Date:   Tue, 10 Jul 2018 12:04:58 -0500
From:   Jeremy Linton <jeremy.linton@....com>
To:     "Rafael J. Wysocki" <rjw@...ysocki.net>
Cc:     "Schmauss, Erik" <erik.schmauss@...el.com>,
        "linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>
Subject: Re: 4.18rc3 TX2 boot failure with "ACPICA: AML parser: attempt to
 continue loading table after error"

On 07/10/2018 11:56 AM, Rafael J. Wysocki wrote:
> On Tuesday, July 10, 2018 5:04:21 PM CEST Jeremy Linton wrote:
>> Hi,
>>
>> On 07/10/2018 06:25 AM, Rafael J. Wysocki wrote:
>>> 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@....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)) {
>>>
>>>
>>
>> This gets rid of the infinite loop, but its still has the problem with
>> acpi_ns_lookup crashing due to -1 in the scope.node.
> 
> OK, so do you mean that something like the patch below is needed for the
> system to boot?

Yes, the machine is back to the pre 4.18 behavior (with the addition of 
a lot of additional ACPI error messages) boot with those two changes.

> ---
>   drivers/acpi/acpica/nsaccess.c |    3 ++-
>   drivers/acpi/acpica/psloop.c   |    3 +++
>   2 files changed, 5 insertions(+), 1 deletion(-)
> 
> 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)) {
> Index: linux-pm/drivers/acpi/acpica/nsaccess.c
> ===================================================================
> --- linux-pm.orig/drivers/acpi/acpica/nsaccess.c
> +++ linux-pm/drivers/acpi/acpica/nsaccess.c
> @@ -286,7 +286,8 @@ acpi_ns_lookup(union acpi_generic_state
>   
>   	/* Get the prefix scope. A null scope means use the root scope */
>   
> -	if ((!scope_info) || (!scope_info->scope.node)) {
> +	if ((!scope_info) || (!scope_info->scope.node) ||
> +	    (scope_info->scope.node == ACPI_ROOT_OBJECT)) {
>   		ACPI_DEBUG_PRINT((ACPI_DB_NAMES,
>   				  "Null scope prefix, using root node (%p)\n",
>   				  acpi_gbl_root_node));
> 

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