diff options
| author | Thomas Gleixner <tglx@linutronix.de> | 2025-12-15 17:52:04 +0100 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2026-01-22 11:11:16 +0100 |
| commit | d7a5da7a0f7fa7ff081140c4f6f971db98882703 (patch) | |
| tree | 5470dbdccb47bf19beda69bdcfd8d078d87f17c0 /kernel/rseq.c | |
| parent | 4fe82cf3024a4bdd2571d584efc25598533d5c96 (diff) | |
rseq: Add fields and constants for time slice extension
Aside of a Kconfig knob add the following items:
- Two flag bits for the rseq user space ABI, which allow user space to
query the availability and enablement without a syscall.
- A new member to the user space ABI struct rseq, which is going to be
used to communicate request and grant between kernel and user space.
- A rseq state struct to hold the kernel state of this
- Documentation of the new mechanism
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20251215155708.669472597@linutronix.de
Diffstat (limited to 'kernel/rseq.c')
| -rw-r--r-- | kernel/rseq.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/kernel/rseq.c b/kernel/rseq.c index 395d8b002350..07c324d5a201 100644 --- a/kernel/rseq.c +++ b/kernel/rseq.c @@ -389,6 +389,8 @@ static bool rseq_reset_ids(void) */ SYSCALL_DEFINE4(rseq, struct rseq __user *, rseq, u32, rseq_len, int, flags, u32, sig) { + u32 rseqfl = 0; + if (flags & RSEQ_FLAG_UNREGISTER) { if (flags & ~RSEQ_FLAG_UNREGISTER) return -EINVAL; @@ -440,6 +442,9 @@ SYSCALL_DEFINE4(rseq, struct rseq __user *, rseq, u32, rseq_len, int, flags, u32 if (!access_ok(rseq, rseq_len)) return -EFAULT; + if (IS_ENABLED(CONFIG_RSEQ_SLICE_EXTENSION)) + rseqfl |= RSEQ_CS_FLAG_SLICE_EXT_AVAILABLE; + scoped_user_write_access(rseq, efault) { /* * If the rseq_cs pointer is non-NULL on registration, clear it to @@ -449,11 +454,13 @@ SYSCALL_DEFINE4(rseq, struct rseq __user *, rseq, u32, rseq_len, int, flags, u32 * clearing the fields. Don't bother reading it, just reset it. */ unsafe_put_user(0UL, &rseq->rseq_cs, efault); + unsafe_put_user(rseqfl, &rseq->flags, efault); /* Initialize IDs in user space */ unsafe_put_user(RSEQ_CPU_ID_UNINITIALIZED, &rseq->cpu_id_start, efault); unsafe_put_user(RSEQ_CPU_ID_UNINITIALIZED, &rseq->cpu_id, efault); unsafe_put_user(0U, &rseq->node_id, efault); unsafe_put_user(0U, &rseq->mm_cid, efault); + unsafe_put_user(0U, &rseq->slice_ctrl.all, efault); } /* |