Messages in this thread Patch in this message | | | Date | Thu, 16 Jun 2022 13:05:48 -0700 | From | "Paul E. McKenney" <> | Subject | Re: [paulmck-rcu:pmladek.2022.06.15a] BUILD SUCCESS WITH WARNING 0ba7324b44282870af740a5a121add62c7f5f730 |
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On Fri, Jun 17, 2022 at 03:33:27AM +0800, kernel test robot wrote: > tree/branch: https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git pmladek.2022.06.15a > branch HEAD: 0ba7324b44282870af740a5a121add62c7f5f730 printk: Wait for the global console lock when the system is going down > > Warning reports: > > https://lore.kernel.org/lkml/202206160411.v3iL3YC0-lkp@intel.com > https://lore.kernel.org/llvm/202206160421.Gnl3tpxc-lkp@intel.com > > Warning: (recently discovered and may have been fixed) > > vmlinux.o: warning: objtool: __ct_user_enter+0x7f: call to __kasan_check_read() leaves .noinstr.text section > vmlinux.o: warning: objtool: __ct_user_exit+0x41: call to __kasan_check_read() leaves .noinstr.text section
Here is the alleged fix, and thank you for testing!
Thanx, Paul
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commit 571252796c089880b804835f6cfc9c3da3ae8c4f Author: Paul E. McKenney <paulmck@kernel.org> Date: Thu Jun 16 09:30:37 2022 -0700
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. 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>
diff --git a/include/linux/context_tracking_state.h b/include/linux/context_tracking_state.h index 0aecc07fb4f50..81c51e5f03143 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
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