users August 2016

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17 participants
18 discussions

Reading thread registers
by Denis Huber 07 Mar '17

07 Mar '17

Hello Genode community, in my checkpoint component I intercepted the Cpu session of a child, through which I get all Thread_capabilities created for and by the child. To store the state of a component I need to store the registers of the threads used by the child. I tried reading the registers through the "Thread_state Cpu_thread::state()" method, but it did not contain any information about (just zeros). I'm using Genode 16.05, kernel Fiasco.OC (pbax9 build). By inspecting the kernel API of foc, I found out that the function l4_thread_ex_regs_ret can read the sp and ip register. By changing the state method in platform_thread.cc (in base-foc) I could get the registers: Thread_state Platform_thread::state() { Thread_state s; if (_pager_obj) s = _pager_obj->state; _pager_obj->state.ip = ~0UL; _pager_obj->state.sp = ~0UL; l4_umword_t flags = 0; l4_thread_ex_regs_ret(_thread.local.dst(), &_pager_obj->state.ip, &_pager_obj->state.sp, &flags); s.sp = _pager_obj->state.sp; s.ip = _pager_obj->state.ip; s.kcap = _gate.remote; s.id = _gate.local.local_name(); s.utcb = _utcb; return s; } But other registers like r0 - r12 are missing. Is there a simple way in Genode to get them? Can I utilize the utcb memory location to find the missing registers? Kind regards Denis

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[tz_vmm demo]- execution time
by John David 03 Nov '16

03 Nov '16

Hello, I want to measure execution time of a function in the secure world of tz_vmm demo. I was wondering if I could use elapsed_ms( ) method in timer_session to measure t1 and t2 so that I can take the difference (t2 -t1). Is there any other way? Best regards, John

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Checkpoint/restore of capabilities
by Denis Huber 24 Oct '16

24 Oct '16

Dear Genode community, as some of you already know, I want to create a checkpoint/restore mechanism for components on Genode 16.05 and Fiasco.OC. I want to create a component which monitors the PD and CPU sessions of its children (= targets for checkpoint/restore) to have access to their memory and thread states. For a complete checkpoint and restore of a child I also need to store the capabilities used by a child. How can I acquire and also restore all these capabilities? After a restore of a component the capability space shall be the "same" as before the checkpoint: 1) The capabilities after the restore shall point to corresponding object identities. 2) Also the capabilities after the restore shall be on the same slot (have the same address) in the capability space as before the checkpoint. The capability space resides in the kernel and Genode does not offer an API to manipulate it. Is there a way to accomplish my goal with Genode's API anyway? Kind regards, Denis

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Heeselicht scenario
by Stefan Kalkowski 11 Oct '16

11 Oct '16

Hello Genode folks, hereby, I'd like to announce my recent activity to turn the Turmvilla scenario published by Norman after last year's Hack'n'Hike into an USB live setup. Instead of the original variation, this scenario enables you to boot Genode natively from an USB stick on top of your favorite Intel x86 hardware. In parallel, you can execute your previous installed OS on disk inside a VirtualBox VM without further modifications. This setup offered me the opportunity to switch to Genode without the need to alter my current Linux working environment. Thinking that I'm not the only one that might be interested in such a setup, I've spent some time during our recent Hack'n'Hike in a nice old house in "Heeselicht" to facilitate the steps to reproduce this setup. If you are undaunted, and like to give it a try, you can have a look at the corresponding issue: https://github.com/genodelabs/genode/issues/2018 There are detailed instructions in the issue. For further assistance, leave a comment at the issue tracker or reply to this email. Regards Stefan -- Stefan Kalkowski Genode Labs http://www.genode-labs.com/ · http://genode.org/

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booting the SABRE tablet from SD card
by Rijurekha Sen 13 Sep '16

