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From: Denis Medvedev <nbr@altlinux.org>
To: devel@lists.altlinux.org
Subject: Re: [devel] I: LTO in %optflags by default
Date: Wed, 25 Aug 2021 10:03:39 +0300
Message-ID: <20210825100339.41800b67@homerun.localdomain> (raw)
In-Reply-To: <20210825095329.334e1e5a1c578563a9435c6b@altlinux.org>

В Wed, 25 Aug 2021 09:53:29 +0300
Andrey Savchenko <bircoph@altlinux.org> пишет:

> On Wed, 25 Aug 2021 08:46:40 +0300 Denis Medvedev wrote:
> > В Wed, 25 Aug 2021 09:27:50 +0400
> > "Ivan A. Melnikov" <iv@altlinux.org> пишет:
> >   
> > > On Tue, Aug 24, 2021 at 09:20:50PM +0300, Dmitry V. Levin wrote:  
> > > > Hi,
> > > > 
> > > > Пришло время включить в Сизифе LTO (link-time optimization).
> > > > К сожалению, ещё не все пакеты собираются с этой оптимизацией,
> > > > некоторые предстоит исправить.    
> > > 
> > > Скажите, а как это влияет на время сборки пакетов?
> > > 
> > > Это тестировалось только на основных архитектурах? На всех?
> > >   
> > 
> > Я, конечно, понимаю, что запоздал с этим,
> > но можно ли включить
> > по умолчаниию заодно вот это:
> > 
> > 
> > -mmitigate-rop
> > Attempt to compile code without unintended return addresses, making
> > ROP just a little harder.
> > 
> > -mindirect-branch=thunk -mfunction-return=thunk
> > Enables retpoline (return trampolines) to mitigate some variants of
> > Spectre V2. The second flag is necessary on Skylake+ due to the
> > fact that the branch target buffer is vulnerable.  
> 
> Но эти опции, ведь, не на всех архитектурах нужны, даже в основной
> сборочнице. Поэтому если и включать, то выборочно в зависимости от
> архитектуры.
>  
> > -fstack-protector-all -Wstack-protector --param ssp-buffer-size=4
> > choice of "-fstack-protector" does not protect all functions . You
> > need -fstack-protector-all to guarantee guards are applied to all
> > functions, although this will likely incur a performance penalty.
> > Consider -fstack-protector-strong as a middle ground. The
> > -Wstack-protector flag here gives warnings for any functions that
> > aren't going to get protected.
> > 
> > -fstack-clash-protection
> > Defeats a class of attacks called stack clashing.  
> 
> Эта может поломать много приложений и может быть значимый удар по
> производительности.
>  
> > ­-Wl,-z,relro,-z,now
> > RELRO (read-only relocation). The options relro & now specified
> > together are known as "Full RELRO". You can specify "Partial RELRO"
> > by omitting the now flag. RELRO marks various ELF memory sections
> > read­only (E.g. the GOT).  
> 
> С точки зрения безопасности это хорошо, а вот тормоза даёт дикие,
> особенно на тяжёлых приложениях типа LO. Возможно, в этом есть смысл
> в специальных ветках, но в Сизиф такое не нужно тянуть.
В таком случае как мне правильно сделать дефолты для особых веток?
Сделать свою версию какого пакета?
> 
> Best regards,
> Andrew Savchenko



  reply	other threads:[~2021-08-25  7:03 UTC|newest]

