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| author | Yeoreum Yun <yeoreum.yun@arm.com> | 2026-03-14 20:51:30 +0300 |
|---|---|---|
| committer | Catalin Marinas <catalin.marinas@arm.com> | 2026-03-27 15:52:04 +0300 |
| commit | 44adf2bf40efe56c68c1563779ab2047eb0a57ea (patch) | |
| tree | bc6699ee5864a3daf0ca6dc588f785d6f35ba8cd /include/uapi | |
| parent | eaa3babcceaaf191228d6ea897f677ed7549d0e2 (diff) | |
| download | linux-44adf2bf40efe56c68c1563779ab2047eb0a57ea.tar.xz | |
arm64: futex: Support futex with FEAT_LSUI
Current futex atomic operations are implemented using LL/SC instructions
while temporarily clearing PSTATE.PAN and setting PSTATE.TCO (if
KASAN_HW_TAGS is enabled). With Armv9.6, FEAT_LSUI provides atomic
instructions for user memory access in the kernel without the need for
PSTATE bits toggling.
Use the FEAT_LSUI instructions to implement the futex atomic operations.
Note that some futex operations do not have a matching LSUI instruction,
(eor or word-sized cmpxchg). For such cases, use cas{al}t to implement
the operation.
Signed-off-by: Yeoreum Yun <yeoreum.yun@arm.com>
[catalin.marinas@arm.com: add comment on -EAGAIN in __lsui_futex_cmpxchg()]
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'include/uapi')
0 files changed, 0 insertions, 0 deletions