csky: Fixup calltrace panic

The implementation of show_stack will panic with wrong fp:

addr    = *fp++;

because the fp isn't checked properly.

The current implementations of show_stack, wchan and stack_trace
haven't been designed properly, so just deprecate them.

This patch is a reference to riscv's way, all codes are modified from
arm's. The patch is passed with:

 - cat /proc/<pid>/stack
 - cat /proc/<pid>/wchan
 - echo c > /proc/sysrq-trigger

Signed-off-by: Guo Ren <guoren@linux.alibaba.com>

2 files changed, 16 insertions, 0 deletions

diff --git a/arch/csky/include/asm/ptrace.h b/arch/csky/include/asm/ptrace.h
index aae5aa96cf54..bcfb7070e48d 100644
--- a/arch/csky/include/asm/ptrace.h
+++ b/arch/csky/include/asm/ptrace.h
@@ -58,6 +58,16 @@ static inline unsigned long kernel_stack_pointer(struct pt_regs *regs)
 	return regs->usp;
 }
 
+static inline unsigned long frame_pointer(struct pt_regs *regs)
+{
+	return regs->regs[4];
+}
+static inline void frame_pointer_set(struct pt_regs *regs,
+				     unsigned long val)
+{
+	regs->regs[4] = val;
+}
+
 extern int regs_query_register_offset(const char *name);
 extern unsigned long regs_get_kernel_stack_nth(struct pt_regs *regs,
 						unsigned int n);
diff --git a/arch/csky/include/asm/thread_info.h b/arch/csky/include/asm/thread_info.h
index 5d33fcfd7f2a..d381a5752f0e 100644
--- a/arch/csky/include/asm/thread_info.h
+++ b/arch/csky/include/asm/thread_info.h
@@ -40,6 +40,12 @@ struct thread_info {
 #define thread_saved_fp(tsk) \
 	((unsigned long)(((struct switch_stack *)(tsk->thread.ksp))->r8))
 
+#define thread_saved_sp(tsk) \
+	((unsigned long)(tsk->thread.ksp))
+
+#define thread_saved_lr(tsk) \
+	((unsigned long)(((struct switch_stack *)(tsk->thread.ksp))->r15))
+
 static inline struct thread_info *current_thread_info(void)
 {
 	unsigned long sp;