Thanks a lot Stefan, Will correlate with the linux binary. Riju
> Hi, > > On 06/14/2017 02:40 PM, rijure...@mpi-sws.org wrote: >> >> We want to read the instruction faulting in NW linux in tz_vmm, >> disassemble it, emulate it in genode code and restart the VM at the next >> instruction of the normal world. Do you think this is feasible, or your >> comments about "synchronous data abort in IMX53 vs. asynchronous aborts >> in >> Versatile Express" don't hold always? > > As I said in my previous mail: I only observed synchronous data-abort on > i.MX53. So I think this is not the show-stopper. > > Anyway please read my whole mail especially the section regarding the > caching issues. Being in your position, I would first correlate the > instruction pointer values with your Linux binary, e.g. using objdump, > before you start to do instruction decoding on cache-incoherent memory. > > Regards > Stefan > >> >> Thanks! >> Riju >> >>> Hello, >>> >>> On 06/13/2017 11:17 AM, Abhishek Kumar wrote: >>>> Hello >>>> I am trying to modify genode trustzone. I want to read the instruction >>>> which lead to data abort exception in normal world, in the `dump` >>>> function in tz_vmm. I have value of all the registers through `_state` >>>> register. We tried with `_state->ip`. On converting 16 bits stored at >>>> the address pointed by _state->ip, we got ARM Thumb instruction: >>>> >>>> STRH R0, [R0, #6] >>>> >>>> >>>> >>>> But the value (R0) + 6, doesn't match dfar. We're not sure if >>>> _state->ip >>>> is the register to go with. We tried with _state->mode[2].lr which is >>>> lr_abt register. But the address stored in lr_abt, lr_abt-16, >>>> lr_abt-32 >>>> all have 0s. >>>> >>>> Which is right register to get the address of the instruction which >>>> caused the data-abort exception? >>> >>> As long as you get an synchronous data-abort from the normal world, >>> reading the current instruction pointer of the 'state' structure is >>> perfectly fine. The mode-specific lr register is useful for the >>> handling >>> of MMU faults within the "normal" world itself. They are not modified, >>> as long as the "normal" world MMU can resolve an access, but some bus >>> resp. CSU is answering that the access is not allowed. This will not >>> change the "normal" world register set. >>> >>> On the other hand, in general a bus fault triggered by unallowed access >>> of the "normal" world does not necessarily mean a synchronous >>> data-abort, although on i.MX53 I only observed those. In general, it >>> can >>> also provoke an asynchronous external data-abort, which means that the >>> instruction pointer is not necessarily pointing to the instruction that >>> triggered the fault. >>> >>> Moreover, looking at the "normal" world's memory from the secure side >>> is >>> troublesome. Because the normal and secure world's memory view is not >>> cache-coherent. Cache entries are always tagged by the NS bit. That >>> means you have to take care to flush caches yourself. If you want to >>> debug instructions, you should instead look at the Linux binary itself >>> and not into the memory on the secure side. To me it looks strange that >>> you identify a Thumb instruction in the kernel here. >>> >>> Btw. these kind of TrustZone/i.MX53 questions were asked repeatedly in >>> the past, and are mostly answered in our TrustZone report: >>> >>> https://genode.org/documentation/articles/trustzone >>> >>> and in the discussions of our mailing list: >>> >>> https://sourceforge.net/p/genode/mailman/search/?q=trustzone >>> >>> Regards >>> Stefan >>> >>>> >>>> Thanks >>>> Abhishek >>>> >>>> >>>> ------------------------------------------------------------------------------ >>>> Check out the vibrant tech community on one of the world's most >>>> engaging tech sites, Slashdot.org! http://sdm.link/slashdot >>>> >>>> >>>> >>>> _______________________________________________ >>>> genode-main mailing list >>>> genode-main@lists.sourceforge.net >>>> https://lists.sourceforge.net/lists/listinfo/genode-main >>>> >>> >>> -- >>> Stefan Kalkowski >>> Genode Labs >>> >>> https://github.com/skalk · http://genode.org/ >>> >>> ------------------------------------------------------------------------------ >>> Check out the vibrant tech community on one of the world's most >>> engaging tech sites, Slashdot.org! http://sdm.link/slashdot >>> _______________________________________________ >>> genode-main mailing list >>> genode-main@lists.sourceforge.net >>> https://lists.sourceforge.net/lists/listinfo/genode-main >>> >> >> >> ------------------------------------------------------------------------------ >> Check out the vibrant tech community on one of the world's most >> engaging tech sites, Slashdot.org! http://sdm.link/slashdot >> _______________________________________________ >> genode-main mailing list >> genode-main@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/genode-main >> > > -- > Stefan Kalkowski > Genode Labs > > https://github.com/skalk · http://genode.org/ > > ------------------------------------------------------------------------------ > Check out the vibrant tech community on one of the world's most > engaging tech sites, Slashdot.org! http://sdm.link/slashdot > _______________________________________________ > genode-main mailing list > genode-main@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/genode-main > ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ genode-main mailing list genode-main@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/genode-main
