[src/trunk]: src/sys/arch/i386/i386 postpone freeing PTPs until TLBs are flushed

[yamt <yamt%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/b3319b293bc0
branches:  trunk
changeset: 556743:b3319b293bc0
user:      yamt <yamt%NetBSD.org@localhost>
date:      Fri Dec 26 11:50:51 2003 +0000

description:
postpone freeing PTPs until TLBs are flushed
to avoid loading invalid TLB entries.  from Stephan Uphoff.

for more details,
see "i386 pmap bug" thread on port-i386@ around Feb, 2003.

diffstat:

 sys/arch/i386/i386/pmap.c |  34 +++++++++++++++++++++++++++++-----
 1 files changed, 29 insertions(+), 5 deletions(-)

diffs (113 lines):

diff -r 9922c2239995 -r b3319b293bc0 sys/arch/i386/i386/pmap.c
--- a/sys/arch/i386/i386/pmap.c Fri Dec 26 11:43:24 2003 +0000
+++ b/sys/arch/i386/i386/pmap.c Fri Dec 26 11:50:51 2003 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: pmap.c,v 1.166 2003/12/10 18:13:32 drochner Exp $      */
+/*     $NetBSD: pmap.c,v 1.167 2003/12/26 11:50:51 yamt Exp $  */
 
 /*
  *
@@ -60,7 +60,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: pmap.c,v 1.166 2003/12/10 18:13:32 drochner Exp $");
+__KERNEL_RCSID(0, "$NetBSD: pmap.c,v 1.167 2003/12/26 11:50:51 yamt Exp $");
 
 #include "opt_cputype.h"
 #include "opt_user_ldt.h"
@@ -2344,11 +2344,14 @@
        vaddr_t blkendva;
        struct vm_page *ptp;
        int32_t cpumask = 0;
+       TAILQ_HEAD(, vm_page) empty_ptps;
 
        /*
         * we lock in the pmap => pv_head direction
         */
 
+       TAILQ_INIT(&empty_ptps);
+
        PMAP_MAP_TO_HEAD_LOCK();
        ptes = pmap_map_ptes(pmap);     /* locks pmap */
 
@@ -2421,12 +2424,17 @@
                                            TAILQ_FIRST(&pmap->pm_obj.memq);
                                ptp->wire_count = 0;
                                ptp->flags |= PG_ZERO;
-                               uvm_pagefree(ptp);
+                               /* Postpone free to shootdown */
+                               uvm_pagerealloc(ptp, NULL, 0);
+                               TAILQ_INSERT_TAIL(&empty_ptps, ptp, listq);
                        }
                }
                pmap_tlb_shootnow(cpumask);
                pmap_unmap_ptes(pmap);          /* unlock pmap */
                PMAP_MAP_TO_HEAD_UNLOCK();
+               /* Now we can free unused ptps */
+               TAILQ_FOREACH(ptp, &empty_ptps, listq)
+                       uvm_pagefree(ptp);
                return;
        }
 
@@ -2512,13 +2520,18 @@
                                pmap->pm_ptphint = pmap->pm_obj.memq.tqh_first;
                        ptp->wire_count = 0;
                        ptp->flags |= PG_ZERO;
-                       uvm_pagefree(ptp);
+                       /* Postpone free to shootdown */
+                       uvm_pagerealloc(ptp, NULL, 0);
+                       TAILQ_INSERT_TAIL(&empty_ptps, ptp, listq);
                }
        }
 
        pmap_tlb_shootnow(cpumask);
        pmap_unmap_ptes(pmap);
        PMAP_MAP_TO_HEAD_UNLOCK();
+       /* Now we can free unused ptps */
+       TAILQ_FOREACH(ptp, &empty_ptps, listq)
+               uvm_pagefree(ptp);
 }
 
 /*
@@ -2536,6 +2549,8 @@
        struct pv_entry *pve, *npve, *killlist = NULL;
        pt_entry_t *ptes, opte;
        int32_t cpumask = 0;
+       TAILQ_HEAD(, vm_page) empty_ptps;
+       struct vm_page *ptp;
 
 #ifdef DIAGNOSTIC
        int bank, off;
@@ -2550,6 +2565,8 @@
                return;
        }
 
+       TAILQ_INIT(&empty_ptps);
+
        /* set pv_head => pmap locking */
        PMAP_HEAD_TO_MAP_LOCK();
 
@@ -2614,7 +2631,10 @@
                                            pve->pv_pmap->pm_obj.memq.tqh_first;
                                pve->pv_ptp->wire_count = 0;
                                pve->pv_ptp->flags |= PG_ZERO;
-                               uvm_pagefree(pve->pv_ptp);
+                               /* Free only after the shootdown */
+                               uvm_pagerealloc(pve->pv_ptp, NULL, 0);
+                               TAILQ_INSERT_TAIL(&empty_ptps, pve->pv_ptp,
+                                   listq);
                        }
                }
                pmap_unmap_ptes(pve->pv_pmap);          /* unlocks pmap */
@@ -2626,6 +2646,10 @@
        simple_unlock(&pvh->pvh_lock);
        PMAP_HEAD_TO_MAP_UNLOCK();
        pmap_tlb_shootnow(cpumask);
+
+       /* Now we can free unused ptps */
+       TAILQ_FOREACH(ptp, &empty_ptps, listq)
+               uvm_pagefree(ptp);
 }
 
 /*