[Skiboot] [PATCH V2 15/21] core/pldm: Find lid attribute from bios tables
Abhishek SIngh Tomar
abhishek at linux.ibm.com
Wed Mar 16 20:09:41 AEDT 2022
Hello Christophe
In function find_lid_by_attr_name(). I doubt the scenario the code will fail if two attribute names
are such that one attribute is substring of other.
Taking example of input variable to function:
str : "ATTR_AB=21,ATTR_A=43,ATTR_X=45
name : "ATTR_A"
expected output is 43 but output received will be 21
> + * parse a string, format:
> + * <ATTR_a>=<lid_id_1>,<ATTR_b>=<lid_id_2>
> + */
> +static int find_lid_by_attr_name(char *str, const char *name,
> + char **lid)
> +{
> + char *p;
> +
> + for (p = strtok(str, ","); p != NULL; p = strtok(NULL, ",")) {
> + if (!strncmp(p, name, strlen(name))) {
> + p += strlen(name) + 1;
> + *lid = strdup(p);
> + return OPAL_SUCCESS;
> + }
> + }
> + prlog(PR_ERR, "%s - lid not found, attr name: %s\n",
> + __func__, name);
> +
> + return OPAL_PARAMETER;
> +}
Though we may not have such scenario in our case of atribute name but sometime this become
reason of failure in parsing string. I suggest to match(compare) length of attribute name in string
with name input variable string length.
Regards
Abhishek Singh Tomar
On Fri, Mar 04, 2022 at 02:11:48PM +0100, Christophe Lombard wrote:
> This specification defines the data structures and messages for
> communicating BIOS settings, BIOS attributes, boot configurations, and
> boot order settings.
>
> Use the GetBIOSTable command to get STRING, Attribute and Attribute values
> tables from the BIOS.
>
> The contents of these tables are needed to read/write the desired lid
> files located on the BMC.
>
> Signed-off-by: Christophe Lombard <clombard at linux.vnet.ibm.com>
> ---
> core/pldm/pldm-bios-requests.c | 138 +++++++++++++++++++++++++++++++++
> core/pldm/pldm.h | 2 +
> 2 files changed, 140 insertions(+)
>
> diff --git a/core/pldm/pldm-bios-requests.c b/core/pldm/pldm-bios-requests.c
> index 0e2f9a25..80ceb471 100644
> --- a/core/pldm/pldm-bios-requests.c
> +++ b/core/pldm/pldm-bios-requests.c
> @@ -84,6 +84,144 @@ static void bios_init_complete(bool success)
> bios_ready = true;
> }
>
> +/*
> + * parse a string, format:
> + * <ATTR_a>=<lid_id_1>,<ATTR_b>=<lid_id_2>
> + */
> +static int find_lid_by_attr_name(char *str, const char *name,
> + char **lid)
> +{
> + char *p;
> +
> + for (p = strtok(str, ","); p != NULL; p = strtok(NULL, ",")) {
> + if (!strncmp(p, name, strlen(name))) {
> + p += strlen(name) + 1;
> + *lid = strdup(p);
> + return OPAL_SUCCESS;
> + }
> + }
> + prlog(PR_ERR, "%s - lid not found, attr name: %s\n",
> + __func__, name);
> +
> + return OPAL_PARAMETER;
> +}
> +
> +/*
> + * Retrieve attribut value from string.
> + *
> + * Ex: string value = "hb_lid_ids"
> + * From STRING table (with string value = "hb_lid_ids") -> string_handle = 60
> + * From ATTR table (with attr name handle = 60) -> attr handle = 8
> + * From ATTR VAL table (with attr handle = 8)
> + * -> CurrentString = ATTR_PERM=81e00663,ATTR_TMP=81e00664, ...
