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From: Borislav Petkov <bp@alien8.de>
To: Nadav Amit <namit@vmware.com>,
	Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	"H . Peter Anvin" <hpa@zytor.com>, X86 ML <x86@kernel.org>,
	Richard Biener <rguenther@suse.de>,
	Logan Gunthorpe <logang@deltatee.com>,
	Sedat Dilek <sedat.dilek@gmail.com>,
	Segher Boessenkool <segher@kernel.crashing.org>,
	linux-arch <linux-arch@vger.kernel.org>,
	Arnd Bergmann <arnd@arndb.de>,
	Luc Van Oostenryck <luc.vanoostenryck@gmail.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	"virtualization@lists.linux-foundation.org"
	<virtualization@lists.linux-foundation.org>,
	Michal Marek <michal.lkml@markovi.net>,
	"linux-sparse@vger.kernel.org" <linux-sparse@vger.kernel.org>,
	Alok Kataria <akataria@vmware.com>,
	Juergen Gross <jgross@suse.com>,
	Andy Lutomirski <luto@kernel.org>,
	Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>
Subject: Re: [PATCH] kbuild, x86: revert macros in extended asm workarounds
Date: Sun, 16 Dec 2018 11:00:42 +0100	[thread overview]
Message-ID: <20181216100042.GA815@zn.tnic> (raw)
In-Reply-To: <07BE39B2-1F99-4AE4-97F3-0871A39C5E7D@vmware.com>

On Sun, Dec 16, 2018 at 02:33:39AM +0000, Nadav Amit wrote:
> In general, I think that from the start it was clear that the motivation for
> the patch-set is not just performance and also better code. For example, I
> see no reason to revert the PV-changes or the lock-prefix changes that
> improved the code readability.

One thing that has caught my eye with the asm macros, which actually
decreases readability, is that I can't see the macro properly expanded
when I do

make <filename>.s

For example, I get

#APP
# 164 "./arch/x86/include/asm/cpufeature.h" 1
        STATIC_CPU_HAS bitnum=$8 cap_byte="boot_cpu_data+35(%rip)" feature=123 t_yes=.L75 t_no=.L78 always=117  #, MEM[(const char *)&boot_cpu_data + 35B],,,,
# 0 "" 2
        .loc 11 164 2 view .LVU480
#NO_APP

but I'd like to see the actual asm as it is really helpful when hacking
on inline asm stuff. And I haven't found a way to make gcc expand asm
macros in .s output.

Now, assuming the gcc inline patch will be backported to gcc8, I think
we should be covered on all modern distros going forward. So I think we
should revert at least the more complex macros.

-- 
Regards/Gruss,
    Boris.

Good mailing practices for 400: avoid top-posting and trim the reply.

  reply	other threads:[~2018-12-16 10:00 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-12-13  9:17 [PATCH] kbuild, x86: revert macros in extended asm workarounds Masahiro Yamada
2018-12-13 10:51 ` Peter Zijlstra
2018-12-15  0:51   ` Masahiro Yamada
2018-12-16  2:33     ` Nadav Amit
2018-12-16 10:00       ` Borislav Petkov [this message]
2018-12-17  1:00         ` Nadav Amit
2018-12-17  9:16 ` Sedat Dilek
2018-12-18 19:33   ` Nadav Amit

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