powerpc: support for latencytop

Implement save_stack_trace_tsk on powerpc, so that we can run with
latencytop.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

2 files changed, 30 insertions, 10 deletions

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index aaf99892d1b3..5e2185432ad3 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -53,6 +53,9 @@ config STACKTRACE_SUPPORT
         bool
         default y
 
+config HAVE_LATENCYTOP_SUPPORT
+        def_bool y
+
 config TRACE_IRQFLAGS_SUPPORT
         bool
         depends on PPC64
diff --git a/arch/powerpc/kernel/stacktrace.c b/arch/powerpc/kernel/stacktrace.c
index 962944038430..6a4fb003fa54 100644
--- a/arch/powerpc/kernel/stacktrace.c
+++ b/arch/powerpc/kernel/stacktrace.c
@@ -10,33 +10,34 @@
  *      2 of the License, or (at your option) any later version.
  */
 
+#include <linux/module.h>
 #include <linux/sched.h>
 #include <linux/stacktrace.h>
 #include <asm/ptrace.h>
+#include <asm/processor.h>
 
 /*
  * Save stack-backtrace addresses into a stack_trace buffer.
  */
-void save_stack_trace(struct stack_trace *trace)
+static void save_context_stack(struct stack_trace *trace, unsigned long sp,
+                        struct task_struct *tsk, int savesched)
 {
-        unsigned long sp;
-
-        asm("mr %0,1" : "=r" (sp));
-
         for (;;) {
                 unsigned long *stack = (unsigned long *) sp;
                 unsigned long newsp, ip;
 
-                if (!validate_sp(sp, current, STACK_FRAME_OVERHEAD))
+                if (!validate_sp(sp, tsk, STACK_FRAME_OVERHEAD))
                         return;
 
                 newsp = stack[0];
                 ip = stack[STACK_FRAME_LR_SAVE];
 
-                if (!trace->skip)
-                        trace->entries[trace->nr_entries++] = ip;
-                else
-                        trace->skip--;
+                if (savesched || !in_sched_functions(ip)) {
+                        if (!trace->skip)
+                                trace->entries[trace->nr_entries++] = ip;
+                        else
+                                trace->skip--;
+                }
 
                 if (trace->nr_entries >= trace->max_entries)
                         return;
@@ -44,3 +45,19 @@ void save_stack_trace(struct stack_trace *trace)
                 sp = newsp;
         }
 }
+
+void save_stack_trace(struct stack_trace *trace)
+{
+        unsigned long sp;
+
+        asm("mr %0,1" : "=r" (sp));
+
+        save_context_stack(trace, sp, current, 1);
+}
+EXPORT_SYMBOL_GPL(save_stack_trace);
+
+void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
+{
+        save_context_stack(trace, tsk->thread.regs->gpr[1], tsk, 0);
+}
+EXPORT_SYMBOL_GPL(save_stack_trace_tsk);