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Subject: Re: [9front] stats(1) suicide
From: arisawa <arisawa@ar.aichi-u.ac.jp>
In-Reply-To: <b370d35e690e4ec0db1c9bcd89adab0e@felloff.net>
Date: Fri, 8 Aug 2014 16:45:53 +0900
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Hello,
I have similar problem with cwfs64x on pc64.

the system is based on the latest release:
9front-3730.5d864bfef728.iso.bz2

I did
rm -rf /sys/src/*
and copied the iso to the /sys/src
and
cd /sys/src && mk install
cd /sys/src/9/pc64
mk
9fat:
cp 9pc64 /n/9fat
fshalt -r

bootargs is .....
user[glenda]: arisawa
cwfs64x 319: suicide: invalid address 0x1056efee8/16384 in syscall =
pc=3D0x22ac56
cwfs64x 319: suicide: sys: bad address in syscall pc=3D0x22ac56
...


9pc64 kernel below works.
--rwxrwxr-x M 20 arisawa sys 3502641 May 28 22:11 /amd64/9pc64

official cwfs source codes are not modified since that day.
note that cwfs64x for 386 works fine

your patch
> ((void**)&ureg)[-1] =3D (void*)noteret;	/* restores BP */
did not help me

2014/08/07 20:56=E3=80=81cinap_lenrek@felloff.net =E3=81=AE=E3=83=A1=E3=83=
=BC=E3=83=AB=EF=BC=9A

> thanks! i know whats wrong.
>=20
> network timeout (alarm note) is the trigger. the bug was introduced =
in:
>=20
> =
http://code.google.com/p/plan9front/source/detail?r=3Da2985da84dc3e147251c=
75c5839d1d074b1e7506&path=3D/sys/src/9/pc64/l.s
>=20
> the problem is that forkret() in l.s doesnt restore BP register from
> the ureg (anymore!). the first argument to a function is passed in BP
> (also known as RARG). as its not loaded from the ureg, the first =
argument
> to the note handler is garbage. which causes the crash. most note =
handlers
> ignore the ureg argument (so it works all fine with other programs), =
but
> not with this alarm note handler which tries todo a stack unwind with =
the
> note jump.
>=20
> i'm at work and have no access to amd64 machine right now so i cant
> test anything, but you can probably fix it with a single line in
> pc64/trap.c, function syscall():
>=20
>=20
>        if(scallnr!=3DRFORK && (up->procctl || up->nnote)){
>                splhi();
>                notify(ureg);
> +				((void**)&ureg)[-1] =3D (void*)noteret;	=
/* restores BP */
>        }
>=20
> --
> cinap