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context_tracking: Use arch_atomic_read() in __ct_state for KASAN

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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>
This commit is contained in:
Paul E. McKenney 2022-06-16 09:30:37 -07:00
parent 08ab707dfc
commit 1dcaa3b462
1 changed files with 1 additions and 1 deletions
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include/linux/context_tracking_state.h
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@ -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