Commit 067b3b41 authored by Thomas Gleixner's avatar Thomas Gleixner Committed by Ingo Molnar
Browse files

rseq: Simplify registration 



There is no point to read the critical section element in the newly
registered user space RSEQ struct first in order to clear it.

Just clear it and be done with it.

Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Reviewed-by: default avatarMathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://patch.msgid.link/20251027084306.274661227@linutronix.de
parent 41b43a6b

kernel/rseq.c

+3 −7
Original line number Diff line number Diff line
@@ -492,11 +492,9 @@ void rseq_syscall(struct pt_regs *regs) 
/*

 * sys_rseq - setup restartable sequences for caller thread.

 */

SYSCALL_DEFINE4(rseq, struct rseq __user *, rseq, u32, rseq_len,

		int, flags, u32, sig)

SYSCALL_DEFINE4(rseq, struct rseq __user *, rseq, u32, rseq_len, int, flags, u32, sig)

{

	int ret;

	u64 rseq_cs;



	if (flags & RSEQ_FLAG_UNREGISTER) {

		if (flags & ~RSEQ_FLAG_UNREGISTER)
@@ -557,11 +555,9 @@ SYSCALL_DEFINE4(rseq, struct rseq __user *, rseq, u32, rseq_len, 
	 * avoid a potential segfault on return to user-space. The proper thing

	 * to do would have been to fail the registration but this would break

	 * older libcs that reuse the rseq area for new threads without

	 * clearing the fields.

	 * clearing the fields. Don't bother reading it, just reset it.

	 */

	if (rseq_get_rseq_cs_ptr_val(rseq, &rseq_cs))

	        return -EFAULT;

	if (rseq_cs && clear_rseq_cs(rseq))

	if (put_user(0UL, &rseq->rseq_cs))

		return -EFAULT;



#ifdef CONFIG_DEBUG_RSEQ