Re: [PATCH] x86/KASLR: use the right memcpy

[Arnd Bergmann]

On Tue, May 30, 2017 at 3:56 PM, Baoquan He <bhe@xxxxxxxxxx> wrote:
> On 05/30/17 at 11:14am, Arnd Bergmann wrote:
>> The decompressor has its own implementation of the string functions,
>> but has to include the right header to get those, while implicitly
>> including linux/string.h may result in a link error:
>>
>> arch/x86/boot/compressed/kaslr.o: In function `choose_random_location':
>> kaslr.c:(.text+0xf51): undefined reference to `_mmx_memcpy'
>>
>> This has appeared now as kaslr started using memcpy. Other files in the
>> decompressor already do the same thing.
>>
>> Fixes: d52e7d5a952c ("x86/KASLR: Parse all 'memmap=' boot option entries")
>> Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
>
> Thanks for this fix, Arnd!
>
> The linking error didn't happen when I tested the patch of d52e7d5a952c.
> Could you tell in what condition it will be triggered? Not sure if I
> should wait for this fix being merged and do a back porting, or can
> defer it if it's not risky.

It only happens on 32-bit kernels with CONFIG_X86_USE_3DNOW, maybe
there are additional requirements.

       Arnd