[Letux-kernel] [PATCH] MIPS: Fix a longstanding error in div64.h

[Zhou Yanjie]

Hi Nikolaus,

On 2021/4/6 下午8:42, H. Nikolaus Schaller wrote:
>> Am 06.04.2021 um 13:24 schrieb Huacai Chen <chenhuacai at kernel.org>:
>>
>> Only 32bit kernel need __div64_32(), but commit c21004cd5b4cb7d479514d4
>> ("MIPS: Rewrite <asm/div64.h> to work with gcc 4.4.0.") makes it depend
>> on 64bit kernel by mistake. This patch fix this longstanding error.
>>
>> Fixes: c21004cd5b4cb7d479514d4 ("MIPS: Rewrite <asm/div64.h> to work with gcc 4.4.0.")
>> Cc: stable at vger.kernel.org
>> Signed-off-by: Huacai Chen <chenhuacai at loongson.cn>
>> ---
>> arch/mips/include/asm/div64.h | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/arch/mips/include/asm/div64.h b/arch/mips/include/asm/div64.h
>> index dc5ea5736440..d199fe36eb46 100644
>> --- a/arch/mips/include/asm/div64.h
>> +++ b/arch/mips/include/asm/div64.h
>> @@ -11,7 +11,7 @@
>>
>> #include <asm-generic/div64.h>
>>
>> -#if BITS_PER_LONG == 64
>> +#if BITS_PER_LONG == 32
>>
>> #include <linux/types.h>
> Hm.
>
> Ingenic jz4780/CI20 build attempt on top ov v5.12-rc6:
>
> In file included from ./include/linux/math64.h:7:0,
>                   from ./include/linux/time.h:6,
>                   from ./include/linux/compat.h:10,
>                   from arch/mips/kernel/asm-offsets.c:12:
> ./include/linux/math64.h: In function 'div_u64_rem':
> ./arch/mips/include/asm/div64.h:29:11: error: invalid type argument of unary '*' (have 'long long unsigned int')
>    __high = *__n >> 32;      \
>             ^
> ./include/asm-generic/div64.h:243:11: note: in expansion of macro '__div64_32'
>     __rem = __div64_32(&(n), __base); \
>             ^
> ./include/linux/math64.h:91:15: note: in expansion of macro 'do_div'
>    *remainder = do_div(dividend, divisor);
>                 ^
>
> Or does it just reveal an unknown bug in my compiler?


I also get these:


In file included from ./include/linux/math64.h:7:0,
                  from ./include/linux/time.h:6,
                  from ./include/linux/compat.h:10,
                  from arch/mips/kernel/asm-offsets.c:12:
./include/linux/math64.h: In function 'div_u64_rem':
./arch/mips/include/asm/div64.h:29:11: error: invalid type argument of 
unary '*' (have 'long long unsigned int')
   __high = *__n >> 32;      \
            ^
./include/asm-generic/div64.h:243:11: note: in expansion of macro 
'__div64_32'
    __rem = __div64_32(&(n), __base); \
            ^
./include/linux/math64.h:91:15: note: in expansion of macro 'do_div'
   *remainder = do_div(dividend, divisor);
                ^
./include/linux/math64.h: In function 'mul_u64_u32_div':
./arch/mips/include/asm/div64.h:29:11: error: invalid type argument of 
unary '*' (have 'long long unsigned int')
   __high = *__n >> 32;      \
            ^
./include/asm-generic/div64.h:243:11: note: in expansion of macro 
'__div64_32'
    __rem = __div64_32(&(n), __base); \
            ^
./include/linux/math64.h:256:14: note: in expansion of macro 'do_div'
   rl.l.high = do_div(rh.ll, divisor);
               ^
./arch/mips/include/asm/div64.h:29:11: error: invalid type argument of 
unary '*' (have 'long long unsigned int')
   __high = *__n >> 32;      \

...


So it seems not a compiler problem.