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Date:   Tue, 30 May 2023 23:42:09 +0200
From:   Thomas =?utf-8?Q?Wei=C3=9Fschuh?= <thomas@t-8ch.de>
To:     Jorge Lopez <jorgealtxwork@gmail.com>
Cc:     hdegoede@redhat.com, platform-driver-x86@vger.kernel.org,
        linux-kernel@vger.kernel.org, ilpo.jarvinen@linux.intel.com
Subject: Re: [PATCH v15 05/13] hp-bioscfg: enum-attributes
Message-ID: <dd9df9e7-9693-4ddc-8429-cc5e0567da17@t-8ch.de>
References: <20230519201300.12964-1-jorge.lopez2@hp.com>
 <20230519201300.12964-6-jorge.lopez2@hp.com>
 <0cbd158e-0742-4e04-9996-bd376f9b555b@t-8ch.de>
 <CAOOmCE8=C_qH862G9sdLS59=QPh6U_78WY0SzJwzZfW+iSUiPA@mail.gmail.com>
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On 2023-05-30 12:01:57-0500, Jorge Lopez wrote:
> On Fri, May 26, 2023 at 10:35 AM Thomas Weißschuh <thomas@t-8ch.de> wrote:
> >
> > On 2023-05-19 15:12:52-0500, Jorge Lopez wrote:
> >
> > <snip>
> >
> > >  .../x86/hp/hp-bioscfg/enum-attributes.c       | 465 ++++++++++++++++++
> > >  1 file changed, 465 insertions(+)
> > >  create mode 100644 drivers/platform/x86/hp/hp-bioscfg/enum-attributes.c
> > >
> > > diff --git a/drivers/platform/x86/hp/hp-bioscfg/enum-attributes.c b/drivers/platform/x86/hp/hp-bioscfg/enum-attributes.c
> > > new file mode 100644
> > > index 000000000000..80842835606d
> > > --- /dev/null
> > > +++ b/drivers/platform/x86/hp/hp-bioscfg/enum-attributes.c
> > > @@ -0,0 +1,465 @@
> > > +// SPDX-License-Identifier: GPL-2.0
> > > +/*
> > > + * Functions corresponding to enumeration type attributes under
> > > + * BIOS Enumeration GUID for use with hp-bioscfg driver.
> > > + *
> > > + * Copyright (c) 2022 HP Development Company, L.P.
> > > + */
> > > +
> > > +#include "bioscfg.h"
> > > +
> > > +GET_INSTANCE_ID(enumeration);
> > > +
> > > +static ssize_t current_value_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
> > > +{
> > > +     int instance_id = get_enumeration_instance_id(kobj);
> > > +
> > > +     if (instance_id < 0)
> > > +             return -EIO;
> > > +
> > > +     return sysfs_emit(buf, "%s\n",
> > > +                      bioscfg_drv.enumeration_data[instance_id].current_value);
> > > +}
> > > +
> > > +/**
> > > + * validate_enumeration_input() -
> > > + * Validate input of current_value against possible values
> > > + *
> > > + * @instance_id: The instance on which input is validated
> > > + * @buf: Input value
> > > + */
> 
> <snip>
> 
> > > +static int hp_populate_enumeration_elements_from_package(union acpi_object *enum_obj,
> > > +                                                      int enum_obj_count,
> > > +                                                      int instance_id)
> > > +{
> > > +     char *str_value = NULL;
> > > +     int value_len;
> > > +     u32 size = 0;
> > > +     u32 int_value;
> > > +     int elem = 0;
> > > +     int reqs;
> > > +     int pos_values;
> > > +     int ret;
> > > +     int eloc;
> > > +     struct enumeration_data *enum_data = &bioscfg_drv.enumeration_data[instance_id];
> > > +
> > > +     for (elem = 1, eloc = 1; elem < enum_obj_count; elem++, eloc++) {
> > > +             /* ONLY look at the first ENUM_ELEM_CNT elements */
> > > +             if (eloc == ENUM_ELEM_CNT)
> > > +                     goto exit_enumeration_package;
> > > +
> > > +             switch (enum_obj[elem].type) {
> > > +             case ACPI_TYPE_STRING:
> > > +                     if (PREREQUISITES != elem && ENUM_POSSIBLE_VALUES != elem) {
> > > +                             ret = hp_convert_hexstr_to_str(enum_obj[elem].string.pointer,
> > > +                                                            enum_obj[elem].string.length,
> > > +                                                            &str_value, &value_len);
> > > +                             if (ret)
> > > +                                     return -EINVAL;
> > > +                     }
