Re: [Valgrind-users] About how to get the guest code memory

[Philippe W. <phi...@sk...>]

On Mon, 2018-08-20 at 17:44 +0800, shuai xi wrote:
> Hi@all, 
> 
> I add some hooks in the vgpreload*.so and get some information from it. The vgpreload*.so is a dynamically library  loaded in the guest code.
> 
> I want to get this information to do some analysis. But i don't know how to get this information from guest code memory to valgrind memory space. 
> 
> I attempt to use a global variable to store this information, but valgrind show me a error that it can not find this global variable's symbol. Because this global variable is in guest code memory space.
> 
> I attempt to write this information in file, because i hook the function malloc. 
> 
> Is there some solution like 'share memory' to deal this problem？
You have to switch from guest to host.
I suggest you read in depth how a (non toy) tool works
(for example, how helgrind wraps pthread functions and
"calls" some host code from the guest code).

Philippe