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From: Vincenzo Frascino <vincenzo.frascino@arm.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org,
	LAK <linux-arm-kernel@lists.infradead.org>,
	LKML <linux-kernel@vger.kernel.org>,
	linux-mips@vger.kernel.org, linux-kselftest@vger.kernel.org,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will.deacon@arm.com>, Arnd Bergmann <arnd@arndb.de>,
	Russell King <linux@armlinux.org.uk>,
	Ralf Baechle <ralf@linux-mips.org>,
	Paul Burton <paul.burton@mips.com>,
	Daniel Lezcano <daniel.lezcano@linaro.org>,
	Mark Salyzyn <salyzyn@android.com>,
	Peter Collingbourne <pcc@google.com>,
	Shuah Khan <shuah@kernel.org>,
	Dmitry Safonov <0x7f454c46@gmail.com>,
	Rasmus Villemoes <linux@rasmusvillemoes.dk>,
	Huw Davies <huw@codeweavers.com>,
	Shijith Thotton <sthotton@marvell.com>,
	Andre Przywara <andre.przywara@arm.com>,
	Dmitry Safonov <dima@arista.com>,
	Andrei Vagin <avagin@openvz.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Andy Lutomirski <luto@kernel.org>,
	Michael Kelley <mikelley@microsoft.com>,
	Sasha Levin <sashal@kernel.org>
Subject: Re: [PATCH v7 00/25] Unify vDSOs across more architectures
Date: Mon, 24 Jun 2019 14:21:03 +0100
Message-ID: <fdded1ed-9404-c80e-c74e-a61716277bda@arm.com> (raw)
In-Reply-To: <alpine.DEB.2.21.1906240142000.32342@nanos.tec.linutronix.de>

Hi Thomas,

On 24/06/2019 01:34, Thomas Gleixner wrote:
> Vincenzo,
> 
> On Fri, 21 Jun 2019, Vincenzo Frascino wrote:
>> vDSO (virtual dynamic shared object) is a mechanism that the Linux
>> kernel provides as an alternative to system calls to reduce where
>> possible the costs in terms of cycles.
>> This is possible because certain syscalls like gettimeofday() do
>> not write any data and return one or more values that are stored
>> in the kernel, which makes relatively safe calling them directly
>> as a library function.
>>
>> Even if the mechanism is pretty much standard, every architecture
>> in the last few years ended up implementing their own vDSO library
>> in the architectural code.
> 
> ....
>  
>> This implementation contains the portings to the common library for: arm64,
>> compat mode for arm64, arm, mips, x86_64, x32, compat mode for x86_64 and
>> i386.
> 
> I picked up the core implementation and the ARM64 and x86 conversion. I did
> some refinements in several places, coding style, naming conventions,
> comments and changelogs including subject prefixes. Please double check!
>

I tested your changes and they seem OK
(git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git timers/vdso).

...
> As you can see from the commit dates, this has soaked for some time in a
> WIP branch and I did extensive regression testing. So far so good.
> 
> Thanks a lot for going through several iterations. It's a very much
> appreciated effort!
> 

It has been a lot of fun and I learned many many things about the vDSOs and the
kernel that I did not know before. Thanks to you for your patience and guidance.

> Especially with the upcoming time namespaces this will avoid a lot of
> duplicated and pointlessly different horrors all over the architecture
> space. Any architecture which wants to gain that support needs to convert
> to the generic VDSO first.
> 
> As you have become the dude who knows almost everything about VDSO
> including all the nasty pitfalls, I propose the patch below.
>

Thanks for this, it means a lot to me.

> Thanks,
> 
> 	tglx
> 
> 8<------------
> Subject: MAINTAINERS: Add entry for the generic VDSO library
> From: Thomas Gleixner <tglx@linutronix.de>
> Date: Mon, 24 Jun 2019 02:03:50 +0200
> 
> Asign the following folks in alphabetic order:
> 
>  - Andy for being the VDSO wizard of x86 and in general. He's also the
>    performance monitor of choice and the code in the generic library is
>    heavily influenced by his previous x86 VDSO work.
> 
>  - Thomas for being the dude who has to deal with any form of time(r)
>    nonsense anyway
> 
>  - Vincenzo for being the poor sod who went through all the different
>    architecture implementations in order to unify them. A lot of knowledge
>    gained from VDSO implementation details to the intricacies of taming the
>    build system.
> 
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> ---
>  MAINTAINERS |   12 ++++++++++++
>  1 file changed, 12 insertions(+)
> 
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -6665,6 +6665,18 @@ L:	kvm@vger.kernel.org
>  S:	Supported
>  F:	drivers/uio/uio_pci_generic.c
>  
> +GENERIC VDSO LIBRARY:
> +M:	Andy Lutomirksy <luto@kernel.org>
> +M:	Thomas Gleixner <tglx@linutronix.de>
> +M:	Vincenzo Frascino <vincenzo.frascino@arm.com>
> +L:	linux-kernel@vger.kernel.org
> +T:	git git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git timers/vdso
> +S:	Maintained
> +F:	lib/vdso
> +F:	kernel/time/vsyscall.c
> +F:	include/vdso
> +F:	include/asm-generic/vdso/vsyscall.h
> +
>  GENWQE (IBM Generic Workqueue Card)
>  M:	Frank Haverkamp <haver@linux.ibm.com>
>  S:	Supported
> 

