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Re: [Qemu-devel] [PATCH v2] coverity-model: model address_space_read/wri

From: Eric Blake
Subject: Re: [Qemu-devel] [PATCH v2] coverity-model: model address_space_read/write
Date: Wed, 15 Mar 2017 07:19:31 -0500
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.8.0

On 03/15/2017 06:58 AM, Peter Maydell wrote:
> On 15 March 2017 at 11:55, Eric Blake <address@hidden> wrote:
>> On 03/15/2017 03:16 AM, Paolo Bonzini wrote:
>>> -MemTxResult address_space_rw(AddressSpace *as, hwaddr addr, MemTxAttrs 
>>> attrs,
>>> -                             uint8_t *buf, int len, bool is_write)
>>> +MemTxResult address_space_read(AddressSpace *as, hwaddr addr,
>>> +                               MemTxAttrs attrs,
>>> +                               uint8_t *buf, int len)
>>>  {
>>>      MemTxResult result;
>>> -
>>>      // TODO: investigate impact of treating reads as producing
>>>      // tainted data, with __coverity_tainted_data_argument__(buf).
>>> -    if (is_write) __bufread(buf, len); else __bufwrite(buf, len);
>> Old code did __bufread for reads,
> Eh? for a read is_write is false, and we use the else clause,
> which is __bufwrite...

Maybe I shouldn't send emails when I've just woken up? It threw me that
we have a function named 'read' relying on coverity's 'write' - but
you're correct that it has always been that way, and thinking about it
more, what is really happening is:

our function named 'read' is emulating getting data from hardware (the
'read' portion) and copying it into the buffer (the 'write' portion);
the Coverity model needs to know about the effects to the buffer, but
could care less about the hardware emulation side.

Okay, you've straightened me out, so I can give:
Reviewed-by: Eric Blake <address@hidden>

Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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