Update Linux to v5.10.109
Sourced from [1]
[1] https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.10.109.tar.xz
Change-Id: I19bca9fc6762d4e63bcf3e4cba88bbe560d9c76c
Signed-off-by: Olivier Deprez <olivier.deprez@arm.com>
diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c
index 5d87b21..2dff7f1 100644
--- a/kernel/tracepoint.c
+++ b/kernel/tracepoint.c
@@ -15,12 +15,57 @@
#include <linux/sched/task.h>
#include <linux/static_key.h>
+enum tp_func_state {
+ TP_FUNC_0,
+ TP_FUNC_1,
+ TP_FUNC_2,
+ TP_FUNC_N,
+};
+
extern tracepoint_ptr_t __start___tracepoints_ptrs[];
extern tracepoint_ptr_t __stop___tracepoints_ptrs[];
DEFINE_SRCU(tracepoint_srcu);
EXPORT_SYMBOL_GPL(tracepoint_srcu);
+enum tp_transition_sync {
+ TP_TRANSITION_SYNC_1_0_1,
+ TP_TRANSITION_SYNC_N_2_1,
+
+ _NR_TP_TRANSITION_SYNC,
+};
+
+struct tp_transition_snapshot {
+ unsigned long rcu;
+ unsigned long srcu;
+ bool ongoing;
+};
+
+/* Protected by tracepoints_mutex */
+static struct tp_transition_snapshot tp_transition_snapshot[_NR_TP_TRANSITION_SYNC];
+
+static void tp_rcu_get_state(enum tp_transition_sync sync)
+{
+ struct tp_transition_snapshot *snapshot = &tp_transition_snapshot[sync];
+
+ /* Keep the latest get_state snapshot. */
+ snapshot->rcu = get_state_synchronize_rcu();
+ snapshot->srcu = start_poll_synchronize_srcu(&tracepoint_srcu);
+ snapshot->ongoing = true;
+}
+
+static void tp_rcu_cond_sync(enum tp_transition_sync sync)
+{
+ struct tp_transition_snapshot *snapshot = &tp_transition_snapshot[sync];
+
+ if (!snapshot->ongoing)
+ return;
+ cond_synchronize_rcu(snapshot->rcu);
+ if (!poll_state_synchronize_srcu(&tracepoint_srcu, snapshot->srcu))
+ synchronize_srcu(&tracepoint_srcu);
+ snapshot->ongoing = false;
+}
+
/* Set to 1 to enable tracepoint debug output */
static const int tracepoint_debug;
@@ -50,7 +95,7 @@
*/
struct tp_probes {
struct rcu_head rcu;
- struct tracepoint_func probes[0];
+ struct tracepoint_func probes[];
};
/* Called in removal of a func but failed to allocate a new tp_funcs */
@@ -268,6 +313,32 @@
}
/*
+ * Count the number of functions (enum tp_func_state) in a tp_funcs array.
+ */
+static enum tp_func_state nr_func_state(const struct tracepoint_func *tp_funcs)
+{
+ if (!tp_funcs)
+ return TP_FUNC_0;
+ if (!tp_funcs[1].func)
+ return TP_FUNC_1;
+ if (!tp_funcs[2].func)
+ return TP_FUNC_2;
+ return TP_FUNC_N; /* 3 or more */
+}
+
+static void tracepoint_update_call(struct tracepoint *tp, struct tracepoint_func *tp_funcs)
+{
+ void *func = tp->iterator;
+
+ /* Synthetic events do not have static call sites */
+ if (!tp->static_call_key)
+ return;
+ if (nr_func_state(tp_funcs) == TP_FUNC_1)
+ func = tp_funcs[0].func;
+ __static_call_update(tp->static_call_key, tp->static_call_tramp, func);
+}
+
+/*
* Add the probe function to a tracepoint.
*/
static int tracepoint_add_func(struct tracepoint *tp,
@@ -297,9 +368,42 @@
* a pointer to it. This array is referenced by __DO_TRACE from
* include/linux/tracepoint.h using rcu_dereference_sched().