-- 
Regards,
Vincenzo

  parent reply index

Thread overview: 108+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-06-21  9:52 Vincenzo Frascino
2019-06-21  9:52 ` [PATCH v7 01/25] kernel: Standardize vdso_datapage Vincenzo Frascino
2019-06-24 13:56   ` Catalin Marinas
2019-06-21  9:52 ` [PATCH v7 02/25] kernel: Define gettimeofday vdso common code Vincenzo Frascino
2019-06-21  9:52 ` [PATCH v7 03/25] kernel: Unify update_vsyscall implementation Vincenzo Frascino
2019-06-21 10:49   ` Huw Davies
2019-06-21  9:52 ` [PATCH v7 04/25] arm64: Substitute gettimeofday with C implementation Vincenzo Frascino
2019-06-24 13:36   ` Will Deacon
2019-06-24 13:59     ` Vincenzo Frascino
2019-06-25 16:18     ` [PATCH 1/3] lib/vdso: Delay mask application in do_hres() Vincenzo Frascino
2019-06-25 16:18       ` [PATCH 2/3] arm64: Fix __arch_get_hw_counter() implementation Vincenzo Frascino
2019-06-25 16:18       ` [PATCH 3/3] arm64: compat: " Vincenzo Frascino
2019-06-25 17:02       ` [PATCH 1/3] lib/vdso: Delay mask application in do_hres() Thomas Gleixner
2019-06-25 18:27         ` Thomas Gleixner
2019-06-25 20:15           ` Andy Lutomirski
2019-06-25 22:24             ` Thomas Gleixner
2019-06-26  6:38         ` Thomas Gleixner
2019-06-26  9:25           ` Vincenzo Frascino
2019-06-26 10:02             ` lib/vdso: Make delta calculation work correctly Thomas Gleixner
2019-06-26 11:08               ` Vincenzo Frascino
2019-06-24 13:58   ` [PATCH v7 04/25] arm64: Substitute gettimeofday with C implementation Catalin Marinas
2019-06-25 15:33   ` Dave Martin
2019-06-26 13:27     ` Vincenzo Frascino
2019-06-26 16:14       ` Dave Martin
2019-06-26 19:01         ` Vincenzo Frascino
2019-06-27 10:01           ` Dave Martin
2019-06-27 10:57             ` Vincenzo Frascino
2019-06-27 11:27               ` Dave Martin
2019-06-27 11:59                 ` Vincenzo Frascino
2019-06-27 14:38                   ` Dave Martin
2019-06-27 15:34                     ` Vincenzo Frascino
2019-06-25 17:43   ` [PATCH] arm64: vdso: Fix compilation with clang < 8 Vincenzo Frascino
2019-06-26 11:36   ` [PATCH v2] arm64: vdso: Fix compilation with clang older then 8 Vincenzo Frascino
     [not found]   ` <CGME20190628130921eucas1p239935b0771032c331911eacc1a69dd2e@eucas1p2.samsung.com>
2019-06-28 13:09     ` [PATCH v7 04/25] arm64: Substitute gettimeofday with C implementation Marek Szyprowski
2019-06-28 14:32       ` Vincenzo Frascino
2019-06-28 16:50         ` Sylwester Nawrocki
2019-06-29  6:58           ` Vincenzo Frascino
2019-07-08 12:57             ` Sylwester Nawrocki
2019-07-08 13:09               ` Vincenzo Frascino
2019-06-21  9:52 ` [PATCH v7 05/25] arm64: Build vDSO with -ffixed-x18 Vincenzo Frascino
2019-06-21  9:52 ` [PATCH v7 06/25] arm64: compat: Add missing syscall numbers Vincenzo Frascino
2019-06-21  9:52 ` [PATCH v7 07/25] arm64: compat: Expose signal related structures Vincenzo Frascino
2019-06-21  9:52 ` [PATCH v7 08/25] arm64: compat: Generate asm offsets for signals Vincenzo Frascino
2019-06-21  9:52 ` [PATCH v7 09/25] lib: vdso: Add compat support Vincenzo Frascino
2019-06-21  9:52 ` [PATCH v7 10/25] arm64: compat: Add vDSO Vincenzo Frascino
2019-06-24 14:00   ` Catalin Marinas
2019-07-10  4:02   ` John Stultz
2019-07-10  6:12     ` Thomas Gleixner
2019-07-10  9:48       ` Vincenzo Frascino
2019-07-10  8:27     ` Will Deacon
2019-07-10  8:58       ` Thomas Gleixner
2019-07-10  9:12         ` Will Deacon
