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Date: Mon, 23 Feb 2015 22:24:27 +0100
From: Corinna Vinschen <corinna-cygwin AT cygwin DOT com>
To: cygwin AT cygwin DOT com
Subject: Re: [PATCH] Teach gdb how to unwind cygwin _sigbe frames
Message-ID: <20150223212427.GB437@calimero.vinschen.de>
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References: <1424715301-13516-1-git-send-email-jon DOT turney AT dronecode DOT org DOT uk>
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On Feb 23 18:15, Jon TURNEY wrote:
> I really wanted to do this by adding some DWARF CFI to the generated sigf=
e.s
> file, but there doesn't seem to currently be a way to correctly describe
> _sigbe's frame using that.

I was wondering about this already.  It seems weird if the CFI stuff
doesn't allow for a situation like that.

> So instead, write a custom unwinder for _sigbe frames, which gets the ret=
urn
> address from the sigstack.
>=20
> Implemented for i386 and amd64.

Cool.  Really.  But, shouldn't that go to the gdb-patches mailing list?

> 4. This unfortunately ends up hardcoding into gdb the offset of sigstackp=
tr in
> the cygwin TLS area from the top of stack, and so will break if that chan=
ges.
> Hopefully that doesn't happen to often.

It happens too often to be ignored.  Wouldn't it make sense to add
a cygwin_internal call to return tls offsets or addresses, the later
if the argument is a pointer to the stack or cygtls area?


Thanks,
Corinna

--=20
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Maintainer                 cygwin AT cygwin DOT com
Red Hat

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