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Re: Adding(?) XI support to MIPS-Linux?

To: Brian Foster <brian.foster@innova-card.com>
Subject: Re: Adding(?) XI support to MIPS-Linux?
From: "Kevin D. Kissell" <kevink@paralogos.com>
Date: Wed, 18 Jun 2008 11:36:53 +0200
Cc: linux-mips@linux-mips.org, David Daney <ddaney@avtrex.com>, Thiemo Seufer <ths@networkno.de>, Andrew Dyer <adyer@righthandtech.com>
In-reply-to: <200806181042.12911.brian.foster@innova-card.com>
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Brian Foster wrote:
 Whilst thinking about the problem and possible solutions,
 it occurred to me there could be a defect in the current
 trampoline:  Suppose there is a signal, either at point A,
 due to <instr> itself, or at point B, which is caught on
 this stack, and the user-land signal-handler ‘return’s.

 Doesn't the signal-handler/sigreturn stack-frame overwrite
 the FP trampoline?   In which case, when the signal-hander
 returns, more-or-less anything could happen.  (And very
 unlikely to be what's wanted!)
When I first integrated the FP emulator into the kernel, back in 2.2.x, I seem to recall that someone found this problem and that I came up with a tweak to signal stack setup that protected the FP branch delay slot trampoline. Maybe I'm mistaken,
or maybe the tweak was lost?

         Regards,

         Kevin K.

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