[PATCH v3 0/1] alpha: Add support for HAVE_ARCH_JUMP_LABEL

[Magnus Lindholm <linmag7@gmail.com>]

This revision addresses Matt Turner's review of v2.

Changes since v2:
- Rebase onto the current local alpha-devel branch.
- Place HAVE_ARCH_JUMP_LABEL beside the other HAVE_ARCH selections.
- Warn and return without patching an out-of-range branch target.
- Remove the unused mutex include. Retain JUMP_LABEL_NOP_SIZE: the
  current generic jump_entry_size() requires it on Alpha.
- Clean up the duplicate NOP comment and extra blank line.
- Document the writable kernel and module text requirement.
- Retain Matt's Reviewed-by.

Batching I-cache synchronization and relative jump table entries remain
possible follow-ups.

The previous submission reported UP2000+ SMP tracepoint and stress
checks. Those results do not establish validation of this revision.
This revision cross-builds successfully with W=1 for Alpha SMP, with
CONFIG_JUMP_LABEL=y, CONFIG_STATIC_KEYS_SELFTEST=y and
CONFIG_TEST_STATIC_KEYS=m. On the ES40, the boot selftest passed and
the static-key test modules completed 10 load/unload cycles on each of
three CPUs (30 total), including cross-module keys. This used a combined
kernel with CMA v2. no new kernel warnings or faults appeared during
those tests.

Magnus Lindholm (1):
  alpha: Add support for HAVE_ARCH_JUMP_LABEL

 .../core/jump-labels/arch-support.txt         |  2 +-
 arch/alpha/Kconfig                            |  1 +
 arch/alpha/include/asm/jump_label.h           | 63 +++++++++++++++
 arch/alpha/kernel/Makefile                    |  2 +
 arch/alpha/kernel/jump_label.c                | 79 +++++++++++++++++++
 5 files changed, 146 insertions(+), 1 deletion(-)
 create mode 100644 arch/alpha/include/asm/jump_label.h
 create mode 100644 arch/alpha/kernel/jump_label.c


base-commit: 0b4cadbe7c39d830dec35c4a2655483de0dae568
-- 
2.43.0