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Age	Commit message (Collapse)	Author
2025-11-04	rseq: Switch to TIF_RSEQ if supported	Thomas Gleixner
	TIF_NOTIFY_RESUME is a multiplexing TIF bit, which is suboptimal especially with the RSEQ fast path depending on it, but not really handling it. Define a separate TIF_RSEQ in the generic TIF space and enable the full separation of fast and slow path for architectures which utilize that. That avoids the hassle with invocations of resume_user_mode_work() from hypervisors, which clear TIF_NOTIFY_RESUME. It makes the therefore required re-evaluation at the end of vcpu_run() a NOOP on architectures which utilize the generic TIF space and have a separate TIF_RSEQ. The hypervisor TIF handling does not include the separate TIF_RSEQ as there is no point in doing so. The guest does neither know nor care about the VMM host applications RSEQ state. That state is only relevant when the ioctl() returns to user space. The fastpath implementation still utilizes TIF_NOTIFY_RESUME for failure handling, but this only happens within exit_to_user_mode_loop(), so arguably the hypervisor ioctl() code is long done when this happens. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Link: https://patch.msgid.link/20251027084307.903622031@linutronix.de
2025-09-17	asm-generic: Provide generic TIF infrastructure	Thomas Gleixner
	Common TIF bits do not have to be defined by every architecture. They can be defined in a generic header. That allows adding generic TIF bits without chasing a gazillion of architecture headers, which is again a unjustified burden on anyone who works on generic infrastructure as it always needs a boat load of work to keep existing architecture code working when adding new stuff. While it is not as horrible as the ignorance of the generic entry infrastructure, it is a welcome mechanism to make architecture people rethink their approach of just leaching generic improvements into architecture code and thereby making it accumulatingly harder to maintain and improve generic code. It's about time that this changes. Provide the infrastructure and split the TIF space in half, 16 generic and 16 architecture specific bits. This could probably be extended by TIF_SINGLESTEP and BLOCKSTEP, but those are only used in architecture specific code. So leave them alone for now. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Acked-by: Arnd Bergmann <arnd@arndb.de>