From: Borislav Petkov <bp@alien8.de>
To: Segher Boessenkool <segher@kernel.crashing.org>
Cc: "Arvind Sankar" <nivedita@alum.mit.edu>,
"Jakub Jelinek" <jakub@redhat.com>,
jgross@suse.com, x86@kernel.org,
"Kees Cook" <keescook@chromium.org>,
"Peter Zijlstra" <peterz@infradead.org>,
linuxppc-dev@lists.ozlabs.org, "Michael Matz" <matz@suse.de>,
"Nick Desaulniers" <ndesaulniers@google.com>,
LKML <linux-kernel@vger.kernel.org>,
"Sergei Trofimovich" <slyfox@gentoo.org>,
clang-built-linux <clang-built-linux@googlegroups.com>,
"Ingo Molnar" <mingo@redhat.com>,
"Paul Mackerras" <paulus@samba.org>,
"Andy Lutomirski" <luto@kernel.org>,
"H. Peter Anvin" <hpa@zytor.com>,
"Frédéric Pierret (fepitre)" <frederic.pierret@qubes-os.org>,
"Thomas Gleixner" <tglx@linutronix.de>,
"Martin Liška" <mliska@suse.cz>,
boris.ostrovsky@oracle.com
Subject: Re: [PATCH] x86: Fix early boot crash on gcc-10, next try
Date: Sun, 26 Apr 2020 00:17:28 +0200 [thread overview]
Message-ID: <20200425221728.GE24294@zn.tnic> (raw)
In-Reply-To: <20200425191549.GF17645@gate.crashing.org>
On Sat, Apr 25, 2020 at 02:15:49PM -0500, Segher Boessenkool wrote:
> My point is that you should explain at *every use* of this why you cannot
> have tail calls *there*. This is very unusual, after all.
>
> There are *very* few places where you want to prevent tail calls, that's
> why there is no attribute for it.
Well, there is only one reason *why* so far - to prevent the stack
canary cookie from being checked before returning from the function
which set it. That could be explained once over the macro definition so
that it can be looked up.
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
WARNING: multiple messages have this Message-ID (diff)
From: Borislav Petkov <bp@alien8.de>
To: Segher Boessenkool <segher@kernel.crashing.org>
Cc: "Jakub Jelinek" <jakub@redhat.com>,
jgross@suse.com, "Michael Matz" <matz@suse.de>,
"Kees Cook" <keescook@chromium.org>,
"Peter Zijlstra" <peterz@infradead.org>,
"Martin Liška" <mliska@suse.cz>,
x86@kernel.org, "Nick Desaulniers" <ndesaulniers@google.com>,
LKML <linux-kernel@vger.kernel.org>,
"Sergei Trofimovich" <slyfox@gentoo.org>,
clang-built-linux <clang-built-linux@googlegroups.com>,
"Arvind Sankar" <nivedita@alum.mit.edu>,
"Ingo Molnar" <mingo@redhat.com>,
"Paul Mackerras" <paulus@samba.org>,
"Andy Lutomirski" <luto@kernel.org>,
"H. Peter Anvin" <hpa@zytor.com>,
"Frédéric Pierret (fepitre)" <frederic.pierret@qubes-os.org>,
"Thomas Gleixner" <tglx@linutronix.de>,
linuxppc-dev@lists.ozlabs.org, boris.ostrovsky@oracle.com
Subject: Re: [PATCH] x86: Fix early boot crash on gcc-10, next try
Date: Sun, 26 Apr 2020 00:17:28 +0200 [thread overview]
Message-ID: <20200425221728.GE24294@zn.tnic> (raw)
In-Reply-To: <20200425191549.GF17645@gate.crashing.org>
On Sat, Apr 25, 2020 at 02:15:49PM -0500, Segher Boessenkool wrote:
> My point is that you should explain at *every use* of this why you cannot
> have tail calls *there*. This is very unusual, after all.
>
> There are *very* few places where you want to prevent tail calls, that's
> why there is no attribute for it.
Well, there is only one reason *why* so far - to prevent the stack
canary cookie from being checked before returning from the function
which set it. That could be explained once over the macro definition so
that it can be looked up.
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
next prev parent reply other threads:[~2020-04-25 22:17 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 [this message]
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
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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