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-rw-r--r--arch/microblaze/kernel/ftrace.c58
1 files changed, 58 insertions, 0 deletions
diff --git a/arch/microblaze/kernel/ftrace.c b/arch/microblaze/kernel/ftrace.c
index c1889b101cb..0952a8b52c3 100644
--- a/arch/microblaze/kernel/ftrace.c
+++ b/arch/microblaze/kernel/ftrace.c
@@ -14,6 +14,64 @@
#include <asm/cacheflush.h>
#include <linux/ftrace.h>
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+/*
+ * Hook the return address and push it in the stack of return addrs
+ * in current thread info.
+ */
+void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr)
+{
+ unsigned long old;
+ int faulted, err;
+ struct ftrace_graph_ent trace;
+ unsigned long return_hooker = (unsigned long)
+ &return_to_handler;
+
+ if (unlikely(atomic_read(&current->tracing_graph_pause)))
+ return;
+
+ /*
+ * Protect against fault, even if it shouldn't
+ * happen. This tool is too much intrusive to
+ * ignore such a protection.
+ */
+ asm volatile(" 1: lwi %0, %2, 0; \
+ 2: swi %3, %2, 0; \
+ addik %1, r0, 0; \
+ 3: \
+ .section .fixup, \"ax\"; \
+ 4: brid 3b; \
+ addik %1, r0, 1; \
+ .previous; \
+ .section __ex_table,\"a\"; \
+ .word 1b,4b; \
+ .word 2b,4b; \
+ .previous;" \
+ : "=&r" (old), "=r" (faulted)
+ : "r" (parent), "r" (return_hooker)
+ );
+
+ if (unlikely(faulted)) {
+ ftrace_graph_stop();
+ WARN_ON(1);
+ return;
+ }
+
+ err = ftrace_push_return_trace(old, self_addr, &trace.depth, 0);
+ if (err == -EBUSY) {
+ *parent = old;
+ return;
+ }
+
+ trace.func = self_addr;
+ /* Only trace if the calling function expects to */
+ if (!ftrace_graph_entry(&trace)) {
+ current->curr_ret_stack--;
+ *parent = old;
+ }
+}
+#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
+
#ifdef CONFIG_DYNAMIC_FTRACE
/* save value to addr - it is save to do it in asm */
static int ftrace_modify_code(unsigned long addr, unsigned int value)