rcu/tree: Mark functions as notrace

hulk inclusion
category: bugfix
bugzilla: 187209, https://gitee.com/openeuler/kernel/issues/I5GWFT
CVE: NA

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

Syzkaller report a softlockup problem, see following logs:
  [   41.463870] watchdog: BUG: soft lockup - CPU#0 stuck for 22s!  [ksoftirqd/0:9]
  [   41.509763] Modules linked in:
  [   41.512295] CPU: 0 PID: 9 Comm: ksoftirqd/0 Not tainted 4.19.90 #13
  [   41.516134] Hardware name: linux,dummy-virt (DT)
  [   41.519182] pstate: 80c00005 (Nzcv daif +PAN +UAO)
  [   41.522415] pc : perf_trace_buf_alloc+0x138/0x238
  [   41.525583] lr : perf_trace_buf_alloc+0x138/0x238
  [   41.528656] sp : ffff8000c137e880
  [   41.531050] x29: ffff8000c137e880 x28: ffff20000850ced0
  [   41.534759] x27: 0000000000000000 x26: ffff8000c137e9c0
  [   41.538456] x25: ffff8000ce5c2ae0 x24: ffff200008358b08
  [   41.542151] x23: 0000000000000000 x22: ffff2000084a50ac
  [   41.545834] x21: ffff8000c137e880 x20: 000000000000001c
  [   41.549516] x19: ffff7dffbfdf88e8 x18: 0000000000000000
  [   41.553202] x17: 0000000000000000 x16: 0000000000000000
  [   41.556892] x15: 1ffff00036e07805 x14: 0000000000000000
  [   41.560592] x13: 0000000000000004 x12: 0000000000000000
  [   41.564315] x11: 1fffefbff7fbf120 x10: ffff0fbff7fbf120
  [   41.568003] x9 : dfff200000000000 x8 : ffff7dffbfdf8904
  [   41.571699] x7 : 0000000000000000 x6 : ffff0fbff7fbf121
  [   41.575398] x5 : ffff0fbff7fbf121 x4 : ffff0fbff7fbf121
  [   41.579086] x3 : ffff20000850cdc8 x2 : 0000000000000008
  [   41.582773] x1 : ffff8000c1376000 x0 : 0000000000000100
  [   41.586495] Call trace:
  [   41.588922]  perf_trace_buf_alloc+0x138/0x238
  [   41.591912]  perf_ftrace_function_call+0x1ac/0x248
  [   41.595123]  ftrace_ops_no_ops+0x3a4/0x488
  [   41.597998]  ftrace_graph_call+0x0/0xc
  [   41.600715]  rcu_dynticks_curr_cpu_in_eqs+0x14/0x70
  [   41.603962]  rcu_is_watching+0xc/0x20
  [   41.606635]  ftrace_ops_no_ops+0x240/0x488
  [   41.609530]  ftrace_graph_call+0x0/0xc
  [   41.612249]  __read_once_size_nocheck.constprop.0+0x1c/0x38
  [   41.615905]  unwind_frame+0x140/0x358
  [   41.618597]  walk_stackframe+0x34/0x60
  [   41.621359]  __save_stack_trace+0x204/0x3b8
  [   41.624328]  save_stack_trace+0x2c/0x38
  [   41.627112]  __kasan_slab_free+0x120/0x228
  [   41.630018]  kasan_slab_free+0x10/0x18
  [   41.632752]  kfree+0x84/0x250
  [   41.635107]  skb_free_head+0x70/0xb0
  [   41.637772]  skb_release_data+0x3f8/0x730
  [   41.640626]  skb_release_all+0x50/0x68
  [   41.643350]  kfree_skb+0x84/0x278
  [   41.645890]  kfree_skb_list+0x4c/0x78
  [   41.648595]  __dev_queue_xmit+0x1a4c/0x23a0
  [   41.651541]  dev_queue_xmit+0x28/0x38
  [   41.654254]  ip6_finish_output2+0xeb0/0x1630
  [   41.657261]  ip6_finish_output+0x2d8/0x7f8
  [   41.660174]  ip6_output+0x19c/0x348
  [   41.663850]  mld_sendpack+0x560/0x9e0
  [   41.666564]  mld_ifc_timer_expire+0x484/0x8a8
  [   41.669624]  call_timer_fn+0x68/0x4b0
  [   41.672355]  expire_timers+0x168/0x498
  [   41.675126]  run_timer_softirq+0x230/0x7a8
  [   41.678052]  __do_softirq+0x2d0/0xba0
  [   41.680763]  run_ksoftirqd+0x110/0x1a0
  [   41.683512]  smpboot_thread_fn+0x31c/0x620
  [   41.686429]  kthread+0x2c8/0x348
  [   41.688927]  ret_from_fork+0x10/0x18

Look into above call stack, we found a recursive call in
'ftrace_graph_call', see a snippet:
    __read_once_size_nocheck.constprop.0
      ftrace_graph_call
        ......
          rcu_dynticks_curr_cpu_in_eqs
            ftrace_graph_call

We analyze that 'rcu_dynticks_curr_cpu_in_eqs' should not be tracable,
and we verify that mark related functions as 'notrace' can avoid the
problem.

