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
WARNING: multiple messages have this Message-ID (diff)
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> 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: 186+ 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 ` 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 2018-10-03 21:30 ` 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 2018-10-03 21:30 ` 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 2018-10-07 9:18 ` Borislav Petkov 2018-10-07 9:18 ` Borislav Petkov 2018-10-07 13:22 ` Segher Boessenkool 2018-10-07 14:13 ` Borislav Petkov 2018-10-07 14:13 ` Borislav Petkov 2018-10-07 15:14 ` Segher Boessenkool 2018-10-07 15:14 ` Segher Boessenkool 2018-10-08 5:58 ` Ingo Molnar 2018-10-08 5:58 ` Ingo Molnar 2018-10-08 5:58 ` Ingo Molnar 2018-10-08 7:53 ` Segher Boessenkool 2018-10-08 7:53 ` Segher Boessenkool 2018-10-07 14:13 ` Borislav Petkov 2018-10-07 15:53 ` Michael Matz 2018-10-07 15:53 ` Michael Matz 2018-10-08 6:13 ` Ingo Molnar 2018-10-08 6:13 ` Ingo Molnar 2018-10-08 8:18 ` Segher Boessenkool 2018-10-08 8:18 ` Segher Boessenkool 2018-10-08 7:31 ` Segher Boessenkool 2018-10-08 7:31 ` Segher Boessenkool 2018-10-08 9:07 ` Richard Biener 2018-10-08 9:07 ` Richard Biener 2018-10-08 10:02 ` Segher Boessenkool 2018-10-08 10:02 ` Segher Boessenkool 2018-10-09 14:53 ` Segher Boessenkool 2018-10-09 14:53 ` Segher Boessenkool 2018-10-10 6:35 ` Ingo Molnar 2018-10-10 6:35 ` Ingo Molnar 2018-10-10 7:12 ` Richard Biener 2018-10-10 7:12 ` Richard Biener 2018-10-10 7:22 ` Ingo Molnar 2018-10-10 7:22 ` Ingo Molnar 2018-10-10 8:03 ` Segher Boessenkool 2018-10-10 8:03 ` Segher Boessenkool 2018-10-10 8:19 ` Borislav Petkov 2018-10-10 8:19 ` Borislav Petkov 2018-10-10 8:19 ` Borislav Petkov 2018-10-10 8:35 ` Richard Biener 2018-10-10 8:35 ` Richard Biener 2018-10-10 18:54 ` Segher Boessenkool 2018-10-10 18:54 ` Segher Boessenkool 2018-10-10 19:14 ` Borislav Petkov 2018-10-10 19:14 ` Borislav Petkov 2018-10-10 19:14 ` Borislav Petkov 2018-10-13 19:33 ` Borislav Petkov 2018-10-13 19:33 ` Borislav Petkov 2018-10-13 21:14 ` Alexander Monakov 2018-10-13 21:14 ` Alexander Monakov 2018-10-13 21:30 ` Borislav Petkov 2018-10-13 21:30 ` Borislav Petkov 2018-10-25 10:24 ` Borislav Petkov 2018-10-25 10:24 ` Borislav Petkov 2018-10-25 10:24 ` Borislav Petkov 2018-10-31 12:55 ` Peter Zijlstra 2018-10-31 12:55 ` Peter Zijlstra 2018-10-31 13:11 ` Peter Zijlstra 2018-10-31 13:11 ` Peter Zijlstra 2018-10-31 16:31 ` Segher Boessenkool 2018-10-31 16:31 ` Segher Boessenkool 2018-11-01 5:20 ` Joe Perches 2018-11-01 5:20 ` Joe Perches 2018-11-01 9:01 ` Peter Zijlstra 2018-11-01 9:01 ` Peter Zijlstra 2018-11-01 9:20 ` Joe Perches 2018-11-01 9:20 ` Joe Perches 2018-11-01 11:15 ` Peter Zijlstra 2018-11-01 11:15 ` Peter Zijlstra 2018-11-01 9:20 ` Joe Perches 2018-11-01 