[PATCH 2/5] sparc32: make show_stack() acquire %fp if @_ksp is not specified

[Tejun Heo <tj@kernel.org>]

show_stack(current or NULL, NULL) is used by arch-independent code to
dump backtrace of the current task; however, sparc32 show_stack()
doesn't implement it and wouldn't print any backtrace when NULL @_ksp
is specfied.

Make show_stack() acquire and use %fp if @tsk is NULL or current and
@_ksp is NULL.  This makes %fp fetching in dump_stack() unnecessary.
Make it use NULL for @_ksp instead.

Only compile tested.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 arch/sparc/kernel/process_32.c | 16 +++++++---------
 1 file changed, 7 insertions(+), 9 deletions(-)

diff --git a/arch/sparc/kernel/process_32.c b/arch/sparc/kernel/process_32.c
index 62eede1..0d57b24 100644
--- a/arch/sparc/kernel/process_32.c
+++ b/arch/sparc/kernel/process_32.c
@@ -153,11 +153,13 @@ void show_stack(struct task_struct *tsk, unsigned long *_ksp)
 	struct reg_window32 *rw;
 	int count = 0;
 
-	if (tsk != NULL)
-		task_base = (unsigned long) task_stack_page(tsk);
-	else
-		task_base = (unsigned long) current_thread_info();
+	if (!tsk)
+		tsk = current;
 
+	if (tsk == current && !_ksp)
+		__asm__ __volatile__("mov	%%fp, %0" : "=r" (_ksp));
+
+	task_base = (unsigned long) task_stack_page(tsk);
 	fp = (unsigned long) _ksp;
 	do {
 		/* Bogus frame pointer? */
@@ -175,11 +177,7 @@ void show_stack(struct task_struct *tsk, unsigned long *_ksp)
 
 void dump_stack(void)
 {
-	unsigned long *ksp;
-
-	__asm__ __volatile__("mov	%%fp, %0"
-			     : "=r" (ksp));
-	show_stack(current, ksp);
+	show_stack(current, NULL);
 }
 
 EXPORT_SYMBOL(dump_stack);
-- 
1.8.1.4