linux-kernel - Re: [PATCHv8 resend 2/2] selftest/x86: add mremap vdso test

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Date:	Tue, 17 May 2016 13:25:04 +0300
From:	Dmitry Safonov <dsafonov@...tuozzo.com>
To:	Andy Lutomirski <luto@...capital.net>,
	Ingo Molnar <mingo@...nel.org>
CC:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Ingo Molnar <mingo@...hat.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>, X86 ML <x86@...nel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	Dmitry Safonov <0x7f454c46@...il.com>,
	Shuah Khan <shuahkh@....samsung.com>,
	<linux-kselftest@...r.kernel.org>
Subject: Re: [PATCHv8 resend 2/2] selftest/x86: add mremap vdso test

On 05/16/2016 09:25 PM, Andy Lutomirski wrote:
> On Mon, May 16, 2016 at 9:24 AM, Dmitry Safonov <dsafonov@...tuozzo.com> wrote:
>> On 05/16/2016 04:54 PM, Ingo Molnar wrote:
>>>
>>>
>>> * Dmitry Safonov <dsafonov@...tuozzo.com> wrote:
>>>
>>>> Should print on success:
>>>> [root@...alhost ~]# ./test_mremap_vdso_32
>>>>         AT_SYSINFO_EHDR is 0xf773f000
>>>> [NOTE]  Moving vDSO: [f773f000, f7740000] -> [a000000, a001000]
>>>> [OK]
>>>> Or segfault if landing was bad (before patches):
>>>> [root@...alhost ~]# ./test_mremap_vdso_32
>>>>         AT_SYSINFO_EHDR is 0xf774f000
>>>> [NOTE]  Moving vDSO: [f774f000, f7750000] -> [a000000, a001000]
>>>> Segmentation fault (core dumped)
>>>
>>>
>>> Can the segfault be caught and recovered from, to print a proper failure
>>> message?
>>
>>
>> Will add segfault handler, thanks.
>>
>
> It may be more complicated that that.  Glibc is likely to explode if
> this happens, and the headers are sufficiently screwed up that it's
> awkward to bypass glibc and call rt_sigaction directly.  I have a test
> that does the latter, though, so it's at least possible, but I'm
> unconvinced it's worth it just for an error message.

Oh, I didn't know that, thanks, Andy.
I'll leave it as is for simplicity.

-- 
Regards,
Dmitry Safonov