Switch to a per-proc SLB cache. Seems to make GENERIC.MP kernels

(much more) stable.  Probably because we could restore an incoherent
SLB cache since there was no locking in the trap return path.

5 files changed, 22 insertions, 15 deletions

diff --git a/sys/arch/powerpc64/include/pcb.h b/sys/arch/powerpc64/include/pcb.h
index 349707f4eac..3bc8295af49 100644
--- a/sys/arch/powerpc64/include/pcb.h
+++ b/sys/arch/powerpc64/include/pcb.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: pcb.h,v 1.6 2020/07/01 16:05:48 kettenis Exp $	*/
+/*	$OpenBSD: pcb.h,v 1.7 2020/08/17 16:55:41 kettenis Exp $	*/
 
 /*
  * Copyright (c) 2020 Mark Kettenis <kettenis@openbsd.org>
@@ -20,6 +20,7 @@
 #define _MACHINE_PCB_H_
 
 #include <machine/reg.h>
+#include <machine/pte.h>
 
 struct pcb {
 	register_t	pcb_sp;
@@ -27,6 +28,7 @@ struct pcb {
 #define PCB_FP		0x000000001
 #define PCB_VEC		0x000000002
 #define PCB_VSX		0x000000004
+	struct slb	pcb_slb[32];
 	vaddr_t		pcb_onfault;
 	vaddr_t		pcb_userva;
 	struct fpreg	pcb_fpstate;
diff --git a/sys/arch/powerpc64/include/pmap.h b/sys/arch/powerpc64/include/pmap.h
index 50ff0464e9c..14316fe5fd0 100644
--- a/sys/arch/powerpc64/include/pmap.h
+++ b/sys/arch/powerpc64/include/pmap.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: pmap.h,v 1.13 2020/07/23 15:09:09 kettenis Exp $	*/
+/*	$OpenBSD: pmap.h,v 1.14 2020/08/17 16:55:41 kettenis Exp $	*/
 
 /*
  * Copyright (c) 2020 Mark Kettenis <kettenis@openbsd.org>
@@ -36,7 +36,6 @@ struct pmap {
 	int			pm_refs;
 	struct pmap_statistics	pm_stats;
 	struct mutex		pm_mtx;
-	struct slb		pm_slb[32];
 };
 
 typedef struct pmap *pmap_t;
diff --git a/sys/arch/powerpc64/powerpc64/machdep.c b/sys/arch/powerpc64/powerpc64/machdep.c
index fee4cd85e5d..2f36148c222 100644
--- a/sys/arch/powerpc64/powerpc64/machdep.c
+++ b/sys/arch/powerpc64/powerpc64/machdep.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: machdep.c,v 1.55 2020/07/21 21:36:58 kettenis Exp $	*/
+/*	$OpenBSD: machdep.c,v 1.56 2020/08/17 16:55:41 kettenis Exp $	*/
 
 /*
  * Copyright (c) 2020 Mark Kettenis <kettenis@openbsd.org>
@@ -738,6 +738,7 @@ setregs(struct proc *p, struct exec_package *pack, u_long stack,
 	frame->srr0 = pack->ep_entry;
 	frame->srr1 = PSL_USER;
 
+	memset(&pcb->pcb_slb, 0, sizeof(pcb->pcb_slb));
 	memset(&pcb->pcb_fpstate, 0, sizeof(pcb->pcb_fpstate));
 	pcb->pcb_flags = 0;
 }
diff --git a/sys/arch/powerpc64/powerpc64/pmap.c b/sys/arch/powerpc64/powerpc64/pmap.c
index a67595e6518..eba61982c17 100644
--- a/sys/arch/powerpc64/powerpc64/pmap.c
+++ b/sys/arch/powerpc64/powerpc64/pmap.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: pmap.c,v 1.40 2020/08/04 16:28:16 kettenis Exp $ */
+/*	$OpenBSD: pmap.c,v 1.41 2020/08/17 16:55:41 kettenis Exp $ */
 
 /*
  * Copyright (c) 2015 Martin Pieuchot
@@ -50,6 +50,8 @@
 #include <sys/param.h>
 #include <sys/atomic.h>
 #include <sys/pool.h>
+#include <sys/proc.h>
+#include <sys/user.h>
 
 #include <uvm/uvm_extern.h>
 
@@ -333,23 +335,24 @@ pmap_slbd_lookup(pmap_t pm, vaddr_t va)
 void
 pmap_slbd_cache(pmap_t pm, struct slb_desc *slbd)
 {
+	struct pcb *pcb = &curproc->p_addr->u_pcb;
 	uint64_t slbe, slbv;
 	int idx;
 
-	PMAP_VP_ASSERT_LOCKED(pm);
+	KASSERT(curproc->p_vmspace->vm_map.pmap == pm);
 
-	for (idx = 0; idx < nitems(pm->pm_slb); idx++) {
-		if (pm->pm_slb[idx].slb_slbe == 0)
+	for (idx = 0; idx < nitems(pcb->pcb_slb); idx++) {
+		if (pcb->pcb_slb[idx].slb_slbe == 0)
 			break;
 	}
-	if (idx == nitems(pm->pm_slb))
-		idx = arc4random_uniform(nitems(pm->pm_slb));
+	if (idx == nitems(pcb->pcb_slb))
+		idx = arc4random_uniform(nitems(pcb->pcb_slb));
 
 	slbe = (slbd->slbd_esid << SLBE_ESID_SHIFT) | SLBE_VALID | idx;
 	slbv = slbd->slbd_vsid << SLBV_VSID_SHIFT;
 
-	pm->pm_slb[idx].slb_slbe = slbe;
-	pm->pm_slb[idx].slb_slbv = slbv;
+	pcb->pcb_slb[idx].slb_slbe = slbe;
+	pcb->pcb_slb[idx].slb_slbv = slbv;
 }
 
 int
diff --git a/sys/arch/powerpc64/powerpc64/vm_machdep.c b/sys/arch/powerpc64/powerpc64/vm_machdep.c
index e872ee5f2da..609593b90be 100644
--- a/sys/arch/powerpc64/powerpc64/vm_machdep.c
+++ b/sys/arch/powerpc64/powerpc64/vm_machdep.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: vm_machdep.c,v 1.4 2020/06/30 20:31:54 kettenis Exp $	*/
+/*	$OpenBSD: vm_machdep.c,v 1.5 2020/08/17 16:55:41 kettenis Exp $	*/
 
 /*-
  * Copyright (c) 1995 Charles M. Hannum.  All rights reserved.
@@ -67,7 +67,6 @@ void
 cpu_fork(struct proc *p1, struct proc *p2, void *stack, void *tcb,
     void (*func)(void *), void *arg)
 {
-	pmap_t pm = p2->p_vmspace->vm_map.pmap;
 	struct pcb *pcb = &p2->p_addr->u_pcb;
 	struct trapframe *tf;
 	struct callframe *cf;
@@ -77,7 +76,10 @@ cpu_fork(struct proc *p1, struct proc *p2, void *stack, void *tcb,
 	/* Copy the pcb. */
 	*pcb = p1->p_addr->u_pcb;
 
-	pmap_extract(pmap_kernel(), (vaddr_t)&pm->pm_slb,
+	/* XXX This should not be necessary but things explodes without it. */
+	memset(&pcb->pcb_slb, 0, sizeof(pcb->pcb_slb));
+
+	pmap_extract(pmap_kernel(), (vaddr_t)&pcb->pcb_slb,
 	    &p2->p_md.md_user_slb_pa);
 	pmap_activate(p2);