From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Split a function for evaluating _OSL called acpi_eval_osc() out of
acpi_run_osc() to facilitate subsequent changes and add some more
parameters sanity checks to the latter.

No intentional functional impact.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
 drivers/acpi/bus.c |   89 ++++++++++++++++++++++++++++++-----------------------
 1 file changed, 52 insertions(+), 37 deletions(-)

--- a/drivers/acpi/bus.c
+++ b/drivers/acpi/bus.c
@@ -195,52 +195,67 @@ static void acpi_dump_osc_data(acpi_hand
 			 OSC_INVALID_REVISION_ERROR | \
 			 OSC_CAPABILITIES_MASK_ERROR)
 
-acpi_status acpi_run_osc(acpi_handle handle, struct acpi_osc_context *context)
+static int acpi_eval_osc(acpi_handle handle, guid_t *guid, int rev,
+			 struct acpi_buffer *cap,
+			 union acpi_object in_params[static 4],
+			 struct acpi_buffer *output)
 {
-	acpi_status status;
 	struct acpi_object_list input;
-	union acpi_object in_params[4];
 	union acpi_object *out_obj;
+	acpi_status status;
+
+	in_params[0].type = ACPI_TYPE_BUFFER;
+	in_params[0].buffer.length = sizeof(*guid);
+	in_params[0].buffer.pointer = (u8 *)guid;
+	in_params[1].type = ACPI_TYPE_INTEGER;
+	in_params[1].integer.value = rev;
+	in_params[2].type = ACPI_TYPE_INTEGER;
+	in_params[2].integer.value = cap->length / sizeof(u32);
+	in_params[3].type = ACPI_TYPE_BUFFER;
+	in_params[3].buffer.length = cap->length;
+	in_params[3].buffer.pointer = cap->pointer;
+	input.pointer = in_params;
+	input.count = 4;
+
+	output->length = ACPI_ALLOCATE_BUFFER;
+	output->pointer = NULL;
+
+	status = acpi_evaluate_object(handle, "_OSC", &input, output);
+	if (ACPI_FAILURE(status) || !output->length)
+		return -ENODATA;
+
+	out_obj = output->pointer;
+	if (out_obj->type != ACPI_TYPE_BUFFER ||
+	    out_obj->buffer.length != cap->length) {
+		acpi_handle_debug(handle, "Invalid _OSC return buffer\n");
+		acpi_dump_osc_data(handle, guid, rev, cap);
+		ACPI_FREE(out_obj);
+		return -ENODATA;
+	}
+
+	return 0;
+}
+
+acpi_status acpi_run_osc(acpi_handle handle, struct acpi_osc_context *context)
+{
+	union acpi_object in_params[4], *out_obj;
+	struct acpi_buffer output;
+	acpi_status status = AE_OK;
 	guid_t guid;
 	u32 errors;
-	struct acpi_buffer output = {ACPI_ALLOCATE_BUFFER, NULL};
+	int ret;
 
-	if (!context)
+	if (!context || !context->cap.pointer ||
+	    context->cap.length < 2 * sizeof(32) ||
+	    guid_parse(context->uuid_str, &guid))
+		return AE_BAD_PARAMETER;
+
+	ret = acpi_eval_osc(handle, &guid, context->rev, &context->cap,
+			    in_params, &output);
+	if (ret)
 		return AE_ERROR;
-	if (guid_parse(context->uuid_str, &guid))
-		return AE_ERROR;
-	context->ret.length = ACPI_ALLOCATE_BUFFER;
-	context->ret.pointer = NULL;
-
-	/* Setting up input parameters */
-	input.count = 4;
-	input.pointer = in_params;
-	in_params[0].type 		= ACPI_TYPE_BUFFER;
-	in_params[0].buffer.length 	= 16;
-	in_params[0].buffer.pointer	= (u8 *)&guid;
-	in_params[1].type 		= ACPI_TYPE_INTEGER;
-	in_params[1].integer.value 	= context->rev;
-	in_params[2].type 		= ACPI_TYPE_INTEGER;
-	in_params[2].integer.value	= context->cap.length/sizeof(u32);
-	in_params[3].type		= ACPI_TYPE_BUFFER;
-	in_params[3].buffer.length 	= context->cap.length;
-	in_params[3].buffer.pointer 	= context->cap.pointer;
-
-	status = acpi_evaluate_object(handle, "_OSC", &input, &output);
-	if (ACPI_FAILURE(status))
-		return status;
-
-	if (!output.length)
-		return AE_NULL_OBJECT;
 
 	out_obj = output.pointer;
-	if (out_obj->type != ACPI_TYPE_BUFFER
-		|| out_obj->buffer.length != context->cap.length) {
-		acpi_handle_debug(handle, "_OSC evaluation returned wrong type");
-		acpi_dump_osc_data(handle, &guid, context->rev, &context->cap);
-		status = AE_TYPE;
-		goto out_kfree;
-	}
 	/* Only take defined error bits into account. */
 	errors = *((u32 *)out_obj->buffer.pointer) & OSC_ERROR_MASK;
 	/* If OSC_QUERY_ENABLE is set, ignore the "capabilities masked" bit. */

