linux-kernel - [PATCH v4 tip/core/rcu 15/15] kcsan: Make reporting aware of KCSAN tests

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Message-Id: <20200415183411.12368-15-paulmck@kernel.org>
Date:   Wed, 15 Apr 2020 11:34:11 -0700
From:   paulmck@...nel.org
To:     linux-kernel@...r.kernel.org, kasan-dev@...glegroups.com,
        kernel-team@...com, mingo@...nel.org
Cc:     elver@...gle.com, andreyknvl@...gle.com, glider@...gle.com,
        dvyukov@...gle.com, cai@....pw, boqun.feng@...il.com,
        "Paul E . McKenney" <paulmck@...nel.org>
Subject: [PATCH v4 tip/core/rcu 15/15] kcsan: Make reporting aware of KCSAN tests

From: Marco Elver <elver@...gle.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@...gle.com>
Signed-off-by: Paul E. McKenney <paulmck@...nel.org>
---
 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 cf41d63d..ac5f834 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;
 }
 
-- 
2.9.5