tools: Add atomic_test_and_set_bit()

Add x86 and generic implementations of atomic_test_and_set_bit() to allow
KVM selftests to atomically manage bitmaps.

Note, the generic version is taken from arch_test_and_set_bit() as of
commit 415d832497 ("locking/atomic: Make test_and_*_bit() ordered on
failure").

Signed-off-by: Peter Gonda <pgonda@google.com>
Co-developed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20221006003409.649993-5-seanjc@google.com

tools/include/asm-generic/atomic-gcc.h

@@ -4,6 +4,7 @@
 
 #include <linux/compiler.h>
 #include <linux/types.h>
+#include <linux/bitops.h>
 
 /*
  * Atomic operations that C can't guarantee us.  Useful for
@@ -69,4 +70,15 @@ static inline int atomic_cmpxchg(atomic_t *v, int oldval, int newval)
 	return cmpxchg(&(v)->counter, oldval, newval);
 }
 
+static inline int atomic_test_and_set_bit(long nr, unsigned long *addr)
+{
+	unsigned long mask = BIT_MASK(nr);
+	long old;
+
+	addr += BIT_WORD(nr);
+
+	old = __sync_fetch_and_or(addr, mask);
+	return !!(old & mask);
+}
+
 #endif /* __TOOLS_ASM_GENERIC_ATOMIC_H */