On 04/26/2011 10:45 AM, Jan Kiszka wrote:
On 2011-04-26 09:42, Avi Kivity wrote:
> On 04/25/2011 11:04 AM, Jan Kiszka wrote:
>> > +
>> > + ptep_user = (pt_element_t __user *)((void *)host_addr +
>> offset);
>> > + if (get_user(pte, ptep_user)) {
>> ^^^^^^^^^^^^
>> This doesn't work for x86-32: pte is 64 bit, but get_user is only
>> defined up to 32 bit on that platform.
>>
>
> I actually considered this, and saw:
>
> #ifdef CONFIG_X86_32
> #define __get_user_8(__ret_gu, __val_gu, ptr) \
> __get_user_x(X, __ret_gu, __val_gu, ptr)
> #else
> #define __get_user_8(__ret_gu, __val_gu, ptr) \
> __get_user_x(8, __ret_gu, __val_gu, ptr)
> #endif
>
> #define get_user(x, ptr) \
> ({ \
> int __ret_gu; \
> unsigned long __val_gu; \
> __chk_user_ptr(ptr); \
> might_fault(); \
> switch (sizeof(*(ptr))) { \
>
> ...
>
> case 8: \
> __get_user_8(__ret_gu, __val_gu, ptr); \
> break; \
>
> ...
>
> } \
> (x) = (__typeof__(*(ptr)))__val_gu; \
> __ret_gu; \
> })
>
> so it should work. How does it fail?
On x86-32, the above macro resolves to __get_user_X, an undefined symbol.
Tricky stuff.
--
error compiling committee.c: too many arguments to function
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