Merge tag 'core-static_call-2020-10-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull static call support from Ingo Molnar:
 "This introduces static_call(), which is the idea of static_branch()
  applied to indirect function calls. Remove a data load (indirection)
  by modifying the text.

  They give the flexibility of function pointers, but with better
  performance. (This is especially important for cases where retpolines
  would otherwise be used, as retpolines can be pretty slow.)

  API overview:

      DECLARE_STATIC_CALL(name, func);
      DEFINE_STATIC_CALL(name, func);
      DEFINE_STATIC_CALL_NULL(name, typename);

      static_call(name)(args...);
      static_call_cond(name)(args...);
      static_call_update(name, func);

  x86 is supported via text patching, otherwise basic indirect calls are
  used, with function pointers.

  There's a second variant using inline code patching, inspired by
  jump-labels, implemented on x86 as well.

  The new APIs are utilized in the x86 perf code, a heavy user of
  function pointers, where static calls speed up the PMU handler by
  4.2% (!).

  The generic implementation is not really excercised on other
  architectures, outside of the trivial test_static_call_init()
  self-test"

* tag 'core-static_call-2020-10-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (21 commits)
  static_call: Fix return type of static_call_init
  tracepoint: Fix out of sync data passing by static caller
  tracepoint: Fix overly long tracepoint names
  x86/perf, static_call: Optimize x86_pmu methods
  tracepoint: Optimize using static_call()
  static_call: Allow early init
  static_call: Add some validation
  static_call: Handle tail-calls
  static_call: Add static_call_cond()
  x86/alternatives: Teach text_poke_bp() to emulate RET
  static_call: Add simple self-test for static calls
  x86/static_call: Add inline static call implementation for x86-64
  x86/static_call: Add out-of-line static call implementation
  static_call: Avoid kprobes on inline static_call()s
  static_call: Add inline static call infrastructure
  static_call: Add basic static call infrastructure
  compiler.h: Make __ADDRESSABLE() symbol truly unique
  jump_label,module: Fix module lifetime for __jump_label_mod_text_reserved()
  module: Properly propagate MODULE_STATE_COMING failure
  module: Fix up module_notifier return values
  ...

4 files changed, 10 insertions, 6 deletions

diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index a8d4f253ed77..2ecf7892a31b 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -2027,10 +2027,11 @@ static int bpf_event_notify(struct notifier_block *nb, unsigned long op,
 {
 	struct bpf_trace_module *btm, *tmp;
 	struct module *mod = module;
+	int ret = 0;
 
 	if (mod->num_bpf_raw_events == 0 ||
 	    (op != MODULE_STATE_COMING && op != MODULE_STATE_GOING))
-		return 0;
+		goto out;
 
 	mutex_lock(&bpf_module_mutex);
 
@@ -2040,6 +2041,8 @@ static int bpf_event_notify(struct notifier_block *nb, unsigned long op,
 		if (btm) {
 			btm->module = module;
 			list_add(&btm->list, &bpf_trace_modules);
+		} else {
+			ret = -ENOMEM;
 		}
 		break;
 	case MODULE_STATE_GOING:
@@ -2055,7 +2058,8 @@ static int bpf_event_notify(struct notifier_block *nb, unsigned long op,
 
 	mutex_unlock(&bpf_module_mutex);
 
-	return 0;
+out:
+	return notifier_from_errno(ret);
 }
 
 static struct notifier_block bpf_module_nb = {
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index d3e5de717df2..25b72a73608a 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -9074,7 +9074,7 @@ static int trace_module_notify(struct notifier_block *self,
 		break;
 	}
 
-	return 0;
+	return NOTIFY_OK;
 }
 
 static struct notifier_block trace_module_nb = {
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index a85effb2373b..beebf2cd364b 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -2646,7 +2646,7 @@ static int trace_module_notify(struct notifier_block *self,
 	mutex_unlock(&trace_types_lock);
 	mutex_unlock(&event_mutex);
 
-	return 0;
+	return NOTIFY_OK;
 }
 
 static struct notifier_block trace_module_nb = {
diff --git a/kernel/trace/trace_printk.c b/kernel/trace/trace_printk.c
index d4e31e969206..bb7783b90361 100644
--- a/kernel/trace/trace_printk.c
+++ b/kernel/trace/trace_printk.c
@@ -96,7 +96,7 @@ static int module_trace_bprintk_format_notify(struct notifier_block *self,
 		if (val == MODULE_STATE_COMING)
 			hold_module_trace_bprintk_format(start, end);
 	}
-	return 0;
+	return NOTIFY_OK;
 }
 
 /*
@@ -174,7 +174,7 @@ __init static int
 module_trace_bprintk_format_notify(struct notifier_block *self,
 		unsigned long val, void *data)
 {
-	return 0;
+	return NOTIFY_OK;
 }
 static inline const char **
 find_next_mod_format(int start_index, void *v, const char **fmt, loff_t *pos)