty returned 0 and took 80 ns to execute
> [   61.309832] do_empty returned 0 and took 80 ns to execute
> [   61.310357] do_empty returned 0 and took 80 ns to execute
> [   61.310871] do_empty returned 0 and took 80 ns to execute
> [   61.311361] do_empty returned 0 and took 80 ns to execute
> [   61.311851] do_empty returned 0 and took 90 ns to execute
> [   61.312358] do_empty returned 0 and took 90 ns to execute
> [   61.312879] do_empty returned 0 and took 80 ns to execute
> 
> Thanks,
> Qi
> 
Hi Barry,

I've done test on Hip08 platform using nokaslr in booting cmdline and 
remove dependency on RANDOMIZED_MODULE_REGION_FULL, on following 4 cases:
1. probed code in module, pre_handler in kernel.
2. probed code in kernel, pre_handler in kernel.
3. probed code in module, pre_handler in module.
4. probed code in kernel, pre_handler in module.

and optprobe works in these 4 cases.

Thanks,
Qi
>>>
>>> Thank you,
>>>
>>> -- 
>>> Masami Hiramatsu <mhiramat@kernel.org>
>>
>> Thanks
>> Barry
>> .
>>
> 
> .