From: Segher Boessenkool <segher@kernel.crashing.org>
To: Nadav Amit <namit@vmware.com>
Cc: Richard Biener <rguenther@suse.de>, Michael Matz <matz@suse.de>,
Borislav Petkov <bp@alien8.de>,
"gcc@gcc.gnu.org" <gcc@gcc.gnu.org>,
Ingo Molnar <mingo@redhat.com>,
LKML <linux-kernel@vger.kernel.org>, X86 ML <x86@kernel.org>,
Masahiro Yamada <yamada.masahiro@socionext.com>,
Sam Ravnborg <sam@ravnborg.org>,
Alok Kataria <akataria@vmware.com>,
Christopher Li <sparse@chrisli.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
"H. Peter Anvin" <hpa@zytor.com>, Jan Beulich <JBeulich@suse.com>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Juergen Gross <jgross@suse.com>,
Kate Stewart <kstewart@linuxfoundation.org>,
Kees Cook <keescook@chromium.org>,
"linux-sparse@vger.kernel.org" <linux-sparse@vger.kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Philippe Ombredanne <pombredanne@nexb.com>,
Thomas Gleixner <tglx@linutronix.de>,
"virtualization@lists.linux-foundation.org"
<virtualization@lists.linux-foundation.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Chris Zankel <chris@zankel.net>,
Max Filippov <jcmvbkbc@gmail.com>,
"linux-xtensa@linux-xtensa.org" <linux-xtensa@linux-xtensa.org>
Subject: Re: PROPOSAL: Extend inline asm syntax with size spec
Date: Wed, 10 Oct 2018 14:21:12 -0500 [thread overview]
Message-ID: <20181010192111.GD29268@gate.crashing.org> (raw)
In-Reply-To: <5ACDEDEA-0E42-45F2-BC80-B96EC2ABC01D@vmware.com>
Hi Nadav,
On Wed, Oct 10, 2018 at 04:31:41PM +0000, Nadav Amit wrote:
> at 7:53 AM, Segher Boessenkool <segher@kernel.crashing.org> wrote:
> > How does this look?
>
> It looks good to me in general. I have a couple of reservations, but I
> suspect you will not want to address them:
>
> 1. It is not backward compatible, requiring a C macro to wrap it, as the
> kernel might be built with different compilers.
How *could* it be backward compatible? There should be an error or at least
a warning if the compiler does not support this, in general.
For the kernel, the kernel already has plenty of infrastructure to support
this (compiler.h etc.) For other applications it is quite trivial, too.
> 2. It is specific to asm.
Yes, and that is on purpose.
> I do not have in mind another use case (excluding
> the __builtin_constant_p), but it would be nicer IMHO to have a builtin
> saying “ignore the cost of this statement” for the matter of optimizations.
That is a hundred or a thousand times more work to design and implement
(including testing etc.) I'm not going to do it, but feel free to try
yourself!
Segher
next prev parent reply other threads:[~2018-10-10 21:57 UTC|newest]
Thread overview: 116+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-03 21:30 [PATCH v9 00/10] x86: macrofying inline asm Nadav Amit
2018-10-03 21:30 ` [PATCH v9 01/10] xtensa: defining LINKER_SCRIPT for the linker script Nadav Amit
2018-10-04 10:00 ` [tip:x86/build] kbuild/arch/xtensa: Define " tip-bot for Nadav Amit
2018-10-03 21:30 ` [PATCH v9 02/10] Makefile: Prepare for using macros for inline asm Nadav Amit
2018-10-04 10:01 ` [tip:x86/build] kbuild/Makefile: Prepare for using macros in inline assembly code to work around asm() related GCC inlining bugs tip-bot for Nadav Amit
2018-11-06 18:57 ` [PATCH v9 02/10] Makefile: Prepare for using macros for inline asm Logan Gunthorpe
2018-11-06 19:18 ` Nadav Amit
2018-11-06 20:01 ` Logan Gunthorpe
2018-11-07 18:01 ` Nadav Amit
2018-11-07 18:53 ` Logan Gunthorpe
2018-11-07 18:56 ` Nadav Amit
2018-11-07 21:43 ` Logan Gunthorpe
2018-11-07 21:50 ` hpa
2018-11-08 6:18 ` Nadav Amit
2018-11-08 17:14 ` Logan Gunthorpe
2018-11-08 19:54 ` Nadav Amit
2018-11-08 20:00 ` Logan Gunthorpe
2018-11-08 20:18 ` Nadav Amit
2018-11-10 22:04 ` Nadav Amit
2018-11-13 4:56 ` Logan Gunthorpe
2018-10-03 21:30 ` [PATCH v9 03/10] x86: objtool: use asm macro for better compiler decisions Nadav Amit
2018-10-04 10:02 ` [tip:x86/build] x86/objtool: Use asm macros to work around GCC inlining bugs tip-bot for Nadav Amit
2018-10-03 21:30 ` [PATCH v9 04/10] x86: refcount: prevent gcc distortions Nadav Amit
2018-10-04 7:57 ` Ingo Molnar
2018-10-04 8:33 ` Ingo Molnar
