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From: David Laight <David.Laight@ACULAB.COM>
To: 'Peter Zijlstra' <peterz@infradead.org>,
	Jakub Jelinek <jakub@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>,
	Sergei Trofimovich <slyfox@gentoo.org>,
	Michael Matz <matz@suse.de>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	"Ingo Molnar" <mingo@redhat.com>,
	"H. Peter Anvin" <hpa@zytor.com>,
	Andy Lutomirski <luto@kernel.org>,
	"x86@kernel.org" <x86@kernel.org>
Subject: RE: [PATCH v2] x86: fix early boot crash on gcc-10
Date: Sat, 18 Apr 2020 13:12:07 +0000	[thread overview]
Message-ID: <26a33cf023024a52bb85bfbe9be2e1fa@AcuMS.aculab.com> (raw)
In-Reply-To: <20200417103808.GW20730@hirez.programming.kicks-ass.net>

From: Peter Zijlstra
> Sent: 17 April 2020 11:38
> 
> On Fri, Apr 17, 2020 at 10:58:59AM +0200, Jakub Jelinek wrote:
> > Or go with the for (;;);, I don't think any compiler optimizes those away;
> > GCC 10 for C++ can optimize away infinite loops that have some conditional
> > exit because the language guarantees forward progress, but the C language
> > rules are different and for unconditional infinite loops GCC doesn't
> > optimize them away even if explicitly asked to -ffinite-loops.
> 
> 'Funnily' there are people building the kernel with C++ :/

Can't you 'make progress' by using longjmp() to exit a signal handler?

	David

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Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)


  reply	other threads:[~2020-04-18 13:12 UTC|newest]

