Add sysfs files at /sys/firmware/acpi/fpdt/FBPT and
/sys/firmware/acpi/fpdt/S3PT that expose the raw contents of the
FPDT subtables.
Note that /sys/firmware/acpi/tables/FPDT only provides the top level
table, not the subtables. Adding access to the subtables enables a
usage model similar to /sys/firmware/dmi/tables/DMI, allowing
userspace tools to interpret newer record types (e.g. String Event
Records, Microcontroller Boot Performance Data Records, etc.) defined
in recent ACPI specifications [1] without requiring kernel changes.
Link: https://uefi.org/specs/ACPI/6.6/05_ACPI_Software_Programming_Model.html#performance-event-record-types [1]
Signed-off-by: Nate DeSimone <nathaniel.l.desimone@intel.com>
[ rjw: Changelog edits ]
Link: https://patch.msgid.link/20260324231456.701-2-nathaniel.l.desimone@intel.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Buggy BIOSes may have invalid FPDT subtables, e.g. on my hardware:
S3PT subtable:
7F20FE30: 53 33 50 54 24 00 00 00-00 00 00 00 00 00 18 01 *S3PT$...........*
7F20FE40: 00 00 00 00 00 00 00 00-00 00 00 00 00 00 00 00 *................*
7F20FE50: 00 00 00 00
Here the first record has zero length.
FBPT subtable:
7F20FE50: 46 42 50 54-3C 00 00 00 46 42 50 54 *....FBPT<...FBPT*
7F20FE60: 02 00 30 02 00 00 00 00-00 00 00 00 00 00 00 00 *..0.............*
7F20FE70: 2A A6 BC 6E 0B 00 00 00-1A 44 41 70 0B 00 00 00 **..n.....DAp....*
7F20FE80: 00 00 00 00 00 00 00 00-00 00 00 00 00 00 00 00 *................*
And here FBPT table has FBPT signature repeated instead of the first
record.
Current code will be looping indefinitely due to zero length records, so
break out of the loop if record length is zero.
While we are here, add proper handling for fpdt_process_subtable()
failures.
Fixes: d1eb86e59b ("ACPI: tables: introduce support for FPDT table")
Cc: All applicable <stable@vger.kernel.org>
Signed-off-by: Vasily Khoruzhick <anarsoul@gmail.com>
[ rjw: Comment edit, added empty code lines ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
acpi_init_fpdt() forgets to call acpi_put_table() in an error path.
Add the missing function call to fix it.
Fixes: d1eb86e59b ("ACPI: tables: introduce support for FPDT table")
Signed-off-by: Jing Xiangfeng <jingxiangfeng@huawei.com>
Acked-by: Zhang Rui <rui.zhang@intel.com>
Reviewed-by: Hanjun Guo <guohanjun@huawei.com>
[ rjw: Subject and changelog edits ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
ACPI Firmware Performance Data Table (FPDT) provides information about
firmware performance during system boot, S3 suspend and S3 resume.
Have the kernel parse the FPDT table, and expose the firmware
performance data to userspace as sysfs attributes under
/sys/firmware/acpi/fpdt/.
Tested-by: Todd Brandt <todd.e.brandt@linux.intel.com>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
