Re: arch/arm/boot/compressed/fdt_check_mem_start.c:62:10: warning: no previous prototype for function 'fdt_check_mem_start'

From: Nick Desaulniers
Date: Wed Aug 25 2021 - 13:41:18 EST


On Sat, Aug 21, 2021 at 1:46 AM Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> wrote:
>
> Dear Robot,
>
> On Sat, Aug 14, 2021 at 7:43 AM kernel test robot <lkp@xxxxxxxxx> wrote:
> > FYI, the error/warning still remains.
>
> Yes, and that's fine, as this function is never called from C code,
> only from assembler.

That's fine, then you can add a prototype to the .c source file. See
what we do for stpcpy: 1e1b6d63d6340.

>
> > tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> > head: dfa377c35d70c31139b1274ec49f87d380996c42
> > commit: 0673cb38951215060d7993b43ad3c45cd413c2c3 ARM: 9045/1: uncompress: Validate start of physical memory against passed DTB
> > date: 6 months ago
> > config: arm-randconfig-r003-20210814 (attached as .config)
> > compiler: clang version 14.0.0 (https://github.com/llvm/llvm-project 62df4df41c939205b2dc0a2a3bfb75b8c1ed74fa)
> > 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=0673cb38951215060d7993b43ad3c45cd413c2c3
> > git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
> > git fetch --no-tags linus master
> > git checkout 0673cb38951215060d7993b43ad3c45cd413c2c3
> > # save the attached .config to linux build tree
> > COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=arm
> >
> > If you fix the issue, kindly add following tag as appropriate
> > Reported-by: kernel test robot <lkp@xxxxxxxxx>
> >
> > All warnings (new ones prefixed by >>):
> >
> > >> arch/arm/boot/compressed/fdt_check_mem_start.c:62:10: warning: no previous prototype for function 'fdt_check_mem_start' [-Wmissing-prototypes]
> > uint32_t fdt_check_mem_start(uint32_t mem_start, const void *fdt)
> > ^
> > arch/arm/boot/compressed/fdt_check_mem_start.c:62:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
> > uint32_t fdt_check_mem_start(uint32_t mem_start, const void *fdt)
> > ^
> > static
> > 1 warning generated.
> >
> >
> > vim +/fdt_check_mem_start +62 arch/arm/boot/compressed/fdt_check_mem_start.c
> >
> > 46
> > 47 /*
> > 48 * Check the start of physical memory
> > 49 *
> > 50 * Traditionally, the start address of physical memory is obtained by masking
> > 51 * the program counter. However, this does require that this address is a
> > 52 * multiple of 128 MiB, precluding booting Linux on platforms where this
> > 53 * requirement is not fulfilled.
> > 54 * Hence validate the calculated address against the memory information in the
> > 55 * DTB, and, if out-of-range, replace it by the real start address.
> > 56 * To preserve backwards compatibility (systems reserving a block of memory
> > 57 * at the start of physical memory, kdump, ...), the traditional method is
> > 58 * always used if it yields a valid address.
> > 59 *
> > 60 * Return value: start address of physical memory to use
> > 61 */
> > > 62 uint32_t fdt_check_mem_start(uint32_t mem_start, const void *fdt)
> >
> > ---
> > 0-DAY CI Kernel Test Service, Intel Corporation
> > https://lists.01.org/hyperkitty/list/kbuild-all@xxxxxxxxxxxx
>
>
>
> --
> Gr{oetje,eeting}s,
>
> Geert
>
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
>
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
> -- Linus Torvalds
>
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--
Thanks,
~Nick Desaulniers