From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Chris Wedgwood <cw@f00f.org>
Cc: akpm@osdl.org, linux-arch@vger.kernel.org, jbaron@redhat.com,
ak@muc.de, arjan@linux.intel.com, benh@kernel.crashing.org,
geert@linux-m68k.org, hugh@veritas.com, kkojima@rr.iij4u.or.jp,
lethal@linux-sh.org, paulus@samba.org, rmk@arm.linux.org.uk,
spyro@f2s.com, tony.luck@intel.com, zippel@linux-m68k.org
Subject: Re: [patch 1/1] make PROT_WRITE imply PROT_READ
Date: Sun, 17 Sep 2006 22:14:06 +0100 [thread overview]
Message-ID: <1158527646.6069.67.camel@localhost.localdomain> (raw)
In-Reply-To: <20060917202408.GA10031@tuatara.stupidest.org>
Ar Sul, 2006-09-17 am 13:24 -0700, ysgrifennodd Chris Wedgwood:
> On Thu, Sep 14, 2006 at 06:39:47PM -0700, akpm@osdl.org wrote:
>
> > Make PROT_WRITE imply PROT_READ for a number of architectures which
> > don't support write only in hardware.
>
> Why don't we WARN where PROT_WRITE is used w/o PROT_READ? Do
> non-trivial or non-contrived applications really use PROT_WRITE and
> assume reads are OK?
Unfortunately yes. This was discovered in the real world.
> It seems once we do this there will be little or no chance of ever
> doing write-only mappings should we want to in the future using this
> mechanism.
Executable types already let us handle that, or as you suggest but the
other way around you add PROT_REALLYLIKEWRITEONLYOK as a new mmap type
(and as PROT_WRITE) for a new binary format later if the CPU ever
supports it. Frankly I think the odds of Intel cpus growing write-only
are remote....
Alan
next prev parent reply other threads:[~2006-09-17 20:51 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-09-15 1:39 [patch 1/1] make PROT_WRITE imply PROT_READ akpm
2006-09-15 4:53 ` Arjan van de Ven
2006-09-15 11:10 ` Alan Cox
2006-09-15 8:06 ` Geert Uytterhoeven
2006-09-15 10:58 ` Alan Cox
2006-09-15 8:47 ` Andi Kleen
2006-09-15 11:12 ` Alan Cox
2006-09-16 0:40 ` Ralf Baechle
2006-09-17 11:59 ` Paul Mundt
2006-09-17 20:24 ` Chris Wedgwood
2006-09-17 20:48 ` Arjan van de Ven
2006-09-17 21:14 ` Alan Cox [this message]
2006-09-17 21:05 ` Arjan van de Ven
2006-09-18 0:57 ` Chris Wedgwood
2006-09-18 2:03 ` Paul Mackerras
2006-09-18 4:31 ` Chris Wedgwood
2006-09-18 8:15 ` Geert Uytterhoeven
2006-09-18 9:26 ` Alan Cox
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