> > > +                     break;
> > > +             case ACPI_TYPE_INTEGER:
> > > +                     int_value = (u32)enum_obj[elem].integer.value;
> > > +                     break;
> > > +             default:
> > > +                     pr_warn("Unsupported object type [%d]\n", enum_obj[elem].type);
> > > +                     continue;
> > > +             }
> > > +
> > > +             /* Check that both expected and read object type match */
> > > +             if (expected_enum_types[eloc] != enum_obj[elem].type) {
> > > +                     pr_err("Error expected type %d for elem %d, but got type %d instead\n",
> > > +                            expected_enum_types[eloc], elem, enum_obj[elem].type);
> > > +                     return -EIO;
> > > +             }
> > > +
> > > +             /* Assign appropriate element value to corresponding field */
> > > +             switch (eloc) {
> > > +             case NAME:
> > > +             case VALUE:
> > > +                     break;
> > > +             case PATH:
> > > +                     strscpy(enum_data->common.path, str_value,
> > > +                             sizeof(enum_data->common.path));
> > > +                     break;
> > > +             case IS_READONLY:
> > > +                     enum_data->common.is_readonly = int_value;
> > > +                     break;
> > > +             case DISPLAY_IN_UI:
> > > +                     enum_data->common.display_in_ui = int_value;
> > > +                     break;
> > > +             case REQUIRES_PHYSICAL_PRESENCE:
> > > +                     enum_data->common.requires_physical_presence = int_value;
> > > +                     break;
> > > +             case SEQUENCE:
> > > +                     enum_data->common.sequence = int_value;
> > > +                     break;
> > > +             case PREREQUISITES_SIZE:
> > > +                     enum_data->common.prerequisites_size = int_value;
> > > +                     if (int_value > MAX_PREREQUISITES_SIZE)
> > > +                             pr_warn("Prerequisites size value exceeded the maximum number of elements supported or data may be malformed\n");
> > > +
> > > +                     /*
> > > +                      * This HACK is needed to keep the expected
> > > +                      * element list pointing to the right obj[elem].type
> > > +                      * when the size is zero. PREREQUISITES
> > > +                      * object is omitted by BIOS when the size is
> > > +                      * zero.
> > > +                      */
> > > +                     if (int_value == 0)
> > > +                             eloc++;
> > > +                     break;
> > > +
> > > +             case PREREQUISITES:
> > > +                     size = min_t(u32, enum_data->common.prerequisites_size, MAX_PREREQUISITES_SIZE);
> >
> > We cannot blindly truncate this to a maximum value.
> > The firmware reported an amount of elements it would return.
> >
> > If this value is to big than we can not just intpret the data as if it
> > was something the firmware did not return.
> >
> > An error needs to be reported to userspace.
> > A default value is not enough as userspace can not interpret this
> > properly.
> >
> 
> It is ok to truncate prerequisite size to MAX_PREREQUISITES_SIZE.
> MAX_PREREQUISITES_SIZE is a value predefined by BIOS when the
> prerequisite values size is invalid ( > MAX_PREREQUISITES_SIZE) and/or
> the prerequisite data is corrupted.
> Neither PREREQUISITES nor PREREQUISITES_SIZE are reported to the
> userspace so there is no need to report a failure on data that is not
> exposed.  One item that needs clarification is the fact that
> regardless if  PREREQUISITES or PREREQUISITES_SIZE are invalid, that
> does not mean other values are invalid.  It is for this reason, we
> need to continue to read all remaining packages.