2018-10-04 8:40 ` hpa
2018-10-04 8:56 ` Ingo Molnar
2018-10-04 8:56 ` Nadav Amit
2018-10-04 9:02 ` hpa
2018-10-04 9:16 ` Ingo Molnar
2018-10-04 19:33 ` H. Peter Anvin
2018-10-04 20:05 ` Nadav Amit
2018-10-04 20:08 ` H. Peter Anvin
2018-10-04 20:29 ` Andy Lutomirski
2018-10-04 23:11 ` H. Peter Anvin
2018-10-06 1:40 ` Rasmus Villemoes
2018-10-04 9:12 ` Ingo Molnar
2018-10-04 9:17 ` hpa
2018-10-04 9:30 ` Nadav Amit
2018-10-04 9:45 ` Ingo Molnar
2018-10-04 10:23 ` Nadav Amit
2018-10-05 9:31 ` Ingo Molnar
2018-10-05 11:20 ` Borislav Petkov
2018-10-05 12:52 ` Ingo Molnar
2018-10-05 20:27 ` [PATCH 0/3] Macrofying inline asm rebased Nadav Amit
2018-10-05 20:27 ` [PATCH 1/3] x86/extable: Macrofy inline assembly code to work around GCC inlining bugs Nadav Amit
2018-10-06 14:42 ` [tip:x86/build] " tip-bot for Nadav Amit
2018-10-05 20:27 ` [PATCH 2/3] x86/cpufeature: " Nadav Amit
2018-10-06 14:43 ` [tip:x86/build] " tip-bot for Nadav Amit
2018-10-05 20:27 ` [PATCH 3/3] x86/jump-labels: " Nadav Amit
2018-10-06 14:44 ` [tip:x86/build] " tip-bot for Nadav Amit
2018-10-08 2:17 ` [PATCH v9 04/10] x86: refcount: prevent gcc distortions Nadav Amit
2018-10-04 8:40 ` Nadav Amit
2018-10-04 9:01 ` Ingo Molnar
2018-10-04 10:02 ` [tip:x86/build] x86/refcount: Work around GCC inlining bug tip-bot for Nadav Amit
2018-10-03 21:30 ` [PATCH v9 05/10] x86: alternatives: macrofy locks for better inlining Nadav Amit
2018-10-04 10:03 ` [tip:x86/build] x86/alternatives: Macrofy lock prefixes to work around GCC inlining bugs tip-bot for Nadav Amit
2018-10-03 21:30 ` [PATCH v9 06/10] x86: bug: prevent gcc distortions Nadav Amit
2018-10-04 10:03 ` [tip:x86/build] x86/bug: Macrofy the BUG table section handling, to work around GCC inlining bugs tip-bot for Nadav Amit
2018-10-03 21:30 ` [PATCH v9 07/10] x86: prevent inline distortion by paravirt ops Nadav Amit
2018-10-04 10:04 ` [tip:x86/build] x86/paravirt: Work around GCC inlining bugs when compiling " tip-bot for Nadav Amit
2018-10-03 21:30 ` [PATCH v9 08/10] x86: extable: use macros instead of inline assembly Nadav Amit
2018-10-03 21:30 ` [PATCH v9 09/10] x86: cpufeature: " Nadav Amit
2018-10-03 21:31 ` [PATCH v9 10/10] x86: jump-labels: " Nadav Amit
2018-10-07 9:18 ` PROPOSAL: Extend inline asm syntax with size spec Borislav Petkov
[not found] ` <20181007132228.GJ29268@gate.crashing.org>
2018-10-07 14:13 ` Borislav Petkov
2018-10-07 15:14 ` Segher Boessenkool
2018-10-08 5:58 ` Ingo Molnar
2018-10-08 7:53 ` Segher Boessenkool
2018-10-07 15:53 ` Michael Matz
2018-10-08 6:13 ` Ingo Molnar
2018-10-08 8:18 ` Segher Boessenkool
2018-10-08 7:31 ` Segher Boessenkool
2018-10-08 9:07 ` Richard Biener
2018-10-08 10:02 ` Segher Boessenkool
2018-10-09 14:53 ` Segher Boessenkool
2018-10-10 6:35 ` Ingo Molnar
2018-10-10 7:12 ` Richard Biener
2018-10-10 7:22 ` Ingo Molnar
2018-10-10 8:03 ` Segher Boessenkool
2018-10-10 8:19 ` Borislav Petkov
2018-10-10 8:35 ` Richard Biener
2018-10-10 18:54 ` Segher Boessenkool
2018-10-10 19:14 ` Borislav Petkov
2018-10-13 19:33 ` Borislav Petkov
2018-10-13 21:14 ` Alexander Monakov
2018-10-13 21:30 ` Borislav Petkov
2018-10-25 10:24 ` Borislav Petkov
2018-10-31 12:55 ` Peter Zijlstra
2018-10-31 13:11 ` Peter Zijlstra
2018-10-31 16:31 ` Segher Boessenkool
2018-11-01 5:20 ` Joe Perches
2018-11-01 9:01 ` Peter Zijlstra
2018-11-01 9:20 ` Joe Perches
2018-11-01 11:15 ` Peter Zijlstra
2018-12-27 4:47 ` Masahiro Yamada
2018-10-10 10:29 ` Richard Biener
2018-10-10 7:53 ` Segher Boessenkool
2018-10-10 16:31 ` Nadav Amit
2018-10-10 19:21 ` Segher Boessenkool [this message]
2018-10-11 7:04 ` Richard Biener
2018-11-29 11:46 ` Masahiro Yamada
2018-11-29 12:25 ` Segher Boessenkool
2018-11-30 9:06 ` Boris Petkov
2018-11-30 13:16 ` Segher Boessenkool
2018-12-10 8:16 ` Masahiro Yamada
2018-11-29 13:07 ` Borislav Petkov
2018-11-29 13:09 ` Richard Biener
2018-11-29 13:16 ` Borislav Petkov
2018-11-29 13:24 ` Richard Biener
2018-10-08 16:24 ` David Laight
2018-10-07 16:09 ` Nadav Amit
2018-10-07 16:46 ` Richard Biener
2018-10-07 19:06 ` Nadav Amit
2018-10-07 19:52 ` Jeff Law
2018-10-08 7:46 ` Richard Biener
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