From: Vincenzo Frascino <vincenzo.frascino@arm.com>
To: "H. Nikolaus Schaller" <hns@goldelico.com>
Cc: Ralf Baechle <ralf@linux-mips.org>,
Paul Burton <paul.burton@mips.com>,
linux-mips@vger.kernel.org,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
MIPS Creator CI20 Development
<mips-creator-ci20-dev@googlegroups.com>,
Discussions about the Letux Kernel
<letux-kernel@openphoenux.org>
Subject: Re: MIPS: bug: gettimeofday syscall broken on CI20 board
Date: Thu, 28 Nov 2019 12:21:04 +0000 [thread overview]
Message-ID: <7b6275c7-ab2b-a647-6bf7-d5e1c4523c98@arm.com> (raw)
In-Reply-To: <AD919A0B-2629-4E8A-8A7A-1E4A868F8BC4@goldelico.com>
[-- Attachment #1: Type: text/plain, Size: 1541 bytes --]
On 28/11/2019 12:11, H. Nikolaus Schaller wrote:
>
>> Am 28.11.2019 um 12:51 schrieb Vincenzo Frascino <vincenzo.frascino@arm.com>:
>>
>> Hi Nikolaus,
>>
>> On 27/11/2019 13:53, H. Nikolaus Schaller wrote:
>> [...]
>>
>>>> vdso_data and mips_vdso_data before are not part of the ABI hence they are not
>>>> bind by a contract with the userspace.
>>>>
>>>> This means that they can change at any point and if a userspace software relies
>>>> on a specific layout of these data structures is doing something wrong.
>>>
>>> Maybe the libs are clever enough to find that out dynamically but I have no
>>> idea about how gettimeofday() and user-space VDSO is implemented to handle such
>>> changes.
>>>
>> As I said userspace applications and libraries should not rely on the layout of
>> vdso_data because this is not part of the ABI.
>>
>> The only thing that userspace requires is to "know" that gettimeofday() exists,
>> than it is gettimeofday() that internally accesses the data structure.
>
> Well, with user-space I include the lib that provides the gettimeofday() syscall
> and reads out the memory region where the VDSO data structure is provided by the
> kernel. And that part comes from Debian. Somehow it does differently with 4.19
> than 5.4. So I summarise all non-kernel code with the term "user-space".
>
The the lib that provides the gettimeofday() changes accordingly with vdso_data.
5.4 and 4.19 have 2 different vdso libraries as well.
> BR,
> Nikolaus
>
--
Regards,
Vincenzo
[-- Attachment #2: pEpkey.asc --]
[-- Type: application/pgp-keys, Size: 14291 bytes --]
next prev parent reply other threads:[~2019-11-28 12:21 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-07 16:21 MIPS: bug: gettimeofday syscall broken on CI20 board? H. Nikolaus Schaller
2019-11-17 13:14 ` MIPS: bug: gettimeofday syscall broken on CI20 board H. Nikolaus Schaller
2019-11-23 7:29 ` H. Nikolaus Schaller
2019-11-26 10:52 ` MIPS: " Vincenzo Frascino
2019-11-27 13:53 ` H. Nikolaus Schaller
2019-11-27 14:29 ` H. Nikolaus Schaller
2019-11-28 12:05 ` Vincenzo Frascino
2019-11-28 12:16 ` H. Nikolaus Schaller
2019-11-28 14:04 ` Vincenzo Frascino
2019-11-28 15:10 ` H. Nikolaus Schaller
2019-11-28 11:51 ` Vincenzo Frascino
2019-11-28 12:11 ` H. Nikolaus Schaller
2019-11-28 12:21 ` Vincenzo Frascino [this message]
2019-11-28 12:33 ` H. Nikolaus Schaller
2019-11-28 13:29 ` Maarten ter Huurne
2019-11-28 13:48 ` H. Nikolaus Schaller
2019-11-28 14:01 ` Vincenzo Frascino
2019-11-28 15:42 ` H. Nikolaus Schaller
2019-11-28 15:07 ` Thomas Bogendoerfer
2019-11-28 15:41 ` H. Nikolaus Schaller
2019-11-28 15:46 ` Vincenzo Frascino
2019-11-28 16:47 ` H. Nikolaus Schaller
2019-11-29 8:57 ` Vincenzo Frascino
2019-11-29 10:53 ` Vincenzo Frascino
2019-11-29 11:51 ` H. Nikolaus Schaller
2019-12-01 3:08 ` [PATCH] Mips32 gettimeofday fix kbuild test robot
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=7b6275c7-ab2b-a647-6bf7-d5e1c4523c98@arm.com \
--to=vincenzo.frascino@arm.com \
--cc=hns@goldelico.com \
--cc=letux-kernel@openphoenux.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mips@vger.kernel.org \
--cc=mips-creator-ci20-dev@googlegroups.com \
--cc=paul.burton@mips.com \
--cc=ralf@linux-mips.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).