It may be that prerequisites are not reported to userspace.
But the following values are:

security level, current value and possible values.

And if prerequisites are garbage then those are now also garbage.

hp_populate_enumeration_package_data() always returns "0".

> In earlier reviews, it was agreed to report a warning  that reads
> 
> /* Report a message and limit prerequisite size to maximum value */
> pr_warn("Enum Prerequisites size value exceeded the maximum number of
> elements supported or data may be malformed\n");
> 
> See lines 370-374
> 
> > (Affects all attributes)
> >
> > > +                     for (reqs = 0; reqs < size; reqs++) {
> > > +                             if (elem >= enum_obj_count) {
> > > +                                     pr_err("Error enum-objects package is too small\n");
> > > +                                     return -EINVAL;
> > > +                             }
> > > +
> > > +                             ret = hp_convert_hexstr_to_str(enum_obj[elem + reqs].string.pointer,
> > > +                                                            enum_obj[elem + reqs].string.length,
> > > +                                                            &str_value, &value_len);
> > > +
> > > +                             if (ret)
> > > +                                     return -EINVAL;
> > > +
> > > +                             strscpy(enum_data->common.prerequisites[reqs],
> > > +                                     str_value,
> > > +                                     sizeof(enum_data->common.prerequisites[reqs]));
> > > +
> > > +                             kfree(str_value);
> > > +                     }
> > > +                     break;
> > > +
> > > +             case SECURITY_LEVEL:
> > > +                     enum_data->common.security_level = int_value;
> > > +                     break;
> > > +
> > > +             case ENUM_CURRENT_VALUE:
> > > +                     strscpy(enum_data->current_value,
> > > +                             str_value, sizeof(enum_data->current_value));
> > > +                     break;
> > > +             case ENUM_SIZE:
> > > +                     enum_data->possible_values_size = int_value;
> > > +                     if (int_value > MAX_VALUES_SIZE)
> > > +                             pr_warn("Possible number values size value exceeded the maximum number of elements supported or data may be malformed\n");
> > > +
> > > +                     /*
> > > +                      * This HACK is needed to keep the expected
> > > +                      * element list pointing to the right obj[elem].type
> > > +                      * when the size is zero. POSSIBLE_VALUES
> > > +                      * object is omitted by BIOS when the size is zero.
> > > +                      */
> > > +                     if (int_value == 0)
> > > +                             eloc++;
> > > +                     break;
> > > +
> > > +             case ENUM_POSSIBLE_VALUES:
> > > +                     size = enum_data->possible_values_size;
> > > +
> > > +                     for (pos_values = 0; pos_values < size && pos_values < MAX_VALUES_SIZE;
> > > +                          pos_values++) {
> > > +                             if (elem >= enum_obj_count) {
> > > +                                     pr_err("Error enum-objects package is too small\n");
> > > +                                     return -EINVAL;
> > > +                             }
> > > +
> > > +                             ret = hp_convert_hexstr_to_str(enum_obj[elem + pos_values].string.pointer,
> > > +                                                            enum_obj[elem + pos_values].string.length,
> > > +                                                            &str_value, &value_len);
> > > +
> > > +                             if (ret)
> > > +                                     return -EINVAL;
> > > +
> > > +                             /*
> > > +                              * ignore strings when possible values size
> > > +                              * is greater than MAX_VALUES_SIZE
> > > +                              */
> > > +                             if (size < MAX_VALUES_SIZE)
> > > +                                     strscpy(enum_data->possible_values[pos_values],
> > > +                                             str_value,
> > > +                                             sizeof(enum_data->possible_values[pos_values]));
> > > +                     }
> > > +                     break;
> > > +             default:
> > > +                     pr_warn("Invalid element: %d found in Enumeration attribute or data may be malformed\n", elem);
> > > +                     break;
> > > +             }
> > > +
> > > +             kfree(str_value);
> > > +     }
> > > +
> > > +exit_enumeration_package:
> > > +     kfree(str_value);
> > > +     return 0;
> > > +}
> > > +
> > > +/**
> > > + * hp_populate_enumeration_package_data() -
> > > + * Populate all properties of an instance under enumeration attribute
> > > + *
> > > + * @enum_obj: ACPI object with enumeration data
> > > + * @instance_id: The instance to enumerate
> > > + * @attr_name_kobj: The parent kernel object
> > > + */
> > > +int hp_populate_enumeration_package_data(union acpi_object *enum_obj,
> > > +                                      int instance_id,
> > > +                                      struct kobject *attr_name_kobj)
> > > +{
> > > +     struct enumeration_data *enum_data = &bioscfg_drv.enumeration_data[instance_id];
> > > +
> > > +     enum_data->attr_name_kobj = attr_name_kobj;
> > > +
> > > +     hp_populate_enumeration_elements_from_package(enum_obj,
> > > +                                                   enum_obj->package.count,
> > > +                                                   instance_id);
> > > +     hp_update_attribute_permissions(enum_data->common.is_readonly,
> > > +                                     &enumeration_current_val);
> > > +     /*
> > > +      * Several attributes have names such "MONDAY". Friendly
> > > +      * user nane is generated to make the name more descriptive
> > > +      */
> > > +     hp_friendly_user_name_update(enum_data->common.path,
> > > +                                  attr_name_kobj->name,
> > > +                                  enum_data->common.display_name,
> > > +                                  sizeof(enum_data->common.display_name));
> > > +     return sysfs_create_group(attr_name_kobj, &enumeration_attr_group);
> > > +}
> > > +
> > > +static int hp_populate_enumeration_elements_from_buffer(u8 *buffer_ptr, u32 *buffer_size,
> > > +                                                     int instance_id)
> > > +{
> > > +     int reqs;
> > > +     int values;
> > > +     struct enumeration_data *enum_data = &bioscfg_drv.enumeration_data[instance_id];
> > > +
> > > +     /*
> > > +      * In earlier implementation, reported errors were ignored
> > > +      * causing the data to remain uninitialized. It is for this
> > > +      * reason functions may return an error and no validation
> > > +      * takes place.
> > > +      */
> >
> > Where is this error returned?
> 
> functions such hp_get_string_from_buffer, hp_get_integer_from_buffer

