Re: [Xen-devel] [PATCH 1/2] x86/e820: fix build with gcc9

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 15.03.19 at 17:07, <andrew.cooper3@xxxxxxxxxx> wrote:
> On 07/03/2019 10:31, Jan Beulich wrote:
>> e820.c: In function ‘clip_to_limit’:
>> .../xen/include/asm/string.h:10:26: error: ‘__builtin_memmove’ offset [-16, 
> -36] is out of the bounds [0, 20484] of
>> object ‘e820’ with type ‘struct e820map’ [-Werror=array-bounds]
>>    10 | #define memmove(d, s, n) __builtin_memmove(d, s, n)
>>       |                          ^~~~~~~~~~~~~~~~~~~~~~~~~~
>> e820.c:404:13: note: in expansion of macro ‘memmove’
>>   404 |             memmove(&e820.map[i], &e820.map[i+1],
>>       |             ^~~~~~~
>> e820.c:36:16: note: ‘e820’ declared here
>>    36 | struct e820map e820;
>>       |                ^~~~
>>
>> While I can't see where the negative offsets would come from, converting
>> the loop index to unsigned type helps. Take the opportunity and also
>> convert several other local variables and copy_e820_map()'s second
>> parameter to unsigned int (and bool in one case).
>>
>> Reported-by: Charles Arnold <carnold@xxxxxxxx>
>> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
> 
> Acked-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, with one request.

Thanks.

>> --- a/xen/arch/x86/e820.c
>> +++ b/xen/arch/x86/e820.c
>> @@ -304,7 +300,7 @@ int __init sanitize_e820_map(struct e820
>>   * thinkpad 560x, for example, does not cooperate with the memory
>>   * detection code.)
>>   */
>> -static int __init copy_e820_map(struct e820entry * biosmap, int nr_map)
>> +static int __init copy_e820_map(struct e820entry * biosmap, unsigned int 
>> nr_map)
>>  {
>>      /* Only one memory region (or negative)? Ignore it */
> 
> This comment is now stale.  I'd just drop the bit in brackets.

Sure, will do.

Jan


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