linux-kernel - arch/x86/kernel/apm_32.c:428:43: sparse: sparse: cast truncates bits from constant value (c0000400 becomes 400)

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Message-ID: <202005102246.mLhqhR0Y%lkp@intel.com>
Date:   Sun, 10 May 2020 22:03:54 +0800
From:   kbuild test robot <lkp@...el.com>
To:     Jesse Brandeburg <jesse.brandeburg@...el.com>
Cc:     kbuild-all@...ts.01.org, linux-kernel@...r.kernel.org,
        Borislav Petkov <bp@...e.de>,
        Andy Shevchenko <andriy.shevchenko@...el.com>
Subject: arch/x86/kernel/apm_32.c:428:43: sparse: sparse: cast truncates bits
 from constant value (c0000400 becomes 400)

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   e99332e7b4cda6e60f5b5916cf9943a79dbef902
commit: 1651e700664b4597ddf4f8adfe435252a0d11277 x86: Fix bitops.h warning with a moved cast
date:   8 weeks ago
reproduce:
        # apt-get install sparse
        # sparse version: v0.6.1-191-gc51a0382-dirty
        git checkout 1651e700664b4597ddf4f8adfe435252a0d11277
        make ARCH=x86_64 allmodconfig
        make C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__'

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


sparse warnings: (new ones prefixed by >>)

>> arch/x86/kernel/apm_32.c:428:43: sparse: sparse: cast truncates bits from constant value (c0000400 becomes 400)

vim +428 arch/x86/kernel/apm_32.c

c7425314c755d5 arch/x86/kernel/apm_32.c Akinobu Mita   2009-08-09  421  
c7425314c755d5 arch/x86/kernel/apm_32.c Akinobu Mita   2009-08-09  422  /*
c7425314c755d5 arch/x86/kernel/apm_32.c Akinobu Mita   2009-08-09  423   * Set up a segment that references the real mode segment 0x40
c7425314c755d5 arch/x86/kernel/apm_32.c Akinobu Mita   2009-08-09  424   * that extends up to the end of page zero (that we have reserved).
c7425314c755d5 arch/x86/kernel/apm_32.c Akinobu Mita   2009-08-09  425   * This is for buggy BIOS's that refer to (real mode) segment 0x40
c7425314c755d5 arch/x86/kernel/apm_32.c Akinobu Mita   2009-08-09  426   * even though they are called in protected mode.
c7425314c755d5 arch/x86/kernel/apm_32.c Akinobu Mita   2009-08-09  427   */
c7425314c755d5 arch/x86/kernel/apm_32.c Akinobu Mita   2009-08-09 @428  static struct desc_struct bad_bios_desc = GDT_ENTRY_INIT(0x4092,
c7425314c755d5 arch/x86/kernel/apm_32.c Akinobu Mita   2009-08-09  429  			(unsigned long)__va(0x400UL), PAGE_SIZE - 0x400 - 1);
^1da177e4c3f41 arch/i386/kernel/apm.c   Linus Torvalds 2005-04-16  430  

:::::: The code at line 428 was first introduced by commit
:::::: c7425314c755d5f94da7c978205c85a7c6201212 x86: Introduce GDT_ENTRY_INIT(), initialize bad_bios_desc statically

:::::: TO: Akinobu Mita <akinobu.mita@...il.com>
:::::: CC: Ingo Molnar <mingo@...e.hu>

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