But the errors returned from those functions are just thrown away, no?

> >
> > > +
> > > +     // VALUE:
> > > +     hp_get_string_from_buffer(&buffer_ptr, buffer_size, enum_data->current_value,
> > > +                               sizeof(enum_data->current_value));
> > > +
> > > +     // PATH:
> > > +     hp_get_string_from_buffer(&buffer_ptr, buffer_size, enum_data->common.path,
> > > +                               sizeof(enum_data->common.path));
> > > +
> > > +     // IS_READONLY:
> > > +     hp_get_integer_from_buffer(&buffer_ptr, buffer_size,
> > > +                                &enum_data->common.is_readonly);
> > > +
> > > +     //DISPLAY_IN_UI:
> > > +     hp_get_integer_from_buffer(&buffer_ptr, buffer_size,
> > > +                                &enum_data->common.display_in_ui);
> > > +
> > > +     // REQUIRES_PHYSICAL_PRESENCE:
> > > +     hp_get_integer_from_buffer(&buffer_ptr, buffer_size,
> > > +                                &enum_data->common.requires_physical_presence);
> > > +
> > > +     // SEQUENCE:
> > > +     hp_get_integer_from_buffer(&buffer_ptr, buffer_size,
> > > +                                &enum_data->common.sequence);
> > > +
> > > +     // PREREQUISITES_SIZE:
> > > +     hp_get_integer_from_buffer(&buffer_ptr, buffer_size,
> > > +                                &enum_data->common.prerequisites_size);
> > > +
> > > +     if (enum_data->common.prerequisites_size > MAX_PREREQUISITES_SIZE) {
> > > +             /* Report a message and limit prerequisite size to maximum value */
> > > +             pr_warn("Enum Prerequisites size value exceeded the maximum number of elements supported or data may be malformed\n");
> > > +             enum_data->common.prerequisites_size = MAX_PREREQUISITES_SIZE;
> > > +     }
> > > +
> > > +     // PREREQUISITES:
> > > +     for (reqs = 0; reqs < enum_data->common.prerequisites_size; reqs++)
> > > +             hp_get_string_from_buffer(&buffer_ptr, buffer_size,
> > > +                                       enum_data->common.prerequisites[reqs],
> > > +                                       sizeof(enum_data->common.prerequisites[reqs]));
> > > +
> > > +     // SECURITY_LEVEL:
> > > +     hp_get_integer_from_buffer(&buffer_ptr, buffer_size,
> > > +                                &enum_data->common.security_level);
> >
> > The reading of all the common elemtns can be extracted into a helper
> > and reused from all the attributes.
> 
> Is extracting all common elements into a helper routine absolutely
> necessary now or can it be refactored after driver is accepted?

