Re: [Patch 2/3] firmware: dmi_scan: add SBMIOS entry and DMI tables

Roy Franz
2015-04-15T04:19:17Z

On Fri, Apr 3, 2015 at 2:36 AM, Ivan.khoronzhuk
<ivan.khoronzhuk-hExfYMNmJl/Cnp4W7fqMDg@public.gmane.org> wrote:
>
>
> On 02.04.15 15:57, Ivan Khoronzhuk wrote:
>>
>> Some utils, like dmidecode and smbios, need to access SMBIOS entry
>> table area in order to get information like SMBIOS version, size, etc.
>> Currently it's done via /dev/mem. But for situation when /dev/mem
>> usage is disabled, the utils have to use dmi sysfs instead, which
>> doesn't represent SMBIOS entry and adds code/delay redundancy when direct
>> access for table is needed.
>>
>> So this patch creates dmi/tables and adds SMBIOS entry point to allow
>> utils in question to work correctly without /dev/mem. Also patch adds
>> raw dmi table to simplify dmi table processing in user space, as
>> proposed by Jean Delvare.
>>

I have made modifications to dmidecode to support this interface, and it
works quite nicely for dmidecode. (changes posted to dmidecode-devel list)
The only open issue I am aware of is how the SMBIOS v3 entry point
will be handled,
especially in cases where there is a v2 and a v3 entry point.
In principal I think this a good change - are there any other open issues?

