4.14-stable patches

added patches:
	fgraph-initialize-tracing_graph_pause-at-task-creation.patch

diff --git a/queue-4.14/fgraph-initialize-tracing_graph_pause-at-task-creation.patch b/queue-4.14/fgraph-initialize-tracing_graph_pause-at-task-creation.patch
new file mode 100644 (file)
index 0000000..f551977
--- /dev/null
+++ b/queue-4.14/fgraph-initialize-tracing_graph_pause-at-task-creation.patch
@@ -0,0 +1,83 @@
+From 7e0a9220467dbcfdc5bc62825724f3e52e50ab31 Mon Sep 17 00:00:00 2001
+From: "Steven Rostedt (VMware)" <rostedt@goodmis.org>
+Date: Fri, 29 Jan 2021 10:13:53 -0500
+Subject: fgraph: Initialize tracing_graph_pause at task creation
+
+From: Steven Rostedt (VMware) <rostedt@goodmis.org>
+
+commit 7e0a9220467dbcfdc5bc62825724f3e52e50ab31 upstream.
+
+On some archs, the idle task can call into cpu_suspend(). The cpu_suspend()
+will disable or pause function graph tracing, as there's some paths in
+bringing down the CPU that can have issues with its return address being
+modified. The task_struct structure has a "tracing_graph_pause" atomic
+counter, that when set to something other than zero, the function graph
+tracer will not modify the return address.
+
+The problem is that the tracing_graph_pause counter is initialized when the
+function graph tracer is enabled. This can corrupt the counter for the idle
+task if it is suspended in these architectures.
+
+   CPU 1                               CPU 2
+   -----                               -----
+  do_idle()
+    cpu_suspend()
+      pause_graph_tracing()
+          task_struct->tracing_graph_pause++ (0 -> 1)
+
+                               start_graph_tracing()
+                                 for_each_online_cpu(cpu) {
+                                   ftrace_graph_init_idle_task(cpu)
+                                     task-struct->tracing_graph_pause = 0 (1 -> 0)
+
+      unpause_graph_tracing()
+          task_struct->tracing_graph_pause-- (0 -> -1)
+
+The above should have gone from 1 to zero, and enabled function graph
+tracing again. But instead, it is set to -1, which keeps it disabled.
+
+There's no reason that the field tracing_graph_pause on the task_struct can
+not be initialized at boot up.
+
+Cc: stable@vger.kernel.org
+Fixes: 380c4b1411ccd ("tracing/function-graph-tracer: append the tracing_graph_flag")
+Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=211339
+Reported-by: pierre.gondois@arm.com
+Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ include/linux/ftrace.h |    4 +++-
+ kernel/trace/ftrace.c  |    2 --
+ 2 files changed, 3 insertions(+), 3 deletions(-)
+
+--- a/include/linux/ftrace.h
++++ b/include/linux/ftrace.h
+@@ -792,7 +792,9 @@ typedef int (*trace_func_graph_ent_t)(st
+ #ifdef CONFIG_FUNCTION_GRAPH_TRACER
+ 
+ /* for init task */
+-#define INIT_FTRACE_GRAPH             .ret_stack = NULL,
++#define INIT_FTRACE_GRAPH                             \
++      .ret_stack              = NULL,                 \
++      .tracing_graph_pause    = ATOMIC_INIT(0),
+ 
+ /*
+  * Stack of return addresses for functions
+--- a/kernel/trace/ftrace.c
++++ b/kernel/trace/ftrace.c
+@@ -6666,7 +6666,6 @@ static int alloc_retstack_tasklist(struc
+               }
+ 
+               if (t->ret_stack == NULL) {
+-                      atomic_set(&t->tracing_graph_pause, 0);
+                       atomic_set(&t->trace_overrun, 0);
+                       t->curr_ret_stack = -1;
+                       /* Make sure the tasks see the -1 first: */
+@@ -6878,7 +6877,6 @@ static DEFINE_PER_CPU(struct ftrace_ret_
+ static void
+ graph_init_task(struct task_struct *t, struct ftrace_ret_stack *ret_stack)
+ {
+-      atomic_set(&t->tracing_graph_pause, 0);
+       atomic_set(&t->trace_overrun, 0);
+       t->ftrace_timestamp = 0;
+       /* make curr_ret_stack visible before we add the ret_stack */