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Date:      Thu, 11 May 2017 00:13:15 +0000
From:      bugzilla-noreply@freebsd.org
To:        freebsd-toolchain@FreeBSD.org
Subject:   [Bug 219153] head, stable/11, release/11.0.1: libkvm (& more?) not updated to handle powerpc/powerpc64 ET_DYN based vmcore.* 's and such
Message-ID:  <bug-219153-29464-2pzrB9DGJx@https.bugs.freebsd.org/bugzilla/>
In-Reply-To: <bug-219153-29464@https.bugs.freebsd.org/bugzilla/>
References:  <bug-219153-29464@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D219153

--- Comment #9 from Mark Millard <markmi@dsl-only.net> ---
(In reply to John Baldwin from comment #5)

As for ps -M /var/crash/vmcore.7 listing no
processes:

main uses kvm_getprocs, which in turn eventually
does:

                        if (KREAD(kd, nl[0].n_value, &nprocs)) {
                                _kvm_err(kd, kd->program, "can't read nproc=
s");
                                return (0);
                        }

but that ends up with:

(gdb) print nprocs
$2 =3D 12873340

(I checked the code and "info reg" and the value
matched.)

So things are already well messed up here.

That in turn ends up used in:

                        size =3D nprocs * sizeof(struct kinfo_proc);
                        kd->procbase =3D (struct kinfo_proc *)_kvm_malloc(k=
d,
size);
                        if (kd->procbase =3D=3D NULL)
                                return (0);

which succeeds but later there is:

                        nprocs =3D kvm_deadprocs(kd, op, arg, nl[1].n_value,
                                              nl[2].n_value, nprocs);
                        if (nprocs <=3D 0) {
                                _kvm_freeprocs(kd);
                                nprocs =3D 0;
                        }

which in kvm_deadprocs gets to:

                if (KREAD(kd, a_allproc, &p)) {
                        _kvm_err(kd, kd->program, "cannot read allproc");
                        return (-1);
                }
                acnt =3D kvm_proclist(kd, what, arg, p, bp, maxcnt);
                if (acnt < 0)
                        return (acnt);

where:

        static int
        kvm_proclist(kvm_t *kd, int what, int arg, struct proc *p,
            struct kinfo_proc *bp, int maxcnt)
        {
                int cnt =3D 0;
. . .

is used via:

kvm_proclist (kd=3D0x41e14000, what=3D5, arg=3D0, p=3D0x0, bp=3D0x42000000,
maxcnt=3D12873340)

and the internal kvm_proclist loop no-ops because of p:

                for (; cnt < maxcnt && p !=3D NULL; p =3D LIST_NEXT(&proc, =
p_list))
{

So no process is listed. After the loop is:

                return (cnt);
        }

And that means:

                        nprocs =3D kvm_deadprocs(kd, op, arg, nl[1].n_value,
                                              nl[2].n_value, nprocs);
                        if (nprocs <=3D 0) {
                                _kvm_freeprocs(kd);
                                nprocs =3D 0;
                        }

ends up with nprocs=3D=3D0 and kd is freed, hopefully including
kd->procbase being freed (I did not look).

But overall: at least one KREAD gets back a junk figure.

And with that I think I will stop for this note.

--=20
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