Re: [PATCH] ACPICA / Interpreter: Fix a regression triggered because of wrong Linux ECDT support

[Greg KH <greg@kroah.com>]

On Wed, Apr 20, 2016 at 10:39:56AM +0800, Lv Zheng wrote:
> 4.5-stable review patch. If anyone has any objects, please let me know.

Huh?  I don't understand this email...



> 
> ---------------
> 
> From: Lv Zheng <lv.zheng@intel.com>
> 
> commit 5508df89756f8378024828e185724a9bd2348985 upstream.
> 
> It is reported that the following commit triggers regressions:
>  Linux commit: efaed9be998b5ae0afb7458e057e5f4402b43fa0
>  ACPICA commit: 31178590dde82368fdb0f6b0e466b6c0add96c57
>  Subject: ACPICA: Events: Enhance acpi_ev_execute_reg_method() to
>           ensure no _REG evaluations can happen during OS early boot
>           stages
> 
> This is because that the ECDT support is not corrected in Linux, and Linux
> requires to execute _REG for ECDT (though this sounds so wrong), we need to
> ensure acpi_gbl_reg_methods_enabled is set before ECDT probing in order
> for _REG to be executed. Since we have to move
> "acpi_gbl_reg_methods_enabled = TRUE" to the initialization step
> happening before ECDT probing, acpi_load_tables() is the best candidate for
> now. Thus this patch fixes the regression by doing so.
> 
> But if the ECDT support is fixed, Linux will not execute _REG for ECDT, and
> ECDT probing will happen before acpi_load_tables(). At that time, we still
> want to ensure acpi_gbl_reg_methods_enabled is set after executing
> acpi_ns_initialize_objects() (under the condition of
> acpi_gbl_group_module_level_code = FALSE), this patch also moves
> acpi_ns_initialize_objects() to acpi_load_tables() accordingly.
> 
> Since acpi_ns_initialize_objects() doesn't seem to be skippable, this
> patch also removes ACPI_NO_OBJECT_INIT for the one invoked in
> acpi_load_tables(). Reported by Chris Bainbridge, Fixed by Lv Zheng.
> 
> Fixes: efaed9be998b (ACPICA: Events: Enhance acpi_ev_execute_reg_method() to ensure no _REG evaluations can happen during OS early boot stages)
> Reported-and-tested-by: Chris Bainbridge <chris.bainbridge@gmail.com>
> Signed-off-by: Lv Zheng <lv.zheng@intel.com>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> ---
>  drivers/acpi/acpica/nsinit.c   |    2 ++
>  drivers/acpi/acpica/tbxfload.c |   14 ++++++++++++++
>  drivers/acpi/acpica/utxfinit.c |   25 +++++++++++--------------
>  3 files changed, 27 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/acpi/acpica/nsinit.c b/drivers/acpi/acpica/nsinit.c
> index bd75d46..ddb436f 100644
> --- a/drivers/acpi/acpica/nsinit.c
> +++ b/drivers/acpi/acpica/nsinit.c
> @@ -83,6 +83,8 @@ acpi_status acpi_ns_initialize_objects(void)
>  
>  	ACPI_FUNCTION_TRACE(ns_initialize_objects);
>  
> +	ACPI_DEBUG_PRINT((ACPI_DB_EXEC,
> +			  "[Init] Completing Initialization of ACPI Objects\n"));
>  	ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
>  			  "**** Starting initialization of namespace objects ****\n"));
>  	ACPI_DEBUG_PRINT_RAW((ACPI_DB_INIT,
> diff --git a/drivers/acpi/acpica/tbxfload.c b/drivers/acpi/acpica/tbxfload.c
> index 278666e..c37d479 100644
> --- a/drivers/acpi/acpica/tbxfload.c
> +++ b/drivers/acpi/acpica/tbxfload.c
> @@ -83,6 +83,20 @@ acpi_status __init acpi_load_tables(void)
>  				"While loading namespace from ACPI tables"));
>  	}
>  
> +	if (!acpi_gbl_group_module_level_code) {
> +		/*
> +		 * Initialize the objects that remain uninitialized. This
> +		 * runs the executable AML that may be part of the
> +		 * declaration of these objects:
> +		 * operation_regions, buffer_fields, Buffers, and Packages.
> +		 */
> +		status = acpi_ns_initialize_objects();
> +		if (ACPI_FAILURE(status)) {
> +			return_ACPI_STATUS(status);
> +		}
> +	}
> +
> +	acpi_gbl_reg_methods_enabled = TRUE;
>  	return_ACPI_STATUS(status);
>  }
>  
> diff --git a/drivers/acpi/acpica/utxfinit.c b/drivers/acpi/acpica/utxfinit.c
> index 721b87c..638fbd4 100644
> --- a/drivers/acpi/acpica/utxfinit.c
> +++ b/drivers/acpi/acpica/utxfinit.c
> @@ -267,7 +267,6 @@ acpi_status __init acpi_initialize_objects(u32 flags)
>  	 * initialized, even if they contain executable AML (see the call to
>  	 * acpi_ns_initialize_objects below).
>  	 */
> -	acpi_gbl_reg_methods_enabled = TRUE;
>  	if (!(flags & ACPI_NO_ADDRESS_SPACE_INIT)) {
>  		ACPI_DEBUG_PRINT((ACPI_DB_EXEC,
>  				  "[Init] Executing _REG OpRegion methods\n"));
> @@ -299,20 +298,18 @@ acpi_status __init acpi_initialize_objects(u32 flags)
>  	 */
>  	if (acpi_gbl_group_module_level_code) {
>  		acpi_ns_exec_module_code_list();
> -	}
>  
> -	/*
> -	 * Initialize the objects that remain uninitialized. This runs the
> -	 * executable AML that may be part of the declaration of these objects:
> -	 * operation_regions, buffer_fields, Buffers, and Packages.
> -	 */
> -	if (!(flags & ACPI_NO_OBJECT_INIT)) {
> -		ACPI_DEBUG_PRINT((ACPI_DB_EXEC,
> -				  "[Init] Completing Initialization of ACPI Objects\n"));
> -
> -		status = acpi_ns_initialize_objects();
> -		if (ACPI_FAILURE(status)) {
> -			return_ACPI_STATUS(status);
> +		/*
> +		 * Initialize the objects that remain uninitialized. This
> +		 * runs the executable AML that may be part of the
> +		 * declaration of these objects:
> +		 * operation_regions, buffer_fields, Buffers, and Packages.
> +		 */
> +		if (!(flags & ACPI_NO_OBJECT_INIT)) {
> +			status = acpi_ns_initialize_objects();
> +			if (ACPI_FAILURE(status)) {
> +				return_ACPI_STATUS(status);
> +			}
>  		}
>  	}
>  
> -- 
> 1.7.10
> 
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