linux-kernel - [PATCH 5/5] kmsan: rework kmsan_in_runtime() handling in kmsan

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Message-ID: <20250507160012.3311104-5-glider@google.com>
Date: Wed,  7 May 2025 18:00:12 +0200
From: Alexander Potapenko <glider@...gle.com>
To: glider@...gle.com
Cc: elver@...gle.com, dvyukov@...gle.com, bvanassche@....org, 
	kent.overstreet@...ux.dev, iii@...ux.ibm.com, akpm@...ux-foundation.org, 
	linux-kernel@...r.kernel.org, kasan-dev@...glegroups.com
Subject: [PATCH 5/5] kmsan: rework kmsan_in_runtime() handling in kmsan_report()

kmsan_report() calls used to require entering/leaving the runtime around
them. To simplify the things, drop this requirement and move calls to
kmsan_enter_runtime()/kmsan_leave_runtime() into kmsan_report().

Cc: Marco Elver <elver@...gle.com>
Cc: Bart Van Assche <bvanassche@....org>
Cc: Kent Overstreet <kent.overstreet@...ux.dev>
Signed-off-by: Alexander Potapenko <glider@...gle.com>
---
 mm/kmsan/core.c            | 8 --------
 mm/kmsan/instrumentation.c | 4 ----
 mm/kmsan/report.c          | 6 +++---
 3 files changed, 3 insertions(+), 15 deletions(-)

diff --git a/mm/kmsan/core.c b/mm/kmsan/core.c
index a97dc90fa6a93..1ea711786c522 100644
--- a/mm/kmsan/core.c
+++ b/mm/kmsan/core.c
@@ -274,11 +274,9 @@ void kmsan_internal_check_memory(void *addr, size_t size,
 			 * bytes before, report them.
 			 */
 			if (cur_origin) {
-				kmsan_enter_runtime();
 				kmsan_report(cur_origin, addr, size,
 					     cur_off_start, pos - 1, user_addr,
 					     reason);
-				kmsan_leave_runtime();
 			}
 			cur_origin = 0;
 			cur_off_start = -1;
@@ -292,11 +290,9 @@ void kmsan_internal_check_memory(void *addr, size_t size,
 				 * poisoned bytes before, report them.
 				 */
 				if (cur_origin) {
-					kmsan_enter_runtime();
 					kmsan_report(cur_origin, addr, size,
 						     cur_off_start, pos + i - 1,
 						     user_addr, reason);
-					kmsan_leave_runtime();
 				}
 				cur_origin = 0;
 				cur_off_start = -1;
@@ -312,11 +308,9 @@ void kmsan_internal_check_memory(void *addr, size_t size,
 			 */
 			if (cur_origin != new_origin) {
 				if (cur_origin) {
-					kmsan_enter_runtime();
 					kmsan_report(cur_origin, addr, size,
 						     cur_off_start, pos + i - 1,
 						     user_addr, reason);
-					kmsan_leave_runtime();
 				}
 				cur_origin = new_origin;
 				cur_off_start = pos + i;
@@ -326,10 +320,8 @@ void kmsan_internal_check_memory(void *addr, size_t size,
 	}
 	KMSAN_WARN_ON(pos != size);
 	if (cur_origin) {
-		kmsan_enter_runtime();
 		kmsan_report(cur_origin, addr, size, cur_off_start, pos - 1,
 			     user_addr, reason);
-		kmsan_leave_runtime();
 	}
 }
 
diff --git a/mm/kmsan/instrumentation.c b/mm/kmsan/instrumentation.c
index 02a405e55d6ca..69f0a57a401c4 100644
--- a/mm/kmsan/instrumentation.c
+++ b/mm/kmsan/instrumentation.c
@@ -312,13 +312,9 @@ EXPORT_SYMBOL(__msan_unpoison_alloca);
 void __msan_warning(u32 origin);
 void __msan_warning(u32 origin)
 {
-	if (!kmsan_enabled || kmsan_in_runtime())
-		return;
-	kmsan_enter_runtime();
 	kmsan_report(origin, /*address*/ NULL, /*size*/ 0,
 		     /*off_first*/ 0, /*off_last*/ 0, /*user_addr*/ NULL,
 		     REASON_ANY);
-	kmsan_leave_runtime();
 }
 EXPORT_SYMBOL(__msan_warning);
 
diff --git a/mm/kmsan/report.c b/mm/kmsan/report.c
index 94a3303fb65e0..d6853ce089541 100644
--- a/mm/kmsan/report.c
+++ b/mm/kmsan/report.c
@@ -157,14 +157,14 @@ void kmsan_report(depot_stack_handle_t origin, void *address, int size,
 	unsigned long ua_flags;
 	bool is_uaf;
 
-	if (!kmsan_enabled)
+	if (!kmsan_enabled || kmsan_in_runtime())
 		return;
 	if (current->kmsan_ctx.depth)
 		return;
 	if (!origin)
 		return;
 
-	kmsan_disable_current();
+	kmsan_enter_runtime();
 	ua_flags = user_access_save();
 	raw_spin_lock(&kmsan_report_lock);
 	pr_err("=====================================================\n");
@@ -217,5 +217,5 @@ void kmsan_report(depot_stack_handle_t origin, void *address, int size,
 	if (panic_on_kmsan)
 		panic("kmsan.panic set ...\n");
 	user_access_restore(ua_flags);
-	kmsan_enable_current();
+	kmsan_leave_runtime();
 }
-- 
2.49.0.967.g6a0df3ecc3-goog