Messages in this thread | | | From | Joel Fernandes <> | Date | Wed, 22 Jun 2022 18:58:26 -0400 | Subject | Re: [PATCH v2 1/1] context_tracking: Use arch_atomic_read() in __ct_state for KASAN |
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Apologies, I accidentally picked this specific commit up in my recent git format-patch which ended up sending it out. Totally unintended.
On Wed, Jun 22, 2022 at 6:51 PM Joel Fernandes (Google) <joel@joelfernandes.org> wrote: > > 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. > > 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 0aecc07fb4f5..81c51e5f0314 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 > > -- > 2.37.0.rc0.104.g0611611a94-goog >
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