Re: [Xen-devel] [PATCH v4] xen/arm64: check XSM Magic from the second unknown module.

[Fu Wei <fu.wei@xxxxxxxxxx>]

Hi Jan,

On 5 April 2016 at 22:16, Jan Beulich <JBeulich@xxxxxxxx> wrote:
>>>> On 05.04.16 at 15:38, <fu.wei@xxxxxxxxxx> wrote:
>> --- a/xen/xsm/xsm_core.c
>> +++ b/xen/xsm/xsm_core.c
>> @@ -19,6 +19,8 @@
>>
>>  #ifdef CONFIG_XSM
>>
>> +#include <asm/setup.h>
>
> This is not a good idea. Note how xsm_policy.c limits this inclusion to
> the CONFIG_HAS_DEVICE_TREE case only, which is the least that
> should be done here too.

OK, good point, thanks , will do.

>
>> @@ -109,6 +111,25 @@ int __init xsm_dt_init(void)
>>
>>      return ret;
>>  }
>> +
>> +/**
>> + * has_xsm_magic - Check XSM Magic of the module header by phy address
>> + * A XSM module has a special header
>> + * ------------------------------------------------
>> + * uint magic | uint target_len | uchar target[8] |
>> + * 0xf97cff8c |        8        |    "XenFlask"   |
>> + * ------------------------------------------------
>> + * 0xf97cff8c is policy magic number (XSM_MAGIC).
>> + * Here we only check the "magic" of the module.
>> + */
>> +bool __init has_xsm_magic(paddr_t start)
>> +{
>> +    xsm_magic_t magic;
>> +
>> +    copy_from_paddr(&magic, start, sizeof(magic) );
>> +
>> +    return ( XSM_MAGIC && magic == XSM_MAGIC );
>
> Is XSM_MAGIC == 0 possible here at all? And if it is, wouldn't it be
> better to avoid the copy_from_paddr() in that case?

yes, good idea, will do

>
> Jan
>



-- 
Best regards,

Fu Wei
Software Engineer
Red Hat Software (Beijing) Co.,Ltd.Shanghai Branch
Ph: +86 21 61221326(direct)
Ph: +86 186 2020 4684 (mobile)
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