From: David Miller <davem@xxxxxxxxxxxxx>
Date: Mon, 19 Jan 2009 22:35:17 -0800 (PST)
> The code in sun4v_data_access_exception() needs some logic to properly
> handle the case of the kernel doing a userspace access. Currently it
> does an OOPS unconditionally when triggered from kernel space, which
> is wrong.
>
> I'll fix this up and post a patch.
Dennis, here is a 2.6.27 based patch that should fix this bug.
sparc64: Fix DAX handling via userspace access from kernel.
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@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
diff --git a/arch/sparc64/kernel/traps.c b/arch/sparc64/kernel/traps.c
index c824df1..eb19724 100644
--- 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@xxxxxxxxxxxxx)
+ * Copyright (C) 1995,1997,2008,2009 David S. Miller (davem@xxxxxxxxxxxxx)
* Copyright (C) 1997,1999,2000 Jakub Jelinek (jakub@xxxxxxxxxx)
*/
@@ -262,6 +262,21 @@ void sun4v_data_access_exception(struct pt_regs *regs, unsigned long addr, unsig
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);
--
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