13 Sep '16

Hi, I compiled the demo according to https://github.com/skalk/genode/blob/i.MX53_tablet_demo/os/src/server/vmm/i…. Next to run the demo in the SABRE tablet, I followed the instruction in http://genode-main.narkive.com/qJXUD6w5/arm-trustzone-demo-in-i-mx53-sabre-…. Created the u-boot.imx using https://eewiki.net/display/linuxonarm/i.MX53+Quick+Start#i.MX53QuickStart-B… for the step 2) 2) sudo dd if=$(U-BOOT-DIR)/u-boot.imx of=/dev/sdb seek=2 bs=512 conv=fsync But when I put in the MMC card in the tablet with the SD card in it and restart the tablet, it just powers on to the default Android which it came with. How to get the u-boot prompt, as mentioned in step 4)? 4) After power up the tablet, U-BOOT prompt (u-boot from MMC is not used), I did as follows: MX53-SMD U-Boot > ext2load mmc 0:1 0x70800000 image.bin How to get this u-boot prompt? https://www.google.de/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0ahUKEwi… has a chapter 3 on various boot options. http://cache.freescale.com/files/32bit/doc/user_guide/IMX53SMDHUG.pdf shows the location of the switches sw26 and sw28 at the back of the board. Does that mean, I should open the back cover of the tablet to change these? Is this what http://genode-main.narkive.com/qJXUD6w5/arm-trustzone-demo-in-i-mx53-sabre-… did? Want to verify the correct thing to do as the tablet is expensive. Thanks! Riju

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Segfault when calling (Cancelable)Lock.unlock?
by Menno Valkema 31 Aug '16

31 Aug '16

Hi Everyone, I'm currently using a Nic_connection to exchange data data between components on linux_x86. Before sending data from the Nic server I first check whether any data can be freed. Even before the first packet is send out, using the code below: while ( _rx.source()->ack_avail() ) { _rx.source()->release_packet( _rx.source()->get_acked_packet() ); } Whenever I'm sending data out from an extern "C" method (callback passed to a c library), the application crashes. Looking with GDB, the issues seems to be with the destructor of the lock guard from the code from packet_stream.h (full GDB output at the bottom of this email). bool ready_for_rx() { Genode::Lock::Guard lock_guard(_rx_queue_lock); return !_rx_queue->empty(); } The destructor of the Guard simply calls the unlock method for the lock. However this crashes. Could it be that the unlock method throws an exception in the destructor, or that there might be uninitialized variables within the lock itself? I'm sort of lost here, because I've used the Nic_connection in similar settings in the past (also called from an extern "C" context as a c code callback). However this time it consistently breaks, whenever I try to sent out the first packet from an extern "c" context (it does work when sending the packet out from normal c++ code. Any suggestions what might causes the crash in my application? Cheers, Menno Program received signal SIGSEGV, Segmentation fault. 0x0000000001143c22 in ~Lock_guard (this=<optimized out>, __in_chrg=<optimized out>) at <project-path...>/repos/base/include/base/lock_guard.h:42 42 ~Lock_guard() { _lock.unlock(); } (gdb) bt #0 0x0000000001143c22 in ~Lock_guard (this=<optimized out>, __in_chrg=<optimized out>) at <project-path...>/repos/base/include/base/lock_guard.h:42 #1 ready_for_rx (this=<optimized out>) at <project-path...>/repos/os/include/os/packet_stream.h:400 #2 ack_avail (this=<optimized out>) at <project-path...>/repos/os/include/os/packet_stream.h:686 ....

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Announcement: Genode OS Framework version 16.08 released
by Christian Helmuth 31 Aug '16

31 Aug '16

This release is packed with lots of improvements in areas ranging from extended base-platform support over networking and virtualization to new tools for statistical profiling. We quite proudly announce extended support for the seL4 kernel as a platform for dynamic and interactive Genode scenarios on x86. The new version enables users of seL4 to compose dynamic operating systems from a plethora of ready-to-use Genode components. Further, the developers from Codelabs contribute their efforts in running unmodified guest operating systems on top their Muen separation kernel with a port of VirtualBox 4. As we consider VirtualBox as key feature of Genode, this release also includes a first experimental version of VirtualBox 5 on top of the NOVA kernel. Another highlight of the new version is a virtual networking component for routing and NAT accompanied by the ability to use the TOR network. The current release contains the following changes and new features. - Base platforms - Interactive and dynamic workloads on top of the seL4 kernel - Binary compatibility across all supported kernels - Xilinx Zynq board support for Parallela, Zedboard, ZC706, ZC702 - Networking - Virtual networking (routing, NAT) - New TOR component - ROM sessions in a network-distributed Genode system - Virtualization - VirtualBox 4 on top of the Muen separation kernel - Experimental version of VirtualBox 5 for NOVA - Libraries and components - Improved ACPI integration - Growing library of "shim" services such as a framebuffer scaler, an input remapper, a ROM fallback service, and a LOG duplicator - Ported 3rd-party software such as diffutils, less, mbed TLS, libxml2, RISC-V front-end server - New file-downloading component - Statistical profiling Find the complete release documentation for the version 16.08 at https://genode.org/documentation/release-notes/16.08 Happy hacking with Genode! -- Christian Helmuth Genode Labs http://www.genode-labs.com/ · http://genode.org/ https://twitter.com/GenodeLabs · /ˈdʒiː.nəʊd/ Genode Labs GmbH · Amtsgericht Dresden · HRB 28424 · Sitz Dresden Geschäftsführer: Dr.-Ing. Norman Feske, Christian Helmuth

