Re: [akpm-mm:mm-nonmm-unstable 77/129] arch/loongarch/net/bpf_jit.c:1322:7: error: call to undeclared function '__bpf_address_lookup'; ISO C99 and later do not support implicit function declarations

[Petr Mladek <pmladek@suse.com>]

On Tue 2026-01-13 09:48:01, Andrew Morton wrote:
> On Wed, 14 Jan 2026 01:37:38 +0800 kernel test robot <lkp@intel.com> wrote:
> 
> > tree:   https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-nonmm-unstable
> > head:   01c8de771f4a779caac5d841b1cb2207ac23330a
> > commit: 0f1766dc93f077061bf42cc6222bb2ade96422a4 [77/129] kallsyms/bpf: rename __bpf_address_lookup() to bpf_address_lookup()
> > config: loongarch-allmodconfig (https://download.01.org/0day-ci/archive/20260114/202601140159.I4b0kwpE-lkp@intel.com/config)
> > compiler: clang version 19.1.7 (https://github.com/llvm/llvm-project cd708029e0b2869e80abe31ddb175f7c35361f90)
> > reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260114/202601140159.I4b0kwpE-lkp@intel.com/reproduce)
> > 
> > If you fix the issue in a separate patch/commit (i.e. not just a new version of
> > the same patch/commit), kindly add following tags
> > | Reported-by: kernel test robot <lkp@intel.com>
> > | Closes: https://lore.kernel.org/oe-kbuild-all/202601140159.I4b0kwpE-lkp@intel.com/
> > 
> > All errors (new ones prefixed by >>):
> > 
> > >> arch/loongarch/net/bpf_jit.c:1322:7: error: call to undeclared function '__bpf_address_lookup'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
> >     1322 |         if (!__bpf_address_lookup((unsigned long)ip, &size, &offset, namebuf))
> >          |              ^
> >    arch/loongarch/net/bpf_jit.c:1322:7: note: did you mean 'bpf_address_lookup'?
> >    include/linux/filter.h:1378:5: note: 'bpf_address_lookup' declared here
> >     1378 | int bpf_address_lookup(unsigned long addr, unsigned long *size,
> >          |     ^
> >    1 error generated.
> 
> Thanks.  Presumably this:
> 
> --- a/arch/loongarch/net/bpf_jit.c~kallsyms-bpf-rename-__bpf_address_lookup-to-bpf_address_lookup-fix
> +++ a/arch/loongarch/net/bpf_jit.c
> @@ -1319,7 +1319,7 @@ int bpf_arch_text_poke(void *ip, enum bp
>  	/* Only poking bpf text is supported. Since kernel function entry
>  	 * is set up by ftrace, we rely on ftrace to poke kernel functions.
>  	 */
> -	if (!__bpf_address_lookup((unsigned long)ip, &size, &offset, namebuf))
> +	if (!bpf_address_lookup((unsigned long)ip, &size, &offset, namebuf))
>  		return -ENOTSUPP;
>  
>  	image = ip - offset;
> _

Yes, this is correct.

JFYI, the "problematic" code has been added into arch/loongarch/net/bpf_jit.c
just a two weeks ago by the commit 73721d8676771c6c ("LoongArch: BPF: Enhance
the bpf_arch_text_poke() function").

The good thing is that it is already in the mainline. It has been
added in 6.19-rc4, see
https://lore.kernel.org/all/CAHk-=wjO7Jq1dR7rdDA2wY=jwg4TTq-C6PjJz0=N=1dSO=3NTg@mail.gmail.com/

I see that you have already pushed a fix into -mm tree.
Thanks a lot for fixing it.

Best Regards,
Petr