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

On Thu, Sep 17, 2020 at 12:14 PM Hao Luo [off-list ref] wrote:

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

You can try just declaring it as __percpu in BPF_CALL_2 macro. That
might work, or not, depending on how exactly BPF_CALL macros are
implemented (I haven't checked).

On Wed, Sep 16, 2020 at 6:14 PM kernel test robot [off-list ref] wrote:

quoted

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 <redacted>


sparse warnings: (new ones prefixed by >>)

quoted

quoted

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@lists.01.org