5:20 ` Joe Perches 2018-12-27 4:47 ` Masahiro Yamada 2018-12-27 4:47 ` Masahiro Yamada 2018-10-10 10:29 ` Richard Biener 2018-10-10 10:29 ` Richard Biener 2018-10-10 7:53 ` Segher Boessenkool 2018-10-10 7:53 ` Segher Boessenkool 2018-10-10 16:31 ` Nadav Amit 2018-10-10 16:31 ` Nadav Amit 2018-10-10 19:21 ` Segher Boessenkool [this message] 2018-10-10 19:21 ` Segher Boessenkool 2018-10-11 7:04 ` Richard Biener 2018-10-11 7:04 ` Richard Biener 2018-11-29 11:46 ` Masahiro Yamada 2018-11-29 11:46 ` Masahiro Yamada 2018-11-29 11:46 ` Masahiro Yamada 2018-11-29 12:25 ` Segher Boessenkool 2018-11-29 12:25 ` Segher Boessenkool 2018-11-30 9:06 ` Boris Petkov via Virtualization 2018-11-30 9:06 ` Boris Petkov 2018-11-30 9:06 ` Boris Petkov 2018-11-30 13:16 ` Segher Boessenkool 2018-11-30 13:16 ` Segher Boessenkool 2018-12-10 8:16 ` Masahiro Yamada 2018-12-10 8:16 ` Masahiro Yamada 2018-12-10 8:16 ` Masahiro Yamada 2018-11-29 13:07 ` Borislav Petkov 2018-11-29 13:07 ` Borislav Petkov via Virtualization 2018-11-29 13:09 ` Richard Biener 2018-11-29 13:09 ` Richard Biener 2018-11-29 13:16 ` Borislav Petkov via Virtualization 2018-11-29 13:16 ` Borislav Petkov 2018-11-29 13:16 ` Borislav Petkov 2018-11-29 13:24 ` Richard Biener 2018-11-29 13:24 ` Richard Biener 2018-10-08 16:24 ` David Laight 2018-10-08 16:24 ` David Laight 2018-10-08 16:24 ` David Laight 2018-10-07 16:09 ` Nadav Amit 2018-10-07 16:09 ` Nadav Amit 2018-10-07 16:13 ` [RESEND] " Nadav Amit 2018-10-07 16:46 ` Richard Biener 2018-10-07 16:46 ` Richard Biener 2018-10-07 19:06 ` Nadav Amit 2018-10-07 19:06 ` Nadav Amit 2018-10-07 19:52 ` Jeff Law 2018-10-07 19:52 ` Jeff Law 2018-10-08 7:46 ` Richard Biener 2018-10-08 7:46 ` Richard Biener
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=20181010192111.GD29268@gate.crashing.org \ --to=segher@kernel.crashing.org \ --cc=JBeulich@suse.com \ --cc=akataria@vmware.com \ --cc=bp@alien8.de \ --cc=chris@zankel.net \ --cc=gcc@gcc.gnu.org \ --cc=gregkh@linuxfoundation.org \ --cc=hpa@zytor.com \ --cc=jcmvbkbc@gmail.com \ --cc=jgross@suse.com \ --cc=jpoimboe@redhat.com \ --cc=keescook@chromium.org \ --cc=kstewart@linuxfoundation.org \ --cc=linux-kernel@vger.kernel.org \ --cc=linux-sparse@vger.kernel.org \ --cc=linux-xtensa@linux-xtensa.org \ --cc=matz@suse.de \ --cc=mingo@redhat.com \ --cc=namit@vmware.com \ --cc=peterz@infradead.org \ --cc=pombredanne@nexb.com \ --cc=rguenther@suse.de \ --cc=sam@ravnborg.org \ --cc=sparse@chrisli.org \ --cc=tglx@linutronix.de \ --cc=torvalds@linux-foundation.org \ --cc=virtualization@lists.linux-foundation.org \ --cc=x86@kernel.org \ --cc=yamada.masahiro@socionext.com \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: linkBe sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes, see mirroring instructions on how to clone and mirror all data and code used by this external index.