From: "Theo de Raadt" <deraadt@openbsd.org>
Subject: Re: sparc64 vs uvm_purge()
To: tech@openbsd.org
Date: Sun, 14 Dec 2025 11:38:57 -0700

With recent fixes to sparc64 kettenis, claudio and I worked on,
this hack isn't needed anymore.

> On 27/11/25(Thu) 19:07, Martin Pieuchot wrote:
> > On 26/11/25(Wed) 12:32, Martin Pieuchot wrote:
> > > sparc64 is subtly broken since uvm_purge() is running in parallel.  It
> > > became obvious that the architecture requires more MD work before more
> > > parts of UVM can run in parallel. 
> > > 
> > > That said, such breakages are not helping.  So here's a diff I sent
> > > before release to not run uvm_purge() w/o KERNEL_LOCK() on sparc64.
> > > I'd like to get it in.  Anyone interested in exposing pmap/UVM races
> > > on sparc64 will now where to start.
> > 
> > Now with the corresponding assert removed, found the hard way by
> > deraadt@.
> > 
> > ok?
> 
> Anyone?
> 
> > Index: uvm/uvm_glue.c
> > ===================================================================
> > RCS file: /cvs/src/sys/uvm/uvm_glue.c,v
> > diff -u -p -r1.94 uvm_glue.c
> > --- uvm/uvm_glue.c	11 Sep 2025 15:28:40 -0000	1.94
> > +++ uvm/uvm_glue.c	27 Nov 2025 18:00:47 -0000
> > @@ -315,8 +315,6 @@ uvm_purge(void)
> >  	struct proc *p = curproc;
> >  	struct vmspace *vm = p->p_vmspace;
> >  
> > -	KERNEL_ASSERT_UNLOCKED();
> > -
> >  #ifdef __HAVE_PMAP_PURGE
> >  	pmap_purge(p);
> >  #endif
> > Index: kern/kern_exit.c
> > ===================================================================
> > RCS file: /cvs/src/sys/kern/kern_exit.c,v
> > diff -u -p -r1.252 kern_exit.c
> > --- kern/kern_exit.c	10 Aug 2025 15:17:57 -0000	1.252
> > +++ kern/kern_exit.c	27 Nov 2025 18:00:06 -0000
> > @@ -253,11 +253,13 @@ exit1(struct proc *p, int xexit, int xsi
> >  			 * It is safe to release them all since exit1()
> >  			 * will not return.
> >  			 */
> > -#ifdef MULTIPROCESSOR
> > +#if defined(MULTIPROCESSOR) && !defined(__sparc64__)
> >  			__mp_release_all(&kernel_lock);
> >  #endif
> >  			uvm_purge();
> > +#if !defined(__sparc64__)
> >  			KERNEL_LOCK();
> > +#endif
> >  		}
> >  	}
> >  
> 
>