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From:   "Rafael J. Wysocki" <rjw@rjwysocki.net>
To:     Jeremy Linton <jeremy.linton@arm.com>
Cc:     "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 13:25:58 +0200
Message-ID: <2264016.O8iB3BUh2s@aspire.rjw.lan>
In-Reply-To: <3574827.zOC4apc8e1@aspire.rjw.lan>
References: <c49a3666-7d23-6a05-703c-1273d79a00cd@arm.com> <218e4339-477d-eb0d-6007-764c8e24229f@arm.com> <3574827.zOC4apc8e1@aspire.rjw.lan>
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On Tuesday, July 10, 2018 1:13:17 PM CEST Rafael J. Wysocki wrote:
> 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);
> 
> --

So maybe something like this:

---
 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
@@ -494,6 +494,9 @@ acpi_status acpi_ps_parse_loop(struct ac
 
 		aml_op_start = parser_state->aml;
 		if (!op) {
+			if (!aml_op_start)
+				return_ACPI_STATUS(AE_AML_INTERNAL);
+
 			status =
 			    acpi_ps_create_op(walk_state, aml_op_start, &op);
 			if (ACPI_FAILURE(status)) {