Hello,
I have been doing some more experimenting with the va_to_pa function and the communication between normal and secure world. I am currently running Genode in the normal world as well. In the normal world I create a RAM dataspace which I then attach to the rm_session of the application. I fill this dataspace with data and I pass the virtual address to the secure world. The va_to_pa function returns an actual value in this case so my problem there was that I had nothing in the page table. The problem however is that this address seems incorrect. When I change data at that physical address in the secure world, the normal world does not see any change in the dataspace when it has control again. At first I thought this might have something to do with the cache but I'm adding the UNCACHED modifier in the declaration of my dataspace and the problem persists.
After some extra testing with as big a dataspace I could manage, I checked the memory for where it was located and I found the dataspace, with all the data in it, at a random memory address. This leads me to believe that the translation of the virtual address of the dataspace to a physical one is simply wrong. I think the virtual address of the dataspace is a local address for that rm_session and that this might cause this mistranslation.
Now my question is, is it possible to find the virtual address of a dataspace or anything in which I can store data that will translate to the correct physical address with the va_to_pa function?
Best regards, Vincent
2015-03-30 8:45 GMT+02:00 Stefan Kalkowski <stefan.kalkowski@...1...
:
Hi Vincent,
On 03/27/2015 04:32 PM, Vincent Raes wrote:
Hello,
Thanks for the advice, it helped a lot. I was indeed confused with the virtual memory since I could I have another question, this time involving the tz_vmm itself. In mmu.h there is a function which should translate a virtual address of the normal world to a physical address in the secure world. However this function only returns 0 due to the ram.h throwing an invalid address when he gets called on by mmu.h. Could this be because I'm using a different kernel in the normal world/ different board so that mmu.h does not translate the addresses correctly?
These small helper functions in mmu.h are used to decode register values of the normal world that potentially contain virtual addresses to physical ones. Thereby it is assumed the guest OS uses the short translation table format of the ARM v7 architecture. If a given address is not found in the page tables, or if the guest OS did not setup the page tables yet (MMU ist still off) you will get a zero as return value.
Regards Stefan
Best regards, Vincent
2015-03-23 9:27 GMT+01:00 Stefan Kalkowski <stefan.kalkowski@...1... mailto:stefan.kalkowski@...1...>:
Hello Vincent, On 03/20/2015 11:40 AM, Vincent Raes wrote: > Hello, > > I am working with TrustZone using Genode and I am trying to passdata
> from the secure world to the normal world and vice versa. Theproblem
> lies with the fact that the normal world can only access a certain part > of the RAM memory the board has to offer so all the data I want to give > to the normal world has to be placed somewhere it can access. And I > can't seem to figure out how to place data at a specific addressusing
> Genode. > > When I try to use pointers to the wanted memory location, the error "No > RM attachment" keeps popping up. This may very well be caused bythe
> fact I am using a pointer to a place that does not yet has a valid data > object in it. I believe the correct answer has something to do with the > use of dataspaces but am not sure how or what kind of dataspace Ineed
> to use for random data I generate myself. To me it seems you first have to understand the difference between virtual memory and physical memory. When using memory addresses in a normal application (and even mostly in the kernel) you are dealingwith
virtual memory addresses that are translated in hardware via the MMUto
physical memory addresses. If you target a memory region that doesnot
relate to a valid translation entry in the translation table of the process, you will get a translation fault. That is what you see withthe
message "No RM attachment". In Genode the RM session is used to administrate the virtual memory address space of a process. In contrast to that: the bus system, and the memory controller are dealing with physical memory addresses, and probably the TrustZone component that splits the memory in normal and secure one too. If you say that the normal world can access only a specific portion of RAM,you
speak about a physical address range. Your intuition was right: in Genode a portion of RAM is abstractedby a
dataspace. In general a RAM dataspace is just an anonymous amount of RAM, where you do cannot determine its location in physical memorywhen
allocating it. In contrast to a RAM dataspace, you can also use anIOMEM
session to request a specific dataspace, normally used formemory-mapped
I/O regions of devices. When allocating an IOMEM region of course you can and have to specify the actual physical location. So in yourcase,
the only possibility to deposit data at a specific RAM location forthe
normal world is to open up an IOMEM session, and attach itsdataspace to
the RM session of your application. BTW: the same was done in our TrustZone example virtual machinemonitor
implmentation (repos/os/src/server/tz_vmm). Regards Stefan > > Thanks in advance for any advice. > > Best regards, > Vincent > > >
> Dive into the World of Parallel Programming The Go Parallel Website, sponsored > by Intel and developed in partnership with Slashdot Media, is your hub for all > things parallel software development, from weekly thought leadership blogs to > news, videos, case studies, tutorials and more. Take a look and join the > conversation now. http://goparallel.sourceforge.net/ > > > > _______________________________________________ > genode-main mailing list > genode-main@lists.sourceforge.net <mailto:genode-main@lists.sourceforge.net> > https://lists.sourceforge.net/lists/listinfo/genode-main > -- Stefan Kalkowski Genode Labs http://www.genode-labs.com/ · http://genode.org/
Dive into the World of Parallel Programming The Go Parallel Website, sponsored by Intel and developed in partnership with Slashdot Media, is your hub for all things parallel software development, from weekly thought leadership blogs to news, videos, case studies, tutorials and more. Take a look and jointhe
conversation now. http://goparallel.sourceforge.net/ _______________________________________________ genode-main mailing list genode-main@lists.sourceforge.net <mailto:genode-main@lists.sourceforge.net> https://lists.sourceforge.net/lists/listinfo/genode-main
Dive into the World of Parallel Programming The Go Parallel Website,
sponsored
by Intel and developed in partnership with Slashdot Media, is your hub
for all
things parallel software development, from weekly thought leadership
blogs to
news, videos, case studies, tutorials and more. Take a look and join the conversation now. http://goparallel.sourceforge.net/
genode-main mailing list genode-main@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/genode-main
-- Stefan Kalkowski Genode Labs
http://www.genode-labs.com/ · http://genode.org/
Dive into the World of Parallel Programming The Go Parallel Website, sponsored by Intel and developed in partnership with Slashdot Media, is your hub for all things parallel software development, from weekly thought leadership blogs to news, videos, case studies, tutorials and more. Take a look and join the conversation now. http://goparallel.sourceforge.net/ _______________________________________________ genode-main mailing list genode-main@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/genode-main