From: kettenis <kettenis@openbsd.org>
Date: Tue, 24 Jan 2023 16:51:05 +0000 (+0000)
Subject: Make sure pmap_page_protect() does the right thing for execute-only
X-Git-Url: http://artulab.com/gitweb/?a=commitdiff_plain;h=38cdd850cf57ee44b29c8547000175c2383f89d5;p=openbsd

Make sure pmap_page_protect() does the right thing for execute-only
mappings and enforce this with a KASSERT like we do on amd64.  Bring
the pmap_protect() inline in line with the amd64 version.

ok miod@, deraadt@
---

diff --git a/sys/arch/hppa/hppa/pmap.c b/sys/arch/hppa/hppa/pmap.c
index 7301e83a273..fcb711c2894 100644
--- a/sys/arch/hppa/hppa/pmap.c
+++ b/sys/arch/hppa/hppa/pmap.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: pmap.c,v 1.180 2023/01/07 10:09:34 kettenis Exp $	*/
+/*	$OpenBSD: pmap.c,v 1.181 2023/01/24 16:51:05 kettenis Exp $	*/
 
 /*
  * Copyright (c) 1998-2004 Michael Shalayeff
@@ -894,6 +894,43 @@ pmap_remove(struct pmap *pmap, vaddr_t sva, vaddr_t eva)
 	pmap_unlock(pmap);
 }
 
+void
+pmap_page_write_protect(struct vm_page *pg)
+{
+	struct pv_entry *pve;
+	int attrs;
+
+	DPRINTF(PDB_FOLLOW|PDB_BITS, ("pmap_page_write_protect(%p)\n", pg));
+
+	attrs = 0;
+	mtx_enter(&pg->mdpage.pvh_mtx);
+	for (pve = pg->mdpage.pvh_list; pve; pve = pve->pv_next) {
+		struct pmap *pmap = pve->pv_pmap;
+		vaddr_t va = pve->pv_va;
+		volatile pt_entry_t *pde;
+		pt_entry_t opte, pte;
+
+		if ((pde = pmap_pde_get(pmap->pm_pdir, va))) {
+			opte = pte = pmap_pte_get(pde, va);
+			if (pte & TLB_GATEWAY)
+				continue;
+			pte &= ~TLB_WRITE;
+			attrs |= pmap_pvh_attrs(pte);
+
+			if (opte != pte) {
+				pmap_pte_flush(pmap, va, opte);
+				pmap_pte_set(pde, va, pte);
+			}
+		}
+	}
+	mtx_leave(&pg->mdpage.pvh_mtx);
+	if (attrs != (PG_PMAP_REF | PG_PMAP_MOD))
+		atomic_clearbits_int(&pg->pg_flags,
+		    attrs ^(PG_PMAP_REF | PG_PMAP_MOD));
+	if (attrs != 0)
+		atomic_setbits_int(&pg->pg_flags, attrs);
+}
+
 void
 pmap_write_protect(struct pmap *pmap, vaddr_t sva, vaddr_t eva, vm_prot_t prot)
 {
diff --git a/sys/arch/hppa/include/pmap.h b/sys/arch/hppa/include/pmap.h
index cfcea8f9aad..be38973a76c 100644
--- a/sys/arch/hppa/include/pmap.h
+++ b/sys/arch/hppa/include/pmap.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: pmap.h,v 1.53 2023/01/01 19:49:17 miod Exp $	*/
+/*	$OpenBSD: pmap.h,v 1.54 2023/01/24 16:51:06 kettenis Exp $	*/
 
 /*
  * Copyright (c) 2002-2004 Michael Shalayeff
@@ -33,6 +33,7 @@
 #include <sys/mutex.h>
 
 #ifdef	_KERNEL
+#include <sys/systm.h>
 #include <machine/pte.h>
 
 struct pmap {
@@ -117,6 +118,7 @@ struct vm_page *pmap_unmap_direct(vaddr_t);
 void pmap_bootstrap(vaddr_t);
 boolean_t pmap_changebit(struct vm_page *, pt_entry_t, pt_entry_t);
 boolean_t pmap_testbit(struct vm_page *, int);
+void pmap_page_write_protect(struct vm_page *);
 void pmap_write_protect(struct pmap *, vaddr_t, vaddr_t, vm_prot_t);
 void pmap_remove(struct pmap *pmap, vaddr_t sva, vaddr_t eva);
 void pmap_page_remove(struct vm_page *pg);
@@ -131,23 +133,21 @@ pmap_prot(struct pmap *pmap, int prot)
 static __inline void
 pmap_page_protect(struct vm_page *pg, vm_prot_t prot)
 {
-	if ((prot & PROT_WRITE) == 0) {
-		if (prot & (PROT_READ | PROT_EXEC))
-			pmap_changebit(pg, 0, PTE_PROT(TLB_WRITE));
-		else
-			pmap_page_remove(pg);
+	if (prot == PROT_READ) {
+		pmap_page_write_protect(pg);
+	} else {
+		KASSERT(prot == PROT_NONE);
+		pmap_page_remove(pg);
 	}
 }
 
 static __inline void
 pmap_protect(struct pmap *pmap, vaddr_t sva, vaddr_t eva, vm_prot_t prot)
 {
-	if ((prot & PROT_WRITE) == 0) {
-		if (prot & (PROT_READ | PROT_EXEC))
-			pmap_write_protect(pmap, sva, eva, prot);
-		else
-			pmap_remove(pmap, sva, eva);
-	}
+	if (prot != PROT_NONE)
+		pmap_write_protect(pmap, sva, eva, prot);
+	else
+		pmap_remove(pmap, sva, eva);
 }
 
 #endif /* _KERNEL */