Re: [PATCH bpf-next 09/13] bpf: reuse subprog argument parsing logic for subprog call checks

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

Hi Andrii,

kernel test robot noticed the following build warnings:

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

url:    https://github.com/intel-lab-lkp/linux/commits/Andrii-Nakryiko/bpf-log-PTR_TO_MEM-memory-size-in-verifier-log/20231205-074451
base:   https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git master
patch link:    https://lore.kernel.org/r/20231204233931.49758-10-andrii%40kernel.org
patch subject: [PATCH bpf-next 09/13] bpf: reuse subprog argument parsing logic for subprog call checks
config: alpha-randconfig-r122-20231205 (https://download.01.org/0day-ci/archive/20231205/202312051916.zf1FwihO-lkp@intel.com/config)
compiler: alpha-linux-gcc (GCC) 13.2.0
reproduce: (https://download.01.org/0day-ci/archive/20231205/202312051916.zf1FwihO-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/202312051916.zf1FwihO-lkp@intel.com/

sparse warnings: (new ones prefixed by >>)
   kernel/bpf/verifier.c:5083:5: sparse: sparse: symbol 'check_ptr_off_reg' was not declared. Should it be static?
   kernel/bpf/verifier.c:7268:5: sparse: sparse: symbol 'check_mem_reg' was not declared. Should it be static?
   kernel/bpf/verifier.c:8254:5: sparse: sparse: symbol 'check_func_arg_reg_off' was not declared. Should it be static?
>> kernel/bpf/verifier.c:9291:5: sparse: sparse: symbol 'btf_check_subprog_call' was not declared. Should it be static?
   kernel/bpf/verifier.c:19733:38: sparse: sparse: subtraction of functions? Share your drugs
   kernel/bpf/verifier.c: note: in included file (through include/linux/bpf.h, include/linux/bpf-cgroup.h):
   include/linux/bpfptr.h:65:40: sparse: sparse: cast to non-scalar
   include/linux/bpfptr.h:65:40: sparse: sparse: cast from non-scalar
   include/linux/bpfptr.h:65:40: sparse: sparse: cast to non-scalar
   include/linux/bpfptr.h:65:40: sparse: sparse: cast from non-scalar
   include/linux/bpfptr.h:65:40: sparse: sparse: cast to non-scalar
   include/linux/bpfptr.h:65:40: sparse: sparse: cast from non-scalar
   include/linux/bpfptr.h:65:40: sparse: sparse: cast to non-scalar
   include/linux/bpfptr.h:65:40: sparse: sparse: cast from non-scalar

vim +/btf_check_subprog_call +9291 kernel/bpf/verifier.c

  9283	
  9284	/* Compare BTF of a function call with given bpf_reg_state.
  9285	 * Returns:
  9286	 * EFAULT - there is a verifier bug. Abort verification.
  9287	 * EINVAL - there is a type mismatch or BTF is not available.
  9288	 * 0 - BTF matches with what bpf_reg_state expects.
  9289	 * Only PTR_TO_CTX and SCALAR_VALUE states are recognized.
  9290	 */
> 9291	int btf_check_subprog_call(struct bpf_verifier_env *env, int subprog,
  9292				   struct bpf_reg_state *regs)
  9293	{
  9294		struct bpf_prog *prog = env->prog;
  9295		struct btf *btf = prog->aux->btf;
  9296		u32 btf_id;
  9297		int err;
  9298	
  9299		if (!prog->aux->func_info)
  9300			return -EINVAL;
  9301	
  9302		btf_id = prog->aux->func_info[subprog].type_id;
  9303		if (!btf_id)
  9304			return -EFAULT;
  9305	
  9306		if (prog->aux->func_info_aux[subprog].unreliable)
  9307			return -EINVAL;
  9308	
  9309		err = btf_check_func_arg_match(env, subprog, btf, btf_id, regs);
  9310		/* Compiler optimizations can remove arguments from static functions
  9311		 * or mismatched type can be passed into a global function.
  9312		 * In such cases mark the function as unreliable from BTF point of view.
  9313		 */
  9314		if (err)
  9315			prog->aux->func_info_aux[subprog].unreliable = true;
  9316		return err;
  9317	}
  9318	

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