Thanks,
Roy

>> Signed-off-by: Ivan Khoronzhuk <ivan.khoronzhuk-hExfYMNmJl/Cnp4W7fqMDg@public.gmane.org>
>> ---
>> .../ABI/testing/sysfs-firmware-dmi-tables | 22 ++++++
>> drivers/firmware/dmi-sysfs.c | 11 ++-
>> drivers/firmware/dmi_scan.c | 80
>> ++++++++++++++++++++++
>> include/linux/dmi.h | 1 +
>> 4 files changed, 107 insertions(+), 7 deletions(-)
>> create mode 100644 Documentation/ABI/testing/sysfs-firmware-dmi-tables
>>
>> diff --git a/Documentation/ABI/testing/sysfs-firmware-dmi-tables
>> b/Documentation/ABI/testing/sysfs-firmware-dmi-tables
>> new file mode 100644
>> index 0000000..f46158c
>> --- /dev/null
>> +++ b/Documentation/ABI/testing/sysfs-firmware-dmi-tables
>> @@ -0,0 +1,22 @@
>> +What: /sys/firmware/dmi/tables/
>> +Date: April 2015
>> +Contact: Ivan Khoronzhuk <ivan.khoronzhuk-hExfYMNmJl/Cnp4W7fqMDg@public.gmane.org>
>> +Description:
>> + The firmware provides DMI structures as a packed list of
>> + data referenced by a SMBIOS table entry point. The SMBIOS
>> + entry point contains general information, like SMBIOS
>> + version, DMI table size, etc. The structure, content and
>> + size of SMBIOS entry point is dependent on SMBIOS version.
>> + The format of SMBIOS entry point, equal as DMI structures
>> + can be read in SMBIOS specification.
>> +
>> + The dmi/tables provides raw SMBIOS entry point and DMI
>> tables
>> + through sysfs as an alternative to utilities reading them
>> + from /dev/mem. The raw SMBIOS entry point and DMI table
>> are
>> + presented as raw attributes and are accessible via:
>> +
>> + /sys/firmware/dmi/tables/smbios_entry_point
>> + /sys/firmware/dmi/tables/DMI
>> +
>> + The complete DMI information can be taken using these two
>> + tables.
>> diff --git a/drivers/firmware/dmi-sysfs.c b/drivers/firmware/dmi-sysfs.c
>> index e0f1cb3..8e1a411 100644
>> --- a/drivers/firmware/dmi-sysfs.c
>> +++ b/drivers/firmware/dmi-sysfs.c
>> @@ -566,7 +566,6 @@ static struct kobj_type dmi_sysfs_entry_ktype = {
>> .default_attrs = dmi_sysfs_entry_attrs,
>> };
>> -static struct kobject *dmi_kobj;
>> static struct kset *dmi_kset;
>> /* Global count of all instances seen. Only for setup */
>> @@ -651,10 +650,11 @@ static int __init dmi_sysfs_init(void)
>> int error = -ENOMEM;
>> int val;
>> - /* Set up our directory */
>> - dmi_kobj = kobject_create_and_add("dmi", firmware_kobj);
>> - if (!dmi_kobj)
>> + if (!dmi_kobj) {
>> + pr_err("dmi-sysfs: dmi entry is absent.\n");
>> + error = -ENOSYS;
>> goto err;
>> + }
>> dmi_kset = kset_create_and_add("entries", NULL, dmi_kobj);
>> if (!dmi_kset)
>> @@ -675,7 +675,6 @@ static int __init dmi_sysfs_init(void)
>> err:
>> cleanup_entry_list();
>> kset_unregister(dmi_kset);
>> - kobject_put(dmi_kobj);
>> return error;
>> }
>> @@ -685,8 +684,6 @@ static void __exit dmi_sysfs_exit(void)
>> pr_debug("dmi-sysfs: unloading.\n");
>> cleanup_entry_list();
>> kset_unregister(dmi_kset);
>> - kobject_del(dmi_kobj);
>> - kobject_put(dmi_kobj);
>> }
>> module_init(dmi_sysfs_init);
>> diff --git a/drivers/firmware/dmi_scan.c b/drivers/firmware/dmi_scan.c
>> index d3aae09..bb19f8b 100644
>> --- a/drivers/firmware/dmi_scan.c
>> +++ b/drivers/firmware/dmi_scan.c
>> @@ -10,6 +10,9 @@
>> #include <asm/dmi.h>
>> #include <asm/unaligned.h>
>> +struct kobject *dmi_kobj;
>> +EXPORT_SYMBOL_GPL(dmi_kobj);
>> +
>> /*
>> * DMI stands for "Desktop Management Interface". It is part
>> * of and an antecedent to, SMBIOS, which stands for System
>> @@ -20,6 +23,9 @@ static const char dmi_empty_string[] = " ";
>> static u32 dmi_ver __initdata;
>> static u32 dmi_len;
>> static u16 dmi_num;
>> +static u8 smbios_entry_point[32];
>> +static int smbios_entry_point_size;
>> +
>> /*
>> * Catch too early calls to dmi_check_system():
>> */
>> @@ -118,6 +124,7 @@ static void dmi_decode_table(u8 *buf,
