Don't set the global bit PG_G for kernel pmap low memory mappings. Use a

new function pmap_prealloc_lowmem_ptp() to setup kernel pmap ptp 0 without
the PG_G bit set. This fixes the remaining reaper -> pmap_page_remove
panics. With much diagnostic help from Art and Theo.

ok  deraadt@

3 files changed, 33 insertions, 10 deletions

diff --git a/sys/arch/i386/i386/machdep.c b/sys/arch/i386/i386/machdep.c
index 2fdda0bb18e..0f32126e5f8 100644
--- a/sys/arch/i386/i386/machdep.c
+++ b/sys/arch/i386/i386/machdep.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: machdep.c,v 1.441 2008/12/04 15:24:18 oga Exp $	*/
+/*	$OpenBSD: machdep.c,v 1.442 2008/12/18 14:17:28 kurt Exp $	*/
 /*	$NetBSD: machdep.c,v 1.214 1996/11/10 03:16:17 thorpej Exp $	*/
 
 /*-
@@ -2961,12 +2961,8 @@ init386(paddr_t first_avail)
 #endif
  
 #if defined(MULTIPROCESSOR)
-	/* install the page after boot args as PT page for first 4M */
-	pmap_enter(pmap_kernel(), (u_long)vtopte(0),
-	   round_page((vaddr_t)(bootargv + bootargc)),
-		VM_PROT_READ|VM_PROT_WRITE,
-		VM_PROT_READ|VM_PROT_WRITE|PMAP_WIRED);
-	memset(vtopte(0), 0, NBPG);  /* make sure it is clean before using */
+	/* install the lowmem ptp after boot args for 1:1 mappings */
+	pmap_prealloc_lowmem_ptp(round_page((paddr_t)(bootargv + bootargc)));
 #endif
 
 	/*
diff --git a/sys/arch/i386/i386/pmap.c b/sys/arch/i386/i386/pmap.c
index bedde99979a..4b7337cdded 100644
--- a/sys/arch/i386/i386/pmap.c
+++ b/sys/arch/i386/i386/pmap.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: pmap.c,v 1.133 2008/12/18 13:43:24 kurt Exp $	*/
+/*	$OpenBSD: pmap.c,v 1.134 2008/12/18 14:17:28 kurt Exp $	*/
 /*	$NetBSD: pmap.c,v 1.91 2000/06/02 17:46:37 thorpej Exp $	*/
 
 /*
@@ -700,7 +700,12 @@ pmap_kenter_pa(vaddr_t va, paddr_t pa, vm_prot_t prot)
 
 	pte = vtopte(va);
 	npte = pa | ((prot & VM_PROT_WRITE)? PG_RW : PG_RO) | PG_V |
-	    pmap_pg_g | PG_U | PG_M;
+	    PG_U | PG_M;
+
+	/* special 1:1 mappings in the first 4MB must not be global */
+	if (va >= (vaddr_t)NBPD)
+		npte |= pmap_pg_g;
+
 	opte = i386_atomic_testset_ul(pte, npte); /* zap! */
 	if (pmap_valid_entry(opte)) {
 		/* NB. - this should not happen. */
@@ -926,6 +931,26 @@ pmap_bootstrap(vaddr_t kva_start)
 }
 
 /*
+ * Pre-allocate PTP 0 for low memory, so that 1:1 mappings for various
+ * trampoline code can be entered.
+ */
+void
+pmap_prealloc_lowmem_ptp(paddr_t ptppa)
+{
+	pt_entry_t *pte, npte;
+	vaddr_t ptpva = (vaddr_t)vtopte(0);
+
+	/* enter pa for pte 0 into recursive map */
+	pte = vtopte(ptpva);
+	npte = ptppa | PG_RW | PG_V | PG_U | PG_M;
+
+	i386_atomic_testset_ul(pte, npte); /* zap! */
+
+	/* make sure it is clean before using */
+	memset((void *)ptpva, 0, NBPG);
+}
+
+/*
  * pmap_init: called from uvm_init, our job is to get the pmap
  * system ready to manage mappings... this mainly means initing
  * the pv_entry stuff.
diff --git a/sys/arch/i386/include/pmap.h b/sys/arch/i386/include/pmap.h
index 2f55cf75e27..fa446e6c2a0 100644
--- a/sys/arch/i386/include/pmap.h
+++ b/sys/arch/i386/include/pmap.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: pmap.h,v 1.49 2008/11/22 18:13:03 mikeb Exp $	*/
+/*	$OpenBSD: pmap.h,v 1.50 2008/12/18 14:17:28 kurt Exp $	*/
 /*	$NetBSD: pmap.h,v 1.44 2000/04/24 17:18:18 thorpej Exp $	*/
 
 /*
@@ -392,6 +392,8 @@ void	pmap_tlb_shootwait(void);
 #define pmap_tlb_shootwait()
 #endif
 
+void	pmap_prealloc_lowmem_ptp(paddr_t);
+
 #define PMAP_GROWKERNEL		/* turn on pmap_growkernel interface */
 
 /*