linux-kernel - kernel/time/clocksource-wdtest.c:47:22: warning: signed shift result (0x27BC86B00) requires 35 bits to represent, but 'long' only has 32 bits

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Message-ID: <202107040532.wqL30yFp-lkp@intel.com>
Date:   Sun, 4 Jul 2021 05:42:36 +0800
From:   kernel test robot <lkp@...el.com>
To:     "Paul E. McKenney" <paulmck@...nel.org>
Cc:     clang-built-linux@...glegroups.com, kbuild-all@...ts.01.org,
        linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>
Subject: kernel/time/clocksource-wdtest.c:47:22: warning: signed shift result
 (0x27BC86B00) requires 35 bits to represent, but 'long' only has 32 bits

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   303392fd5c160822bf778270b28ec5ea50cab2b4
commit: 1253b9b87e42ab6a3d5c2cb27af2bdd67d7e50ff clocksource: Provide kernel module to test clocksource watchdog
date:   11 days ago
config: mips-randconfig-r015-20210702 (attached as .config)
compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project 9eb613b2de3163686b1a4bd1160f15ac56a4b083)
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
        # install mips cross compiling tool for clang build
        # apt-get install binutils-mips-linux-gnu
        # https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=1253b9b87e42ab6a3d5c2cb27af2bdd67d7e50ff
        git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
        git fetch --no-tags linus master
        git checkout 1253b9b87e42ab6a3d5c2cb27af2bdd67d7e50ff
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=mips 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@...el.com>

All warnings (new ones prefixed by >>):

>> kernel/time/clocksource-wdtest.c:47:22: warning: signed shift result (0x27BC86B00) requires 35 bits to represent, but 'long' only has 32 bits [-Wshift-overflow]
           .mult                   = TICK_NSEC << JIFFIES_SHIFT, /* details above */
                                     ~~~~~~~~~ ^  ~~~~~~~~~~~~~
   1 warning generated.


vim +/long +47 kernel/time/clocksource-wdtest.c

    39	
    40	static struct clocksource clocksource_wdtest_jiffies = {
    41		.name			= "wdtest-jiffies",
    42		.rating			= 1, /* lowest valid rating*/
    43		.uncertainty_margin	= TICK_NSEC,
    44		.read			= wdtest_jiffies_read,
    45		.mask			= CLOCKSOURCE_MASK(32),
    46		.flags			= CLOCK_SOURCE_MUST_VERIFY,
  > 47		.mult			= TICK_NSEC << JIFFIES_SHIFT, /* details above */
    48		.shift			= JIFFIES_SHIFT,
    49		.max_cycles		= 10,
    50	};
    51	

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

Download attachment ".config.gz" of type "application/gzip" (28286 bytes)