[PATCH AUTOSEL 6.2 04/21] context_tracking: Fix noinstr vs KASAN

[Sasha Levin]

From: Peter Zijlstra <peterz@xxxxxxxxxxxxx>

[ Upstream commit 0e26e1de0032779e43929174339429c16307a299 ]

Low level noinstr context-tracking code is calling out to instrumented
code on KASAN:

  vmlinux.o: warning: objtool: __ct_user_enter+0x72: call to __kasan_check_write() leaves .noinstr.text section
  vmlinux.o: warning: objtool: __ct_user_exit+0x47: call to __kasan_check_write() leaves .noinstr.text section

Use even lower level atomic methods to avoid the instrumentation.

Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20230112195542.458034262@xxxxxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 kernel/context_tracking.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c
index 77978e3723771..a09f1c19336ae 100644
--- a/kernel/context_tracking.c
+++ b/kernel/context_tracking.c
@@ -510,7 +510,7 @@ void noinstr __ct_user_enter(enum ctx_state state)
 			 * In this we case we don't care about any concurrency/ordering.
 			 */
 			if (!IS_ENABLED(CONFIG_CONTEXT_TRACKING_IDLE))
-				atomic_set(&ct->state, state);
+				arch_atomic_set(&ct->state, state);
 		} else {
 			/*
 			 * Even if context tracking is disabled on this CPU, because it's outside
@@ -527,7 +527,7 @@ void noinstr __ct_user_enter(enum ctx_state state)
 			 */
 			if (!IS_ENABLED(CONFIG_CONTEXT_TRACKING_IDLE)) {
 				/* Tracking for vtime only, no concurrent RCU EQS accounting */
-				atomic_set(&ct->state, state);
+				arch_atomic_set(&ct->state, state);
 			} else {
 				/*
 				 * Tracking for vtime and RCU EQS. Make sure we don't race
@@ -535,7 +535,7 @@ void noinstr __ct_user_enter(enum ctx_state state)
 				 * RCU only requires RCU_DYNTICKS_IDX increments to be fully
 				 * ordered.
 				 */
-				atomic_add(state, &ct->state);
+				arch_atomic_add(state, &ct->state);
 			}
 		}
 	}
@@ -630,12 +630,12 @@ void noinstr __ct_user_exit(enum ctx_state state)
 			 * In this we case we don't care about any concurrency/ordering.
 			 */
 			if (!IS_ENABLED(CONFIG_CONTEXT_TRACKING_IDLE))
-				atomic_set(&ct->state, CONTEXT_KERNEL);
+				arch_atomic_set(&ct->state, CONTEXT_KERNEL);
 
 		} else {
 			if (!IS_ENABLED(CONFIG_CONTEXT_TRACKING_IDLE)) {
 				/* Tracking for vtime only, no concurrent RCU EQS accounting */
-				atomic_set(&ct->state, CONTEXT_KERNEL);
+				arch_atomic_set(&ct->state, CONTEXT_KERNEL);
 			} else {
 				/*
 				 * Tracking for vtime and RCU EQS. Make sure we don't race
@@ -643,7 +643,7 @@ void noinstr __ct_user_exit(enum ctx_state state)
 				 * RCU only requires RCU_DYNTICKS_IDX increments to be fully
 				 * ordered.
 				 */
-				atomic_sub(state, &ct->state);
+				arch_atomic_sub(state, &ct->state);
 			}
 		}
 	}
-- 
2.39.0