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

kernel test robot
2024-08-17T20:09:54Z

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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