From 1dcaa3b462265f688613163a1562a65ee53a3311 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Thu, 16 Jun 2022 09:30:37 -0700 Subject: [PATCH] context_tracking: Use arch_atomic_read() in __ct_state for KASAN Context tracking's __ct_state() function can be invoked from noinstr state where RCU is not watching. This means that its use of atomic_read() causes KASAN to invoke the non-noinstr __kasan_check_read() function from the noinstr function __ct_state(). This is problematic because someone tracing the __kasan_check_read() function could get a nasty surprise because of RCU not watching. This commit therefore replaces the __ct_state() function's use of atomic_read() with arch_atomic_read(), which KASAN does not attempt to add instrumention to. Reported-by: kernel test robot Signed-off-by: Paul E. McKenney Cc: Frederic Weisbecker Cc: Marco Elver Reviewed-by: Marco Elver --- include/linux/context_tracking_state.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/include/linux/context_tracking_state.h b/include/linux/context_tracking_state.h index e20a74bc05979..4a4d56f771802 100644 --- a/include/linux/context_tracking_state.h +++ b/include/linux/context_tracking_state.h @@ -49,7 +49,7 @@ DECLARE_PER_CPU(struct context_tracking, context_tracking); static __always_inline int __ct_state(void) { - return atomic_read(this_cpu_ptr(&context_tracking.state)) & CT_STATE_MASK; + return arch_atomic_read(this_cpu_ptr(&context_tracking.state)) & CT_STATE_MASK; } #endif -- 2.30.2