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From: Pavel Machek <pavel@ucw.cz>
To: Sedat Dilek <sedat.dilek@gmail.com>
Cc: Segher Boessenkool <segher@kernel.crashing.org>,
	Arvind Sankar <nivedita@alum.mit.edu>,
	Thomas Gleixner <tglx@linutronix.de>,
	Nick Desaulniers <ndesaulniers@google.com>,
	"Paul E. McKenney" <paulmck@kernel.org>,
	Ingo Molnar <mingo@redhat.com>, Arnd Bergmann <arnd@arndb.de>,
	Borislav Petkov <bp@alien8.de>,
	"maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)"
	<x86@kernel.org>, "H. Peter Anvin" <hpa@zytor.com>,
	"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
	Zhenzhong Duan <zhenzhong.duan@oracle.com>,
	Kees Cook <keescook@chromium.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Juergen Gross <jgross@suse.com>,
	Andy Lutomirski <luto@kernel.org>,
	Andrew Cooper <andrew.cooper3@citrix.com>,
	LKML <linux-kernel@vger.kernel.org>,
	clang-built-linux <clang-built-linux@googlegroups.com>,
	Will Deacon <will@kernel.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
Subject: Re: [PATCH] x86: work around clang IAS bug referencing __force_order
Date: Wed, 9 Sep 2020 00:25:24 +0200	[thread overview]
Message-ID: <20200908222524.GE1005@bug> (raw)
In-Reply-To: <CA+icZUWGHo3mkN4=ZYeU37p8KJhxTXS5QKcAvq_HaqTHmFkw2g@mail.gmail.com>

On Sat 2020-08-22 11:51:56, Sedat Dilek wrote:
> On Sat, Aug 22, 2020 at 11:23 AM Sedat Dilek <sedat.dilek@gmail.com> wrote:
> >
> > On Sat, Aug 22, 2020 at 10:42 AM Segher Boessenkool
> > <segher@kernel.crashing.org> wrote:
> > >
> > > Hi Arvind,
> > >
> > > On Fri, Aug 21, 2020 at 11:55:52PM -0400, Arvind Sankar wrote:
> > > > Cc Segher.
> > > >
> > > > Segher, we were looking at gcc PR82602, where IRA could reorder volatile
> > > > asm's (reported on ARM). The fix was backported to gcc-6.
> > >
> > > I know ;-)
> > >
> > > > Do you know if
> > > > there is any reason the problem couldn't occur on x86 on older gcc
> > > > without the fix?
> > >
> > > No, I see no particular reason, at least GCC 5 seems vulnerable.  (The
> > > GCC 5 release branch was closed at the time this bug report was made,
> > > already).  There is no reason I see why it would work on x86 but fail
> > > elsewhere, either.
> > >
> >
> > [1] says:
> >
> > Current Minimal Requirements
> > ...
> > ====================== ===============  ========================================
> >         Program        Minimal version       Command to check the version
> > ====================== ===============  ========================================
> > GNU C                  4.9              gcc --version
> >
> > - Sedat -
> >
> > [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/changes.rst#n32
> 
> [ CC Miguel Ojeda (Compiler Attributes maintainer) ]
> 
> There exist gcc-4.8 and gcc-4.9 for Debian/jessie where EOL was June
> 30, 2020 (see [1] and [2]).
> 
> In the latest available version "4.9.2-10+deb8u1" I see no PR82602 was
> backported (see [3] and [4]).
> 
> I am asking myself who is using such ancient compilers?
> Recently, I threw away GCC-8 from my Debian system.

I do have 4.9.2 on some systems. They work well, and are likely to compile
significantly faster than newer ones.

Please don't break them.

