Re: [Qemu-devel] QEMU to generate host binary

[Alex Bennée]

Dr. David Alan Gilbert <address@hidden> writes:

> * Ayaz Akram (address@hidden) wrote:
>> Thanks for your answers. The thing that i still do not get is once we have
>> host assembly code (output assembly log generated for compiled TBs ),
>> should we still worry about problems like self modifying code and other
>> dynamic conditions? Moreover, assuming static linking, will not this code
>> be enough to generate .text section of an executable that could be run
>> directly on host (if somehow other sections of that host executable can be
>> generated, which is itself difficult) ?
>
> It can certainly help, but you can still walk into a piece of code
> that you've not previously translated, and a shared library for example
> might change, and your code might change due to other things such as
> randomisation of library loading addresses.
<snip>
> You say 'should we still worry about problems like self modifying code and 
> other
> dynamic conditions?' - well you hope that for most 'normal' programs that
> self modification doesn't happen; but it keeps turning up even when you don't
> expect it, e.g. loading/unloading of plugins or if you happen to be
> emulating a JIT (such as qemu!).

I think PLT patching is another case of self modifying code you often
come across.

-- 
Alex Bennée