[patch 05/96] sparc64: Fix DAX handling via userspace access from kernel.

Greg KH
2009-03-14T00:20:27Z

[-- Attachment #1: sparc64-fix-dax-handling-via-userspace-access-from-kernel.patch --]
[-- Type: text/plain, Size: 1778 bytes --]

2.6.27-stable review patch. If anyone has any objections, please let us know.

------------------

From: David S. Miller <davem@davemloft.net>

[ Upstream commit fcd26f7ae2ea5889134e8b3d60a42ce8b993c95f ]

If we do a userspace access from kernel mode, and get a
data access exception, we need to check the exception
table just like a normal fault does.

The spitfire DAX handler was doing this, but such logic
was missing from the sun4v DAX code.

Reported-by: Dennis Gilmore <dgilmore@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
arch/sparc64/kernel/traps.c | 17 ++++++++++++++++-
1 file changed, 16 insertions(+), 1 deletion(-)

--- a/arch/sparc64/kernel/traps.c
+++ b/arch/sparc64/kernel/traps.c
@@ -1,6 +1,6 @@
/* arch/sparc64/kernel/traps.c
*
- * Copyright (C) 1995,1997,2008 David S. Miller (davem@davemloft.net)
+ * Copyright (C) 1995,1997,2008,2009 David S. Miller (davem@davemloft.net)
* Copyright (C) 1997,1999,2000 Jakub Jelinek (jakub@redhat.com)
*/

@@ -262,6 +262,21 @@ void sun4v_data_access_exception(struct
return;

if (regs->tstate & TSTATE_PRIV) {
+ /* Test if this comes from uaccess places. */
+ const struct exception_table_entry *entry;
+
+ entry = search_exception_tables(regs->tpc);
+ if (entry) {
+ /* Ouch, somebody is trying VM hole tricks on us... */
+#ifdef DEBUG_EXCEPTIONS
+ printk("Exception: PC<%016lx> faddr<UNKNOWN>\n", regs->tpc);
+ printk("EX_TABLE: insn<%016lx> fixup<%016lx>\n",
+ regs->tpc, entry->fixup);
+#endif
+ regs->tpc = entry->fixup;
+ regs->tnpc = regs->tpc + 4;
+ return;
+ }
printk("sun4v_data_access_exception: ADDR[%016lx] "
"CTX[%04x] TYPE[%04x], going.\n",
addr, ctx, type);