>> }
>> static phys_addr_t dmi_base;
>> +static u8 *dmi_table;
>> static int __init dmi_walk_early(void (*decode)(const struct
>> dmi_header *,
>> void *))
>> @@ -476,6 +483,8 @@ static int __init dmi_present(const u8 *buf)
>> if (memcmp(buf, "_SM_", 4) == 0 &&
>> buf[5] < 32 && dmi_checksum(buf, buf[5])) {
>> smbios_ver = get_unaligned_be16(buf + 6);
>> + smbios_entry_point_size = buf[5];
>> + memcpy(smbios_entry_point, buf, smbios_entry_point_size);
>> /* Some BIOS report weird SMBIOS version, fix that up */
>> switch (smbios_ver) {
>> @@ -508,6 +517,9 @@ static int __init dmi_present(const u8 *buf)
>> dmi_ver >> 8, dmi_ver & 0xFF,
>> (dmi_ver < 0x0300) ? "" : ".x");
>> } else {
>> + smbios_entry_point_size = 15;
>> + memcpy(smbios_entry_point, buf,
>> + smbios_entry_point_size);
>> dmi_ver = (buf[14] & 0xF0) << 4 |
>> (buf[14] & 0x0F);
>> pr_info("Legacy DMI %d.%d present.\n",
>> @@ -535,6 +547,8 @@ static int __init dmi_smbios3_present(const u8 *buf)
>> dmi_ver &= 0xFFFFFF;
>> dmi_len = get_unaligned_le32(buf + 12);
>> dmi_base = get_unaligned_le64(buf + 16);
>> + smbios_entry_point_size = buf[6];
>> + memcpy(smbios_entry_point, buf, smbios_entry_point_size);
>> /*
>> * The 64-bit SMBIOS 3.0 entry point no longer has a field
>> @@ -638,6 +652,72 @@ void __init dmi_scan_machine(void)
>> dmi_initialized = 1;
>> }
>> +static ssize_t raw_table_read(struct file *file, struct kobject *kobj,
>> + struct bin_attribute *attr, char *buf,
>> + loff_t pos, size_t count)
>> +{
>> + memcpy(buf, attr->private + pos, count);
>> + return count;
>> +}
>> +
>> +static BIN_ATTR(smbios_entry_point, S_IRUSR, raw_table_read, NULL, 0);
>> +struct bin_attribute bin_attr_dmi_table =
>> + __BIN_ATTR(DMI, S_IRUSR, raw_table_read, NULL, 0);
>
>
> missed static here
>
>
>> +
>> +static int __init dmi_init(void)
>> +{
>> + int ret = -ENOMEM;
>> + struct kobject *tables_kobj = NULL;
>> +
>> + if (!dmi_available) {
>> + ret = -ENOSYS;
>> + goto err;
>> + }
>> +
>> + /* Set up dmi directory at /sys/firmware/dmi */
>> + dmi_kobj = kobject_create_and_add("dmi", firmware_kobj);
>> + if (!dmi_kobj)
>> + goto err;
>> +
>> + tables_kobj = kobject_create_and_add("tables", dmi_kobj);
>> + if (!tables_kobj)
>> + goto err;
>> +
>> + bin_attr_smbios_entry_point.size = smbios_entry_point_size;
>> + bin_attr_smbios_entry_point.private = smbios_entry_point;
>> + ret = sysfs_create_bin_file(tables_kobj,
>> &bin_attr_smbios_entry_point);
>> + if (ret)
>> + goto err;
>> +
>> + dmi_table = dmi_remap(dmi_base, dmi_len);
>> + if (!dmi_table)
>> + goto err;
>> +
>> + bin_attr_dmi_table.size = dmi_len;
>> + bin_attr_dmi_table.private = dmi_table;
>> + ret = sysfs_create_bin_file(tables_kobj, &bin_attr_dmi_table);
>> + if (ret) {
>> + dmi_unmap(dmi_table);
>> + goto err;
>> + }
>> +
>> + return 0;
>> +err:
>> + pr_err("dmi: Firmware registration failed.\n");
>> +
>> + if (tables_kobj)
>> + sysfs_remove_bin_file(tables_kobj,
>> + &bin_attr_smbios_entry_point);
>> + kobject_del(tables_kobj);
>> + kobject_put(tables_kobj);
>> + kobject_del(dmi_kobj);
>> + kobject_put(dmi_kobj);
>> + dmi_kobj = NULL;
>> +
>> + return ret;
>> +}
>> +subsys_initcall(dmi_init);
>> +
>> /**
>> * dmi_set_dump_stack_arch_desc - set arch description for dump_stack()
>> *
>> diff --git a/include/linux/dmi.h b/include/linux/dmi.h
>> index f820f0a..9f55f46 100644
>> --- a/include/linux/dmi.h
>> +++ b/include/linux/dmi.h
>> @@ -93,6 +93,7 @@ struct dmi_dev_onboard {
>> int devfn;
>> };
>> +extern struct kobject *dmi_kobj;
>> extern int dmi_check_system(const struct dmi_system_id *list);
>> const struct dmi_system_id *dmi_first_match(const struct dmi_system_id
>> *list);
>> extern const char * dmi_get_system_info(int field);
>
>
> --
> Regards,
> Ivan Khoronzhuk
>