On 22/05/2025 1:45 pm, Nicola Vetrini wrote:
> On 2025-05-21 20:00, Andrew Cooper wrote:
>> On 21/05/2025 3:36 pm, Andrew Cooper wrote:
>>> diff --git a/xen/arch/x86/include/asm/msr.h
>>> b/xen/arch/x86/include/asm/msr.h
>>> index 0d3b1d637488..4c4f18b3a54d 100644
>>> --- a/xen/arch/x86/include/asm/msr.h
>>> +++ b/xen/arch/x86/include/asm/msr.h
>>> @@ -69,20 +69,20 @@ static inline void wrmsr_ns(uint32_t msr,
>>> uint32_t lo, uint32_t hi)
>>> /* wrmsr with exception handling */
>>> static inline int wrmsr_safe(unsigned int msr, uint64_t val)
>>> {
>>> - int rc;
>>> - uint32_t lo, hi;
>>> - lo = (uint32_t)val;
>>> - hi = (uint32_t)(val >> 32);
>>> -
>>> - __asm__ __volatile__(
>>> - "1: wrmsr\n2:\n"
>>> - ".section .fixup,\"ax\"\n"
>>> - "3: movl %5,%0\n; jmp 2b\n"
>>> - ".previous\n"
>>> - _ASM_EXTABLE(1b, 3b)
>>> - : "=&r" (rc)
>>> - : "c" (msr), "a" (lo), "d" (hi), "0" (0), "i" (-EFAULT));
>>> - return rc;
>>> + uint32_t lo = val, hi = val >> 32;
>>> +
>>> + asm_inline goto (
>>> + "1: wrmsr\n\t"
>>> + _ASM_EXTABLE(1b, %l[fault])
>>> + :
>>> + : "a" (lo), "c" (msr), "d" (hi)
>>> + :
>>> + : fault );
>>> +
>>> + return 0;
>>> +
>>> + fault:
>>> + return -EFAULT;
>>> }
>>
>> It turns out this is the first piece of Eclair-scanned code using asm
>> goto.
>>
>> https://gitlab.com/xen-project/hardware/xen-staging/-/jobs/10108558677
>> (The run also contained an equivalent change to xsetbv())
>>
>> We're getting R1.1 and R2.6 violations.
>>
>> R1.1 complains about [STD.adrslabl] "label address" not being valid C99.
>>
>> R2.6 complains about unused labels.
>>
>> I expect this means that Eclair doesn't know how to interpret asm goto()
>> yet. The labels listed are reachable from inside the asm block.
>>
>
> That has been fixed upstream. I'll reach out to you when that fix
> trickles down to the runners, so that you're able to test and push
> that change.
Oh, fantastic thanks.
I'll hold off pushing until then.
~Andrew
