Date: Sat, 18 Sep 2010 20:26:36 +0200 From: Attilio Rao <attilio@freebsd.org> To: Andriy Gapon <avg@icyb.net.ua> Cc: freebsd-hackers@freebsd.org Subject: Re: KDB_TRACE and no backend Message-ID: <AANLkTingR6k6xdQJ3cZH8EkJeCWnq5vzeEjGHNaDv8AT@mail.gmail.com> In-Reply-To: <4C94A138.8050905@icyb.net.ua> References: <4C94A138.8050905@icyb.net.ua>
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2010/9/18 Andriy Gapon <avg@icyb.net.ua>:
>
> Here's a small patch that adds support for printing stack trace in form o=
f frame
> addresses when KDB_TRACE is enabled, but there is no debugger backend con=
figured.
> The patch is styled after "cheap" variant of stack_ktr.
>
> What do you think (useful/useless, correct, etc) ?
>
> --- a/sys/kern/subr_kdb.c
> +++ b/sys/kern/subr_kdb.c
> @@ -37,6 +37,7 @@
> =C2=A0#include <sys/pcpu.h>
> =C2=A0#include <sys/proc.h>
> =C2=A0#include <sys/smp.h>
> +#include <sys/stack.h>
> =C2=A0#include <sys/sysctl.h>
>
> =C2=A0#include <machine/kdb.h>
> @@ -295,10 +296,16 @@
> =C2=A0void
> =C2=A0kdb_backtrace(void)
> =C2=A0{
> + =C2=A0 =C2=A0 =C2=A0 struct stack st;
> + =C2=A0 =C2=A0 =C2=A0 int i;
>
> - =C2=A0 =C2=A0 =C2=A0 if (kdb_dbbe !=3D NULL && kdb_dbbe->dbbe_trace !=
=3D NULL) {
> - =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 printf("KDB: stack bac=
ktrace:\n");
> + =C2=A0 =C2=A0 =C2=A0 printf("KDB: stack backtrace:\n");
> + =C2=A0 =C2=A0 =C2=A0 if (kdb_dbbe !=3D NULL && kdb_dbbe->dbbe_trace !=
=3D NULL)
> =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0kdb_dbbe->dbbe_tra=
ce();
> + =C2=A0 =C2=A0 =C2=A0 else {
> + =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 stack_save(&st);
> + =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 for (i =3D 0; i < st.d=
epth; i++)
> + =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =
=C2=A0 printf("#%d %p\n", i, (void*)(uintptr_t)st.pcs[i]);
> =C2=A0 =C2=A0 =C2=A0 =C2=A0}
> =C2=A0}
You have to eventually wrap this logic within the 'STACK' option
(opt_stack.h for the check) because stack_save() will be uneffective
otherwise. STACK should be mandatory for DDB I guess, but it is not
for KDB.
Thanks,
Attilio
--=20
Peace can only be achieved by understanding - A. Einstein
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