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From:   "Rafael J. Wysocki" <rjw@rjwysocki.net>
To:     Jeremy Linton <jeremy.linton@arm.com>
Cc:     "Rafael J. Wysocki" <rafael@kernel.org>,
        "Schmauss, Erik" <erik.schmauss@intel.com>,
        "linux-acpi@vger.kernel.org" <linux-acpi@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-arm-kernel@lists.infradead.org" 
        <linux-arm-kernel@lists.infradead.org>,
        Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Subject: Re: 4.18rc3 TX2 boot failure with "ACPICA: AML parser: attempt to continue loading table after error"
Date:   Tue, 10 Jul 2018 13:13:17 +0200
Message-ID: <3574827.zOC4apc8e1@aspire.rjw.lan>
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On Tuesday, July 10, 2018 5:44:05 AM CEST Jeremy Linton wrote:
> Hi,
> 
> On 07/09/2018 04:28 PM, Rafael J. Wysocki wrote:
> > On Mon, Jul 9, 2018 at 10:45 PM, Jeremy Linton <jeremy.linton@arm.com> wrote:
> >> Hi,
> >>
> >> First thanks for the patch..
> >>
> >> On 07/08/2018 04:14 AM, Rafael J. Wysocki wrote:
> >>>
> >>> On Monday, July 2, 2018 11:41:42 PM CEST Jeremy Linton wrote:
> >>>>
> >>>> Hi,
> >>>>
> >>>> I'm experiencing two problems with commit 5088814a6e931 which is
> >>>> "ACPICA: AML parser: attempt to continue loading table after error"
> >>>>
> >>>> The first is this boot failure on a thunderX2:
> >>>>
> >>>> [   10.770098] ACPI Error: Ignore error and continue table load
> >>
> >>
> >> [trimming]
> >>
> >>>> ]---
> >>>>
> >>>> Which does appear to be the result of some bad data in the table, but it
> >>>> was working with 4.17, and reverting this commit solves the problem.
> >>>
> >>>
> >>> Does the patch below make any difference?
> >>>
> >>> ---
> >>>    drivers/acpi/acpica/psobject.c |    3 +++
> >>>    1 file changed, 3 insertions(+)
> >>>
> >>> Index: linux-pm/drivers/acpi/acpica/psobject.c
> >>> ===================================================================
> >>> --- linux-pm.orig/drivers/acpi/acpica/psobject.c
> >>> +++ linux-pm/drivers/acpi/acpica/psobject.c
> >>> @@ -39,6 +39,9 @@ static acpi_status acpi_ps_get_aml_opcod
> >>>          ACPI_FUNCTION_TRACE_PTR(ps_get_aml_opcode, walk_state);
> >>>          walk_state->aml = walk_state->parser_state.aml;
> >>> +       if (!walk_state->aml)
> >>> +               return AE_CTRL_PARSE_CONTINUE;
> >>> +
> >>
> >>
> >> Well this seems to avoid the crash, but now it hangs right after on the
> >> "Ignore error and continue table load" message.
> > 
> > Well, maybe we should just abort in that case.
> > 
> > I'm wondering what happens if you replace the return statement in the
> > patch above with
> > 
> > return_ACPI_STATUS(AE_AML_BAD_OPCODE)
> 
> Yes, that is where I went when I applied the patch but I used 
> AE_CTRL_TERMINATE, which terminates the loop in acpi_ps_parse_loop() and 
> that appears to successfully finish/terminate the initial parsing pass. 
> But, it then crashes in acpi_ns_lookup called via the 
> acpi_walk_resources sequences that goes through ut_evalute_object() due 
> to the path/scope_info->scope.node being ACPI_ROOT_OBJECT (-1) and 
> bypassing the null check. Adding a ACPI_ROOT_OBJECT check as well as the 
> null checks in acpi_ns_lookup results in a successful boot. Tracking 
> down how the terminate (or whatever) is leaving the info->prefix_node 
> (in acpi_ns_evaluate) set to ROOT_OBJECT instead of null, is something I 
> don't yet understand.
> 
> Anyway, I tried Using BAD_OPCODE rather than TERMINATE and it seems to 
> have the same basic result as PARSE_CONTINUE.

OK, thanks!

I evidently didn't look deep enough.

Can you please check the patch below?

I'm not sure if we can pass this broken state to
acpi_ps_complete_final_op(), so it may be necessary to return
an error directly when aml_op_start is NULL.

---
 drivers/acpi/acpica/psloop.c |    3 +++
 1 file changed, 3 insertions(+)

Index: linux-pm/drivers/acpi/acpica/psloop.c
===================================================================
--- linux-pm.orig/drivers/acpi/acpica/psloop.c
+++ linux-pm/drivers/acpi/acpica/psloop.c
@@ -493,6 +493,9 @@ acpi_status acpi_ps_parse_loop(struct ac
 		ASL_CV_CAPTURE_COMMENTS(walk_state);
 
 		aml_op_start = parser_state->aml;
+		if (!aml_op_start)
+			break;
+
 		if (!op) {
 			status =
 			    acpi_ps_create_op(walk_state, aml_op_start, &op);