microblaze: Snapshot thread flags

Some thread flags can be set remotely, and so even when IRQs are disabled,
the flags can change under our feet. Generally this is unlikely to cause a
problem in practice, but it is somewhat unsound, and KCSAN will
legitimately warn that there is a data race.

To avoid such issues, a snapshot of the flags has to be taken prior to
using them. Some places already use READ_ONCE() for that, others do not.

Convert them all to the new flag accessor helpers.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Michal Simek <michal.simek@xilinx.com>
Acked-by: Paul E. McKenney <paulmck@kernel.org>
Link: https://lore.kernel.org/r/20211129130653.2037928-8-mark.rutland@arm.com

Author: mrutland-arm

arch/microblaze/kernel/signal.c

@@ -283,7 +283,7 @@ static void do_signal(struct pt_regs *regs, int in_syscall)
 #ifdef DEBUG_SIG
 	pr_info("do signal: %p %d\n", regs, in_syscall);
 	pr_info("do signal2: %lx %lx %ld [%lx]\n", regs->pc, regs->r1,
-			regs->r12, current_thread_info()->flags);
+			regs->r12, read_thread_flags());
 #endif
 
 	if (get_signal(&ksig)) {