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Re: [PATCH 2/3] MIPS: Preliminary vdso.

To: Manuel Lauss <>
Subject: Re: [PATCH 2/3] MIPS: Preliminary vdso.
From: Ralf Baechle <>
Date: Tue, 23 Feb 2010 22:35:18 +0100
Cc: David Daney <>,
In-reply-to: <>
Original-recipient: rfc822;
References: <> <> <>
User-agent: Mutt/1.5.20 (2009-08-17)
On Tue, Feb 23, 2010 at 09:40:38PM +0100, Manuel Lauss wrote:

> > This is a preliminary patch to add a vdso to all user processes.
> > Still missing are ELF headers and .eh_frame information.  But it is
> > enough to allow us to move signal trampolines off of the stack.  Note
> > that emulation of branch delay slots in the FPU emulator still
> > requires the stack.
> >
> > We allocate a single page (the vdso) and write all possible signal
> > trampolines into it.  The stack is moved down by one page and the vdso
> > is mapped into this space.
> Is there anything special required (i.e. special glibc, ..) to make use of 
> these
> fine patches?

No - the way the signal handlers return is almost entirely hidden from
userland.  Only a few applications that have the need to unwind beyond
the signal stackframe may run into problems and have to be updated and
GDB is one of those that we identified.


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