On 28.03.2025 00:33, Stefano Stabellini wrote:
> On Mon, 24 Mar 2025, Jan Beulich wrote:
>> On 22.03.2025 00:09, Stefano Stabellini wrote:
>>> @@ -384,21 +382,40 @@ int bitmap_to_xenctl_bitmap(struct xenctl_bitmap
>>> *xenctl_bitmap,
>>> uint8_t zero = 0;
>>> int err = 0;
>>> unsigned int xen_bytes = DIV_ROUND_UP(nbits, BITS_PER_BYTE);
>>> - uint8_t *bytemap = xmalloc_array(uint8_t, xen_bytes);
>>> -
>>> - if ( !bytemap )
>>> - return -ENOMEM;
>>> + uint8_t last;
>>>
>>> guest_bytes = DIV_ROUND_UP(xenctl_bitmap->nr_bits, BITS_PER_BYTE);
>>> copy_bytes = min(guest_bytes, xen_bytes);
>>>
>>> - bitmap_long_to_byte(bytemap, bitmap, nbits);
>>> + if ( IS_ENABLED(__BIG_ENDIAN) )
>>> + {
>>> + uint8_t *bytemap = xmalloc_array(uint8_t, xen_bytes);
>>>
>>> - if ( copy_bytes &&
>>> - copy_to_guest(xenctl_bitmap->bitmap, bytemap, copy_bytes) )
>>> - err = -EFAULT;
>>> + if ( !bytemap )
>>> + return -ENOMEM;
>>>
>>> - xfree(bytemap);
>>> + bitmap_long_to_byte(bytemap, bitmap, nbits);
>>> + last = bytemap[nbits/8];
>>
>> Same style nit as before.
>>
>>> + if ( copy_bytes &&
>>
>> copy_bytes > 1
>>
>>> + copy_to_guest(xenctl_bitmap->bitmap, bytemap, copy_bytes - 1)
>>> )
>>> + err = -EFAULT;
>>> +
>>> + xfree(bytemap);
>>> + }
>>> + else
>>> + {
>>> + const uint8_t *bytemap = (const uint8_t *)bitmap;
>>> + last = bytemap[nbits/8];
>>> +
>>> + if ( copy_bytes &&
>>> + copy_to_guest(xenctl_bitmap->bitmap, bytemap, copy_bytes - 1)
>>> )
>>> + err = -EFAULT;
>>
>> The two identical instances would imo better stay common, even if this may
>> require another function-scope variable (to invoke xfree() on after the
>> copy-out).
>
> That's not possible because bytemap is defined differently in the two
> cases so it has to be defined within the if block.
Hence why I said "even if this may require another function-scope variable".
Jan
