[PATCH v2 0/2] ACPI: sysfs: Expose BDAT data region

[Jamie Nguyen <jamien@nvidia.com>]

The BIOS Data ACPI Table (BDAT) points to a firmware data structure that
carries memory training results and other boot-time data. Patch 2 exposes
that data as /sys/firmware/acpi/tables/data/BDAT, like the existing BERT
and CCEL data files.

Patch 1 fixes a leak in the existing data file code, where data_attr is
not freed if sysfs_create_bin_file() fails. It moves the file creation and
the cleanup into acpi_table_data_init(), and patch 2 builds on that.

Changes in v2:
- New patch 1, fixing the data_attr leak for BERT and CCEL as well.
- Patch 2: the BDAT callback only checks the table and sets the address
  and size of the data, and returns -ENOMEM if mapping the header fails.

v1: https://lore.kernel.org/r/20261009232955.866131-1-jamien@nvidia.com

Tested on an arm64 server (64K pages):

- The file matches a /dev/mem dump of the data region taken in the same
  boot, byte for byte, and decodes with valid CRCs.
- With lockdown=integrity, /dev/mem is refused and the file still reads.
- Malformed BDAT tables loaded via initrd table upgrade (test-only change
  adding BDAT to table_sigs[]) are rejected without creating a file: no
  "BDATHEAD" signature, size below the header, non-memory address space,
  zero address, and a table shorter than struct acpi_table_bdat.
- With a test-only change that makes sysfs_create_bin_file() fail with
  -EEXIST for one BDAT table, kmemleak reports its data_attr as leaked
  without patch 1, and the data_attr is freed with patch 1 applied.

Jamie Nguyen (2):
  ACPI: sysfs: Fix data_attr leak when creating a data file fails
  ACPI: sysfs: Expose BDAT data region

 Documentation/ABI/testing/sysfs-firmware-acpi | 12 ++++
 drivers/acpi/sysfs.c                          | 69 ++++++++++++++++---
 2 files changed, 71 insertions(+), 10 deletions(-)


base-commit: af32da41b0327b9c6a37856ba82b6760d6c8d10e
-- 
2.43.0