riscv: Add dump stack in show_regs

Like commit 1149aad10b ("arm64: Add dump_backtrace() in show_regs"),
dump the stack in riscv show_regs as common code expects.

Reviewed-by: Atish Patra <atish.patra@wdc.com>
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

arch/riscv/include/asm/bug.h

@@ -85,6 +85,7 @@ do {								\
 struct pt_regs;
 struct task_struct;
 
+void __show_regs(struct pt_regs *regs);
 void die(struct pt_regs *regs, const char *str);
 void do_trap(struct pt_regs *regs, int signo, int code, unsigned long addr);
 

arch/riscv/include/asm/stacktrace.h

@@ -13,5 +13,7 @@ struct stackframe {
 
 extern void notrace walk_stackframe(struct task_struct *task, struct pt_regs *regs,
 				    bool (*fn)(void *, unsigned long), void *arg);
+extern void dump_backtrace(struct pt_regs *regs, struct task_struct *task,
+			   const char *loglvl);
 
 #endif /* _ASM_RISCV_STACKTRACE_H */

arch/riscv/kernel/process.c

@@ -18,6 +18,7 @@
 #include <asm/unistd.h>
 #include <asm/processor.h>
 #include <asm/csr.h>
+#include <asm/stacktrace.h>
 #include <asm/string.h>
 #include <asm/switch_to.h>
 #include <asm/thread_info.h>
@@ -39,7 +40,7 @@ void arch_cpu_idle(void)
 	raw_local_irq_enable();
 }
 
-void show_regs(struct pt_regs *regs)
+void __show_regs(struct pt_regs *regs)
 {
 	show_regs_print_info(KERN_DEFAULT);
 
@@ -69,6 +70,12 @@ void show_regs(struct pt_regs *regs)
 	pr_cont("status: " REG_FMT " badaddr: " REG_FMT " cause: " REG_FMT "\n",
 		regs->status, regs->badaddr, regs->cause);
 }
+void show_regs(struct pt_regs *regs)
+{
+	__show_regs(regs);
+	if (!user_mode(regs))
+		dump_backtrace(regs, NULL, KERN_DEFAULT);
+}
 
 void start_thread(struct pt_regs *regs, unsigned long pc,
 	unsigned long sp)

arch/riscv/kernel/stacktrace.c

@@ -101,10 +101,16 @@ static bool print_trace_address(void *arg, unsigned long pc)
 	return true;
 }
 
+void dump_backtrace(struct pt_regs *regs, struct task_struct *task,
+		    const char *loglvl)
+{
+	pr_cont("%sCall Trace:\n", loglvl);
+	walk_stackframe(task, regs, print_trace_address, (void *)loglvl);
+}
+
 void show_stack(struct task_struct *task, unsigned long *sp, const char *loglvl)
 {
-	pr_cont("Call Trace:\n");
+	dump_backtrace(NULL, task, loglvl);
-	walk_stackframe(task, NULL, print_trace_address, (void *)loglvl);
 }
 
 static bool save_wchan(void *arg, unsigned long pc)

arch/riscv/kernel/traps.c

@@ -17,6 +17,7 @@
 #include <linux/module.h>
 #include <linux/irq.h>
 
+#include <asm/bug.h>
 #include <asm/processor.h>
 #include <asm/ptrace.h>
 #include <asm/csr.h>
@@ -67,7 +68,7 @@ void do_trap(struct pt_regs *regs, int signo, int code, unsigned long addr)
 			tsk->comm, task_pid_nr(tsk), signo, code, addr);
 		print_vma_addr(KERN_CONT " in ", instruction_pointer(regs));
 		pr_cont("\n");
-		show_regs(regs);
+		__show_regs(regs);
 	}
 
 	force_sig_fault(signo, code, (void __user *)addr);