Remove I-sync stuff from pmap_changebit(). The AARM says that we

only have to sync the I-stream when the mapping is removed or changed,
and since the I-stream is fetch-only, changing protection bits does
not constitute changing the mapping (the VA->PA translation is still
the same).

From NetBSD

diff --git a/sys/arch/alpha/alpha/pmap.c b/sys/arch/alpha/alpha/pmap.c
index cdff1f5..bdd3b40 100644 (file)
--- a/sys/arch/alpha/alpha/pmap.c
+++ b/sys/arch/alpha/alpha/pmap.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: pmap.c,v 1.67 2014/01/05 14:37:08 miod Exp $ */
+/* $OpenBSD: pmap.c,v 1.68 2014/01/06 20:21:32 miod Exp $ */
 /* $NetBSD: pmap.c,v 1.154 2000/12/07 22:18:55 thorpej Exp $ */
 
 /*-
@@ -2578,7 +2578,6 @@ pmap_changebit(struct vm_page *pg, u_long set, u_long mask, cpuid_t cpu_id)
        pt_entry_t *pte, npte;
        vaddr_t va;
        boolean_t hadasm, isactive;
-       boolean_t needisync, needkisync = FALSE;
 
 #ifdef DEBUG
        if (pmapdebug & PDB_BITS)
@@ -2599,28 +2598,7 @@ pmap_changebit(struct vm_page *pg, u_long set, u_long mask, cpuid_t cpu_id)
                if (*pte != npte) {
                        hadasm = (pmap_pte_asm(pte) != 0);
                        isactive = PMAP_ISACTIVE(pv->pv_pmap, cpu_id);
-                       /*
-                        * Determine what we need to do about the I-stream.
-                        * If PG_EXEC was set, we mark a user pmap as needing
-                        * an I-sync on the way out to userspace.  We always
-                        * need an immediate I-sync for the kernel pmap.
-                        */
-                       needisync = FALSE;
-                       if (pmap_pte_exec(pte)) {
-                               if (pv->pv_pmap == pmap_kernel())
-                                       needkisync = TRUE;
-                               else {
-                                       PMAP_SET_NEEDISYNC(pv->pv_pmap);
-                                       if (pv->pv_pmap->pm_cpus != 0)
-                                               needisync = TRUE;
-                               }
-                       } else {
-                               /* Never clear FOE on non-exec mappings. */
-                               npte |= PG_FOE;
-                       }
                        PMAP_SET_PTE(pte, npte);
-                       if (needisync)
-                               PMAP_SYNC_ISTREAM_USER(pv->pv_pmap);
                        PMAP_INVALIDATE_TLB(pv->pv_pmap, va, hadasm, isactive,
                            cpu_id);
                        PMAP_TLB_SHOOTDOWN(pv->pv_pmap, va,
@@ -2628,9 +2606,6 @@ pmap_changebit(struct vm_page *pg, u_long set, u_long mask, cpuid_t cpu_id)
                }
                PMAP_UNLOCK(pv->pv_pmap);
        }
-
-       if (needkisync)
-               PMAP_SYNC_ISTREAM_KERNEL();
 }
 
 /*