Re: [PATCH] Remove structure passing and assignment to save stack and no coping structures.

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

Hi Karim,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on linus/master]
[also build test WARNING on v4.15-rc8 next-20180115]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Karim-Eshapa/Remove-structure-passing-and-assignment-to-save-stack-and-no-coping-structures/20180116-130502
reproduce:
        # apt-get install sparse
        make ARCH=x86_64 allmodconfig
        make C=1 CF=-D__CHECK_ENDIAN__


sparse warnings: (new ones prefixed by >>)

>> kernel/bpf/verifier.c:1002:29: sparse: incorrect type in argument 2 (different modifiers) @@ expected struct tnum @@ got structstruct tnum @@
   kernel/bpf/verifier.c:1002:29: expected struct tnum
   kernel/bpf/verifier.c:1002:29: got struct tnum const
>> kernel/bpf/verifier.c:1003:17: sparse: not addressable
   kernel/bpf/verifier.c:1028:29: sparse: incorrect type in argument 2 (different modifiers) @@ expected struct tnum @@ got structstruct tnum @@
   kernel/bpf/verifier.c:1028:29: expected struct tnum
   kernel/bpf/verifier.c:1028:29: got struct tnum const
   kernel/bpf/verifier.c:1029:17: sparse: not addressable
   kernel/bpf/verifier.c:1969:46: sparse: incorrect type in argument 2 (different modifiers) @@ expected struct tnum @@ got structstruct tnum @@
   kernel/bpf/verifier.c:1969:46: expected struct tnum
   kernel/bpf/verifier.c:1969:46: got struct tnum const
>> kernel/bpf/verifier.c:1970:26: sparse: incorrect type in argument 3 (different modifiers) @@ expected struct tnum lib @@ got structstruct tnum lib @@
   kernel/bpf/verifier.c:1970:26: expected struct tnum lib
   kernel/bpf/verifier.c:1970:26: got struct tnum const
   kernel/bpf/verifier.c:4527:38: sparse: subtraction of Share your drugs
>> kernel/bpf/verifier.c:1002:17: sparse: call with no type!
   kernel/bpf/verifier.c:1028:17: sparse: call with no type!
   kernel/bpf/verifier.c: In function 'check_pkt_ptr_alignment':
   kernel/bpf/verifier.c:1003:3: error: lvalue required as unary '&' operand
    &tnum_const(ip_align + reg->off + off));
    ^
   kernel/bpf/verifier.c:1002:21: warning: passing argument 2 of 'tnum_add' discards 'const' qualifier from pointer target type
    tnum_add(&reg_off, &reg->var_off,
    ^
   In file included from include/linux/bpf_verifier.h:12:0,
    from kernel/bpf/verifier.c:17:
   include/linux/tnum.h:29:6: note: expected 'struct tnum but argument is of type 'const struct tnum
    void tnum_add(struct tnum struct tnum struct tnum
    ^~~~~~~~
   kernel/bpf/verifier.c: In function 'check_generic_ptr_alignment':
   kernel/bpf/verifier.c:1029:3: error: lvalue required as unary '&' operand
    &tnum_const(reg->off + off));
    ^
   kernel/bpf/verifier.c:1028:21: warning: passing argument 2 of 'tnum_add' discards 'const' qualifier from pointer target type
    tnum_add(&reg_off, &reg->var_off,
    ^
   In file included from include/linux/bpf_verifier.h:12:0,
    from kernel/bpf/verifier.c:17:
   include/linux/tnum.h:29:6: note: expected 'struct tnum but argument is of type 'const struct tnum
    void tnum_add(struct tnum struct tnum struct tnum
    ^~~~~~~~
   kernel/bpf/verifier.c: In function 'adjust_ptr_min_max_vals':
   kernel/bpf/verifier.c:1969:31: warning: passing argument 2 of 'tnum_add' discards 'const' qualifier from pointer target type
    tnum_add(&dst_reg->var_off, &ptr_reg->var_off,
    ^
   In file included from include/linux/bpf_verifier.h:12:0,
    from kernel/bpf/verifier.c:17:
   include/linux/tnum.h:29:6: note: expected 'struct tnum but argument is of type 'const struct tnum
    void tnum_add(struct tnum struct tnum struct tnum
    ^~~~~~~~
   kernel/bpf/verifier.c:1970:4: warning: passing argument 3 of 'tnum_add' discards 'const' qualifier from pointer target type
    &off_reg->var_off);
    ^
   In file included from include/linux/bpf_verifier.h:12:0,
    from kernel/bpf/verifier.c:17:
   include/linux/tnum.h:29:6: note: expected 'struct tnum but argument is of type 'const struct tnum
    void tnum_add(struct tnum struct tnum struct tnum
    ^~~~~~~~

vim +1002 kernel/bpf/verifier.c

   980	
   981	static int check_pkt_ptr_alignment(struct bpf_verifier_env *env,
   982					   const struct bpf_reg_state *reg,
   983					   int off, int size, bool strict)
   984	{
   985		struct tnum reg_off;
   986		int ip_align;
   987	
   988		/* Byte size accesses are always allowed. */
   989		if (!strict || size == 1)
   990			return 0;
   991	
   992		/* For platforms that do not have a Kconfig enabling
   993		 * CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS the value of
   994		 * NET_IP_ALIGN is universally set to '2'.  And on platforms
   995		 * that do set CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS, we get
   996		 * to this code only in strict mode where we want to emulate
   997		 * the NET_IP_ALIGN==2 checking.  Therefore use an
   998		 * unconditional IP align value of '2'.
   999		 */
  1000		ip_align = 2;
  1001	
> 1002		tnum_add(&reg_off, &reg->var_off,
> 1003			&tnum_const(ip_align + reg->off + off));
  1004		if (!tnum_is_aligned(reg_off, size)) {
  1005			char tn_buf[48];
  1006	
  1007			tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
  1008			verbose(env,
  1009				"misaligned packet access off %d+%s+%d+%d size %d\n",
  1010				ip_align, tn_buf, reg->off, off, size);
  1011			return -EACCES;
  1012		}
  1013	
  1014		return 0;
  1015	}
  1016	
  1017	static int check_generic_ptr_alignment(struct bpf_verifier_env *env,
  1018					       const struct bpf_reg_state *reg,
  1019					       const char *pointer_desc,
  1020					       int off, int size, bool strict)
  1021	{
  1022		struct tnum reg_off;
  1023	
  1024		/* Byte size accesses are always allowed. */
  1025		if (!strict || size == 1)
  1026			return 0;
  1027	
> 1028		tnum_add(&reg_off, &reg->var_off,
  1029			&tnum_const(reg->off + off));
  1030		if (!tnum_is_aligned(reg_off, size)) {
  1031			char tn_buf[48];
  1032	
  1033			tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
  1034			verbose(env, "misaligned %saccess off %s+%d+%d size %d\n",
  1035				pointer_desc, tn_buf, reg->off, off, size);
  1036			return -EACCES;
  1037		}
  1038	
  1039		return 0;
  1040	}
  1041	

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