Merge tag 'trace-v5.11-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull tracing fixes from Steven Rostedt:

 - Initialize tracing-graph-pause at task creation, not start of
   function tracing, to avoid corrupting the pause counter.

 - Set "pause-on-trace" for latency tracers as that option breaks their
   output (regression).

 - Fix the wrong error return for setting kretprobes on future modules
   (before they are loaded).

 - Fix re-registering the same kretprobe.

 - Add missing value check for added RCU variable reload.

* tag 'trace-v5.11-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  tracepoint: Fix race between tracing and removing tracepoint
  kretprobe: Avoid re-registration of the same kretprobe earlier
  tracing/kprobe: Fix to support kretprobe events on unloaded modules
  tracing: Use pause-on-trace with the latency tracers
  fgraph: Initialize tracing_graph_pause at task creation

1 files changed, 28 insertions, 8 deletions

diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index f7fb5d135930..d5a3eb74a657 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -1954,28 +1954,48 @@ bool __weak arch_kprobe_on_func_entry(unsigned long offset)
 	return !offset;
 }
 
-bool kprobe_on_func_entry(kprobe_opcode_t *addr, const char *sym, unsigned long offset)
+/**
+ * kprobe_on_func_entry() -- check whether given address is function entry
+ * @addr: Target address
+ * @sym:  Target symbol name
+ * @offset: The offset from the symbol or the address
+ *
+ * This checks whether the given @addr+@offset or @sym+@offset is on the
+ * function entry address or not.
+ * This returns 0 if it is the function entry, or -EINVAL if it is not.
+ * And also it returns -ENOENT if it fails the symbol or address lookup.
+ * Caller must pass @addr or @sym (either one must be NULL), or this
+ * returns -EINVAL.
+ */
+int kprobe_on_func_entry(kprobe_opcode_t *addr, const char *sym, unsigned long offset)
 {
 	kprobe_opcode_t *kp_addr = _kprobe_addr(addr, sym, offset);
 
 	if (IS_ERR(kp_addr))
-		return false;
+		return PTR_ERR(kp_addr);
 
-	if (!kallsyms_lookup_size_offset((unsigned long)kp_addr, NULL, &offset) ||
-						!arch_kprobe_on_func_entry(offset))
-		return false;
+	if (!kallsyms_lookup_size_offset((unsigned long)kp_addr, NULL, &offset))
+		return -ENOENT;
 
-	return true;
+	if (!arch_kprobe_on_func_entry(offset))
+		return -EINVAL;
+
+	return 0;
 }
 
 int register_kretprobe(struct kretprobe *rp)
 {
-	int ret = 0;
+	int ret;
 	struct kretprobe_instance *inst;
 	int i;
 	void *addr;
 
-	if (!kprobe_on_func_entry(rp->kp.addr, rp->kp.symbol_name, rp->kp.offset))
+	ret = kprobe_on_func_entry(rp->kp.addr, rp->kp.symbol_name, rp->kp.offset);
+	if (ret)
+		return ret;
+
+	/* If only rp->kp.addr is specified, check reregistering kprobes */
+	if (rp->kp.addr && check_kprobe_rereg(&rp->kp))
 		return -EINVAL;
 
 	if (kretprobe_blacklist_size) {