This is a note to let you know that I've just added the patch titled
mips,kgdb: fix recursive page fault with CONFIG_KPROBES
to the 3.0-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
mips-kgdb-fix-recursive-page-fault-with-config_kprobes.patch
and it can be found in the queue-3.0 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From f0a996eeeda214f4293e234df33b29bec003b536 Mon Sep 17 00:00:00 2001
From: Jason Wessel <[email protected]>
Date: Fri, 10 Aug 2012 12:21:15 -0500
Subject: mips,kgdb: fix recursive page fault with CONFIG_KPROBES
From: Jason Wessel <[email protected]>
commit f0a996eeeda214f4293e234df33b29bec003b536 upstream.
This fault was detected using the kgdb test suite on boot and it
crashes recursively due to the fact that CONFIG_KPROBES on mips adds
an extra die notifier in the page fault handler. The crash signature
looks like this:
kgdbts:RUN bad memory access test
KGDB: re-enter exception: ALL breakpoints killed
Call Trace:
[<807b7548>] dump_stack+0x20/0x54
[<807b7548>] dump_stack+0x20/0x54
The fix for now is to have kgdb return immediately if the fault type
is DIE_PAGE_FAULT and allow the kprobe code to decide what is supposed
to happen.
Cc: Masami Hiramatsu <[email protected]>
Cc: David S. Miller <[email protected]>
Signed-off-by: Jason Wessel <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
arch/mips/kernel/kgdb.c | 9 +++++++++
1 file changed, 9 insertions(+)
--- a/arch/mips/kernel/kgdb.c
+++ b/arch/mips/kernel/kgdb.c
@@ -283,6 +283,15 @@ static int kgdb_mips_notify(struct notif
struct pt_regs *regs = args->regs;
int trap = (regs->cp0_cause & 0x7c) >> 2;
+#ifdef CONFIG_KPROBES
+ /*
+ * Return immediately if the kprobes fault notifier has set
+ * DIE_PAGE_FAULT.
+ */
+ if (cmd == DIE_PAGE_FAULT)
+ return NOTIFY_DONE;
+#endif /* CONFIG_KPROBES */
+
/* Userspace events, ignore. */
if (user_mode(regs))
return NOTIFY_DONE;
Patches currently in stable-queue which might be from
[email protected] are
queue-3.0/mips-kgdb-fix-recursive-page-fault-with-config_kprobes.patch
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