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From: =?utf-8?Q?Llu=C3=ADs_Vilanova?= <vilanova@ac.upc.edu>
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Date: Sun, 25 Jun 2017 15:20:06 +0300
In-Reply-To: <87mv91tn7d.fsf@linaro.org> ("Alex =?utf-8?Q?Benn=C3=A9e=22's?=
	message of "Wed, 21 Jun 2017 15:44:22 +0100")
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Subject: Re: [Qemu-devel] Tracing guest virtual addresses
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To: Alex =?utf-8?Q?Benn=C3=A9e?= <alex.bennee@linaro.org>
Cc: Peter Maydell <peter.maydell@linaro.org>, Jayanto Minocha <jayanto@gmail.com>, QEMU Developers <qemu-devel@nongnu.org>

Alex Benn=C3=A9e writes:

> Peter Maydell <peter.maydell@linaro.org> writes:

>> On 20 June 2017 at 12:02, Llu=C3=ADs Vilanova <vilanova@ac.upc.edu> wrot=
e:
>>> 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.
>>>=20
>>>> I've been going over the archives, and it looks like I need to instrum=
ent
>>>> tcg_out_tlb_load. Am I on the right path ?
>>>=20
>>> 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 app=
reciate
>>> it if you can point me to the smallest possible failing example.
>>=20
>> 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.


Cheers,
  Lluis