Re: [PATCH bpf-next v3 4/6] bpf: Introduce bpf_per_cpu_ptr()

From: Hao Luo
Date: Thu Sep 17 2020 - 15:13:48 EST


I need to cast the pointer to "const void __percpu *" before passing
into per_cpu_ptr. I will update and resend.

On Wed, Sep 16, 2020 at 6:14 PM kernel test robot <lkp@xxxxxxxxx> wrote:
>
> Hi Hao,
>
> Thank you for the patch! Perhaps something to improve:
>
> [auto build test WARNING on bpf-next/master]
>
> url: https://github.com/0day-ci/linux/commits/Hao-Luo/bpf-BTF-support-for-ksyms/20200917-064052
> base: https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git master
> config: powerpc-randconfig-s032-20200916 (attached as .config)
> compiler: powerpc64-linux-gcc (GCC) 9.3.0
> reproduce:
> wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
> chmod +x ~/bin/make.cross
> # apt-get install sparse
> # sparse version: v0.6.2-201-g24bdaac6-dirty
> # save the attached .config to linux build tree
> COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' ARCH=powerpc
>
> If you fix the issue, kindly add following tag as appropriate
> Reported-by: kernel test robot <lkp@xxxxxxxxx>
>
>
> sparse warnings: (new ones prefixed by >>)
>
> >> kernel/bpf/helpers.c:631:31: sparse: sparse: incorrect type in initializer (different address spaces) @@ expected void const [noderef] __percpu *__vpp_verify @@ got void const * @@
> >> kernel/bpf/helpers.c:631:31: sparse: expected void const [noderef] __percpu *__vpp_verify
> >> kernel/bpf/helpers.c:631:31: sparse: got void const *
>
> # https://github.com/0day-ci/linux/commit/3f6ea3c1c73efe466a96ff7499219fe3b03b8f48
> git remote add linux-review https://github.com/0day-ci/linux
> git fetch --no-tags linux-review Hao-Luo/bpf-BTF-support-for-ksyms/20200917-064052
> git checkout 3f6ea3c1c73efe466a96ff7499219fe3b03b8f48
> vim +631 kernel/bpf/helpers.c
>
> 625
> 626 BPF_CALL_2(bpf_per_cpu_ptr, const void *, ptr, u32, cpu)
> 627 {
> 628 if (cpu >= nr_cpu_ids)
> 629 return (unsigned long)NULL;
> 630
> > 631 return (unsigned long)per_cpu_ptr(ptr, cpu);
> 632 }
> 633
> 634 const struct bpf_func_proto bpf_per_cpu_ptr_proto = {
> 635 .func = bpf_per_cpu_ptr,
> 636 .gpl_only = false,
> 637 .ret_type = RET_PTR_TO_MEM_OR_BTF_ID_OR_NULL,
> 638 .arg1_type = ARG_PTR_TO_PERCPU_BTF_ID,
> 639 .arg2_type = ARG_ANYTHING,
> 640 };
> 641
> > 642 const struct bpf_func_proto bpf_get_current_task_proto __weak;
> 643 const struct bpf_func_proto bpf_probe_read_user_proto __weak;
> 644 const struct bpf_func_proto bpf_probe_read_user_str_proto __weak;
> 645 const struct bpf_func_proto bpf_probe_read_kernel_proto __weak;
> 646 const struct bpf_func_proto bpf_probe_read_kernel_str_proto __weak;
> 647
>
> ---
> 0-DAY CI Kernel Test Service, Intel Corporation
> https://lists.01.org/hyperkitty/list/kbuild-all@xxxxxxxxxxxx