[PATCH 4.8 69/92] s390/dumpstack: restore reliable indicator for call traces

[Greg Kroah-Hartman]

4.8-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Heiko Carstens <heiko.carstens@xxxxxxxxxx>

commit d0208639dbc6fe97a25054df44faa2d19aca9380 upstream.

Before merging all different stack tracers the call traces printed had
an indicator if an entry can be considered reliable or not.
Unreliable entries were put in braces, reliable not. Currently all
lines contain these extra braces.

This patch restores the old behaviour by adding an extra "reliable"
parameter to the callback functions. Only show_trace makes currently
use of it.

Before:
[    0.804751] Call Trace:
[    0.804753] ([<000000000017d0e0>] try_to_wake_up+0x318/0x5e0)
[    0.804756] ([<0000000000161d64>] create_worker+0x174/0x1c0)

After:
[    0.804751] Call Trace:
[    0.804753] ([<000000000017d0e0>] try_to_wake_up+0x318/0x5e0)
[    0.804756]  [<0000000000161d64>] create_worker+0x174/0x1c0

Fixes: 758d39ebd3d5 ("s390/dumpstack: merge all four stack tracers")
Signed-off-by: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
Signed-off-by: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 arch/s390/include/asm/processor.h |    2 +-
 arch/s390/kernel/dumpstack.c      |   17 +++++++++++------
 arch/s390/kernel/perf_event.c     |    2 +-
 arch/s390/kernel/stacktrace.c     |    4 ++--
 arch/s390/oprofile/init.c         |    2 +-
 5 files changed, 16 insertions(+), 11 deletions(-)

--- a/arch/s390/include/asm/processor.h
+++ b/arch/s390/include/asm/processor.h
@@ -192,7 +192,7 @@ struct task_struct;
 struct mm_struct;
 struct seq_file;
 
-typedef int (*dump_trace_func_t)(void *data, unsigned long address);
+typedef int (*dump_trace_func_t)(void *data, unsigned long address, int reliable);
 void dump_trace(dump_trace_func_t func, void *data,
 		struct task_struct *task, unsigned long sp);
 
--- a/arch/s390/kernel/dumpstack.c
+++ b/arch/s390/kernel/dumpstack.c
@@ -38,10 +38,10 @@ __dump_trace(dump_trace_func_t func, voi
 		if (sp < low || sp > high - sizeof(*sf))
 			return sp;
 		sf = (struct stack_frame *) sp;
+		if (func(data, sf->gprs[8], 0))
+			return sp;
 		/* Follow the backchain. */
 		while (1) {
-			if (func(data, sf->gprs[8]))
-				return sp;
 			low = sp;
 			sp = sf->back_chain;
 			if (!sp)
@@ -49,6 +49,8 @@ __dump_trace(dump_trace_func_t func, voi
 			if (sp <= low || sp > high - sizeof(*sf))
 				return sp;
 			sf = (struct stack_frame *) sp;
+			if (func(data, sf->gprs[8], 1))
+				return sp;
 		}
 		/* Zero backchain detected, check for interrupt frame. */
 		sp = (unsigned long) (sf + 1);
@@ -56,7 +58,7 @@ __dump_trace(dump_trace_func_t func, voi
 			return sp;
 		regs = (struct pt_regs *) sp;
 		if (!user_mode(regs)) {
-			if (func(data, regs->psw.addr))
+			if (func(data, regs->psw.addr, 1))
 				return sp;
 		}
 		low = sp;
@@ -90,7 +92,7 @@ struct return_address_data {
 	int depth;
 };
 
-static int __return_address(void *data, unsigned long address)
+static int __return_address(void *data, unsigned long address, int reliable)
 {
 	struct return_address_data *rd = data;
 
@@ -109,9 +111,12 @@ unsigned long return_address(int depth)
 }
 EXPORT_SYMBOL_GPL(return_address);
 
-static int show_address(void *data, unsigned long address)
+static int show_address(void *data, unsigned long address, int reliable)
 {
-	printk("([<%016lx>] %pSR)\n", address, (void *)address);
+	if (reliable)
+		printk(" [<%016lx>] %pSR \n", address, (void *)address);
+	else
+		printk("([<%016lx>] %pSR)\n", address, (void *)address);
 	return 0;
 }
 
--- a/arch/s390/kernel/perf_event.c
+++ b/arch/s390/kernel/perf_event.c
@@ -222,7 +222,7 @@ static int __init service_level_perf_reg
 }
 arch_initcall(service_level_perf_register);
 
-static int __perf_callchain_kernel(void *data, unsigned long address)
+static int __perf_callchain_kernel(void *data, unsigned long address, int reliable)
 {
 	struct perf_callchain_entry_ctx *entry = data;
 
--- a/arch/s390/kernel/stacktrace.c
+++ b/arch/s390/kernel/stacktrace.c
@@ -27,12 +27,12 @@ static int __save_address(void *data, un
 	return 1;
 }
 
-static int save_address(void *data, unsigned long address)
+static int save_address(void *data, unsigned long address, int reliable)
 {
 	return __save_address(data, address, 0);
 }
 
-static int save_address_nosched(void *data, unsigned long address)
+static int save_address_nosched(void *data, unsigned long address, int reliable)
 {
 	return __save_address(data, address, 1);
 }
--- a/arch/s390/oprofile/init.c
+++ b/arch/s390/oprofile/init.c
@@ -13,7 +13,7 @@
 #include <linux/init.h>
 #include <asm/processor.h>
 
-static int __s390_backtrace(void *data, unsigned long address)
+static int __s390_backtrace(void *data, unsigned long address, int reliable)
 {
 	unsigned int *depth = data;