riscv: Enable ARCH_STACKWALK

Convert to ARCH_STACKWALK to reduce duplicated code in stack trace.
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

arch/riscv/Kconfig

@@ -14,6 +14,7 @@ config RISCV
 	def_bool y
 	select ARCH_CLOCKSOURCE_INIT
 	select ARCH_SUPPORTS_ATOMIC_RMW
+	select ARCH_STACKWALK
 	select ARCH_HAS_BINFMT_FLAT
 	select ARCH_HAS_DEBUG_VM_PGTABLE
 	select ARCH_HAS_DEBUG_VIRTUAL if MMU

arch/riscv/kernel/head.S

@@ -177,7 +177,6 @@ setup_trap_vector:
 
 END(_start)
 
-	__INIT
 ENTRY(_start_kernel)
 	/* Mask all interrupts */
 	csrw CSR_IE, zero

arch/riscv/kernel/stacktrace.c

@@ -19,7 +19,7 @@ register unsigned long sp_in_global __asm__("sp");
 #ifdef CONFIG_FRAME_POINTER
 
 void notrace walk_stackframe(struct task_struct *task, struct pt_regs *regs,
-			     bool (*fn)(unsigned long, void *), void *arg)
+			     bool (*fn)(void *, unsigned long), void *arg)
 {
 	unsigned long fp, sp, pc;
 
@@ -43,7 +43,7 @@ void notrace walk_stackframe(struct task_struct *task, struct pt_regs *regs,
 		unsigned long low, high;
 		struct stackframe *frame;
 
-		if (unlikely(!__kernel_text_address(pc) || fn(arg, pc)))
+		if (unlikely(!__kernel_text_address(pc) || !fn(arg, pc)))
 			break;
 
 		/* Validate frame pointer */
@@ -85,7 +85,7 @@ void notrace walk_stackframe(struct task_struct *task,
 
 	ksp = (unsigned long *)sp;
 	while (!kstack_end(ksp)) {
-		if (__kernel_text_address(pc) && unlikely(fn(arg, pc)))
+		if (__kernel_text_address(pc) && unlikely(!fn(arg, pc)))
 			break;
 		pc = (*ksp++) - 0x4;
 	}
@@ -93,12 +93,12 @@ void notrace walk_stackframe(struct task_struct *task,
 
 #endif /* CONFIG_FRAME_POINTER */
 
-static bool print_trace_address(unsigned long pc, void *arg)
+static bool print_trace_address(void *arg, unsigned long pc)
 {
 	const char *loglvl = arg;
 
 	print_ip_sym(loglvl, pc);
-	return false;
+	return true;
 }
 
 void show_stack(struct task_struct *task, unsigned long *sp, const char *loglvl)
@@ -112,9 +112,9 @@ static bool save_wchan(void *arg, unsigned long pc)
 	if (!in_sched_functions(pc)) {
 		unsigned long *p = arg;
 		*p = pc;
-		return true;
+		return false;
 	}
-	return false;
+	return true;
 }
 
 unsigned long get_wchan(struct task_struct *task)
@@ -128,39 +128,10 @@ unsigned long get_wchan(struct task_struct *task)
 
 #ifdef CONFIG_STACKTRACE
 
-static bool __save_trace(unsigned long pc, void *arg, bool nosched)
-{
-	struct stack_trace *trace = arg;
-
-	if (unlikely(nosched && in_sched_functions(pc)))
-		return false;
-	if (unlikely(trace->skip > 0)) {
-		trace->skip--;
-		return false;
-	}
-
-	trace->entries[trace->nr_entries++] = pc;
-	return (trace->nr_entries >= trace->max_entries);
-}
-
-static bool save_trace(void *arg, unsigned long pc)
-{
-	return __save_trace(pc, arg, false);
-}
-
-/*
- * Save stack-backtrace addresses into a stack_trace buffer.
- */
-void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
-{
-	walk_stackframe(tsk, NULL, save_trace, trace);
-}
-EXPORT_SYMBOL_GPL(save_stack_trace_tsk);
-
-void save_stack_trace(struct stack_trace *trace)
+void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie,
+		     struct task_struct *task, struct pt_regs *regs)
 {
-	save_stack_trace_tsk(NULL, trace);
+	walk_stackframe(task, regs, consume_entry, cookie);
 }
-EXPORT_SYMBOL_GPL(save_stack_trace);
 
 #endif /* CONFIG_STACKTRACE */