Messages in this thread Patch in this message | | | From | Frederic Weisbecker <> | Subject | [PATCH 20/20] context_tracking: Use arch_atomic_read() in __ct_state for KASAN | Date | Tue, 28 Jun 2022 15:16:19 +0200 |
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From: "Paul E. McKenney" <paulmck@kernel.org>
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 <lkp@intel.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Cc: Frederic Weisbecker <frederic@kernel.org> Cc: Marco Elver <elver@google.com> Reviewed-by: Marco Elver <elver@google.com> --- 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 e20a74bc0597..4a4d56f77180 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 -- 2.25.1
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