Date: Wed, 06 Apr 2011 10:17:00 -0700 From: Julian Elischer <julian@freebsd.org> To: John Baldwin <jhb@freebsd.org> Cc: freebsd-current@freebsd.org, Justin Hibbits <chmeeedalf@gmail.com>, Navdeep Parhar <nparhar@gmail.com>, FreeBSD Current <current@freebsd.org> Subject: Re: KGDB stack traces in the kernel. Message-ID: <4D9CA00C.20307@freebsd.org> In-Reply-To: <201104060845.11771.jhb@freebsd.org> References: <4D9A4CE5.5090900@freebsd.org> <4D9B7C92.6030901@freebsd.org> <BANLkTinPdVUac6YGwf4GvOE7gtndbQERaQ@mail.gmail.com> <201104060845.11771.jhb@freebsd.org>
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On 4/6/11 5:45 AM, John Baldwin wrote:
> On Tuesday, April 05, 2011 4:35:44 pm Navdeep Parhar wrote:
>> On Tue, Apr 5, 2011 at 1:33 PM, Julian Elischer<julian@freebsd.org> wrote:
>>> On 4/4/11 6:04 PM, Justin Hibbits wrote:
>>>
>> What does ddb do? It always seems to get this stuff correct.
> ddb knows to stop when it gets to a non-kernel address, and it uses string
> compares on function names to identify trap frames. For example in
> sys/amd64/amd64/db_trace.c:
>
>
> if (strcmp(name, "calltrap") == 0 ||
> strcmp(name, "fork_trampoline") == 0 ||
> strcmp(name, "nmi_calltrap") == 0 ||
> strcmp(name, "Xdblfault") == 0)
> frame_type = TRAP;
>
> Hah, kgdb just needs to be updated (this is from trgt_amd64.c):
>
> const struct frame_unwind *
> kgdb_trgt_trapframe_sniffer(struct frame_info *next_frame)
> {
> char *pname;
> CORE_ADDR pc;
>
> pc = frame_pc_unwind(next_frame);
> pname = NULL;
> find_pc_partial_function(pc,&pname, NULL, NULL);
> if (pname == NULL)
> return (NULL);
> if (strcmp(pname, "calltrap") == 0 ||
> strcmp(pname, "nmi_calltrap") == 0 ||
> (pname[0] == 'X'&& pname[1] != '_'))
> return (&kgdb_trgt_trapframe_unwind);
> /* printf("%s: %lx =%s\n", __func__, pc, pname); */
> return (NULL);
> }
>
I'll give that a try
> Can probably just add 'fork_trampoline' to that conditional. I think i386
> needs a similar fix in kgdb. Not sure about other architectures:
>
> Index: trgt_amd64.c
> ===================================================================
> --- trgt_amd64.c (revision 220190)
> +++ trgt_amd64.c (working copy)
> @@ -184,6 +184,7 @@
> if (pname == NULL)
> return (NULL);
> if (strcmp(pname, "calltrap") == 0 ||
> + strcmp(pname, "fork_trampoline") == 0 ||
> strcmp(pname, "nmi_calltrap") == 0 ||
> (pname[0] == 'X'&& pname[1] != '_'))
> return (&kgdb_trgt_trapframe_unwind);
> Index: trgt_i386.c
> ===================================================================
> --- trgt_i386.c (revision 220190)
> +++ trgt_i386.c (working copy)
> @@ -374,6 +374,7 @@
> if (strcmp(pname, "dblfault_handler") == 0)
> return (&kgdb_trgt_dblfault_unwind);
> if (strcmp(pname, "calltrap") == 0 ||
> + strcmp(pname, "fork_trampoline") == 0 ||
> (pname[0] == 'X'&& pname[1] != '_'))
> return (&kgdb_trgt_trapframe_unwind);
> /* printf("%s: %llx =%s\n", __func__, pc, pname); */
>
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