Introduce a new cmmu method to return the preferred cache mode bits for the

kernel APR. Return write-back for every design but those involving 88410,
where write through is returned.

Apparently the use of writeback on single-processor kernels using 88410 (197SP,
197DP) has only been working by fat chance, and the last two years of uvm
changes, as well as the switch to ELF (causing kernel rodata to move `up')
exposes silent memory corruption on (88410-size) aliased addresses.
(I am guilty of not using my 197DP board much after making 197LE write-back
capable, as 197LE turned out to be faster and more stable, for I would have
noticed this earlier).

Further thought needs to happen about this. It might be possible to switch to
writeback by default again as long as bus_dma maps things write-through on
88410 designs, and perhaps with a part of the kernel mapped with a write-through
BATC, since BATC have precedence upon page tables. Right now I'm trying to get
a stable release out of the door.

4 files changed, 40 insertions, 10 deletions

diff --git a/sys/arch/m88k/include/cmmu.h b/sys/arch/m88k/include/cmmu.h
index 5a6ddb9c023..40324d10f5f 100644
--- a/sys/arch/m88k/include/cmmu.h
+++ b/sys/arch/m88k/include/cmmu.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: cmmu.h,v 1.28 2013/02/17 18:07:36 miod Exp $ */
+/*	$OpenBSD: cmmu.h,v 1.29 2013/02/19 21:02:06 miod Exp $ */
 /*
  * Mach Operating System
  * Copyright (c) 1993-1992 Carnegie Mellon University
@@ -42,6 +42,7 @@ struct cmmu_p {
 
 	cpuid_t (*cpu_number)(void);
 
+	apr_t (*kapr_cmode)(void);
 	void (*set_sapr)(apr_t);
 	void (*set_uapr)(apr_t);
 
@@ -82,6 +83,7 @@ extern __cpu_simple_lock_t cmmu_cpu_lock;
 #define	cpu_configuration_print(cpu)	(cmmu->cpu_configuration_print)(cpu)
 #define	cmmu_shutdown			(cmmu->shutdown)
 #define	cmmu_cpu_number			(cmmu->cpu_number)
+#define	cmmu_kapr_cmode			(cmmu->kapr_cmode)
 #define	cmmu_set_sapr(apr)		(cmmu->set_sapr)(apr)
 #define	cmmu_set_uapr(apr)		(cmmu->set_uapr)(apr)
 #define	cmmu_tlbis(cpu, va, pte) 	(cmmu->tlb_inv_s)(cpu, va, pte)
diff --git a/sys/arch/m88k/m88k/m8820x_machdep.c b/sys/arch/m88k/m88k/m8820x_machdep.c
index 7756f577fab..0395f99d067 100644
--- a/sys/arch/m88k/m88k/m8820x_machdep.c
+++ b/sys/arch/m88k/m88k/m8820x_machdep.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: m8820x_machdep.c,v 1.51 2013/02/17 18:07:36 miod Exp $	*/
+/*	$OpenBSD: m8820x_machdep.c,v 1.52 2013/02/19 21:02:06 miod Exp $	*/
 /*
  * Copyright (c) 2004, 2007, 2010, 2011, Miodrag Vallat.
  *
@@ -90,6 +90,7 @@ extern	void m8820x_copypage(vaddr_t, vaddr_t);
 cpuid_t	m8820x_init(void);
 void	m8820x_cpu_configuration_print(int);
 void	m8820x_shutdown(void);
+apr_t	m8820x_apr_cmode(void);
 void	m8820x_set_sapr(apr_t);
 void	m8820x_set_uapr(apr_t);
 void	m8820x_tlbis(cpuid_t, vaddr_t, pt_entry_t);
@@ -108,6 +109,7 @@ const struct cmmu_p cmmu8820x = {
 	m8820x_cpu_configuration_print,
 	m8820x_shutdown,
 	m8820x_cpu_number,
+	m8820x_apr_cmode,
 	m8820x_set_sapr,
 	m8820x_set_uapr,
 	m8820x_tlbis,
@@ -526,6 +528,13 @@ m8820x_shutdown()
 	CMMU_UNLOCK;
 }
 
+/* not used */
+apr_t
+m8820x_apr_cmode()
+{
+	return CACHE_DFL;
+}
+
 void
 m8820x_set_sapr(apr_t ap)
 {
diff --git a/sys/arch/m88k/m88k/pmap.c b/sys/arch/m88k/m88k/pmap.c
index fcfb7cb8427..f3e4d11b63a 100644
--- a/sys/arch/m88k/m88k/pmap.c
+++ b/sys/arch/m88k/m88k/pmap.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: pmap.c,v 1.69 2013/02/14 05:50:49 miod Exp $	*/
+/*	$OpenBSD: pmap.c,v 1.70 2013/02/19 21:02:06 miod Exp $	*/
 
