netdev - Re: [PATCH bpf-next v1 10/15] bpf: Wire up freeing of referenced PTR_TO_BTF

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Message-ID: <202202210547.JnjWSpPA-lkp@intel.com>
Date:   Mon, 21 Feb 2022 05:43:11 +0800
From:   kernel test robot <lkp@...el.com>
To:     Kumar Kartikeya Dwivedi <memxor@...il.com>, bpf@...r.kernel.org
Cc:     kbuild-all@...ts.01.org, Alexei Starovoitov <ast@...nel.org>,
        Andrii Nakryiko <andrii@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Toke Høiland-Jørgensen <toke@...hat.com>,
        Jesper Dangaard Brouer <hawk@...nel.org>,
        netfilter-devel@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: [PATCH bpf-next v1 10/15] bpf: Wire up freeing of referenced
 PTR_TO_BTF_ID in map

Hi Kumar,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on next-20220217]
[cannot apply to bpf-next/master bpf/master linus/master v5.17-rc4 v5.17-rc3 v5.17-rc2 v5.17-rc4]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Kumar-Kartikeya-Dwivedi/Introduce-typed-pointer-support-in-BPF-maps/20220220-215105
base:    3c30cf91b5ecc7272b3d2942ae0505dd8320b81c
config: openrisc-randconfig-s032-20220220 (https://download.01.org/0day-ci/archive/20220221/202202210547.JnjWSpPA-lkp@intel.com/config)
compiler: or1k-linux-gcc (GCC) 11.2.0
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: v0.6.4-dirty
        # https://github.com/0day-ci/linux/commit/09a47522ec608218eb6aabd5011316d78ad245e0
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Kumar-Kartikeya-Dwivedi/Introduce-typed-pointer-support-in-BPF-maps/20220220-215105
        git checkout 09a47522ec608218eb6aabd5011316d78ad245e0
        # save the config file to linux build tree
        mkdir build_dir
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.2.0 make.cross C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' O=build_dir ARCH=openrisc SHELL=/bin/bash kernel/bpf/

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@...el.com>

All error/warnings (new ones prefixed by >>):

   kernel/bpf/syscall.c: In function 'bpf_map_free_ptr_to_btf_id':
>> kernel/bpf/syscall.c:669:32: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
     669 |                 off_desc->dtor((void *)old_ptr);
         |                                ^
   In file included from arch/openrisc/include/asm/atomic.h:131,
                    from include/linux/atomic.h:7,
                    from include/asm-generic/bitops/lock.h:5,
                    from arch/openrisc/include/asm/bitops.h:41,
                    from include/linux/bitops.h:33,
                    from include/linux/log2.h:12,
                    from include/asm-generic/div64.h:55,
                    from ./arch/openrisc/include/generated/asm/div64.h:1,
                    from include/linux/math.h:6,
                    from include/linux/math64.h:6,
                    from include/linux/time.h:6,
                    from include/linux/ktime.h:24,
                    from include/linux/timer.h:6,
                    from include/linux/workqueue.h:9,
                    from include/linux/bpf.h:9,
                    from kernel/bpf/syscall.c:4:
   In function '__xchg',
       inlined from 'bpf_map_free_ptr_to_btf_id' at kernel/bpf/syscall.c:668:13:
>> arch/openrisc/include/asm/cmpxchg.h:160:24: error: call to '__xchg_called_with_bad_pointer' declared with attribute error: Bad argument size for xchg
     160 |                 return __xchg_called_with_bad_pointer();
         |                        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


vim +669 kernel/bpf/syscall.c

   640	
   641	/* Caller must ensure map_value_has_ptr_to_btf_id is true. Note that this
   642	 * function can be called on a map value while the map_value is visible to BPF
   643	 * programs, as it ensures the correct synchronization, and we already enforce
   644	 * the same using the verifier on the BPF program side, esp. for referenced
   645	 * pointers.
   646	 */
   647	void bpf_map_free_ptr_to_btf_id(struct bpf_map *map, void *map_value)
   648	{
   649		struct bpf_map_value_off *tab = map->ptr_off_tab;
   650		u64 *btf_id_ptr;
   651		int i;
   652	
   653		for (i = 0; i < tab->nr_off; i++) {
   654			struct bpf_map_value_off_desc *off_desc = &tab->off[i];
   655			u64 old_ptr;
   656	
   657			btf_id_ptr = map_value + off_desc->offset;
   658			if (!(off_desc->flags & BPF_MAP_VALUE_OFF_F_REF)) {
   659				/* On 32-bit platforms, WRITE_ONCE 64-bit store tearing
   660				 * into two 32-bit stores is fine for us, as we only
   661				 * permit pointer values to be stored at this address,
   662				 * which are word sized, so the other half of 64-bit
   663				 * value will always be zeroed.
   664				 */
   665				WRITE_ONCE(*btf_id_ptr, 0);
   666				continue;
   667			}
   668			old_ptr = xchg(btf_id_ptr, 0);
 > 669			off_desc->dtor((void *)old_ptr);
   670		}
   671	}
   672	

---
0-DAY CI Kernel Test Service, Intel Corporation
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