Merge tag 'ftrace-v7.1' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

Pull ftrace update from Steven Rostedt:

 - Speed up ftrace_lookup_symbols() for single lookups

   The kallsyms lookup in ftrace_lookup_symbols() does a linear search
   over each symbol. This is fine when it must match multiple strings,
   but when there's only a single string being searched for, using a
   binary search is much more efficient. When a single string is passed
   in to search, use the binary search method.

* tag 'ftrace-v7.1' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ftrace: Use kallsyms binary search for single-symbol lookup

1 files changed, 22 insertions, 0 deletions

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 413310912609..7eac1472cc57 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -9267,6 +9267,15 @@ static int kallsyms_callback(void *data, const char *name, unsigned long addr)
  * @addrs array, which needs to be big enough to store at least @cnt
  * addresses.
  *
+ * For a single symbol (cnt == 1), uses kallsyms_lookup_name() which
+ * performs an O(log N) binary search via the sorted kallsyms index.
+ * This avoids the full O(N) linear scan over all kernel symbols that
+ * the multi-symbol path requires.
+ *
+ * For multiple symbols, uses a single-pass linear scan via
+ * kallsyms_on_each_symbol() with binary search into the sorted input
+ * array.
+ *
  * Returns: 0 if all provided symbols are found, -ESRCH otherwise.
  */
 int ftrace_lookup_symbols(const char **sorted_syms, size_t cnt, unsigned long *addrs)
@@ -9274,6 +9283,19 @@ int ftrace_lookup_symbols(const char **sorted_syms, size_t cnt, unsigned long *a
 	struct kallsyms_data args;
 	int found_all;
 
+	/* Fast path: single symbol uses O(log N) binary search */
+	if (cnt == 1) {
+		addrs[0] = kallsyms_lookup_name(sorted_syms[0]);
+		if (addrs[0] && ftrace_location(addrs[0]))
+			return 0;
+		/*
+		 * Binary lookup can fail for duplicate symbol names
+		 * where the first match is not ftrace-instrumented.
+		 * Retry with linear scan.
+		 */
+	}
+
+	/* Batch path: single-pass O(N) linear scan */
 	memset(addrs, 0, sizeof(*addrs) * cnt);
 	args.addrs = addrs;
 	args.syms = sorted_syms;