Seperate members of "struct pcb" that are accessed using physical addresses

from thos that are exclusively accessed using virtual addresses and add
padding between them to make sure they don't share a cache line.  Fixes
random crashes on at least PA-8700 and PA-7200 based machines.  Without this,
the PA-7200 based C110 wouldn't stay up long enough to do an install.

ok miod@

1 files changed, 15 insertions, 3 deletions

diff --git a/sys/arch/hppa/include/pcb.h b/sys/arch/hppa/include/pcb.h
index 612c4231586..68d7a0ba384 100644
--- a/sys/arch/hppa/include/pcb.h
+++ b/sys/arch/hppa/include/pcb.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: pcb.h,v 1.10 2005/03/26 20:04:37 mickey Exp $	*/
+/*	$OpenBSD: pcb.h,v 1.11 2007/07/29 20:15:56 kettenis Exp $	*/
 
 /*
  * Copyright (c) 1999-2004 Michael Shalayeff
@@ -34,10 +34,22 @@
 
 struct pcb {
 	u_int64_t pcb_fpregs[HPPA_NFPREGS+1];	/* not in the trapframe */
-	u_int		pcb_onfault;	/* SW copy fault handler */
-	pa_space_t	pcb_space;	/* copy pmap_space, for asm's sake */
 	vaddr_t		pcb_uva;	/* KVA for U-area */
+
+	/*
+	 * The members above are primarily accessed by there physical
+	 * address, wheras the members below are accessed exclusively
+	 * by there virtual address.  Unfortunately this structure
+	 * ends up being non-equivalently mapped, which will cause
+	 * data corruption if those members share a cache line.  Since
+	 * the maximum cache line size is 64 bytes, adding 64 bytes of
+	 * padding makes sure that will never happen.
+	 */
+	u_char		pcb_pad[64];
+
 	u_int		pcb_ksp;	/* kernel sp for ctxsw */
+	u_int		pcb_onfault;	/* SW copy fault handler */
+	pa_space_t	pcb_space;	/* copy pmap_space, for asm's sake */
 
 	/* things used for hpux emulation */
 	void		*pcb_sigreturn;