[PATCH v7 0/2] Update ifunc resolver interface

[Yury Khrustalev]

Support extending ifunc resolver interface with extra HWCAP fields
and add hwcap3 and hwcap4.

Corresponding ABI spec update (merged):
https://github.com/ARM-software/abi-aa/pull/320

This patch adds helper function that allows accessing HWCAP elements
through the parameters passed to an ifunc resolver in a portable way.

Regression tested on AArch64 and no regressions have been found.

OK for trunk?

base commit: 25f1d94576

Changes in v7:
 - Returned enum for the 1st arg of the helper function.
 - Made size macros that help check size of the __ifunc_arg_t
   struct private.
 - Rebased on master.
Link to v6:
https://patchwork.sourceware.org/project/glibc/list/?series=47315

Changes in v6:
 - Updated commit message for the second patch.
 - Added test of an actual ifunc resolver that uses helper function.
Link to v5:
https://patchwork.sourceware.org/project/glibc/list/?series=46717

Changes in v5:
 - Fixed bug in the helper function.
 - Added tests for the helper function.
 - Dropped commit that would incorrectly initialise arg for
   resolver functions.
 - Dropped enum for HWCAP elements IDs.
Link to v4:
https://inbox.sourceware.org/libc-alpha/20250425113522.3310684-1-yury.khrustalev@arm.com/

Changes in v4:
 - Revert to using fields in the __ifunc_arg_t struct.
 - Update prototype of the ifunc resolver to use pointer to uint64_t
   rather than pointer to the __ifunc_arg_t struct. Note that this
   prototype is backward-compatible with the previous version.
 - Add helper function to access HWCAP elements in a portable way.
Link to v3:
https://inbox.sourceware.org/libc-alpha/20250422124322.3056938-1-yury.khrustalev@arm.com/

Changes in v3:
 - Instead of adding new fields to __ifunc_arg_t introduce a union
   to allow further seamless extension and at the same time letting
   existing code compile without change.
Link to v2:
https://inbox.sourceware.org/libc-alpha/20250404141511.1767584-1-yury.khrustalev@arm.com/

Changes in v2:
 - Expanded comment in <sys/ifunc.h> to explain how to use the _size
   field to check the version of the contents of the __ifunc_arg_t
   struct.
Link to v1:
https://inbox.sourceware.org/libc-alpha/20250401141851.129625-1-yury.khrustalev@arm.com/

---

Yury Khrustalev (2):
  aarch64: add support for hwcap3,4
  aarch64: add __ifunc_hwcap function to be used in ifunc resolvers

 sysdeps/aarch64/Makefile          |  7 ++-
 sysdeps/aarch64/dl-irel.h         | 21 ++++++-
 sysdeps/aarch64/sys/ifunc.h       | 65 +++++++++++++++++++--
 sysdeps/aarch64/tst-ifunc-arg-1.c | 15 +++++
 sysdeps/aarch64/tst-ifunc-arg-2.c | 14 +++++
 sysdeps/aarch64/tst-ifunc-arg-3.c | 97 +++++++++++++++++++++++++++++++
 sysdeps/aarch64/tst-ifunc-arg-4.c | 67 +++++++++++++++++++++
 7 files changed, 277 insertions(+), 9 deletions(-)
 create mode 100644 sysdeps/aarch64/tst-ifunc-arg-3.c
 create mode 100644 sysdeps/aarch64/tst-ifunc-arg-4.c

-- 
2.39.5