From 010b7723c0a3b9ad58f50b715dbe2e7781d29400 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Tue, 28 Apr 2026 09:34:45 +0200 Subject: rseq: Don't advertise time slice extensions if disabled If time slice extensions have been disabled on the kernel command line, then advertising them in RSEQ flags is wrong. Adjust the conditionals to reflect reality, fixup the misleading comments about the gap of these flags and the rseq::flags field. Fixes: d6200245c75e ("rseq: Allow registering RSEQ with slice extension") Signed-off-by: Thomas Gleixner Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Dmitry Vyukov Tested-by: Dmitry Vyukov Link: https://patch.msgid.link/20260428224427.437059375%40kernel.org Cc: stable@vger.kernel.org --- include/uapi/linux/rseq.h | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'include') diff --git a/include/uapi/linux/rseq.h b/include/uapi/linux/rseq.h index f69344fe6c08..ca6fe1f9d05e 100644 --- a/include/uapi/linux/rseq.h +++ b/include/uapi/linux/rseq.h @@ -28,7 +28,7 @@ enum rseq_cs_flags_bit { RSEQ_CS_FLAG_NO_RESTART_ON_PREEMPT_BIT = 0, RSEQ_CS_FLAG_NO_RESTART_ON_SIGNAL_BIT = 1, RSEQ_CS_FLAG_NO_RESTART_ON_MIGRATE_BIT = 2, - /* (3) Intentional gap to put new bits into a separate byte */ + /* (3) Intentional gap to keep new bits separate */ /* User read only feature flags */ RSEQ_CS_FLAG_SLICE_EXT_AVAILABLE_BIT = 4, @@ -161,6 +161,9 @@ struct rseq { * - RSEQ_CS_FLAG_NO_RESTART_ON_PREEMPT * - RSEQ_CS_FLAG_NO_RESTART_ON_SIGNAL * - RSEQ_CS_FLAG_NO_RESTART_ON_MIGRATE + * + * It is now used for feature status advertisement by the kernel. + * See: enum rseq_cs_flags_bit for further information. */ __u32 flags; -- cgit v1.2.3