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Subject: Re: valgrind on amd64 crashes when delivering signal for threaded
 application
From: Stanislav Sedov <stas@freebsd.org>
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Date: Wed, 23 Apr 2014 23:18:57 -0700
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To: Mikolaj Golub <trociny@freebsd.org>
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On Apr 23, 2014, at 1:01 PM, Mikolaj Golub <trociny@freebsd.org> wrote:

>  --- coregrind/m_sigframe/sigframe-amd64-freebsd.c.orig  2014-04-23 =
22:39:45.000000000 +0300
>  +++ coregrind/m_sigframe/sigframe-amd64-freebsd.c       2014-04-23 =
22:40:23.000000000 +0300
>  @@ -250,7 +250,7 @@ static Addr build_sigframe(ThreadState *
>      UWord err;
>=20
>      rsp -=3D sizeof(*frame);
>  -   rsp =3D VG_ROUNDDN(rsp, 16);
>  +   rsp =3D VG_ROUNDDN(rsp, 16) - 8;
>      frame =3D (struct sigframe *)rsp;
>=20
>      if (!extend(tst, rsp, sizeof(*frame)))
>=20
> Unfortunately, I have poor understanding of valgrind internals and
> what is going on exactly when it delivers a signal to the process, so
> failed to find a proper fix.

This sounds like a proper solution to me though.  Stack handling in =
valgrind
is indeed convoluted, but it seems in this case it clearly misaligns the =
stack
as it does not take into account the return address.  Any objections if =
I commit
this fix to valgrind-freebsd?

Thanks a lot for tracking this!

--
ST4096-RIPE