A few general questions

[Anita Müller]

Hello

Dynamorio seems like a really good tool for what I need but I had a few questions regarding it's functionality

1) Is there a good way to prepopulate certain instructions in the cache? I have seen the dr_prepopulate_cache() function and that it's supposed to be called between dr_app_setup() and dr_app_start(). I'm confused on how this is done since I might not know the module base address (that I get from the module onload event) of blocks I want to populate. Additionally, does prepopulating them allow for any instrumentation similar to a basic block event?
2) Is there a way to trigger an event when an indirect branch takes a branch it hasn't taken before? This would be applied to every indirect instruction. I could do this via meta instructions but just wondered if Dynamorio provided a convenient way to do this
3) For the -thread_private option, is there a way to group certain threads to use the same code caches? For example if there were 3 threads and I needed to instrument 2 of them using method A and 1 using method B, could I have the two threads using method A to share the same code cache instead of having their own individual ones. The one using method B would still have it's own code cache

Thanks

[Derek Bruening]

On Fri, Oct 14, 2022 at 3:18 PM Anita Müller <mulle...@gmail.com> wrote:

Hello

Dynamorio seems like a really good tool for what I need but I had a few questions regarding it's functionality

1) Is there a good way to prepopulate certain instructions in the cache? I have seen the dr_prepopulate_cache() function and that it's supposed to be called between dr_app_setup() and dr_app_start(). I'm confused on how this is done since I might not know the module base address (that I get from the module onload event) of blocks I want to populate. Additionally, does prepopulating them allow for any instrumentation similar to a basic block event?

The tags are typically obtained from sampling or possibly a plain-DR pass and then a heavyweight client is set up and prepopulated with that instrumentation.

 

2) Is there a way to trigger an event when an indirect branch takes a branch it hasn't taken before? This would be applied to every indirect instruction. I could do this via meta instructions but just wondered if Dynamorio provided a convenient way to do this

There is no built-in event, no.

 

3) For the -thread_private option, is there a way to group certain threads to use the same code caches? For example if there were 3 threads and I needed to instrument 2 of them using method A and 1 using method B, could I have the two threads using method A to share the same code cache instead of having their own individual ones. The one using method B would still have it's own code cache

This is not implemented, no.  I think there is an issue filed on it somewhere.

 

Thanks

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