> + * NVRAM=81e0066b,...,pnor.toc=NA"
> + */
> +static int find_bios_table_attr_values_by_string(const char *str,
> + char **current_string)
> +{
> + const struct pldm_bios_string_table_entry *string_entry;
> + const struct pldm_bios_attr_table_entry *attr_entry;
> + const struct pldm_bios_attr_val_table_entry *val_entry;
> + uint16_t string_handle, attr_handle;
> + struct variable_field currentString;
> +
> + if ((!bios_string_table) || (!bios_attr_table))
> + return OPAL_PARAMETER;
> +
> + /* decode string table */
> + string_entry = pldm_bios_table_string_find_by_string(
> + bios_string_table, bios_string_length, str);
> + if (!string_entry) {
> + prlog(PR_ERR, "String table entry not found, str: %s\n",
> + str);
> + return OPAL_PARAMETER;
> + }
> +
> + /* get the string handle for the entry */
> + string_handle = pldm_bios_table_string_entry_decode_handle(string_entry);
> + prlog(PR_TRACE, "%s - string_handle: %d\n", __func__, string_handle);
> +
> + /* decode attribute table */
> + attr_entry = pldm_bios_table_attr_find_by_string_handle(
> + bios_attr_table, bios_attr_length, string_handle);
> + if (!attr_entry) {
> + prlog(PR_ERR, "Attribute table entry not found, string_handle: %d\n",
> + string_handle);
> + return OPAL_PARAMETER;
> + }
> +
> + /* get the attribute handle from the attribute table entry */
> + attr_handle = pldm_bios_table_attr_entry_decode_attribute_handle(attr_entry);
> + prlog(PR_TRACE, "%s - attr_handle: %d\n", __func__, attr_handle);
> +
> + /* decode attribute value table */
> + val_entry = pldm_bios_table_attr_value_find_by_handle(
> + bios_val_table, bios_val_length, attr_handle);
> +
> + if (!val_entry) {
> + prlog(PR_ERR, "Attribute val table entry not found, attr_handle: %d\n",
> + attr_handle);
> + return OPAL_PARAMETER;
> + }
> +
> + /* get Current String Itself */
> + pldm_bios_table_attr_value_entry_string_decode_string(
> + val_entry,
> + ¤tString);
> + *current_string = strdup(currentString.ptr);
> +
> + return OPAL_SUCCESS;
> +}
> +
> +#define HB_LID_IDS "hb_lid_ids"
> +
> +/*
> + * Find lid attribute from bios tables
> + */
> +int pldm_bios_find_lid_by_attr_name(const char *name, char **lid)
> +{
> + char *hb_lid_ids_string = NULL;
> + int rc = OPAL_SUCCESS;
> +
> + if (!bios_ready)
> + return OPAL_HARDWARE;
> +
> + /* find current attribut string */
> + rc = find_bios_table_attr_values_by_string(HB_LID_IDS, &hb_lid_ids_string);
> + if (rc)
> + goto err;
> +
> + /* find lid attribut from current string */
> + rc = find_lid_by_attr_name(hb_lid_ids_string, name, lid);
> + if (rc)
> + goto err;
> +
> + free(hb_lid_ids_string);
> +
> + prlog(PR_DEBUG, "%s - lid: %s, attr name: %s\n",
> + __func__, *lid, name);
> +
> + return OPAL_SUCCESS;
> +
> +err:
> + if (hb_lid_ids_string)
> + free(hb_lid_ids_string);
> +
> + return rc;
> +}
> +
> +/*
> + * Get lid ids string from bios tables
> + */
> +int pldm_bios_get_lids_id(char **lid_ids_string)
> +{
> + if (!bios_ready)
> + return OPAL_HARDWARE;
> +
> + /* find current attribut string */
> + return find_bios_table_attr_values_by_string(HB_LID_IDS, lid_ids_string);
> +}
> +
> /*
> * Send/receive a PLDM GetBIOSTable request message
> */
> diff --git a/core/pldm/pldm.h b/core/pldm/pldm.h
> index d90ff84c..4f3d262a 100644
> --- a/core/pldm/pldm.h
> +++ b/core/pldm/pldm.h
> @@ -51,6 +51,8 @@ int pldm_rx_handle_request(struct pldm_rx_data *rx);
> int pldm_mctp_responder_init(void);
>
> /* Requester support */
> +int pldm_bios_find_lid_by_attr_name(const char *name, char **lid);
> +int pldm_bios_get_lids_id(char **lid_ids_string);
> int pldm_bios_init(void);
>
> void pldm_platform_exit(void);
> --
> 2.35.1
>
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