linux-kernel - [PATCH 5/9] kcsan: Refactor access

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Message-Id: <20210414112825.3008667-6-elver@google.com>
Date:   Wed, 14 Apr 2021 13:28:21 +0200
From:   Marco Elver <elver@...gle.com>
To:     elver@...gle.com, paulmck@...nel.org
Cc:     mark.rutland@....com, will@...nel.org, dvyukov@...gle.com,
        glider@...gle.com, boqun.feng@...il.com,
        kasan-dev@...glegroups.com, linux-kernel@...r.kernel.org
Subject: [PATCH 5/9] kcsan: Refactor access_info initialization

From: Mark Rutland <mark.rutland@....com>

In subsequent patches we'll want to split kcsan_report() into distinct
handlers for each report type. The largest bit of common work is
initializing the `access_info`, so let's factor this out into a helper,
and have the kcsan_report_*() functions pass the `aaccess_info` as a
parameter to kcsan_report().

There should be no functional change as a result of this patch.

Signed-off-by: Mark Rutland <mark.rutland@....com>
Signed-off-by: Marco Elver <elver@...gle.com>
---
 kernel/kcsan/report.c | 42 +++++++++++++++++++++++++-----------------
 1 file changed, 25 insertions(+), 17 deletions(-)

diff --git a/kernel/kcsan/report.c b/kernel/kcsan/report.c
index 8bfa970965a1..d8441bed065c 100644
--- a/kernel/kcsan/report.c
+++ b/kernel/kcsan/report.c
@@ -596,18 +596,10 @@ static noinline bool prepare_report(unsigned long *flags,
 	}
 }
 
-static void kcsan_report(const volatile void *ptr, size_t size, int access_type,
-			 enum kcsan_value_change value_change,
+static void kcsan_report(const struct access_info *ai, enum kcsan_value_change value_change,
 			 enum kcsan_report_type type, struct other_info *other_info)
 {
 	unsigned long flags = 0;
-	const struct access_info ai = {
-		.ptr		= ptr,
-		.size		= size,
-		.access_type	= access_type,
-		.task_pid	= in_task() ? task_pid_nr(current) : -1,
-		.cpu_id		= raw_smp_processor_id()
-	};
 
 	kcsan_disable_current();
 
@@ -620,14 +612,14 @@ static void kcsan_report(const volatile void *ptr, size_t size, int access_type,
 	 */
 	lockdep_off();
 
-	if (prepare_report(&flags, type, &ai, other_info)) {
+	if (prepare_report(&flags, type, ai, other_info)) {
 		/*
 		 * Never report if value_change is FALSE, only if we it is
 		 * either TRUE or MAYBE. In case of MAYBE, further filtering may
 		 * be done once we know the full stack trace in print_report().
 		 */
 		if (value_change != KCSAN_VALUE_CHANGE_FALSE)
-			print_report(value_change, type, &ai, other_info);
+			print_report(value_change, type, ai, other_info);
 
 		release_report(&flags, other_info);
 	}
@@ -636,22 +628,38 @@ static void kcsan_report(const volatile void *ptr, size_t size, int access_type,
 	kcsan_enable_current();
 }
 
+static struct access_info prepare_access_info(const volatile void *ptr, size_t size,
+					      int access_type)
+{
+	return (struct access_info) {
+		.ptr		= ptr,
+		.size		= size,
+		.access_type	= access_type,
+		.task_pid	= in_task() ? task_pid_nr(current) : -1,
+		.cpu_id		= raw_smp_processor_id()
+	};
+}
+
 void kcsan_report_set_info(const volatile void *ptr, size_t size, int access_type,
 			   int watchpoint_idx)
 {
-	kcsan_report(ptr, size, access_type, KCSAN_VALUE_CHANGE_MAYBE,
-		     KCSAN_REPORT_CONSUMED_WATCHPOINT, &other_infos[watchpoint_idx]);
+	const struct access_info ai = prepare_access_info(ptr, size, access_type);
+
+	kcsan_report(&ai, KCSAN_VALUE_CHANGE_MAYBE, KCSAN_REPORT_CONSUMED_WATCHPOINT,
+		     &other_infos[watchpoint_idx]);
 }
 
 void kcsan_report_known_origin(const volatile void *ptr, size_t size, int access_type,
 			       enum kcsan_value_change value_change, int watchpoint_idx)
 {
-	kcsan_report(ptr, size, access_type, value_change,
-		     KCSAN_REPORT_RACE_SIGNAL, &other_infos[watchpoint_idx]);
+	const struct access_info ai = prepare_access_info(ptr, size, access_type);
+
+	kcsan_report(&ai, value_change, KCSAN_REPORT_RACE_SIGNAL, &other_infos[watchpoint_idx]);
 }
 
 void kcsan_report_unknown_origin(const volatile void *ptr, size_t size, int access_type)
 {
-	kcsan_report(ptr, size, access_type, KCSAN_VALUE_CHANGE_TRUE,
-		     KCSAN_REPORT_RACE_UNKNOWN_ORIGIN, NULL);
+	const struct access_info ai = prepare_access_info(ptr, size, access_type);
+
+	kcsan_report(&ai, KCSAN_VALUE_CHANGE_TRUE, KCSAN_REPORT_RACE_UNKNOWN_ORIGIN, NULL);
 }
-- 
2.31.1.295.g9ea45b61b8-goog