[rcu:dev.2020.05.26b 56/70] kernel/rcu/refperf.c:389: undefined reference to `__umoddi3'

[kbuild test robot]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git dev.2020.05.26b
head:   795279db1396bf66621fa3f343fa990fe543b89e
commit: 756c011f78747dc49a1e79a521fd77093849586b [56/70] refperf: Allow decimal nanoseconds
config: m68k-randconfig-r024-20200601 (attached as .config)
compiler: m68k-linux-gcc (GCC) 9.3.0
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        git checkout 756c011f78747dc49a1e79a521fd77093849586b
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=m68k 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kbuild test robot <lkp@xxxxxxxxx>

All errors (new ones prefixed by >>, old ones prefixed by <<):

m68k-linux-ld: kernel/rcu/refperf.o: in function `main_func':
>> kernel/rcu/refperf.c:389: undefined reference to `__umoddi3'
>> m68k-linux-ld: kernel/rcu/refperf.c:378: undefined reference to `__udivdi3'
m68k-linux-ld: kernel/rcu/refperf.c:389: undefined reference to `__udivdi3'

vim +389 kernel/rcu/refperf.c

   328	
   329	// The main_func is the main orchestrator, it performs a bunch of
   330	// experiments.  For every experiment, it orders all the readers
   331	// involved to start and waits for them to finish the experiment. It
   332	// then reads their timestamps and starts the next experiment. Each
   333	// experiment progresses from 1 concurrent reader to N of them at which
   334	// point all the timestamps are printed.
   335	static int main_func(void *arg)
   336	{
   337		int exp, r;
   338		char buf1[64];
   339		char buf[512];
   340	
   341		set_cpus_allowed_ptr(current, cpumask_of(nreaders % nr_cpu_ids));
   342		set_user_nice(current, MAX_NICE);
   343	
   344		if (holdoff)
   345			schedule_timeout_interruptible(holdoff * HZ);
   346		VERBOSE_PERFOUT("main_func task started");
   347		atomic_inc(&n_init);
   348	
   349		// Wait for all threads to start.
   350		wait_event(main_wq, atomic_read(&n_init) == (nreaders + 1));
   351	
   352		// Start exp readers up per experiment
   353		for (exp = 0; exp < nreaders && !torture_must_stop(); exp++) {
   354			if (torture_must_stop())
   355				goto end;
   356	
   357			reset_readers(exp);
   358			atomic_set(&nreaders_exp, exp + 1);
   359	
   360			exp_idx = exp;
   361	
   362			for (r = 0; r <= exp; r++) {
   363				atomic_set(&reader_tasks[r].start, 1);
   364				wake_up(&reader_tasks[r].wq);
   365			}
   366	
   367			VERBOSE_PERFOUT("main_func: experiment started, waiting for %d readers",
   368					exp);
   369	
   370			wait_event(main_wq,
   371				   !atomic_read(&nreaders_exp) || torture_must_stop());
   372	
   373			VERBOSE_PERFOUT("main_func: experiment ended");
   374	
   375			if (torture_must_stop())
   376				goto end;
   377	
 > 378			reader_tasks[exp].result_avg = 1000 * process_durations(exp) / ((exp + 1) * loops);
   379		}
   380	
   381		// Print the average of all experiments
   382		PERFOUT("END OF TEST. Calculating average duration per loop (nanoseconds)...\n");
   383	
   384		buf[0] = 0;
   385		strcat(buf, "\n");
   386		strcat(buf, "Threads\tTime(ns)\n");
   387	
   388		for (exp = 0; exp < nreaders; exp++) {
 > 389			sprintf(buf1, "%d\t%llu.%03d\n", exp + 1, reader_tasks[exp].result_avg / 1000, (int)(reader_tasks[exp].result_avg % 1000));
   390			strcat(buf, buf1);
   391		}
   392	
   393		PERFOUT("%s", buf);
   394	
   395		// This will shutdown everything including us.
   396		if (shutdown) {
   397			shutdown_start = 1;
   398			wake_up(&shutdown_wq);
   399		}
   400	
   401		// Wait for torture to stop us
   402		while (!torture_must_stop())
   403			schedule_timeout_uninterruptible(1);
   404	
   405	end:
   406		torture_kthread_stopping("main_func");
   407		return 0;
   408	}
   409	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@xxxxxxxxxxxx

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