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authorJason Wessel <jason.wessel@windriver.com>2012-08-10 12:21:15 -0500
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2012-10-21 09:17:10 -0700
commit72630f70509e26bdce8059e93a18969961cec862 (patch)
tree664bb8b6d4081af5387558b11102f99292a0ce02
parent57600cd8d471a6a0a1f97ecdc838954fd202c28f (diff)
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mips,kgdb: fix recursive page fault with CONFIG_KPROBES
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. Signed-off-by: Jason Wessel <jason.wessel@windriver.com> Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--arch/mips/kernel/kgdb.c9
1 files changed, 9 insertions, 0 deletions
diff --git a/arch/mips/kernel/kgdb.c b/arch/mips/kernel/kgdb.c
index f4546e9..23817a6 100644
--- a/arch/mips/kernel/kgdb.c
+++ b/arch/mips/kernel/kgdb.c
@@ -283,6 +283,15 @@ static int kgdb_mips_notify(struct notifier_block *self, unsigned long cmd,
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;