Re: [PATCH v11 05/14] HP BIOSCFG driver - ordered-attributes
From: Jorge Lopez
Date: Fri May 05 2023 - 12:10:31 EST
On Sun, Apr 23, 2023 at 1:55 AM <thomas@xxxxxxxx> wrote:
>
> On 2023-04-20 11:54:45-0500, Jorge Lopez wrote:
> > .../x86/hp/hp-bioscfg/ordered-attributes.c | 563 ++++++++++++++++++
> > 1 file changed, 563 insertions(+)
> > create mode 100644 drivers/platform/x86/hp/hp-bioscfg/ordered-attributes.c
> >
> > diff --git a/drivers/platform/x86/hp/hp-bioscfg/ordered-attributes.c b/drivers/platform/x86/hp/hp-bioscfg/ordered-attributes.c
> > new file mode 100644
> > index 000000000000..5e5d540f728d
> > --- /dev/null
> > +++ b/drivers/platform/x86/hp/hp-bioscfg/ordered-attributes.c
> > @@ -0,0 +1,563 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * Functions corresponding to ordered list type attributes under
> > + * BIOS ORDERED LIST GUID for use with hp-bioscfg driver.
> > + *
> > + * Copyright (c) 2022 HP Development Company, L.P.
> > + */
> > +
> > +#include "bioscfg.h"
> > +
> > +GET_INSTANCE_ID(ordered_list);
> > +
> > +static ssize_t current_value_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
> > +{
> > +
> > + int instance_id = get_ordered_list_instance_id(kobj);
> > +
> > + if (instance_id < 0)
> > + return -EIO;
> > +
> > + return sysfs_emit(buf, "%s\n",
> > + bioscfg_drv.ordered_list_data[instance_id].current_value);
> > +}
> > +
> > +/*
> > + * validate_ordered_list_value -
> > + * Validate input of current_value against possible values
>
> Does the firmware not also validate this?
>
> If so it may be easier to just let it do so and remove the validations
> from the driver.
Yes. the firmware validates the data.
Will remove the validation
>
> > + *
> > + * @instance_id: The instance on which input is validated
> > + * @buf: Input value
> > + */
> > +static int validate_ordered_list_values(int instance_id, const char *buf)
> > +{
> > + int ret = 0;
> > + int found = 0;
> > + char *new_values = NULL;
> > + char *value;
> > + int elem;
> > + int elem_found = 0;
> > +
> > + /* Is it a read only attribute */
> > + if (bioscfg_drv.ordered_list_data[instance_id].common.is_readonly)
> > + return -EIO;
> > +
> > + new_values = kstrdup(buf, GFP_KERNEL);
> > +
> > + /*
> > + * Changes to ordered list values require checking that new
> > + * values are found in the list of elements.
> > + */
> > + elem_found = 0;
> > + while (elem_found < bioscfg_drv.ordered_list_data[instance_id].elements_size) {
> > +
> > + value = strsep(&new_values, ",");
>
> The docs say the separator is semicolon.
BIOS reports the current value using ',' as separator instead of ";".
./hp-bioscfg/attributes/UEFI Boot Order/current_value
HDD:M.2:3,HDD:USB:1(Disabled),HDD:M.2:4,HDD:M.2:1,HDD:M.2:2,NETWORK
IPV4:EMBEDDED:1,NETWORK IPV6:EMBEDDED:1,NETWORK
IPV4:EXPANSION:1,NETWORK IPV6:EXPANSION:1
To avoid having to convert from "," to ";" and vice versa, I will
update the documentation to reflect the use of "'," commas as the
separator
>
> > + if (value != NULL) {
> > + if (!*value)
> > + continue;
> > + elem_found++;
> > + }
> > +
> > + found = 0;
> > + for (elem = 0; elem < bioscfg_drv.ordered_list_data[instance_id].elements_size; elem++) {
> > + if (!strcasecmp(bioscfg_drv.ordered_list_data[instance_id].elements[elem], value)) {
>
> It's surprising that this is case-insensitive.
As validated in earlier reviews, BIOS rejects strings that do not
match the internal values.
>
> > + found = 1;
> > + break;
> > + }
> > + }
> > +
> > +
> > + if (!found) {
> > + ret = -EINVAL;
> > + goto out_list_value;
> > + }
> > + }
> > +
> > + if (elem_found == bioscfg_drv.ordered_list_data[instance_id].elements_size) {
> > + pr_warn("Number of new values is not equal to number of ordered list elements (%d)\n",
> > + bioscfg_drv.ordered_list_data[instance_id].elements_size);
> > + ret = -EINVAL;
> > + goto out_list_value;
> > + }
> > +
> > +out_list_value:
> > + kfree(new_values);
> > + return ret;
> > +}
>
> This algorithm does not seem to validate that different values are
> provided.