									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

      parent reply	other threads:[~2020-09-08 22:25 UTC|newest]

Thread overview: 63+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-27 13:53 [PATCH] x86: work around clang IAS bug referencing __force_order Arnd Bergmann
2020-08-01 11:50 ` Sedat Dilek
2020-08-06 22:13   ` Thomas Gleixner
2020-08-07  7:03     ` Sedat Dilek
2020-08-04  0:09 ` Nick Desaulniers
2020-08-14 17:29   ` Sedat Dilek
2020-08-14 21:19     ` Sedat Dilek
2020-08-14 22:57       ` Nick Desaulniers
2020-08-15  0:26         ` Nick Desaulniers
2020-08-15  3:28           ` Sedat Dilek
2020-08-15  8:23             ` Sedat Dilek
2020-08-15 10:46               ` Sedat Dilek
2020-08-15 14:39                 ` Sedat Dilek
2020-08-16  9:37                   ` Sedat Dilek
2020-08-06 22:11 ` Thomas Gleixner
2020-08-13  0:12   ` Nick Desaulniers
2020-08-13  8:49     ` David Laight
2020-08-13 17:20     ` Arvind Sankar
2020-08-13 17:28     ` Thomas Gleixner
2020-08-13 17:37       ` Paul E. McKenney
2020-08-13 18:09         ` Arvind Sankar
2020-08-13 18:20           ` Paul E. McKenney
2020-08-20 10:44           ` Thomas Gleixner
2020-08-20 13:06             ` Arvind Sankar
2020-08-21  0:37               ` Thomas Gleixner
2020-08-21 23:04                 ` Arvind Sankar
2020-08-21 23:16                   ` Nick Desaulniers
2020-08-21 23:25                     ` Arvind Sankar
2020-08-22  0:43                     ` Thomas Gleixner
2020-08-22  3:55                       ` Arvind Sankar
2020-08-22  8:41                         ` Segher Boessenkool
2020-08-22  9:23                           ` Sedat Dilek
2020-08-22  9:51                             ` Sedat Dilek
2020-08-22 10:26                               ` Segher Boessenkool
2020-08-22 10:35                                 ` Arnd Bergmann
2020-08-22 18:17                               ` Miguel Ojeda
2020-08-22 21:08                                 ` Linus Torvalds
2020-08-22 23:10                                   ` Arvind Sankar
2020-08-23  0:10                                     ` Linus Torvalds
2020-08-23  1:16                                       ` Arvind Sankar
2020-08-23 21:25                                         ` [PATCH] x86/asm: Replace __force_order with memory clobber Arvind Sankar
2020-08-24 17:50                                           ` Nathan Chancellor
2020-08-24 19:13                                           ` Miguel Ojeda
2020-08-25 15:19                                             ` Arvind Sankar
2020-08-25 15:21                                               ` Sedat Dilek
2020-09-02 15:33                                           ` [PATCH v2] " Arvind Sankar
2020-09-02 15:58                                             ` David Laight
2020-09-02 16:14                                               ` Arvind Sankar
2020-09-02 16:08                                             ` Arvind Sankar
2020-09-02 20:26                                               ` David Laight
2020-09-02 17:16                                             ` Segher Boessenkool
2020-09-02 17:36                                               ` Arvind Sankar
2020-09-02 18:19                                             ` Miguel Ojeda
2020-09-02 18:24                                               ` Arvind Sankar
2020-09-02 23:21                                           ` [PATCH v3] " Arvind Sankar
2020-09-03  2:17                                             ` Kees Cook
2020-09-03  5:34                                             ` Miguel Ojeda
2020-09-30 20:50                                             ` Kees Cook
2020-10-01 10:12                                             ` [tip: x86/asm] x86/asm: Replace __force_order with a " tip-bot2 for Arvind Sankar
2020-10-13  9:30                                             ` tip-bot2 for Arvind Sankar
2020-08-22 21:17                                 ` [PATCH] x86: work around clang IAS bug referencing __force_order Arvind Sankar
2020-08-23 13:31                                   ` David Laight
2020-09-08 22:25                               ` Pavel Machek [this message]

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