Re: [PATCH bpf-next v2 3/5] bpf: support bpf_fastcall patterns for kfuncs

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

Hi Eduard,

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/Eduard-Zingerman/bpf-rename-nocsr-bpf_fastcall-in-verifier/20240817-095340
base:   https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git master
patch link:    https://lore.kernel.org/r/20240817015140.1039351-4-eddyz87%40gmail.com
patch subject: [PATCH bpf-next v2 3/5] bpf: support bpf_fastcall patterns for kfuncs
config: arc-randconfig-002-20240817 (https://download.01.org/0day-ci/archive/20240818/202408180356.YZnBVEv3-lkp@intel.com/config)
compiler: arceb-elf-gcc (GCC) 13.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240818/202408180356.YZnBVEv3-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/202408180356.YZnBVEv3-lkp@intel.com/

All warnings (new ones prefixed by >>):

   kernel/bpf/verifier.c: In function 'kfunc_fastcall_clobber_mask':
>> kernel/bpf/verifier.c:16146:33: warning: variable 'params' set but not used [-Wunused-but-set-variable]
   16146 |         const struct btf_param *params;
         |                                 ^~~~~~


vim +/params +16146 kernel/bpf/verifier.c

 16142	
 16143	/* Same as helper_fastcall_clobber_mask() but for kfuncs, see comment above */
 16144	static u32 kfunc_fastcall_clobber_mask(struct bpf_kfunc_call_arg_meta *meta)
 16145	{
 16146		const struct btf_param *params;
 16147		u32 vlen, i, mask;
 16148	
 16149		params = btf_params(meta->func_proto);
 16150		vlen = btf_type_vlen(meta->func_proto);
 16151		mask = 0;
 16152		if (!btf_type_is_void(btf_type_by_id(meta->btf, meta->func_proto->type)))
 16153			mask |= BIT(BPF_REG_0);
 16154		for (i = 0; i < vlen; ++i)
 16155			mask |= BIT(BPF_REG_1 + i);
 16156		return mask;
 16157	}
 16158	

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