 /*
  * Copyright (c) 2001-2004, 2010, Miodrag Vallat.
@@ -136,7 +136,7 @@ struct pmap kernel_pmap_store;
 /* #define	CACHE_PT	(CPU_IS88100 ? CACHE_INH : CACHE_WT) */
 #define	CACHE_PT	CACHE_WT
 
-#if defined(M88110) && defined(MULTIPROCESSOR)
+#if defined(M88110) && defined(M88410)
 apr_t	kernel_apr_cmode = CACHE_DFL;		/* might be downgraded to WT */
 #define	KERNEL_APR_CMODE	kernel_apr_cmode
 #else
@@ -639,11 +639,10 @@ pmap_bootstrap(paddr_t s_rom, paddr_t e_rom)
 
 #if defined(M88110)
 	if (CPU_IS88110) {
-#ifdef MULTIPROCESSOR
-		/* XXX until whatever causes the kernel to hang without
-		   XXX is understood and fixed */
-		kernel_apr_cmode = CACHE_WT;
-#else
+#if defined(M88410)
+		kernel_apr_cmode = cmmu_kapr_cmode();
+#endif
+#ifndef MULTIPROCESSOR
 		default_apr &= ~CACHE_GLOBAL;
 #endif
 	}
diff --git a/sys/arch/mvme88k/mvme88k/m88110.c b/sys/arch/mvme88k/mvme88k/m88110.c
index 7f98f4cfb5b..3eb4441663f 100644
--- a/sys/arch/mvme88k/mvme88k/m88110.c
+++ b/sys/arch/mvme88k/mvme88k/m88110.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: m88110.c,v 1.77 2013/02/17 18:07:36 miod Exp $	*/
+/*	$OpenBSD: m88110.c,v 1.78 2013/02/19 21:02:06 miod Exp $	*/
 
 /*
  * Copyright (c) 2010, 2011, Miodrag Vallat.
@@ -100,6 +100,8 @@ void	m88110_cpu_configuration_print(int);
 void	m88410_cpu_configuration_print(int);
 void	m88110_shutdown(void);
 cpuid_t	m88110_cpu_number(void);
+apr_t	m88110_kapr_cmode(void);
+apr_t	m88410_kapr_cmode(void);
 void	m88110_set_sapr(apr_t);
 void	m88110_set_uapr(apr_t);
 void	m88110_tlbis(cpuid_t, vaddr_t, pt_entry_t);
@@ -128,6 +130,7 @@ const struct cmmu_p cmmu88110 = {
 	m88110_cpu_configuration_print,
 	m88110_shutdown,
 	m88110_cpu_number,
+	m88110_kapr_cmode,
 	m88110_set_sapr,
 	m88110_set_uapr,
 	m88110_tlbis,
@@ -153,6 +156,7 @@ const struct cmmu_p cmmu88410 = {
 	m88410_cpu_configuration_print,
 	m88110_shutdown,
 	m88110_cpu_number,
+	m88410_kapr_cmode,
 	m88110_set_sapr,
 	m88110_set_uapr,
 	m88110_tlbis,
@@ -440,6 +444,18 @@ m88110_shutdown(void)
 {
 }
 
+apr_t
+m88110_kapr_cmode(void)
+{
+	return CACHE_DFL;
+}
+
+apr_t
+m88410_kapr_cmode(void)
+{
+	return CACHE_WT;
+}
+
 void
 m88110_set_sapr(apr_t ap)
 {
@@ -1019,6 +1035,10 @@ m88410_dma_cachectl_local(paddr_t _pa, psize_t _size, int op)
 			bcopy(lines, (void *)pa1, sz1);
 		if (sz2 != 0)
 			bcopy(lines + MC88110_CACHE_LINE, (void *)pa2, sz2);
+		if (sz1 != 0)
+			m88110_cmmu_wbinv_locked(pa1, MC88110_CACHE_LINE);
+		if (sz2 != 0)
+			m88110_cmmu_wbinv_locked(pa2, MC88110_CACHE_LINE);
 	} else {
 		while (size != 0) {
 			count = (pa & PAGE_MASK) == 0 && size >= PAGE_SIZE ?