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Stack overflow protection/detection
by Johannes Schlatow 31 Aug '16

31 Aug '16

Hi all, I guess you are familiar with the problem of stack overflows in multi-threaded components. I already encountered a bunch of weird errors that were hard to track down until I remembered that it could simply be caused by a too small stack. I know that Genode's policy is to use single-threaded components. Occasionally, however, one needs additional threads, especially when using 3rd party libraries. Stack overflows are not only very annoying and time consuming but can (imo) also be mitigated rather easily. I therefore think it would be worth implementing a protection or detection mechanism for this in Genode. The "problem" here is actually the `Stack_allocator` which places the stacks of the component threads consecutively in memory. I.e. if one thread exceeds its allocated stack area, it likely corrupts the stack of another thread (of the same component). Hence, one could improve the `Stack_allocator` so that it keeps a guard page between the stacks in order to cause a page fault on any stack overflow. This comes at the cost of a slightly increased complexity and possibly also an increased memory consumption (because it requires a second-level translation table). Alternatively, I can imagine a kernel-level (base-hw) approach which uses canaries at the top of each stack. Every time the kernel switches to a user thread, it checks whether the canary is still alive. If not, another thread's stack must have overflowed. Of course, this method is only reliable if we can assume that every memory word on the stack will be initialised (preferably sequentially). Note that I'm not eager to implement these techniques in the near future. Nevertheless, I thought it would be great to start a discussion and collect comments and additional ideas. Looking forward to your feedback! Cheers Johannes

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Genode 16.05 Fault handler
by Denis Huber 30 Aug '16

30 Aug '16

Dear Genode community, in Genode 16.05 the old usage of Signal_receivers and Signal_contexts is considered deprecated. Instead Signal_handler and Signal_transmitter shall be used. I am trying to use a Signal_handler as a fault handler for env's address space. I wrote a short test to illustrate the problem [1]. [1] https://github.com/702nADOS/genode-CheckpointRestore-SharedMemory/blob/c9a5… The output of [1] is as follows: " [init -> pf-signal_handler] --- pf-signal_handler started --- no RM attachment (WRITE pf_addr=1000 pf_ip=100061c from 2ae000) Genode::Pager_entrypoint::entry()::<lambda(Genode::Pager_object*)>: Could not resolve pf=1000 ip=100061c " The signal handler was registered correctly, because the line " Genode::Core_pd_session_component::submit(Genode::Capability<Genode::Signal_context>, unsigned int)::<lambda(Genode::Signal_context_component*)>: invalid signal-context capability " is missing. However, the method _handle_fault() is never entered. What am I doing wrong? Kind regards, Denis

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Upgrade session before quota exceedes
by Denis Huber 25 Aug '16

25 Aug '16

Dear Genode community, I want to dynamically create Region maps through an RM session (amount not known at compile time). If the RAM quota of the session exceedes, I want to upgrade the RAM quota of the session. For this case I wrote a small test [1] which creates Region maps until an exception is thrown and I tried to catch it. I realized that the exception was thrown in another thread (core's entrypoint probably), meaning I cannot catch it in my test component's thread. [1] https://github.com/702nADOS/genode-CheckpointRestore-SharedMemory/blob/0a78… For a better insight I logged the RAM quota consumption in Rm_session_component::create. The output of my test looks as follows: [init -> rm_stresser] --- Rm-creation-stresser started --- [init -> rm_stresser] Round 0 Alloc avail: 49152 [init -> rm_stresser] Round 1 Alloc avail: 36864 [init -> rm_stresser] Round 2 Alloc avail: 24576 [init -> rm_stresser] Round 3 Alloc avail: 12288 [init -> rm_stresser] Round 4 Alloc avail: 0 [init -> rm_stresser] Round 5 Quota exceeded! amount=61440, size=8192, consumed=61440 Uncaught exception of type 'Genode::Allocator::Out_of_memory' Warning: abort called - thread: entrypoint Is there an easy way to upgrade a session's RAM quota before allocating objects with no available RAM? If there is already a component in Genode which solves my problem, I would love to see the source code :) Kind regards, Denis

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users August 2016