On Thu, 18 Dec 2025 21:36:08 +0100
"Rafael J. Wysocki" <rafael@kernel.org> wrote:

> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> 
> Split a function for evaluating _OSL called acpi_eval_osc() out of

_OSC

> acpi_run_osc() to facilitate subsequent changes and add some more
> parameters sanity checks to the latter.
> 
> No intentional functional impact.
> 
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

One comment on the fun static keyword usage.  Next time I have
to ask/answer some silly C questions in an interview that one is definitely going
in :)
> ---
>  drivers/acpi/bus.c |   89 ++++++++++++++++++++++++++++++-----------------------
>  1 file changed, 52 insertions(+), 37 deletions(-)
> 
> --- a/drivers/acpi/bus.c
> +++ b/drivers/acpi/bus.c
> @@ -195,52 +195,67 @@ static void acpi_dump_osc_data(acpi_hand
>  			 OSC_INVALID_REVISION_ERROR | \
>  			 OSC_CAPABILITIES_MASK_ERROR)
>  
> -acpi_status acpi_run_osc(acpi_handle handle, struct acpi_osc_context *context)
> +static int acpi_eval_osc(acpi_handle handle, guid_t *guid, int rev,
> +			 struct acpi_buffer *cap,
> +			 union acpi_object in_params[static 4],

This static usage has such non intuitive behavior maybe use
the new at_least marking in compiler_types.h to indicate
what protection against wrong sizes it can offer.

> +			 struct acpi_buffer *output)
>  {
> -	acpi_status status;
>  	struct acpi_object_list input;
> -	union acpi_object in_params[4];
>  	union acpi_object *out_obj;
> +	acpi_status status;
> +
> +	in_params[0].type = ACPI_TYPE_BUFFER;
> +	in_params[0].buffer.length = sizeof(*guid);
> +	in_params[0].buffer.pointer = (u8 *)guid;
> +	in_params[1].type = ACPI_TYPE_INTEGER;
> +	in_params[1].integer.value = rev;
> +	in_params[2].type = ACPI_TYPE_INTEGER;
> +	in_params[2].integer.value = cap->length / sizeof(u32);
> +	in_params[3].type = ACPI_TYPE_BUFFER;
> +	in_params[3].buffer.length = cap->length;
> +	in_params[3].buffer.pointer = cap->pointer;
> +	input.pointer = in_params;
> +	input.count = 4;
> +
> +	output->length = ACPI_ALLOCATE_BUFFER;
> +	output->pointer = NULL;
> +
> +	status = acpi_evaluate_object(handle, "_OSC", &input, output);
> +	if (ACPI_FAILURE(status) || !output->length)
> +		return -ENODATA;
> +
> +	out_obj = output->pointer;
> +	if (out_obj->type != ACPI_TYPE_BUFFER ||
> +	    out_obj->buffer.length != cap->length) {
> +		acpi_handle_debug(handle, "Invalid _OSC return buffer\n");
> +		acpi_dump_osc_data(handle, guid, rev, cap);
> +		ACPI_FREE(out_obj);
> +		return -ENODATA;
> +	}
> +
> +	return 0;
> +}

On Fri, Dec 19, 2025 at 1:44 PM Jonathan Cameron
<jonathan.cameron@huawei.com> wrote:
>
> On Thu, 18 Dec 2025 21:36:08 +0100
> "Rafael J. Wysocki" <rafael@kernel.org> wrote:
>
> > From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> >
> > Split a function for evaluating _OSL called acpi_eval_osc() out of
>
> _OSC

Yup, thanks!

> > acpi_run_osc() to facilitate subsequent changes and add some more
> > parameters sanity checks to the latter.
> >
> > No intentional functional impact.
> >
> > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
>
> One comment on the fun static keyword usage.  Next time I have
> to ask/answer some silly C questions in an interview that one is definitely going
> in :)
> > ---
> >  drivers/acpi/bus.c |   89 ++++++++++++++++++++++++++++++-----------------------
> >  1 file changed, 52 insertions(+), 37 deletions(-)
> >
> > --- a/drivers/acpi/bus.c
> > +++ b/drivers/acpi/bus.c
> > @@ -195,52 +195,67 @@ static void acpi_dump_osc_data(acpi_hand
> >                        OSC_INVALID_REVISION_ERROR | \
> >                        OSC_CAPABILITIES_MASK_ERROR)
> >
> > -acpi_status acpi_run_osc(acpi_handle handle, struct acpi_osc_context *context)
> > +static int acpi_eval_osc(acpi_handle handle, guid_t *guid, int rev,
> > +                      struct acpi_buffer *cap,
> > +                      union acpi_object in_params[static 4],
>
> This static usage has such non intuitive behavior maybe use
> the new at_least marking in compiler_types.h to indicate
> what protection against wrong sizes it can offer.

I'll have a look at that, thanks!