diff options
| author | Thomas Gleixner <tglx@kernel.org> | 2026-06-02 11:09:59 +0200 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2026-06-03 11:38:51 +0200 |
| commit | 042df0c1d48609a85580dcbaff498c95ced20a5f (patch) | |
| tree | dec68717e0917a52adf84e5943c2fb762a2387c5 /init | |
| parent | 3ca9595d9fb6cce6633a5b03d98c2aecb5499838 (diff) | |
futex: Add robust futex unlock IP range
There will be a VDSO function to unlock robust futexes in user space. The
unlock sequence is racy vs. clearing the list_pending_op pointer in the
tasks robust list head. To plug this race the kernel needs to know the
instruction window. As the VDSO is per MM the addresses are stored in
mm_struct::futex.
Architectures which implement support for this have to update these
addresses when the VDSO is (re)mapped and indicate the pending op pointer
size which is matching the IP.
Arguably this could be resolved by chasing mm->context->vdso->image, but
that's architecture specific and requires to touch quite some cache
lines. Having it in mm::futex reduces the cache line impact and avoids
having yet another set of architecture specific functionality.
To support multi size robust list applications (gaming) this provides two
ranges when COMPAT is enabled.
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: André Almeida <andrealmeid@igalia.com>
Link: https://patch.msgid.link/20260602090535.718926819@kernel.org
Diffstat (limited to 'init')
| -rw-r--r-- | init/Kconfig | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/init/Kconfig b/init/Kconfig index 2937c4d308ae..165b08e336a8 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -1842,6 +1842,12 @@ config FUTEX_MPOL depends on FUTEX && NUMA default y +config HAVE_FUTEX_ROBUST_UNLOCK + bool + +config FUTEX_ROBUST_UNLOCK + def_bool FUTEX && HAVE_GENERIC_VDSO && GENERIC_IRQ_ENTRY && RSEQ && HAVE_FUTEX_ROBUST_UNLOCK + config EPOLL bool "Enable eventpoll support" if EXPERT default y |