riscv: Cleanup stacktrace

1. add asm/stacktrace.h for walk_stackframe and struct stackframe
2. remove unnecessary blank lines in stacktrace.c
3. fix warning "no previous prototype for ‘fill_callchain’"
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

arch/riscv/include/asm/stacktrace.h

+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef _ASM_RISCV_STACKTRACE_H
+#define _ASM_RISCV_STACKTRACE_H
+
+#include <linux/sched.h>
+#include <asm/ptrace.h>
+
+struct stackframe {
+	unsigned long fp;
+	unsigned long ra;
+};
+
+extern void notrace walk_stackframe(struct task_struct *task, struct pt_regs *regs,
+				    bool (*fn)(unsigned long, void *), void *arg);
+
+#endif /* _ASM_RISCV_STACKTRACE_H */

arch/riscv/kernel/perf_callchain.c

@@ -4,11 +4,7 @@
 #include <linux/perf_event.h>
 #include <linux/uaccess.h>
 
-/* Kernel callchain */
-struct stackframe {
-	unsigned long fp;
-	unsigned long ra;
-};
+#include <asm/stacktrace.h>
 
 /*
  * Get the return address for a single stackframe and return a pointer to the
@@ -74,13 +70,11 @@ void perf_callchain_user(struct perf_callchain_entry_ctx *entry,
 		fp = user_backtrace(entry, fp, 0);
 }
 
-bool fill_callchain(unsigned long pc, void *entry)
+static bool fill_callchain(unsigned long pc, void *entry)
 {
 	return perf_callchain_store(entry, pc);
 }
 
-void notrace walk_stackframe(struct task_struct *task,
-	struct pt_regs *regs, bool (*fn)(unsigned long, void *), void *arg);
 void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry,
 			   struct pt_regs *regs)
 {

arch/riscv/kernel/stacktrace.c

@@ -12,15 +12,12 @@
 #include <linux/stacktrace.h>
 #include <linux/ftrace.h>
 
+#include <asm/stacktrace.h>
+
 register unsigned long sp_in_global __asm__("sp");
 
 #ifdef CONFIG_FRAME_POINTER
 
-struct stackframe {
-	unsigned long fp;
-	unsigned long ra;
-};
-
 void notrace walk_stackframe(struct task_struct *task, struct pt_regs *regs,
 			     bool (*fn)(unsigned long, void *), void *arg)
 {
@@ -96,7 +93,6 @@ void notrace walk_stackframe(struct task_struct *task,
 
 #endif /* CONFIG_FRAME_POINTER */
 
-
 static bool print_trace_address(unsigned long pc, void *arg)
 {
 	const char *loglvl = arg;
@@ -130,7 +126,6 @@ unsigned long get_wchan(struct task_struct *task)
 	return pc;
 }
 
-
 #ifdef CONFIG_STACKTRACE
 
 static bool __save_trace(unsigned long pc, void *arg, bool nosched)