[PATCH AUTOSEL 6.1 04/21] context_tracking: Fix noinstr vs KASAN

Sasha Levin
2023-02-26T03:43:41Z

From: Peter Zijlstra <peterz@infradead.org>

[ 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@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20230112195542.458034262@infradead.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
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