It's not necessary.

> >
> > > +
> > > +     // ENUM_CURRENT_VALUE:
> > > +     hp_get_string_from_buffer(&buffer_ptr, buffer_size,
> > > +                               enum_data->current_value,
> > > +                               sizeof(enum_data->current_value));
> > > +     // ENUM_SIZE:
> > > +     hp_get_integer_from_buffer(&buffer_ptr, buffer_size,
> > > +                                &enum_data->possible_values_size);
> > > +
> > > +     if (enum_data->possible_values_size > MAX_VALUES_SIZE) {
> > > +             /* Report a message and limit possible values size to maximum value */
> > > +             pr_warn("Enum Possible size value exceeded the maximum number of elements supported or data may be malformed\n");
> > > +             enum_data->possible_values_size = MAX_VALUES_SIZE;
> > > +     }
> > > +
> > > +     // ENUM_POSSIBLE_VALUES:
> > > +
> > > +     for (values = 0; values < enum_data->possible_values_size; values++)
> > > +             hp_get_string_from_buffer(&buffer_ptr, buffer_size,
> > > +                                       enum_data->possible_values[values],
> > > +                                       sizeof(enum_data->possible_values[values]));
> > > +
> > > +     return 0;
> > > +}
> > > +
> > > +/**
> > > + * hp_populate_enumeration_buffer_data() -
> > > + * Populate all properties of an instance under enumeration attribute
> > > + *
> > > + * @buffer_ptr: Buffer pointer
> > > + * @buffer_size: Buffer size
> > > + * @instance_id: The instance to enumerate
> > > + * @attr_name_kobj: The parent kernel object
> > > + */
> > > +int hp_populate_enumeration_buffer_data(u8 *buffer_ptr, u32 *buffer_size,
> > > +                                     int instance_id,
> > > +                                     struct kobject *attr_name_kobj)
> > > +{
> > > +     struct enumeration_data *enum_data = &bioscfg_drv.enumeration_data[instance_id];
> > > +
> > > +     enum_data->attr_name_kobj = attr_name_kobj;
> > > +
> > > +     /* Populate enumeration elements */
> > > +     hp_populate_enumeration_elements_from_buffer(buffer_ptr, buffer_size, instance_id);
> > > +
> > > +     hp_update_attribute_permissions(enum_data->common.is_readonly,
> > > +                                     &enumeration_current_val);
> > > +     /*
> > > +      * Several attributes have names such "MONDAY". A Friendlier
> > > +      * user nane is generated to make the name more descriptive
> > > +      */
> > > +     hp_friendly_user_name_update(enum_data->common.path,
> > > +                                  attr_name_kobj->name,
> > > +                                  enum_data->common.display_name,
> > > +                                  sizeof(enum_data->common.display_name));
> > > +
> > > +     return sysfs_create_group(attr_name_kobj, &enumeration_attr_group);
> > > +}
> > > +
> > > +/**
> > > + * hp_exit_enumeration_attributes() - Clear all attribute data
> > > + *
> > > + * Clears all data allocated for this group of attributes
> > > + */
> > > +void hp_exit_enumeration_attributes(void)
> > > +{
> > > +     int instance_id;
> > > +
> > > +     for (instance_id = 0; instance_id < bioscfg_drv.enumeration_instances_count;
> > > +          instance_id++) {
> > > +             struct enumeration_data *enum_data = &bioscfg_drv.enumeration_data[instance_id];
> > > +             struct kobject *attr_name_kobj = enum_data->attr_name_kobj;
> > > +
> > > +             if (attr_name_kobj)
> > > +                     sysfs_remove_group(attr_name_kobj, &enumeration_attr_group);
> > > +     }
> > > +     bioscfg_drv.enumeration_instances_count = 0;
> > > +
> > > +     kfree(bioscfg_drv.enumeration_data);
> > > +     bioscfg_drv.enumeration_data = NULL;
> > > +}
> > > --
> > > 2.34.1
> > >