5 files changed, 59 insertions, 0 deletions

diff --git a/arch/nds32/Kconfig b/arch/nds32/Kconfig
index 1d4248fa55e9..853497fe4266 100644
--- a/arch/nds32/Kconfig
+++ b/arch/nds32/Kconfig
@@ -40,6 +40,7 @@ config NDS32
         select NO_IOPORT_MAP
         select RTC_LIB
         select THREAD_INFO_IN_TASK
+        select HAVE_FUNCTION_TRACER
         help
           Andes(nds32) Linux support.
 
diff --git a/arch/nds32/Makefile b/arch/nds32/Makefile
index 63f4f173e5f4..3509fac10491 100644
--- a/arch/nds32/Makefile
+++ b/arch/nds32/Makefile
@@ -5,6 +5,10 @@ KBUILD_DEFCONFIG := defconfig
 
 comma = ,
 
+ifdef CONFIG_FUNCTION_TRACER
+arch-y += -malways-save-lp -mno-relax
+endif
+
 KBUILD_CFLAGS   += $(call cc-option, -mno-sched-prolog-epilog)
 KBUILD_CFLAGS   += -mcmodel=large
 
diff --git a/arch/nds32/include/asm/ftrace.h b/arch/nds32/include/asm/ftrace.h
new file mode 100644
index 000000000000..bac7657f576a
--- /dev/null
+++ b/arch/nds32/include/asm/ftrace.h
@@ -0,0 +1,20 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef __ASM_NDS32_FTRACE_H
+#define __ASM_NDS32_FTRACE_H
+
+#ifdef CONFIG_FUNCTION_TRACER
+
+#define HAVE_FUNCTION_GRAPH_FP_TEST
+
+#define MCOUNT_ADDR ((unsigned long)(_mcount))
+/* mcount call is composed of three instructions:
+ * sethi + ori + jral
+ */
+#define MCOUNT_INSN_SIZE 12
+
+extern void _mcount(unsigned long parent_ip);
+
+#endif /* CONFIG_FUNCTION_TRACER */
+
+#endif /* __ASM_NDS32_FTRACE_H */
diff --git a/arch/nds32/kernel/Makefile b/arch/nds32/kernel/Makefile
index 42792743e8b9..27cded39fa66 100644
--- a/arch/nds32/kernel/Makefile
+++ b/arch/nds32/kernel/Makefile
@@ -21,3 +21,9 @@ extra-y := head.o vmlinux.lds
 
 
 obj-y                           += vdso/
+
+obj-$(CONFIG_FUNCTION_TRACER)   += ftrace.o
+
+ifdef CONFIG_FUNCTION_TRACER
+CFLAGS_REMOVE_ftrace.o = $(CC_FLAGS_FTRACE)
+endif
diff --git a/arch/nds32/kernel/ftrace.c b/arch/nds32/kernel/ftrace.c
new file mode 100644
index 000000000000..563f64c070b3
--- /dev/null
+++ b/arch/nds32/kernel/ftrace.c
@@ -0,0 +1,28 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/ftrace.h>
+#include <linux/uaccess.h>
+#include <asm/cacheflush.h>
+
+extern void (*ftrace_trace_function)(unsigned long, unsigned long,
+                                     struct ftrace_ops*, struct pt_regs*);
+
+noinline void __naked ftrace_stub(unsigned long ip, unsigned long parent_ip,
+                                  struct ftrace_ops *op, struct pt_regs *regs)
+{
+        __asm__ ("");  /* avoid to optimize as pure function */
+}
+
+noinline void _mcount(unsigned long parent_ip)
+{
+        /* save all state by the compiler prologue */
+
+        unsigned long ip = (unsigned long)__builtin_return_address(0);
+
+        if (ftrace_trace_function != ftrace_stub)
+                ftrace_trace_function(ip - MCOUNT_INSN_SIZE, parent_ip,
+                                      NULL, NULL);
+
+        /* restore all state by the compiler epilogue */
+}
+EXPORT_SYMBOL(_mcount);