Thread overview: 75+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-24 18:20 Dmitry V. Levin
2021-08-24 18:21 ` Dmitry V. Levin
2021-08-24 18:22 ` Dmitry V. Levin
2021-08-25  0:04   ` Dmitry V. Levin
2021-08-25  8:18     ` Vitaly Lipatov
2021-08-25  8:28       ` Ivan A. Melnikov
2021-08-25  8:38         ` Vitaly Lipatov
2021-08-25  9:18           ` Andrey Savchenko
2021-08-25 17:14             ` [devel] devel-static Dmitry V. Levin
2021-08-25 17:25               ` Alexey Sheplyakov
2021-08-25 19:19                 ` Andrey Savchenko
2021-08-25 19:14               ` Andrey Savchenko
2021-08-25 19:58                 ` Vitaly Lipatov
2021-08-25 20:52                   ` Andrey Savchenko
2021-08-25 21:06                     ` Vitaly Lipatov
2021-08-25 21:36                       ` Andrey Savchenko
2021-08-27 19:43   ` [devel] Статические библиотеки и thin LTO (Was: I: LTO in %optflags by default) Alexey Sheplyakov
2021-08-27 22:18     ` [devel] Статические библиотеки и thin LTO Vitaly Chikunov
2021-08-29  6:34       ` Alexey Sheplyakov
2021-08-30  9:18         ` Dmitry V. Levin
2021-08-30  9:30           ` Andrey Savchenko
2021-08-30  9:39             ` Dmitry V. Levin
2021-08-30 14:36               ` Andrey Savchenko
2021-08-30  9:50           ` Arseny Maslennikov
2021-08-24 18:23 ` [devel] I: LTO in %optflags by default Dmitry V. Levin
2021-08-24 19:19 ` Dmitry V. Levin
2021-08-25  0:33   ` Dmitry V. Levin
2021-08-26  6:00     ` [devel] I: LTO in %optflags by defaulta (top-level asm) Vitaly Chikunov
2021-08-25  5:27 ` [devel] I: LTO in %optflags by default Ivan A. Melnikov
2021-08-25  5:46   ` Denis Medvedev
2021-08-25  5:50     ` Denis Medvedev
2021-08-25  6:53     ` Andrey Savchenko
2021-08-25  7:03       ` Denis Medvedev [this message]
2021-08-25  7:32         ` Andrey Savchenko
2021-08-26 18:43         ` Michael Shigorin
2021-08-25  7:12       ` Ivan A. Melnikov
2021-08-25  8:14       ` Alexey Tourbin
2021-08-25  8:39         ` Andrey Savchenko
2021-08-25  7:12     ` Alexey Sheplyakov
2021-08-25 16:28     ` Dmitry V. Levin
2021-08-25 17:48   ` Dmitry V. Levin
2021-08-25  7:37 ` Alexey Sheplyakov
2021-08-25 18:07   ` [devel] Administrivia Dmitry V. Levin
2021-08-25 19:25     ` Alexey Sheplyakov
2021-08-25 20:03       ` Alexey V. Vissarionov
2021-08-26 19:02         ` [devel] Administrivii Michael Shigorin
2021-08-26 19:18           ` [devel] debugedit Dmitry V. Levin
2021-10-13  9:16             ` [devel] debugedit DWARF version 0 Denis Medvedev
2021-10-13  9:51               ` Dmitry V. Levin
2021-10-13  9:51                 ` Denis Medvedev
2021-08-25 19:27   ` [devel] I: LTO in %optflags by default Andrey Savchenko
2021-08-25 23:54     ` Dmitry V. Levin
2021-08-26  9:35       ` Alexey V. Vissarionov
2021-08-26 19:33       ` Andrey Savchenko
2021-08-27  0:37         ` Dmitry V. Levin
2021-08-27  8:07           ` Sergey V Turchin
2021-08-27  9:11           ` Alexey V. Vissarionov
2021-08-27 10:00           ` Alexey Sheplyakov
2021-08-27 12:54             ` Dmitry V. Levin
2021-08-25 10:45 ` Vitaly Lipatov
2021-08-25 16:20   ` Dmitry V. Levin
2021-08-25 20:23     ` Vitaly Lipatov
2021-08-25 20:30       ` Dmitry V. Levin
2021-08-25 21:24 ` Dmitry V. Levin
2021-08-25 23:07   ` Aleksey Novodvorsky
2021-08-25 23:19     ` Dmitry V. Levin
2021-08-25 23:54       ` Andrey Savchenko
2021-08-26  0:04         ` Dmitry V. Levin
2021-08-26  6:39           ` Andrey Savchenko
2021-08-26  7:25             ` Vitaly Lipatov
2021-08-27  0:20             ` Dmitry V. Levin
2021-08-26  9:40           ` Alexey V. Vissarionov
2021-08-26  4:23       ` alexei
2021-08-26  8:24         ` Dmitry V. Levin
2021-08-26  0:26 ` Dmitry V. Levin

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