s390/stacktrace: add save_stack_trace_regs()

Implement save_stack_trace_regs, so that a stack trace of a kprobe
event can be obtained.

Without this we see following warning:
"save_stack_trace_regs() not implemented yet."
when we execute:
echo stacktrace > /sys/kernel/debug/tracing/trace_options
echo "p kfree" >> /sys/kernel/debug/tracing/kprobe_events
echo 1 > /sys/kernel/debug/tracing/events/kprobes/enable

Reported-by: Chunyu Hu <chuhu@redhat.com>
Signed-off-by: Pratyush Anand <panand@redhat.com>
[heiko.carstens@de.ibm.com]: changed patch to use __save_stack_trace()
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Tested-by: Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 11 insertions, 0 deletions

diff --git a/arch/s390/kernel/stacktrace.c b/arch/s390/kernel/stacktrace.c
index e0fec2d8ac40..8f64ebd63767 100644
--- a/arch/s390/kernel/stacktrace.c
+++ b/arch/s390/kernel/stacktrace.c
@@ -103,3 +103,14 @@ void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
                 trace->entries[trace->nr_entries++] = ULONG_MAX;
 }
 EXPORT_SYMBOL_GPL(save_stack_trace_tsk);
+
+void save_stack_trace_regs(struct pt_regs *regs, struct stack_trace *trace)
+{
+        unsigned long sp;
+
+        sp = kernel_stack_pointer(regs);
+        __save_stack_trace(trace, sp);
+        if (trace->nr_entries < trace->max_entries)
+                trace->entries[trace->nr_entries++] = ULONG_MAX;
+}
+EXPORT_SYMBOL_GPL(save_stack_trace_regs);