[PATCH 2/2] kcsan: Make reporting aware of KCSAN tests

[Marco Elver <elver@google.com>]

Reporting hides KCSAN runtime functions in the stack trace, with
filtering done based on function names. Currently this included all
functions (or modules) that would match "kcsan_". Make the filter aware
of KCSAN tests, which contain "kcsan_test", and are no longer skipped in
the report.

This is in preparation for adding a KCSAN test module.

Signed-off-by: Marco Elver <elver@google.com>
---
 kernel/kcsan/report.c | 30 +++++++++++++++++++++++-------
 1 file changed, 23 insertions(+), 7 deletions(-)

diff --git a/kernel/kcsan/report.c b/kernel/kcsan/report.c
index cf41d63dd0cd..ac5f8345bae9 100644
--- a/kernel/kcsan/report.c
+++ b/kernel/kcsan/report.c
@@ -262,16 +262,32 @@ static const char *get_thread_desc(int task_id)
 static int get_stack_skipnr(const unsigned long stack_entries[], int num_entries)
 {
 	char buf[64];
-	int len;
-	int skip = 0;
+	char *cur;
+	int len, skip;
 
-	for (; skip < num_entries; ++skip) {
+	for (skip = 0; skip < num_entries; ++skip) {
 		len = scnprintf(buf, sizeof(buf), "%ps", (void *)stack_entries[skip]);
-		if (!strnstr(buf, "csan_", len) &&
-		    !strnstr(buf, "tsan_", len) &&
-		    !strnstr(buf, "_once_size", len))
-			break;
+
+		/* Never show tsan_* or {read,write}_once_size. */
+		if (strnstr(buf, "tsan_", len) ||
+		    strnstr(buf, "_once_size", len))
+			continue;
+
+		cur = strnstr(buf, "kcsan_", len);
+		if (cur) {
+			cur += sizeof("kcsan_") - 1;
+			if (strncmp(cur, "test", sizeof("test") - 1))
+				continue; /* KCSAN runtime function. */
+			/* KCSAN related test. */
+		}
+
+		/*
+		 * No match for runtime functions -- @skip entries to skip to
+		 * get to first frame of interest.
+		 */
+		break;
 	}
+
 	return skip;
 }
 
-- 
2.26.0.110.g2183baf09c-goog