riscv/ftrace: Add ARCH_SUPPORTS_FTRACE_OPS support

Cc: Greentime Hu <greentime@andestech.com>
Signed-off-by: Alan Kao <alankao@andestech.com>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>

arch/riscv/include/asm/ftrace.h

@@ -9,6 +9,7 @@
 #define HAVE_FUNCTION_GRAPH_FP_TEST
 #endif
 
+#define ARCH_SUPPORTS_FTRACE_OPS 1
 #ifndef __ASSEMBLY__
 void _mcount(void);
 static inline unsigned long ftrace_call_adjust(unsigned long addr)

arch/riscv/kernel/mcount-dyn.S

@@ -74,9 +74,12 @@ ENTRY(ftrace_caller)
 	/*
 	 * a0: the address in the caller when calling ftrace_caller
 	 * a1: the caller's return address
+	 * a2: the address of global variable function_trace_op
 	 */
 	ld	a1, -8(s0)
 	addi	a0, ra, -MCOUNT_INSN_SIZE
+	la	t5, function_trace_op
+	ld	a2, 0(t5)
 
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 	/*