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From: Grant Grundler <grundler@parisc-linux.org>
To: John David Anglin <dave@hiauly1.hia.nrc.ca>
Cc: parisc-linux@parisc-linux.org
Subject: Re: [parisc-linux] Space registers and how to use them
Date: Wed, 5 Oct 2005 22:59:36 -0600	[thread overview]
Message-ID: <20051006045936.GA27034@colo.lackof.org> (raw)
In-Reply-To: <200509251803.j8PI3tLI014517@hiauly1.hia.nrc.ca>

On Sun, Sep 25, 2005 at 02:03:55PM -0400, John David Anglin wrote:
> > John was just saying it doesn't matter since parisc-linux uses
> > the same value in all four (sr4-7) space registers.
> 
> It's possible for user code to mess with sr4.  It's not a
> privileged register.

Certainly. But in the kernel those are KERNEL_SPACE (zero).
We save/restore the user space values for sr4-7.
We clear sr4-sr7 in linux_gateway_entry (arch/parisc/kernel/syscall.S)
for syscalls.  We do the same for interrupts in virt_map macro in entry.S.

grant
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  reply	other threads:[~2005-10-06  4:59 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-09-25  3:43 [parisc-linux] Space registers and how to use them Matthew Wilcox
     [not found] ` <43367383.6030307@tiscali.be>
2005-09-25 17:35   ` Grant Grundler
2005-09-25 18:03     ` John David Anglin
2005-10-06  4:59       ` Grant Grundler [this message]
2005-09-25 17:43 ` John David Anglin
2005-09-25 18:17   ` Matthew Wilcox

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