diff options
| author | Peter Zijlstra <peterz@infradead.org> | 2026-01-19 11:23:57 +0100 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2026-01-22 11:11:19 +0100 |
| commit | d6200245c75e832af2087bc60ba2e6641a90eee9 (patch) | |
| tree | feeadc6916f20663e5354428eff6403cea0a37c5 /kernel/rseq.c | |
| parent | 830969e7821af377bdc1bb016929ff28c78490e8 (diff) | |
rseq: Allow registering RSEQ with slice extension
Since glibc cares about the number of syscalls required to initialize a new
thread, allow initializing rseq with slice extension on. This avoids having to
do another prctl().
Requested-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260121143207.814193010@infradead.org
Diffstat (limited to 'kernel/rseq.c')
| -rw-r--r-- | kernel/rseq.c | 12 |
1 files changed, 10 insertions, 2 deletions
diff --git a/kernel/rseq.c b/kernel/rseq.c index 275d70114107..1c5490a172a8 100644 --- a/kernel/rseq.c +++ b/kernel/rseq.c @@ -424,7 +424,7 @@ SYSCALL_DEFINE4(rseq, struct rseq __user *, rseq, u32, rseq_len, int, flags, u32 return 0; } - if (unlikely(flags)) + if (unlikely(flags & ~(RSEQ_FLAG_SLICE_EXT_DEFAULT_ON))) return -EINVAL; if (current->rseq.usrptr) { @@ -459,8 +459,12 @@ 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)) + if (IS_ENABLED(CONFIG_RSEQ_SLICE_EXTENSION)) { rseqfl |= RSEQ_CS_FLAG_SLICE_EXT_AVAILABLE; + if (rseq_slice_extension_enabled() && + (flags & RSEQ_FLAG_SLICE_EXT_DEFAULT_ON)) + rseqfl |= RSEQ_CS_FLAG_SLICE_EXT_ENABLED; + } scoped_user_write_access(rseq, efault) { /* @@ -488,6 +492,10 @@ SYSCALL_DEFINE4(rseq, struct rseq __user *, rseq, u32, rseq_len, int, flags, u32 current->rseq.len = rseq_len; current->rseq.sig = sig; +#ifdef CONFIG_RSEQ_SLICE_EXTENSION + current->rseq.slice.state.enabled = !!(rseqfl & RSEQ_CS_FLAG_SLICE_EXT_ENABLED); +#endif + /* * If rseq was previously inactive, and has just been * registered, ensure the cpu_id_start and cpu_id fields |