Date: Fri, 7 Jun 2019 19:24:55 -0700 From: Mark Millard <marklmi@yahoo.com> To: FreeBSD PowerPC ML <freebsd-ppc@freebsd.org> Subject: crash of 32-bit powerpc -r347549 kernel built via system-clang-8, an earlier problem: Process (pid 1) got signal 11 Message-ID: <7B6A6973-AB76-4DDF-8729-F6CC08CFD87C@yahoo.com>
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I earlier tried making a debug kernel build via system-clang-8, as
reported in a different thread.
Well, I tried with debug with DIAGNOSTICS and got an earlier
problem:
Process (pid 1) got signal 11
from sys/kern/kern_sig.c 's code that looks like:
static int
issignal(struct thread *td)
. . .
case (intptr_t)SIG_DFL:
/*
* Don't take default actions on system =
processes.
*/
if (p->p_pid <=3D 1) {
#ifdef DIAGNOSTIC
/*
* Are you sure you want to ignore =
SIGSEGV
* in init? XXX
*/
printf("Process (pid %lu) got signal =
%d\n",
(u_long)p->p_pid, sig);
#endif
break; /* =3D=3D ignore */
}
So I changed the code to do a kdb_enter:
static int
issignal(struct thread *td)
. . .
switch =
((intptr_t)p->p_sigacts->ps_sigact[_SIG_IDX(sig)]) {
=20
case (intptr_t)SIG_DFL:
/*
* Don't take default actions on system =
processes.
*/
if (p->p_pid <=3D 1) {
#ifdef DIAGNOSTIC
//if (p->p_pid=3D=3D1 && sig=3D=3D11) =
break; // HACK!!!
/*
* Are you sure you want to ignore =
SIGSEGV
* in init? XXX
*/
printf("Process (pid %lu) got signal =
%d\n",
(u_long)p->p_pid, sig);
if (p->p_pid=3D=3D1 && sig=3D=3D11) =
kdb_enter(NULL, "p_pid 1 got sig 11"); // HACK!!!
#endif
break; /* =3D=3D ignore */
}
Testing with this reported (for example):
KDB: enter p_pid 1 got signal 11
[ thread pid 1 tid 100002 ]
Stopped at kdb_enter+0x74: addi r3,r0,0x0
db> bt
Tracing pid 1 tid 100002 td 0x1506ae0
0xd6b7c950: at cursig+0x55c
0xd6b7ca10: at ast+0x508
0xd6b7ca40: user DSI read trap @ 0x1c000020 by 0x1812f74: srr1=3D0xd032
r1=3D0xffffde90 cr=3D0x20000000 xer=3D0 ctr=3D0 =
sr=3D0x40000000 frame=3D0xd6b7ca48
db>
Another example "trap @" was 0xfa5005af (still by 0x1812f74 and with the =
rest
matching). (The 0xfa5005af "trap @" value looks like a potentially =
deliberate
pattern that might indicate something.)
These happen before the panic reported previously reported.
This happens for both usefdt mode and not using the mode, but
only for clang-based (not gcc 4.2.1 based).
It may be that the usefdt mode status controls which "trap @" figure
shows up.
The following lines displayed just before the "got signal"
line:
Trying to mount root from ufs:/dev/ufs/FBSDG4rootfs [rw,noatime]...
Launching APs: 1 3 2
WARNING: WITNESS option enabled, . . .
WARNING: DIAGNOSTIC option enabled, . . .
(Sometimes some of the text is interlaced/garbled but this
gives an idea of when in the sequence the signals start.)
(Note: The test machine is a 2-socket/2-core-each PowerMac G5,
used via 32-bit FreeBSD here.)
=3D=3D=3D
Mark Millard
marklmi at yahoo.com
( dsl-only.net went
away in early 2018-Mar)
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