*/
- rcu_assign_pointer(tp->funcs, tp_funcs);
- if (!static_key_enabled(&tp->key))
- static_key_slow_inc(&tp->key);
+ switch (nr_func_state(tp_funcs)) {
+ case TP_FUNC_1: /* 0->1 */
+ /*
+ * Make sure new static func never uses old data after a
+ * 1->0->1 transition sequence.
+ */
+ tp_rcu_cond_sync(TP_TRANSITION_SYNC_1_0_1);
+ /* Set static call to first function */
+ tracepoint_update_call(tp, tp_funcs);
+ /* Both iterator and static call handle NULL tp->funcs */
+ rcu_assign_pointer(tp->funcs, tp_funcs);
+ static_key_enable(&tp->key);
+ break;
+ case TP_FUNC_2: /* 1->2 */
+ /* Set iterator static call */
+ tracepoint_update_call(tp, tp_funcs);
+ /*
+ * Iterator callback installed before updating tp->funcs.
+ * Requires ordering between RCU assign/dereference and
+ * static call update/call.
+ */
+ fallthrough;
+ case TP_FUNC_N: /* N->N+1 (N>1) */
+ rcu_assign_pointer(tp->funcs, tp_funcs);
+ /*
+ * Make sure static func never uses incorrect data after a
+ * N->...->2->1 (N>1) transition sequence.
+ */
+ if (tp_funcs[0].data != old[0].data)
+ tp_rcu_get_state(TP_TRANSITION_SYNC_N_2_1);
+ break;
+ default:
+ WARN_ON_ONCE(1);
+ break;
+ }
+
release_probes(old);
return 0;
}
@@ -325,15 +429,53 @@
/* Failed allocating new tp_funcs, replaced func with stub */
return 0;
- if (!tp_funcs) {
+ switch (nr_func_state(tp_funcs)) {
+ case TP_FUNC_0: /* 1->0 */
/* Removed last function */
if (tp->unregfunc && static_key_enabled(&tp->key))
tp->unregfunc();
- if (static_key_enabled(&tp->key))
- static_key_slow_dec(&tp->key);
+ static_key_disable(&tp->key);
+ /* Set iterator static call */
+ tracepoint_update_call(tp, tp_funcs);
+ /* Both iterator and static call handle NULL tp->funcs */
+ rcu_assign_pointer(tp->funcs, NULL);
+ /*
+ * Make sure new static func never uses old data after a
+ * 1->0->1 transition sequence.
+ */
+ tp_rcu_get_state(TP_TRANSITION_SYNC_1_0_1);
+ break;
+ case TP_FUNC_1: /* 2->1 */
+ rcu_assign_pointer(tp->funcs, tp_funcs);
+ /*
+ * Make sure static func never uses incorrect data after a
+ * N->...->2->1 (N>2) transition sequence. If the first
+ * element's data has changed, then force the synchronization
+ * to prevent current readers that have loaded the old data
+ * from calling the new function.
+ */
+ if (tp_funcs[0].data != old[0].data)
+ tp_rcu_get_state(TP_TRANSITION_SYNC_N_2_1);
+ tp_rcu_cond_sync(TP_TRANSITION_SYNC_N_2_1);
+ /* Set static call to first function */
+ tracepoint_update_call(tp, tp_funcs);
+ break;
+ case TP_FUNC_2: /* N->N-1 (N>2) */
+ fallthrough;
+ case TP_FUNC_N:
+ rcu_assign_pointer(tp->funcs, tp_funcs);
+ /*
+ * Make sure static func never uses incorrect data after a
+ * N->...->2->1 (N>2) transition sequence.
+ */
+ if (tp_funcs[0].data != old[0].data)
+ tp_rcu_get_state(TP_TRANSITION_SYNC_N_2_1);
+ break;
+ default:
+ WARN_ON_ONCE(1);
+ break;
}
- rcu_assign_pointer(tp->funcs, tp_funcs);
release_probes(old);
return 0;
}
@@ -596,7 +738,7 @@
case MODULE_STATE_UNFORMED:
break;
}
- return ret;
+ return notifier_from_errno(ret);
}
static struct notifier_block tracepoint_module_nb = {