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 <202006160420.iatdr9ab%lkp@intel.com>
In-Reply-To: <202006160420.iatdr9ab%lkp@intel.com>
From:   Syed Nayyar Waris <syednwaris@gmail.com>
Date:   Fri, 19 Jun 2020 12:30:35 +0530
Message-ID: <CACG_h5qUZsR7Zd9a+BQJqyuJZBrv-en+gC-sgcV+xV+A5ZOBhA@mail.gmail.com>
Subject: Re: [PATCH v8 4/4] gpio: xilinx: Utilize for_each_set_clump macro
To:     kernel test robot <lkp@intel.com>
Cc:     Linus Walleij <linus.walleij@linaro.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        kbuild-all@lists.01.org,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        William Breathitt Gray <vilhelm.gray@gmail.com>,
        Bartosz Golaszewski <bgolaszewski@baylibre.com>,
        Michal Simek <michal.simek@xilinx.com>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
        linux-arm Mailing List <linux-arm-kernel@lists.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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>
> Hi Syed,
>
> Thank you for the patch! Perhaps something to improve:
>
> [auto build test WARNING on 444fc5cde64330661bf59944c43844e7d4c2ccd8]
>
> url:    https://github.com/0day-ci/linux/commits/Syed-Nayyar-Waris/Introduce-the-for_each_set_clump-macro/20200615-205729
> base:    444fc5cde64330661bf59944c43844e7d4c2ccd8
> config: sparc64-randconfig-s032-20200615 (attached as .config)
> compiler: sparc64-linux-gcc (GCC) 9.3.0
> reproduce:
>         # apt-get install sparse
>         # sparse version: v0.6.2-rc1-3-g55607964-dirty
>         # save the attached .config to linux build tree
>         make W=1 C=1 ARCH=sparc64 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__'
>

>
>
> sparse warnings: (new ones prefixed by >>)
>
> >> include/linux/bitmap.h:639:45: sparse: sparse: shift too big (64) for type unsigned long
> >> include/linux/bitmap.h:639:45: sparse: sparse: shift too big (64) for type unsigned long
>    include/linux/bitmap.h:594:63: sparse: sparse: shift too big (64) for type unsigned long
> >> include/linux/bitmap.h:639:45: sparse: sparse: shift too big (64) for type unsigned long
> >> include/linux/bitmap.h:638:17: sparse: sparse: invalid access past the end of 'old' (8 8)
>

Hi All,

It seems to me that to reproduce this warning, I have to use the
sparc64 compiler. I have installed 'sparc64-linux-gnu-gcc' on my
computer.
I have to specify that this compiler needs to be used for build
process. How/ Where do I specify this?

I have downloaded the config.gz (has config file) and placed it at the
root of the linux kernel project tree. But the Makefile STILL has
'gcc' as the compiler. When I build, it is the 'gcc' compiler being
used and not 'sparc64-linux-gnu-gcc'. I know I can manually change the
Makefile to use sparc64 compiler, but I think there must be some more
elegant way to do this, perhaps using make menuconfig?

Kindly illuminate as to how shall I reproduce the compiler warning.

Regards
Syed Nayyar Waris

> vim +639 include/linux/bitmap.h
>
> 169c474fb22d8a William Breathitt Gray 2019-12-04  613
> 803024b6c8a375 Syed Nayyar Waris      2020-06-15  614  /**
> 803024b6c8a375 Syed Nayyar Waris      2020-06-15  615   * bitmap_set_value - set n-bit value within a memory region
> 803024b6c8a375 Syed Nayyar Waris      2020-06-15  616   * @map: address to the bitmap memory region
> 803024b6c8a375 Syed Nayyar Waris      2020-06-15  617   * @value: value of nbits
> 803024b6c8a375 Syed Nayyar Waris      2020-06-15  618   * @start: bit offset of the n-bit value
> 803024b6c8a375 Syed Nayyar Waris      2020-06-15  619   * @nbits: size of value in bits
> 803024b6c8a375 Syed Nayyar Waris      2020-06-15  620   */
> 803024b6c8a375 Syed Nayyar Waris      2020-06-15  621  static inline void bitmap_set_value(unsigned long *map,
> 803024b6c8a375 Syed Nayyar Waris      2020-06-15  622                               unsigned long value,
> 803024b6c8a375 Syed Nayyar Waris      2020-06-15  623                               unsigned long start, unsigned long nbits)
> 803024b6c8a375 Syed Nayyar Waris      2020-06-15  624  {
> 803024b6c8a375 Syed Nayyar Waris      2020-06-15  625   const size_t index = BIT_WORD(start);
> 803024b6c8a375 Syed Nayyar Waris      2020-06-15  626   const unsigned long offset = start % BITS_PER_LONG;
> 803024b6c8a375 Syed Nayyar Waris      2020-06-15  627   const unsigned long ceiling = roundup(start + 1, BITS_PER_LONG);
> 803024b6c8a375 Syed Nayyar Waris      2020-06-15  628   const unsigned long space = ceiling - start;
> 803024b6c8a375 Syed Nayyar Waris      2020-06-15  629
> 803024b6c8a375 Syed Nayyar Waris      2020-06-15  630   value &= GENMASK(nbits - 1, 0);
> 803024b6c8a375 Syed Nayyar Waris      2020-06-15  631
> 803024b6c8a375 Syed Nayyar Waris      2020-06-15  632   if (space >= nbits) {
> 803024b6c8a375 Syed Nayyar Waris      2020-06-15  633           map[index] &= ~(GENMASK(nbits + offset - 1, offset));
> 803024b6c8a375 Syed Nayyar Waris      2020-06-15  634           map[index] |= value << offset;
> 803024b6c8a375 Syed Nayyar Waris      2020-06-15  635   } else {
> 803024b6c8a375 Syed Nayyar Waris      2020-06-15  636           map[index] &= ~BITMAP_FIRST_WORD_MASK(start);
> 803024b6c8a375 Syed Nayyar Waris      2020-06-15  637           map[index] |= value << offset;
> 803024b6c8a375 Syed Nayyar Waris      2020-06-15 @638           map[index + 1] &= ~BITMAP_LAST_WORD_MASK(start + nbits);
> 803024b6c8a375 Syed Nayyar Waris      2020-06-15 @639           map[index + 1] |= (value >> space);
> 803024b6c8a375 Syed Nayyar Waris      2020-06-15  640   }
> 803024b6c8a375 Syed Nayyar Waris      2020-06-15  641  }
> 803024b6c8a375 Syed Nayyar Waris      2020-06-15  642
>
> :::::: The code at line 639 was first introduced by commit
> :::::: 803024b6c8a375ba9e9e9467595d7d52d4f6a38e bitops: Introduce the for_each_set_clump macro
>
> :::::: TO: Syed Nayyar Waris <syednwaris@gmail.com>