Re: [Qemu-devel] Tracing guest virtual addresses

[Alex Bennée]

Lluís Vilanova <address@hidden> writes:

> Alex Bennée writes:
>
>> Peter Maydell <address@hidden> writes:
>
>>> On 20 June 2017 at 12:02, Lluís Vilanova <address@hidden> wrote:
>>>> Jayanto Minocha writes:
>>>>> But that is only used to instrument the cpu_ld/cpu_st macros, which is 
>>>>> only
>>>>> called in the case of a tlb miss.
>>>>
>>>>> I've been going over the archives, and it looks like I need to instrument
>>>>> tcg_out_tlb_load. Am I on the right path ?
>>>>
>>>> That event should trace all guest memory accesses performed by the CPU. If 
>>>> you
>>>> found any case where this does not hold, it is likely a bug and I'd 
>>>> appreciate
>>>> it if you can point me to the smallest possible failing example.
>>>
>>> Does it catch memory accesses that are performed via helper functions,
>>> or only ones done by inline TCG code?
>
>> AFAICT it inserts a helper call on the TCG ld/st ops. I wonder why not
>> just ensure we always take the slow path and put the helpers in the
>> access functions there? You could even apply an address mask if you only
>> want to look at certain address ranges.
>
> It also catches accesses performed by helpers.

Don't helper accesses also pass through the SoftMMU? Or are we talking
about user-space access as well here?

>
>
> Cheers,
>   Lluis


--
Alex Bennée