Re: decompress.c:(.text.FSE_buildDTable_internal+0x2cc): undefined reference to `__clzdi2'

[Nick Terrell <terrelln@fb.com>]

> On Jan 5, 2022, at 11:02 AM, kernel test robot <lkp@intel.com> wrote:
> 
> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> head:   c9e6606c7fe92b50a02ce51dda82586ebdf99b48
> commit: e0c1b49f5b674cca7b10549c53b3791d0bbc90a8 lib: zstd: Upgrade to latest upstream zstd version 1.4.10
> date:   8 weeks ago
> config: mips-randconfig-r025-20220105 (https://download.01.org/0day-ci/archive/20220106/202201060233.mO6P39bM-lkp@intel.com/config )
> compiler: mips64el-linux-gcc (GCC) 11.2.0
> 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
>        # https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=e0c1b49f5b674cca7b10549c53b3791d0bbc90a8
>        git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
>        git fetch --no-tags linus master
>        git checkout e0c1b49f5b674cca7b10549c53b3791d0bbc90a8
>        # save the config file to linux build tree
>        mkdir build_dir
>        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.2.0 make.cross O=build_dir ARCH=mips SHELL=/bin/bash
> 
> If you fix the issue, kindly add following tag as appropriate
> Reported-by: kernel test robot <lkp@intel.com>
> 
> All errors (new ones prefixed by >>):
> 
>   mips64el-linux-ld: arch/mips/boot/compressed/decompress.o: in function `FSE_buildDTable_internal':
>>> decompress.c:(.text.FSE_buildDTable_internal+0x2cc): undefined reference to `__clzdi2'
>   mips64el-linux-ld: arch/mips/boot/compressed/decompress.o: in function `BIT_initDStream':
>   decompress.c:(.text.BIT_initDStream+0x7c): undefined reference to `__clzdi2'
>   mips64el-linux-ld: decompress.c:(.text.BIT_initDStream+0x158): undefined reference to `__clzdi2'
>   mips64el-linux-ld: arch/mips/boot/compressed/decompress.o: in function `ZSTD_buildFSETable_body_default.constprop.0':
>>> decompress.c:(.text.ZSTD_buildFSETable_body_default.constprop.0+0x2a8): undefined reference to `__clzdi2'
>   mips64el-linux-ld: arch/mips/boot/compressed/decompress.o: in function `FSE_readNCount_body_default':
>>> decompress.c:(.text.FSE_readNCount_body_default+0x130): undefined reference to `__ctzdi2'
>>> mips64el-linux-ld: decompress.c:(.text.FSE_readNCount_body_default+0x1a4): undefined reference to `__ctzdi2'
>>> mips64el-linux-ld: decompress.c:(.text.FSE_readNCount_body_default+0x2e4): undefined reference to `__clzdi2'
>   mips64el-linux-ld: arch/mips/boot/compressed/decompress.o: in function `HUF_readStats_body_default':
>>> decompress.c:(.text.HUF_readStats_body_default+0x184): undefined reference to `__clzdi2'
>>> mips64el-linux-ld: decompress.c:(.text.HUF_readStats_body_default+0x1b4): undefined reference to `__clzdi2'
>   mips64el-linux-ld: arch/mips/boot/compressed/decompress.o: in function `ZSTD_DCtx_getParameter':
>>> decompress.c:(.text.ZSTD_DCtx_getParameter+0x60): undefined reference to `__clzdi2'

These are complaining about usage of __builtin_c{l,t}z(). The code before this change also used
__builtin_clz(), so this isn't new. E.g. the call in BIT_initDStream() is present before the change,
it just moved locations. So these errors aren't new.

This is breaking the MIPS boot code when zstd compressed kernels are enabled, and was
Introduced in commit a510b61613 [0][1]. The fix is to include the definitions from `lib/clz_ctz.c` [2].
The same problem was fixed for s390 in this patch [3].

CC: Paul Cercueil

Best,
Nick Terrell

[0] https://lore.kernel.org/lkml/20200901142651.1165237-3-paul@crapouillou.net/
[1] https://github.com/torvalds/linux/commit/a510b616131f85215ba156ed67e5ed1c0701f80f
[2] https://github.com/torvalds/linux/blob/master/lib/clz_ctz.c
[3] https://lore.kernel.org/all/patch-1.thread-f0f589.git-f0f58936888f.your-ad-here.call-01627564869-ext-2765@work.hours/

> ---
> 0-DAY CI Kernel Test Service, Intel Corporation
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