On Tue, Sep 06, 2016 at 11:51:10AM -0400, Peter Jones wrote:
> This adds the EFI Spec version from the system table to sysfs as
> /sys/firmware/efi/spec_version .
>
> Userland tools need this information in order to work around
> specification deficiencies in 2.4 and earlier firmwares. Specifically,
> UEFI 2.4 and 2.5+ treat management of BootOrder very differently (See
> UEFI 2.4 section 3.1.1 vs UEFI 2.5 section 3.1), which means on older
> firmware we'll want to work around BDS's boot order management by adding
> fwupdate entries to BootOrder. We'd prefer not to do this on newer
> firmware, as it is both non-sensical in terms of what it expresses, and
> it results in more relatively failure prone flash writes.
>
> Signed-off-by: Peter Jones <pjones@xxxxxxxxxx>
> ---
> Documentation/ABI/testing/sysfs-firmware-efi | 6 +++
> drivers/firmware/efi/efi.c | 66 ++++++++++++++++++++++++++++
> 2 files changed, 72 insertions(+)
>
> diff --git a/Documentation/ABI/testing/sysfs-firmware-efi b/Documentation/ABI/testing/sysfs-firmware-efi
> index e794eac..4eec7c2 100644
> --- a/Documentation/ABI/testing/sysfs-firmware-efi
> +++ b/Documentation/ABI/testing/sysfs-firmware-efi
> @@ -28,3 +28,9 @@ Description: Displays the physical addresses of all EFI Configuration
> versions are always printed first, i.e. ACPI20 comes
> before ACPI.
> Users: dmidecode
> +
> +What: /sys/firmware/efi/spec_version
> +Date: August 2016
> +Contact: linux-efi@xxxxxxxxxxxxxxx
> +Description: Displays the UEFI Specification revision the firmware claims to
> + be based upon.
> diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
> index 5a2631a..c7cdd3f 100644
> --- a/drivers/firmware/efi/efi.c
> +++ b/drivers/firmware/efi/efi.c
> @@ -141,11 +141,76 @@ static ssize_t fw_platform_size_show(struct kobject *kobj,
> return sprintf(buf, "%d\n", efi_enabled(EFI_64BIT) ? 64 : 32);
> }
>
> +static ssize_t spec_version_show(struct kobject *kobj,
> + struct kobj_attribute *attr,
> + char *buf)
> +{
> + u16 major, minor;
> + ssize_t rc;
> +
> + if (!buf)
> + return -EINVAL;
> +
> + /* The spec says:
> + * The revision of the EFI Specification to which this table
> + * conforms. The upper 16 bits of this field contain the major
> + * revision value, and the lower 16 bits contain the minor revision
> + * value. The minor revision values are binary coded decimals and are
> + * limited to the range of 00..99.
> + *
> + * When printed or displayed UEFI spec revision is referred as (Major
> + * revision).(Minor revision upper decimal).(Minor revision lower
> + * decimal) or (Major revision).(Minor revision upper decimal) in
> + * case Minor revision lower decimal is set to 0. For example:
> + *
> + * A specification with the revision value ((2<<16) | (30)) would be
> + * referred as 2.3;
> + * A specification with the revision value ((2<<16) | (31)) would be
> + * referred as 2.3.1
> + *
> + * Then later it says:
> + * Related Definitions
> + * #define EFI_SYSTEM_TABLE_SIGNATURE 0x5453595320494249
> + * #define EFI_2_40_SYSTEM_TABLE_REVISION ((2<<16) | (40))
> + * #define EFI_2_31_SYSTEM_TABLE_REVISION ((2<<16) | (31))
> + * #define EFI_2_30_SYSTEM_TABLE_REVISION ((2<<16) | (30))
> + * #define EFI_2_20_SYSTEM_TABLE_REVISION ((2<<16) | (20))
> + * #define EFI_2_10_SYSTEM_TABLE_REVISION ((2<<16) | (10))
> + * #define EFI_2_00_SYSTEM_TABLE_REVISION ((2<<16) | (00))
> + * #define EFI_1_10_SYSTEM_TABLE_REVISION ((1<<16) | (10))
> + * #define EFI_1_02_SYSTEM_TABLE_REVISION ((1<<16) | (02))
> + * #define EFI_SPECIFICATION_VERSION EFI_SYSTEM_TABLE_REVISION
> + * #define EFI_SYSTEM_TABLE_REVISION EFI_2_40_SYSTEM_TABLE_REVISION
> + *
> + * (Apparently this bit of the spec failed to get updated for 2.5
> + * and 2.6; UefiSpec.h in Tiano has been updated, though.)
> + *
> + * This of course does not match the description above at all, but it
> + * does match the code in Tiano. So we decode it Tiano's way.
> + */
> + major = (efi.spec_version & 0xffff0000) >> 16;
> + minor = (efi.spec_version & 0x0000ffff);
> +
> + if ((minor % 10) == 0)
> + rc = sprintf(buf, "%u.%u", major, minor / 10);
> + else
> + rc = sprintf(buf, "%u.%u.%u", major, minor / 10, minor % 10);
> +
> + if (rc < 0) {
> + char *str;
> +
> + str = strcpy(buf, "(unknown)");
> + return str - buf;
str points to the same address as buf, so the return value will be 0 here...
With that addressed,
Reviewed-by: Lukas Wunner <lukas@xxxxxxxxx>
> + }
> + return rc;
> +}
> +
> static struct kobj_attribute efi_attr_fw_vendor = __ATTR_RO(fw_vendor);
> static struct kobj_attribute efi_attr_runtime = __ATTR_RO(runtime);
> static struct kobj_attribute efi_attr_config_table = __ATTR_RO(config_table);
> static struct kobj_attribute efi_attr_fw_platform_size =
> __ATTR_RO(fw_platform_size);
> +static struct kobj_attribute efi_attr_spec_version = __ATTR_RO(spec_version);
>
> static struct attribute *efi_subsys_attrs[] = {
> &efi_attr_systab.attr,
> @@ -153,6 +218,7 @@ static struct attribute *efi_subsys_attrs[] = {
> &efi_attr_runtime.attr,
> &efi_attr_config_table.attr,
> &efi_attr_fw_platform_size.attr,
> + &efi_attr_spec_version.attr,
> NULL,
> };
>
> --
> 2.7.4
--
To unsubscribe from this list: send the line "unsubscribe linux-efi" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