Thread overview: 89+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-14 16:44 [PATCH] x86: fix early boot crash on gcc-10 Sergei Trofimovich
2020-03-16 13:04 ` Peter Zijlstra
2020-03-16 13:26   ` Jakub Jelinek
2020-03-16 13:42     ` Peter Zijlstra
2020-03-16 17:54       ` Borislav Petkov
2020-03-16 18:03         ` Jakub Jelinek
2020-03-17 14:36           ` Borislav Petkov
2020-03-17 14:39             ` Jakub Jelinek
2020-03-17 14:49               ` Borislav Petkov
2020-03-17 16:35                 ` David Laight
2020-03-25 13:31                 ` Borislav Petkov
2020-03-26 21:54                   ` Sergei Trofimovich
2020-03-26 22:35                     ` Borislav Petkov
2020-03-28  8:48                       ` [PATCH v2] " Sergei Trofimovich
2020-04-13 14:15                         ` [tip: x86/urgent] x86: Fix " tip-bot2 for Sergei Trofimovich
2020-04-13 16:35                         ` [PATCH v2] x86: fix " Borislav Petkov
2020-04-14 13:50                           ` Michael Matz
2020-04-15  7:48                             ` Borislav Petkov
2020-04-15 14:53                               ` Michael Matz
2020-04-15 22:19                                 ` Sergei Trofimovich
2020-04-17  7:57                                   ` Borislav Petkov
2020-04-17  8:07                                     ` Jakub Jelinek
2020-04-17  8:42                                       ` Borislav Petkov
2020-04-17  8:58                                         ` Jakub Jelinek
2020-04-17  9:09                                           ` Borislav Petkov
2020-04-17 18:15                                             ` Nick Desaulniers
2020-04-17 18:22                                               ` Nick Desaulniers
2020-04-17 19:06                                                 ` Jakub Jelinek
2020-04-17 19:49                                                   ` Nick Desaulniers
2020-04-17 19:53                                                     ` Nick Desaulniers
2020-04-20 14:04                                                     ` Michael Matz
2020-04-22 10:23                                                       ` Borislav Petkov
2020-04-22 11:40                                                         ` Peter Zijlstra
2020-04-22 13:49                                                           ` Borislav Petkov
2020-04-22 13:55                                                             ` Jakub Jelinek
2020-04-22 14:16                                                               ` Martin Liška
2020-04-22 15:06                                                                 ` Michael Matz
2020-04-22 16:53                                                                 ` Borislav Petkov
2020-04-22 17:02                                                                   ` Jakub Jelinek
2020-04-22 18:47                                                                   ` Nick Desaulniers
2020-04-22 18:55                                                         ` Nick Desaulniers
2020-04-22 19:21                                                           ` Borislav Petkov
2020-04-22 21:05                                                             ` Nick Desaulniers
2020-04-22 21:26                                                               ` Borislav Petkov
2020-04-22 22:57                                                                 ` Nick Desaulniers
2020-04-23 12:53                                                                   ` Borislav Petkov
2020-04-23 16:12                                                                     ` [PATCH] x86: Fix early boot crash on gcc-10, next try Borislav Petkov
2020-04-23 17:30                                                                       ` Borislav Petkov
2020-04-23 18:02                                                                         ` Nick Desaulniers
2020-04-23 18:27                                                                           ` Borislav Petkov
2020-04-27 11:37                                                                         ` [tip: x86/build] x86/build: Check whether the compiler is sane tip-bot2 for Borislav Petkov
2020-04-23 19:40                                                                       ` [PATCH] x86: Fix early boot crash on gcc-10, next try Kees Cook
2020-04-25  1:46                                                                       ` Arvind Sankar
2020-04-25  8:57                                                                         ` Borislav Petkov
2020-04-25 11:09                                                                           ` Jürgen Groß
2020-04-25 15:04                                                                           ` Arvind Sankar
2020-04-25 15:04                                                                             ` Arvind Sankar
2020-04-25 17:31                                                                             ` Borislav Petkov
2020-04-25 17:31                                                                               ` Borislav Petkov
2020-04-25 17:52                                                                               ` Borislav Petkov
2020-04-25 17:52                                                                                 ` Borislav Petkov
2020-04-27 17:07                                                                                 ` David Laight
2020-04-27 17:07                                                                                   ` David Laight
2020-04-25 18:37                                                                               ` Segher Boessenkool
2020-04-25 18:37                                                                                 ` Segher Boessenkool
2020-04-25 18:53                                                                                 ` Borislav Petkov
2020-04-25 18:53                                                                                   ` Borislav Petkov
2020-04-25 19:15                                                                                   ` Segher Boessenkool
2020-04-25 19:15                                                                                     ` Segher Boessenkool
2020-04-25 22:17                                                                                     ` Borislav Petkov
2020-04-25 22:17                                                                                       ` Borislav Petkov
2020-04-25 22:25                                                                                     ` Arvind Sankar
2020-04-25 22:25                                                                                       ` Arvind Sankar
2020-04-17 10:38                                           ` [PATCH v2] x86: fix early boot crash on gcc-10 Peter Zijlstra
2020-04-18 13:12                                             ` David Laight [this message]
2020-04-17 10:41                                     ` Peter Zijlstra
2020-03-16 18:20         ` [PATCH] " Arvind Sankar
2020-03-16 18:54           ` Arvind Sankar
2020-03-16 19:53             ` Arvind Sankar
2020-03-16 20:08               ` Jakub Jelinek
2020-03-16 20:40                 ` Arvind Sankar
2020-03-16 22:12     ` Sergei Trofimovich
2020-03-17 11:46       ` Jakub Jelinek
2020-03-17 18:10         ` Sergei Trofimovich
2020-03-16 18:22 ` Arvind Sankar
2020-03-26 23:16 ` [PATCH v2] " Sergei Trofimovich
2020-04-27 11:37 ` [tip: x86/build] x86: Fix early boot crash on gcc-10, next try tip-bot2 for Borislav Petkov
2020-05-15 11:20 ` [tip: x86/urgent] x86: Fix early boot crash on gcc-10, third try tip-bot2 for Borislav Petkov
2020-05-19 11:49   ` Sasha Levin

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