sh: kprobes: Fix up race against probe point removal.
Handle a corner case where another CPU or debugger removes the probe
point from underneath us.
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
diff --git a/arch/sh/kernel/kprobes.c b/arch/sh/kernel/kprobes.c
index f0e1c78..a478ba7 100644
--- a/arch/sh/kernel/kprobes.c
+++ b/arch/sh/kernel/kprobes.c
@@ -252,6 +252,17 @@
p = get_kprobe(addr);
if (!p) {
/* Not one of ours: let kernel handle it */
+ if (*(kprobe_opcode_t *)addr != BREAKPOINT_INSTRUCTION) {
+ /*
+ * The breakpoint instruction was removed right
+ * after we hit it. Another cpu has removed
+ * either a probepoint or a debugger breakpoint
+ * at this address. In either case, no further
+ * handling of this interrupt is appropriate.
+ */
+ ret = 1;
+ }
+
goto no_kprobe;
}