[PATCH 0/3] efi/libstub: reduce size by optimizing GUID storage

[Vincent Mailhol]

The EFI stub is size-sensitive. Several call sites currently pass GUID
macro addresses directly, or keep GUID objects as automatic local
variables. With gcc, this materializes the GUID at the call site,
resulting in several assembly instructions. Using static storage instead
emits 16 bytes of GUID data and only one instruction to pass its
address.

The first two patches convert direct GUID references and automatic GUID
variables to static storage. The last patch factors GUID objects that
are shared within the same translation unit.

For the full series, on an x86_64 build with gcc 15.3.0, bloat-o-meter
reports:

  add/remove: 21/0 grow/shrink: 0/12 up/down: 400/-1200 (-800)
  Function                                     old     new   delta
  tbl_guid                                       -      32     +32
  pci_proto                                      -      32     +32
  guid                                           -      32     +32
  cc_guid                                        -      32     +32
  tpm2_guid                                      -      16     +16
  text_to_dp_guid                                -      16     +16
  tcg2_guid                                      -      16     +16
  smbios_guid                                    -      16     +16
  rng_table_guid                                 -      16     +16
  rng_proto                                      -      16     +16
  rng_algo_raw                                   -      16     +16
  proto                                          -      16     +16
  linux_eventlog_guid                            -      16     +16
  lf2_proto_guid                                 -      16     +16
  info_guid                                      -      16     +16
  graphics_output_guid                           -      16     +16
  fs_proto                                       -      16     +16
  edid_discovered_guid                           -      16     +16
  edid_active_guid                               -      16     +16
  console_out_device_guid                        -      16     +16
  apple_set_os_guid                              -      16     +16
  efi_get_memory_map                           707     696     -11
  efi_pci_disable_bridge_busmaster            1199    1184     -15
  efi_get_random_bytes                         216     188     -28
  efi_remap_image                              357     328     -29
  efi_load_initrd                             1113    1065     -48
  efi_get_smbios_record                        283     226     -57
  efi_random_get_seed                         1368    1297     -71
  efi_measure_tagged_event                     935     854     -81
  efi_retrieve_eventlog                       1686    1570    -116
  handle_cmdline_files                        2501    2341    -160
  efi_stub_entry                              4180    3953    -227
  efi_setup_graphics                          2210    1853    -357
  Total: Before=29223, After=28423, chg -2.74%

See this as my penitence for adding the BLI feature: I am giving you
back the bytes that I consumed, and even more.

Signed-off-by: Vincent Mailhol <mailhol@xxxxxxxxxx>
---
Vincent Mailhol (3):
      efi/libstub: move direct GUID references to static storage
      efi/libstub: make local GUID variables static
      efi/libstub: factor shared static GUID variables

 drivers/firmware/efi/libstub/efi-stub-entry.c    |  2 +-
 drivers/firmware/efi/libstub/efi-stub-helper.c   | 10 +++++-----
 drivers/firmware/efi/libstub/efi-stub.c          |  2 +-
 drivers/firmware/efi/libstub/file.c              |  8 ++++----
 drivers/firmware/efi/libstub/gop.c               | 17 ++++++++++-------
 drivers/firmware/efi/libstub/kaslr.c             |  2 +-
 drivers/firmware/efi/libstub/mem.c               |  2 +-
 drivers/firmware/efi/libstub/pci.c               |  2 +-
 drivers/firmware/efi/libstub/random.c            |  8 ++++----
 drivers/firmware/efi/libstub/riscv.c             |  2 +-
 drivers/firmware/efi/libstub/smbios.c            |  3 ++-
 drivers/firmware/efi/libstub/tpm.c               |  8 ++++----
 drivers/firmware/efi/libstub/unaccepted_memory.c |  2 +-
 drivers/firmware/efi/libstub/x86-stub.c          | 13 +++++++------
 drivers/firmware/efi/libstub/zboot.c             |  3 ++-
 15 files changed, 45 insertions(+), 39 deletions(-)
---
base-commit: cee9395acd8043be0644b25c34bfa86623f2b935
change-id: 20260903-libstub_guid_cleanup-7aad27f1c0c5

Best regards,
--  
Vincent Mailhol <mailhol@xxxxxxxxxx>