Re: [PATCH bpf-next v5] bpf: Support 64-bit pointers to kfuncs

[kernel test robot <lkp@intel.com>]

Hi Ilya,

kernel test robot noticed the following build errors:

[auto build test ERROR on bpf-next/master]

url:    https://github.com/intel-lab-lkp/linux/commits/Ilya-Leoshkevich/bpf-Support-64-bit-pointers-to-kfuncs/20230405-221738
base:   https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git master
patch link:    https://lore.kernel.org/r/20230405141407.172357-1-iii%40linux.ibm.com
patch subject: [PATCH bpf-next v5] bpf: Support 64-bit pointers to kfuncs
config: i386-randconfig-r022-20230403 (https://download.01.org/0day-ci/archive/20230406/202304060240.OeUgnjzZ-lkp@intel.com/config)
compiler: gcc-11 (Debian 11.3.0-8) 11.3.0
reproduce (this is a W=1 build):
        # https://github.com/intel-lab-lkp/linux/commit/43119fecff7ac0771f037a6dc128ceb791917466
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review Ilya-Leoshkevich/bpf-Support-64-bit-pointers-to-kfuncs/20230405-221738
        git checkout 43119fecff7ac0771f037a6dc128ceb791917466
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 O=build_dir ARCH=i386 olddefconfig
        make W=1 O=build_dir ARCH=i386 SHELL=/bin/bash kernel/

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>
| Link: https://lore.kernel.org/oe-kbuild-all/202304060240.OeUgnjzZ-lkp@intel.com/

All errors (new ones prefixed by >>):

   kernel/bpf/core.c: In function 'bpf_jit_get_func_addr':
>> kernel/bpf/core.c:1207:23: error: implicit declaration of function 'bpf_get_kfunc_addr'; did you mean 'bpf_jit_get_func_addr'? [-Werror=implicit-function-declaration]
    1207 |                 err = bpf_get_kfunc_addr(prog, insn->imm, insn->off, &addr);
         |                       ^~~~~~~~~~~~~~~~~~
         |                       bpf_jit_get_func_addr
   kernel/bpf/core.c: At top level:
   kernel/bpf/core.c:1638:12: warning: no previous prototype for 'bpf_probe_read_kernel' [-Wmissing-prototypes]
    1638 | u64 __weak bpf_probe_read_kernel(void *dst, u32 size, const void *unsafe_ptr)
         |            ^~~~~~~~~~~~~~~~~~~~~
   kernel/bpf/core.c:2075:6: warning: no previous prototype for 'bpf_patch_call_args' [-Wmissing-prototypes]
    2075 | void bpf_patch_call_args(struct bpf_insn *insn, u32 stack_depth)
         |      ^~~~~~~~~~~~~~~~~~~
   cc1: some warnings being treated as errors


vim +1207 kernel/bpf/core.c

  1182	
  1183	int bpf_jit_get_func_addr(const struct bpf_prog *prog,
  1184				  const struct bpf_insn *insn, bool extra_pass,
  1185				  u64 *func_addr, bool *func_addr_fixed)
  1186	{
  1187		s16 off = insn->off;
  1188		s32 imm = insn->imm;
  1189		u8 *addr;
  1190		int err;
  1191	
  1192		*func_addr_fixed = insn->src_reg != BPF_PSEUDO_CALL;
  1193		if (!*func_addr_fixed) {
  1194			/* Place-holder address till the last pass has collected
  1195			 * all addresses for JITed subprograms in which case we
  1196			 * can pick them up from prog->aux.
  1197			 */
  1198			if (!extra_pass)
  1199				addr = NULL;
  1200			else if (prog->aux->func &&
  1201				 off >= 0 && off < prog->aux->func_cnt)
  1202				addr = (u8 *)prog->aux->func[off]->bpf_func;
  1203			else
  1204				return -EINVAL;
  1205		} else if (insn->src_reg == BPF_PSEUDO_KFUNC_CALL &&
  1206			   bpf_jit_supports_far_kfunc_call()) {
> 1207			err = bpf_get_kfunc_addr(prog, insn->imm, insn->off, &addr);
  1208			if (err)
  1209				return err;
  1210		} else {
  1211			/* Address of a BPF helper call. Since part of the core
  1212			 * kernel, it's always at a fixed location. __bpf_call_base
  1213			 * and the helper with imm relative to it are both in core
  1214			 * kernel.
  1215			 */
  1216			addr = (u8 *)__bpf_call_base + imm;
  1217		}
  1218	
  1219		*func_addr = (unsigned long)addr;
  1220		return 0;
  1221	}
  1222	

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