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This patch fixes a race condition triggered by the thread test running on Linux inside VirtualBox. The 'test_stack_alloc' sporadically produced one of two errors: A segfault in the 'Thread::deinit_platform_thread' on the attempt to access the 'native_thread' of the to-be-destructed thread (this data structure is located on the thread's stack). Or, an error message about a region conflict within the stack area. The problem was that two instances of 'Region_map_mmap' issued a sequence of munmap and mmap each. Even though each instance locked the attach/detach operations, the lock was held per instance. In a situation where two instances performed attach/detach operations in parallel, the syscall sequences could interfere with each other. In the test scenario, the two region-map instances are the test's address space and the stack area. When creating a thread, the thread's trace-control dataspace is attached at an arbitrary place (picked by the Linux kernel) within the address space whereas the stack is attached at the stack area. The problem is the following sequence: Thread A wants to destruct a thread: 1. Remove stack from stack area (issue unmap syscall) 2. Preserve virtual address range that was occupied from the stack so that Linux won't use it (issue mmap syscall) Thread B wants to construct a thread: 1. Request trace-control dataspace from CPU session 2. Attach trace-control dataspace to address space at a location picked by the Linux kernel (issue mmap syscall) The problem occurs when thread B's second step is executed in between the steps 1 and 2 of thread A and the Linux kernel picks the just-unmapped address as the location for the new trace-control mapping. Now, the trace control dataspace is mapped at the virtual address that was designated for the stack of the to-be-created thread, and the attempt to map the real stack fails. The patch fixes the problem by replacing the former region-map-local locks by a component-global lock. Furthermore, it cleans up core's implementation of the support function for the region-map-mmap implementation, eliminating the temporary unlocking of the region-map lock during RPC. |
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.. | ||
base | ||
base-fiasco | ||
base-foc | ||
base-hw | ||
base-linux | ||
base-nova | ||
base-okl4 | ||
base-pistachio | ||
base-sel4 | ||
dde_bsd | ||
dde_ipxe | ||
dde_linux | ||
dde_rump | ||
demo | ||
gems | ||
hello_tutorial | ||
libports | ||
os | ||
ports | ||
ports-foc | ||
README |
=============================== Genode source-code repositories =============================== This directory contains the source-code repositories of the Genode OS Framework. Each sub directory has the same principle layout as described in the build-system manual: :Build-system manual: [https://genode.org/documentation/developer-resources/build_system] The build system uses a configurable selection of those reposities to obtain the source codes for the build process. The repositories are not independent but build upon of each other: :'base': This directory contains the source-code repository of the fundamental frameworks and interfaces of Genode. Furthermore, it contains the generic parts of core. :'base-<platform>': These directories contain platform-specific source-code repositories complementing the 'base' repository. The following platforms are supported: :'linux': Linux kernel (both x86_32 and x86_64) :'nova': NOVA hypervisor developed at University of Technology Dresden See [https://genode.org/documentation/platforms/nova] :'foc': Fiasco.OC is a modernized version of the Fiasco microkernel with a completely revised kernel interface fostering capability-based security. It is not compatible with L4/Fiasco. See [https://genode.org/documentation/platforms/foc] :'hw': The hw platform allows the execution of Genode on bare ARM and x86 hardware without the need for a separate kernel. The kernel functionality is included in core except in the special case of the Muen separation kernel. See [https://genode.org/documentation/platforms/hw] and [https://genode.org/documentation/platforms/muen] :'okl4': OKL4 kernel (x86_32 and ARM) developed at Open-Kernel-Labs. See [https://genode.org/documentation/platforms/okl4] :'pistachio': L4ka::Pistachio kernel developed at University of Karlsruhe. See [https://genode.org/documentation/platforms/pistachio] :'fiasco': L4/Fiasco kernel developed at University of Technology Dresden. See [https://genode.org/documentation/platforms/fiasco] :'sel4': seL4 microkernel developed at NICTA/General Dynamics See[https://sel4.systems/] :'os': This directory contains the non-base OS components such as the init process, device drivers, and basic system services. :'demo': This directory contains the source-code repository of various services and applications that we use for demonstration purposes. For example, a graphical application launcher called Launchpad and the Scout tutorial browser. :'hello_tutorial': Tutorial for creating a simple client-server scenario with Genode. This repository includes documentation and the complete source code. :'libports': This source-code repository contains ports of popular open-source libraries to Genode, most importantly the C library. The repository contains no upstream source code but means to download the code and adapt it to Genode. For instructions about how to use this mechanism, please consult the README file at the top level of the repository. Among the 3rd-party libraries are Qt5, libSDL, freetype, Python, ncurses, Mesa, and libav. :'dde_linux': This source-code repository contains the device driver environment for executing Linux device drivers natively on Genode. Currently, this repository hosts the USB stack. :'dde_ipxe': This source-code repository contains the device-driver environment for executing drivers of the iPXE project. :'dde_bsd': This source-code repository contains the device-driver environment for drivers of the OpenBSD operating system. :'dde_rump': This source-code repository contains the port of rump kernels, which are used to execute subsystems of the NetBSD kernel as user level processes. The repository contains a server that uses a rump kernel to provide various NetBSD file systems to Genode. :'ports': This source-code repository hosts ports of 3rd-party applications to Genode. The repository does not contain upstream source code but provides a mechanism for downloading the official source distributions and adapt them to the Genode environment. The used mechanism is roughly the same as used for the 'libports' repository. Please consult 'libports/README' for further information. :'ports-<platform>': These platform-specific source-code repositories contain software that capitalizes special features of the respective kernel platform. For the Fiasco.OC platform, 'ports-foc' hosts a port of the L4Linux kernel. For further information, please refer to the README file at the top level of the respective repository. :'gems': This source-code repository contains Genode applications that use both native Genode interfaces as well as features of other high-level repositories, in particular shared libraries provided by 'libports'.