Comparing mainline kernel, we find that commit ff5c4f5c ("rcu/tree:
Mark the idle relevant functions noinstr") mark related functions as
'noinstr' which implies notrace, noinline and sticks things in the
.noinstr.text section.
Link: https://lore.kernel.org/all/20200416114706.625340212@infradead.org/

Currently 'noinstr' mechanism has not been introduced, so we would not
directly backport that commit (otherwise more changes may be introduced).
Instead, we mark the functions as 'notrace' where it is 'noinstr' in
that commit.
Signed-off-by: NZheng Yejian <zhengyejian1@huawei.com>
Reviewed-by: NZhen Lei <thunder.leizhen@huawei.com>
Signed-off-by: NYongqiang Liu <liuyongqiang13@huawei.com>

kernel/rcu/tree.c

@@ -275,7 +275,7 @@ static DEFINE_PER_CPU(struct rcu_dynticks, rcu_dynticks) = {
  * Record entry into an extended quiescent state.  This is only to be
  * called when not already in an extended quiescent state.
  */
-static void rcu_dynticks_eqs_enter(void)
+static notrace void rcu_dynticks_eqs_enter(void)
 {
 	struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks);
 	int seq;
@@ -298,7 +298,7 @@ static void rcu_dynticks_eqs_enter(void)
  * Record exit from an extended quiescent state.  This is only to be
  * called from an extended quiescent state.
  */
-static void rcu_dynticks_eqs_exit(void)
+static notrace void rcu_dynticks_eqs_exit(void)
 {
 	struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks);
 	int seq;
@@ -343,7 +343,7 @@ static void rcu_dynticks_eqs_online(void)
  *
  * No ordering, as we are sampling CPU-local information.
  */
-bool rcu_dynticks_curr_cpu_in_eqs(void)
+static __always_inline bool rcu_dynticks_curr_cpu_in_eqs(void)
 {
 	struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks);
 
@@ -706,7 +706,7 @@ static struct rcu_node *rcu_get_root(struct rcu_state *rsp)
  * the possibility of usermode upcalls having messed up our count
  * of interrupt nesting level during the prior busy period.
  */
-static void rcu_eqs_enter(bool user)
+static notrace void rcu_eqs_enter(bool user)
 {
 	struct rcu_state *rsp;
 	struct rcu_data *rdp;
@@ -763,7 +763,7 @@ void rcu_idle_enter(void)
  * If you add or remove a call to rcu_user_enter(), be sure to test with
  * CONFIG_RCU_EQS_DEBUG=y.
  */
-void rcu_user_enter(void)
+notrace void rcu_user_enter(void)
 {
 	lockdep_assert_irqs_disabled();
 	rcu_eqs_enter(true);
@@ -781,7 +781,7 @@ void rcu_user_enter(void)
  * If you add or remove a call to rcu_nmi_exit(), be sure to test
  * with CONFIG_RCU_EQS_DEBUG=y.
  */
-void rcu_nmi_exit(void)
+notrace void rcu_nmi_exit(void)
 {
 	struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks);
 
@@ -829,7 +829,7 @@ void rcu_nmi_exit(void)
  * If you add or remove a call to rcu_irq_exit(), be sure to test with
  * CONFIG_RCU_EQS_DEBUG=y.
  */
-void rcu_irq_exit(void)
+notrace void rcu_irq_exit(void)
 {
 	struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks);
 
@@ -864,7 +864,7 @@ void rcu_irq_exit_irqson(void)
  * allow for the possibility of usermode upcalls messing up our count of
  * interrupt nesting level during the busy period that is just now starting.
  */
-static void rcu_eqs_exit(bool user)
+static notrace void rcu_eqs_exit(bool user)
 {
 	struct rcu_dynticks *rdtp;
 	long oldval;
@@ -914,7 +914,7 @@ void rcu_idle_exit(void)
  * If you add or remove a call to rcu_user_exit(), be sure to test with
  * CONFIG_RCU_EQS_DEBUG=y.
  */
-void rcu_user_exit(void)
+void notrace rcu_user_exit(void)
 {
 	rcu_eqs_exit(1);
 }
@@ -932,7 +932,7 @@ void rcu_user_exit(void)
  * If you add or remove a call to rcu_nmi_enter(), be sure to test
  * with CONFIG_RCU_EQS_DEBUG=y.
  */
-void rcu_nmi_enter(void)
+notrace void rcu_nmi_enter(void)
 {
 	struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks);
 	long incby = 2;
@@ -982,7 +982,7 @@ void rcu_nmi_enter(void)
  * If you add or remove a call to rcu_irq_enter(), be sure to test with
  * CONFIG_RCU_EQS_DEBUG=y.
  */
-void rcu_irq_enter(void)
+notrace void rcu_irq_enter(void)
 {
 	struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks);
 

kernel/rcu/tree_plugin.h

@@ -2677,7 +2677,7 @@ static void rcu_bind_gp_kthread(void)
 }
 
 /* Record the current task on dyntick-idle entry. */
-static void rcu_dynticks_task_enter(void)
+static notrace void rcu_dynticks_task_enter(void)
 {
 #if defined(CONFIG_TASKS_RCU) && defined(CONFIG_NO_HZ_FULL)
 	WRITE_ONCE(current->rcu_tasks_idle_cpu, smp_processor_id());
@@ -2685,7 +2685,7 @@ static void rcu_dynticks_task_enter(void)
 }
 
 /* Record no current task on dyntick-idle exit. */
-static void rcu_dynticks_task_exit(void)
+static notrace void rcu_dynticks_task_exit(void)
 {
 #if defined(CONFIG_TASKS_RCU) && defined(CONFIG_NO_HZ_FULL)
 	WRITE_ONCE(current->rcu_tasks_idle_cpu, -1);