Date: Sat, 17 Feb 2007 12:51:34 +0100 From: Michael Nottebrock <lofi@freebsd.org> To: Rink Springer <rink@freebsd.org> Cc: freebsd-stable@freebsd.org Subject: Re: sysctl segfaulting Message-ID: <200702171251.35639.lofi@freebsd.org> In-Reply-To: <20070217103904.GB91175@rink.nu> References: <200702170947.49001.lofi@freebsd.org> <200702171136.50919.lofi@freebsd.org> <20070217103904.GB91175@rink.nu>
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On Saturday, 17. February 2007 11:39, Rink Springer wrote:
> Hi Michael,
>
> On Sat, Feb 17, 2007 at 11:36:46AM +0100, Michael Nottebrock wrote:
> > So I tried recompiling libc with debug cflags ("-g3 -O -pipe"), but this
> > only makes the backtrace in gdb much longer, but still without any
> > function names.
>
> Hmm, 'make install' appears to strip the debugging info.
Duh, I keep forgetting that.
> Please try=20
> gdb-ing /usr/obj/usr/src/sbin/sysctl/sysctl instead (assuming you use
> default the /usr/obj path like I do)
I recompiled/reinstalled both sysctl and libc with CFLAGS=3D-g3 and STRIP=
=3D"" and=20
now I get:
[lofi@lofi]:0:~ > gdb /sbin/sysctl
GNU gdb 6.1.1 [FreeBSD]
Copyright 2004 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain condition=
s.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB. Type "show warranty" for details.
This GDB was configured as "i386-marcel-freebsd"...
(gdb) set args kern.clockrate
(gdb) run
Starting program: /sbin/sysctl kern.clockrate
kern.clockrate:
Program received signal SIGSEGV, Segmentation fault.
0x08049696 in S_clockinfo (l2=3D20, p=3D0x804e000)=20
at /usr/src/sbin/sysctl/sysctl.c:333
333 printf(hflag ? "{ hz =3D %'d, tick =3D %'d, profhz =3D %'d,=
stathz=20
=3D %'d }" :
(gdb) bt
#0 0x08049696 in S_clockinfo (l2=3D20, p=3D0x804e000)
at /usr/src/sbin/sysctl/sysctl.c:333
#1 0x0804a5f2 in show_var (oid=3D0xbfbfea80, nlen=3D2)
at /usr/src/sbin/sysctl/sysctl.c:690
#2 0x08049093 in parse (string=3D0xbfbfecb1 "kern.clockrate")
at /usr/src/sbin/sysctl/sysctl.c:208
#3 0x08048e77 in main (argc=3D0, argv=3D0xbfbfeba0)=20
at /usr/src/sbin/sysctl/sysctl.c:152
(gdb) list
328 struct clockinfo *ci =3D (struct clockinfo*)p;
329 if (l2 !=3D sizeof(*ci)) {
330 warnx("S_clockinfo %d !=3D %d", l2, sizeof(*ci));
331 return (0);
332 }
333 printf(hflag ? "{ hz =3D %'d, tick =3D %'d, profhz =3D %'d,=
stathz=20
=3D %'d }" :
334 "{ hz =3D %d, tick =3D %d, profhz =3D %d, stathz =
=3D %d }",
335 ci->hz, ci->tick, ci->profhz, ci->stathz);
336 return (0);
337 }
(gdb) print ci->hz
Error accessing memory address 0x804e000: Bad address.
(gdb) print ci->tick
Error accessing memory address 0x804e004: Bad address.
(gdb) print ci->profhz
Error accessing memory address 0x804e010: Bad address.
(gdb) print ci->stathz
Error accessing memory address 0x804e00c: Bad address.
(gdb) print ci
$1 =3D (struct clockinfo *) 0x804e000
(gdb) print p
$2 =3D (void *) 0x804e000
(gdb) print l2
$3 =3D 20
=2D-=20
,_, | Michael Nottebrock | lofi@freebsd.org
(/^ ^\) | FreeBSD - The Power to Serve | http://www.freebsd.org
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