2019-07-10  9:47     ` Vincenzo Frascino
2019-07-10 13:41       ` Vincenzo Frascino
2019-07-10 13:04   ` [PATCH] arm64: vdso: Fix ABI regression in compat vdso Vincenzo Frascino
2019-07-10 13:25     ` Will Deacon
2019-07-10 13:42       ` Vincenzo Frascino
2019-07-10 14:01   ` [PATCH v2] " Vincenzo Frascino
2019-07-10 15:44     ` John Stultz
2019-07-10 15:53       ` Vincenzo Frascino
2019-07-11  9:45     ` Will Deacon
2019-07-11 10:34       ` Thomas Gleixner
2019-07-11 11:32         ` Will Deacon
2019-06-21  9:52 ` [PATCH v7 11/25] arm64: Refactor vDSO code Vincenzo Frascino
2019-06-21  9:52 ` [PATCH v7 12/25] arm64: compat: vDSO setup for compat layer Vincenzo Frascino
2019-06-21  9:52 ` [PATCH v7 13/25] arm64: elf: vDSO code page discovery Vincenzo Frascino
2019-06-21  9:52 ` [PATCH v7 14/25] arm64: compat: Get sigreturn trampolines from vDSO Vincenzo Frascino
2019-06-21  9:52 ` [PATCH v7 15/25] arm64: Add vDSO compat support Vincenzo Frascino
2019-06-21  9:52 ` [PATCH v7 16/25] arm: Add support for generic vDSO Vincenzo Frascino
2019-12-04 13:51   ` [PATCH v7 16/25] arm: Add support for generic vDSO (causing crash) Guenter Roeck
2019-12-04 13:58     ` Vincenzo Frascino
2019-12-04 16:16       ` Guenter Roeck
2019-12-04 17:15         ` Vincenzo Frascino
2019-12-04 19:39           ` Guenter Roeck
2019-12-05  9:42           ` Philippe Mathieu-Daudé
2019-12-05 10:00             ` Vincenzo Frascino
2019-12-05 11:02               ` Arnd Bergmann
2019-12-05 14:56                 ` Philippe Mathieu-Daudé
2019-06-21  9:52 ` [PATCH v7 17/25] arm: Add clock_getres entry point Vincenzo Frascino
2019-06-21  9:52 ` [PATCH v7 18/25] arm: Add clock_gettime64 " Vincenzo Frascino
2019-06-21  9:52 ` [PATCH v7 19/25] mips: Add support for generic vDSO Vincenzo Frascino
2019-07-26  5:15   ` Paul Burton
2019-07-26 16:29     ` [PATCH 0/2] mips: vdso: Fix Makefile Vincenzo Frascino
2019-07-26 16:29       ` [PATCH 1/2] mips: vdso: Fix source path Vincenzo Frascino
2019-07-26 16:29       ` [PATCH 2/2] mips: vdso: Fix flip/flop vdso building bug Vincenzo Frascino
2019-07-28 22:20       ` [PATCH 0/2] mips: vdso: Fix Makefile Paul Burton
2019-06-21  9:52 ` [PATCH v7 20/25] mips: Add clock_getres entry point Vincenzo Frascino
2019-07-26  5:15   ` Paul Burton
2019-06-21  9:52 ` [PATCH v7 21/25] mips: Add clock_gettime64 " Vincenzo Frascino
2019-07-26  5:15   ` Paul Burton
2019-06-21  9:52 ` [PATCH v7 22/25] x86: Add support for generic vDSO Vincenzo Frascino
2019-06-21  9:52 ` [PATCH v7 23/25] x86: Add clock_getres entry point Vincenzo Frascino
2019-06-21  9:52 ` [PATCH v7 24/25] x86: Add clock_gettime64 " Vincenzo Frascino
2019-06-21  9:52 ` [PATCH v7 25/25] kselftest: Extend vDSO selftest Vincenzo Frascino
2019-06-24  0:34 ` [PATCH v7 00/25] Unify vDSOs across more architectures Thomas Gleixner
2019-06-24  1:15   ` Andy Lutomirski
2019-06-24  7:42     ` Thomas Gleixner
2019-06-24 13:21   ` Vincenzo Frascino [this message]
2019-06-24 14:18   ` Thomas Gleixner
2019-06-24 14:23     ` Russell King - ARM Linux admin
2019-06-24 14:49       ` Catalin Marinas
2019-06-24 16:20         ` Vincenzo Frascino
2019-10-25 11:42         ` Geert Uytterhoeven
2019-06-24 18:41   ` Paul Burton
2019-06-24 23:16     ` Vincenzo Frascino
2019-06-25 17:11       ` Paul Burton
2019-06-25 17:17         ` Vincenzo Frascino
2019-06-24 12:50 ` Andre Przywara

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