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Subject: Re: make PROT_WRITE imply PROT_READ
From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Arjan van de Ven <arjan@infradead.org>
Cc: Ulrich Drepper <drepper@gmail.com>, Pavel Machek <pavel@ucw.cz>,
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       linux-kernel@vger.kernel.org
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Date: Fri, 30 Jun 2006 13:20:59 +0100
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Ar Gwe, 2006-06-30 am 10:35 +0200, ysgrifennodd Arjan van de Ven:
> apps like JVM's forgot PROT_EXEC and break when the hardware enforces it
> apps that forget PROT_READ break when the kernel/hardware enforce it
> 
> not too much difference....

There is quite a difference. The _EXEC case behaves predictably for the
platforms that support it. At least I am not aware of cases that is not
true. The _READ case without the fault handling patch behaves
unpredictably depending on the precise ordering of events on a clean
page. 

Alan