selftests/futex: Fix futex_wait() for 32bit ARM

On 32bit ARM systems gcc-12 will use 32bit timestamps while gcc-13 and later
will use 64bit timestamps. The problem is that SYS_futex will continue
pointing at the 32bit system call. This makes the futex_wait test fail like
this:

waiter failed errno 110
not ok 1 futex_wake private returned: 0 Success
waiter failed errno 110
not ok 2 futex_wake shared (page anon) returned: 0 Success
waiter failed errno 110
not ok 3 futex_wake shared (file backed) returned: 0 Success

Instead of compiling differently depending on the gcc version, use the
-D_FILE_OFFSET_BITS=64 -D_TIME_BITS=64 options to ensure that 64bit timestamps
are used. Then use ifdefs to make SYS_futex point to the 64bit system call.

Signed-off-by: Dan Carpenter <[e-mail]>
Signed-off-by: Sebastian Andrzej Siewior <[e-mail]>
Signed-off-by: Borislav Petkov (AMD) <[e-mail]>
Reviewed-by: André Almeida <[e-mail]>
Tested-by: Anders Roxell <[e-mail]>
Link: https://lore.kernel.org/[e-mail]

tools/testing/selftests/futex/functional/Makefile

···
 # SPDX-License-Identifier: GPL-2.0
 INCLUDES := -I../include -I../../ $(KHDR_INCLUDES)
-CFLAGS := $(CFLAGS) -g -O2 -Wall -pthread $(INCLUDES) $(KHDR_INCLUDES)
+CFLAGS := $(CFLAGS) -g -O2 -Wall -pthread -D_FILE_OFFSET_BITS=64 -D_TIME_BITS=64 $(INCLUDES) $(KHDR_INCLUDES)
 LDLIBS := -lpthread -lrt -lnuma
 
 LOCAL_HDRS := \

tools/testing/selftests/futex/include/futextest.h

···
 #define SYS_futex SYS_futex_time64
 #endif
 
+/*
+ * On 32bit systems if we use "-D_FILE_OFFSET_BITS=64 -D_TIME_BITS=64" or if
+ * we are using a newer compiler then the size of the timestamps will be 64bit,
+ * however, the SYS_futex will still point to the 32bit futex system call.
+ */
+#if __SIZEOF_POINTER__ == 4 && defined(SYS_futex_time64) && \
+	defined(_TIME_BITS) && _TIME_BITS == 64
+# undef SYS_futex
+# define SYS_futex SYS_futex_time64
+#endif
+
 /**
  * futex() - SYS_futex syscall wrapper
  * @uaddr:	address of first futex