>
> So if "possible_values" is "foo,bar,baz" this function would accept
> "foo,foo,foo".
>
BIOS will reject strings such as "foo,foo,foo" when the current value
is "foo,bar,baz". It is ok to provide a string which items are
ordered differently. i.e. "baz,bar,foo"
validate_ordered_list_values() function will be removed as indicated earlier.
> > +
> > +/*
> > + * validate_ordered_input() -
> > + * Validate input of current_value against possible values
> > + *
> > + * @instance_id: The instance on which input is validated
> > + * @buf: Input value
> > + */
> > +static int validate_ordered_list_input(int instance_id, const char *buf)
> > +{
> > + int ret = 0;
> > +
> > + ret = validate_ordered_list_values(instance_id, buf);
> > + if (ret < 0)
> > + return -EINVAL;
> > +
> > + /*
> > + * set pending reboot flag depending on
> > + * "RequiresPhysicalPresence" value
> > + */
> > + if (bioscfg_drv.ordered_list_data[instance_id].common.requires_physical_presence)
> > + bioscfg_drv.pending_reboot = true;
> > +
> > + return ret;
> > +}
> > +
> > +static void update_ordered_list_value(int instance_id, char *attr_value)
> > +{
> > + strscpy(bioscfg_drv.ordered_list_data[instance_id].current_value,
> > + attr_value,
> > + sizeof(bioscfg_drv.ordered_list_data[instance_id].current_value));
> > +}
> > +
> > +ATTRIBUTE_S_COMMON_PROPERTY_SHOW(display_name_language_code, ordered_list);
> > +static struct kobj_attribute ordered_list_display_langcode =
> > + __ATTR_RO(display_name_language_code);
> > +
> > +ATTRIBUTE_S_COMMON_PROPERTY_SHOW(display_name, ordered_list);
> > +static struct kobj_attribute ordered_list_display_name =
> > + __ATTR_RO(display_name);
> > +
> > +ATTRIBUTE_PROPERTY_STORE(current_value, ordered_list);
> > +static struct kobj_attribute ordered_list_current_val =
> > + __ATTR_RW_MODE(current_value, 0644);
> > +
> > +
> > +ATTRIBUTE_N_COMMON_PROPERTY_SHOW(prerequisites_size, ordered_list);
> > +static struct kobj_attribute ordered_list_prerequisites_size_val =
> > + __ATTR_RO(prerequisites_size);
> > +
> > +ATTRIBUTE_V_COMMON_PROPERTY_SHOW(prerequisites, ordered_list);
> > +static struct kobj_attribute ordered_list_prerequisites_val =
> > + __ATTR_RO(prerequisites);
> > +
> > +ATTRIBUTE_N_PROPERTY_SHOW(elements_size, ordered_list);
> > +static struct kobj_attribute ordered_list_elements_size_val =
> > + __ATTR_RO(elements_size);
>
> "size" and "length" attributes are fairly useless to userspace.
> They can't be trusted to provide information about another attribute as
> the information can be out of date when the other attribute is read.
>
Prerequisites, prerequisites_size and elements_size will be removed
> > +
> > +ATTRIBUTE_VALUES_PROPERTY_SHOW(elements, ordered_list);
> > +static struct kobj_attribute ordered_list_elements_val =
> > + __ATTR_RO(elements);
> > +
<snip>
> > +
> > +
> > +int populate_ordered_list_elements_from_package(union acpi_object *order_obj,
> > + int order_obj_count,
> > + int instance_id)
> > +{
> > + char *str_value = NULL;
> > + int value_len;
> > + int ret = 0;
> > + u32 size = 0;
> > + u32 int_value;
> > + int elem = 0;
> > + int reqs;
> > + int eloc;
> > + char *tmpstr = NULL;
> > + char *part_tmp = NULL;
> > + int tmp_len = 0;
> > + char *part = NULL;
> > +
> > + if (!order_obj)
> > + return -EINVAL;
> > +
> > + strscpy(bioscfg_drv.ordered_list_data[instance_id].common.display_name_language_code,
> > + LANG_CODE_STR,
> > + sizeof(bioscfg_drv.ordered_list_data[instance_id].common.display_name_language_code));
>
> This seems to be the same for every type. Can it not be moved into
> common code?
Each instance requires to report 'display_name_language_code' hence it
cannot be moved to a common code.
>
<snip>