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. So this patch adds SMBIOS area to dmi-sysfs in order to allow utils in question to work correctly with dmi sysfs interface. Reviewed-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx> Signed-off-by: Ivan Khoronzhuk <ivan.khoronzhuk@xxxxxxxxxx> --- v1: https://lkml.org/lkml/2015/1/23/643 v2: https://lkml.org/lkml/2015/1/26/345 v3: https://lkml.org/lkml/2015/1/28/768 v4..v2: firmware: dmi_scan: add symbol to get SMBIOS entry area - used u8 type for smbios_header var firmware: dmi-sysfs: add SMBIOS entry point area attribute - replaced -ENODATA on -EINVAL v3..v2: firmware: dmi_scan: add symbol to get SMBIOS entry area firmware: dmi-sysfs: add SMBIOS entry point area attribute - combined in one patch - added SMBIOS information to ABI sysfs-dmi documentaton v2..v1: firmware: dmi_scan: add symbol to get SMBIOS entry area - used additional static var to hold SMBIOS raw table size - changed format of get_smbios_entry_area symbol returned pointer on const smbios table firmware: dmi-sysfs: add SMBIOS entry point area attribute - adopted to updated get_smbios_entry_area symbol - removed redundant array to save smbios table Documentation/ABI/testing/sysfs-firmware-dmi | 10 +++++++ drivers/firmware/dmi-sysfs.c | 42 ++++++++++++++++++++++++++++ drivers/firmware/dmi_scan.c | 26 +++++++++++++++++ include/linux/dmi.h | 3 ++ 4 files changed, 81 insertions(+) diff --git a/Documentation/ABI/testing/sysfs-firmware-dmi b/Documentation/ABI/testing/sysfs-firmware-dmi index c78f9ab..3a9ffe8 100644 --- a/Documentation/ABI/testing/sysfs-firmware-dmi +++ b/Documentation/ABI/testing/sysfs-firmware-dmi @@ -12,6 +12,16 @@ Description: cannot ensure that the data as exported to userland is without error either. + 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. + That's why SMBIOS entry point is represented in dmi sysfs + like a raw attribute and is accessible via + /sys/firmware/dmi/smbios_raw_header. The format of SMBIOS + entry point header can be read in SMBIOS specification. + DMI is structured as a large table of entries, where each entry has a common header indicating the type and length of the entry, as well as a firmware-provided diff --git a/drivers/firmware/dmi-sysfs.c b/drivers/firmware/dmi-sysfs.c index e0f1cb3..9b396d7 100644 --- a/drivers/firmware/dmi-sysfs.c +++ b/drivers/firmware/dmi-sysfs.c @@ -29,6 +29,8 @@ #define MAX_ENTRY_TYPE 255 /* Most of these aren't used, but we consider the top entry type is only 8 bits */ +static const u8 *smbios_raw_header; + struct dmi_sysfs_entry { struct dmi_header dh; struct kobject kobj; @@ -646,9 +648,37 @@ static void cleanup_entry_list(void) } } +static ssize_t smbios_entry_area_raw_read(struct file *filp, + struct kobject *kobj, + struct bin_attribute *bin_attr, + char *buf, loff_t pos, size_t count) +{ + ssize_t size; + + size = bin_attr->size; + + if (size > pos) + size -= pos; + else + return 0; + + if (count < size) + size = count; + + memcpy(buf, &smbios_raw_header[pos], size); + + return size; +} + +static struct bin_attribute smbios_raw_area_attr = { + .read = smbios_entry_area_raw_read, + .attr = {.name = "smbios_raw_header", .mode = 0400}, +}; + static int __init dmi_sysfs_init(void) { int error = -ENOMEM; + int size; int val; /* Set up our directory */ @@ -669,6 +699,18 @@ static int __init dmi_sysfs_init(void) goto err; } + smbios_raw_header = dmi_get_smbios_entry_area(&size); + if (!smbios_raw_header) { + pr_debug("dmi-sysfs: SMBIOS raw data is not available.\n"); + error = -EINVAL; + goto err; + } + + /* Create the raw binary file to access the entry area */ + smbios_raw_area_attr.size = size; + if (sysfs_create_bin_file(dmi_kobj, &smbios_raw_area_attr)) + goto err; + pr_debug("dmi-sysfs: loaded.\n"); return 0; diff --git a/drivers/firmware/dmi_scan.c b/drivers/firmware/dmi_scan.c index 420c8d8..99c5f6c 100644 --- a/drivers/firmware/dmi_scan.c +++ b/drivers/firmware/dmi_scan.c @@ -113,6 +113,8 @@ static void dmi_table(u8 *buf, int len, int num, } } +static u8 smbios_header[32]; +static int smbios_header_size; static phys_addr_t dmi_base; static u16 dmi_len; static u16 dmi_num; @@ -474,6 +476,8 @@ 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_header_size = buf[5]; + memcpy(smbios_header, buf, smbios_header_size); /* Some BIOS report weird SMBIOS version, fix that up */ switch (smbios_ver) { @@ -505,6 +509,8 @@ static int __init dmi_present(const u8 *buf) pr_info("SMBIOS %d.%d present.\n", dmi_ver >> 8, dmi_ver & 0xFF); } else { + smbios_header_size = 15; + memcpy(smbios_header, buf, smbios_header_size); dmi_ver = (buf[14] & 0xF0) << 4 | (buf[14] & 0x0F); pr_info("Legacy DMI %d.%d present.\n", @@ -531,6 +537,8 @@ 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_header_size = buf[6]; + memcpy(smbios_header, buf, smbios_header_size); /* * The 64-bit SMBIOS 3.0 entry point no longer has a field @@ -944,3 +952,21 @@ void dmi_memdev_name(u16 handle, const char **bank, const char **device) } } EXPORT_SYMBOL_GPL(dmi_memdev_name); + +/** + * dmi_get_smbios_entry_area - copy SMBIOS entry point area to array. + * @size - pointer to assign actual size of SMBIOS entry point area. + * + * returns NULL if table is not available, otherwise returns pointer on + * SMBIOS entry point area array. + */ +const u8 *dmi_get_smbios_entry_area(int *size) +{ + if (!smbios_header_size || !dmi_available) + return NULL; + + *size = smbios_header_size; + + return smbios_header; +} +EXPORT_SYMBOL_GPL(dmi_get_smbios_entry_area); diff --git a/include/linux/dmi.h b/include/linux/dmi.h index f820f0a..8e1a28d 100644 --- a/include/linux/dmi.h +++ b/include/linux/dmi.h @@ -109,6 +109,7 @@ extern int dmi_walk(void (*decode)(const struct dmi_header *, void *), void *private_data); extern bool dmi_match(enum dmi_field f, const char *str); extern void dmi_memdev_name(u16 handle, const char **bank, const char **device); +const u8 *dmi_get_smbios_entry_area(int *size); #else @@ -140,6 +141,8 @@ static inline void dmi_memdev_name(u16 handle, const char **bank, const char **device) { } static inline const struct dmi_system_id * dmi_first_match(const struct dmi_system_id *list) { return NULL; } +static inline const u8 *dmi_get_smbios_entry_area(int *size) + { return NULL; } #endif -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
