On 20/11/2018 10:27, Juergen Gross wrote:
> On 09/11/2018 19:12, Daniel Kiper wrote:
>> On Fri, Nov 02, 2018 at 01:37:29PM +0100, Juergen Gross wrote:>>> +
>>> + asm volatile ("wrmsr" : : "c" (msr), "a" (pfn), "d" (0) : "memory");
>>> +}
>>> +
>>> +int
>>> +grub_xen_hypercall (grub_uint32_t callno, grub_uint32_t a0,
>>> + grub_uint32_t a1, grub_uint32_t a2,
>>> + grub_uint32_t a3, grub_uint32_t a4,
>>> + grub_uint32_t a5 __attribute__ ((unused)))
>>> +{
>>> + grub_uint32_t __res, __ign0, __ign1, __ign2, __ign3, __ign4;
>>> +
>>> + asm volatile ("call *%[callno]"
>>> + : "=a" (__res), "=b" (__ign0), "=c" (__ign1), "=d" (__ign2),
>>> + "=S" (__ign3), "=D" (__ign4)
>>> + : "1" (a0), "2" (a1), "3" (a2), "4" (a3), "5" (a4),
>>
>> I think that you can drop all __ign* variables if you specify proper
>> registers in input argument. If this does not work you can use "+"
>> modifier instead of "=" in the output argument.
>
> I'll have a try.
Doesn't work.
Specifying only the input registers neglects the hypercall
clobbering those.
Using the "+" modifier lets gcc complain.
I'll just use a single dummy variable.
Juergen
_______________________________________________
Grub-devel mailing list
Grub-devel@gnu.org
https://lists.gnu.org/mailman/listinfo/grub-devel
