[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <20150603070441.GB26167@gmail.com>
Date: Wed, 3 Jun 2015 09:04:41 +0200
From: Ingo Molnar <mingo@...nel.org>
To: Steven Rostedt <rostedt@...dmis.org>
Cc: Denys Vlasenko <dvlasenk@...hat.com>,
Linus Torvalds <torvalds@...ux-foundation.org>,
Borislav Petkov <bp@...en8.de>,
"H. Peter Anvin" <hpa@...or.com>,
Andy Lutomirski <luto@...capital.net>,
Oleg Nesterov <oleg@...hat.com>,
Frederic Weisbecker <fweisbec@...il.com>,
Alexei Starovoitov <ast@...mgrid.com>,
Will Drewry <wad@...omium.org>,
Kees Cook <keescook@...omium.org>, x86@...nel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] x86/asm/entry/32: Open-code CLEAR_RREGS. No code
changes.
* Steven Rostedt <rostedt@...dmis.org> wrote:
> On Tue, 2 Jun 2015 21:04:01 +0200
> Denys Vlasenko <dvlasenk@...hat.com> wrote:
>
> > This macro is small, has only four callsites, and one of them is slightly
> > different using a conditional parameter.
> >
> > A few saved lines aren't worth the resulting obfuscation.
>
> I'm curious, why? Did someone recommend this change? I don't see it as
> obfuscation at all.
So here are a few easy questions, I'm wondering how many minutes it takes for you
to answer them correctly:
- What does the CLEAR_RREGS name stand for?
- What is this macro's purpose?
- In a single case CLEAR_RREGS takes a 'r9' argument:
arch/x86/ia32/ia32entry.S: CLEAR_RREGS
arch/x86/ia32/ia32entry.S: CLEAR_RREGS
arch/x86/ia32/ia32entry.S: CLEAR_RREGS r9
arch/x86/ia32/ia32entry.S: CLEAR_RREGS
arch/x86/ia32/ia32entry.S: CLEAR_RREGS
What is the 'r9' argument's purpose and why is activated in the place where
it's activated?
The CLEAR_RREGS macro has zero comments. If it takes more than a quick glance to
determine all these three first-order questions from the source code, then it's an
obvious code cleanliness fail which needs to be improved.
Thanks,
Ingo
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists