kernel.git/arch/um/kernel/skas/syscall.c, branch master

um: simplify syscall header files

2025-07-11T06:49:02Z

Since Thomas's recent commit 2af10530639b ("um/x86: Add system call table to header file") , we now have two extern declarations of the syscall table, one internal and one external, and they don't even match on 32-bit. Clean this up and remove all the extra code. Reviewed-by: Thomas Weißschuh Link: https://patch.msgid.link/20250704141243.a68366f6acc3.If8587a4aafdb90644fc6d0b2f5e31a2d1887915f@changeid Signed-off-by: Johannes Berg

um: work around sched_yield not yielding in time-travel mode

2025-03-18T10:06:20Z

sched_yield by a userspace may not actually cause scheduling in time-travel mode as no time has passed. In the case seen it appears to be a badly implemented userspace spinlock in ASAN. Unfortunately, with time-travel it causes an extreme slowdown or even deadlock depending on the kernel configuration (CONFIG_UML_MAX_USERSPACE_ITERATIONS). Work around it by accounting time to the process whenever it executes a sched_yield syscall. Signed-off-by: Benjamin Berg Link: https://patch.msgid.link/20250314130815.226872-1-benjamin@sipsolutions.net Signed-off-by: Johannes Berg

um: fix time-travel syscall scheduling hack

2024-09-12T18:46:23Z

The schedule() call there really never did anything at least since the introduction of the EEVDF scheduler, but now I found a case where we permanently hang in a loop of -ERESTARTNOINTR (due to locking.) Work around it by making any syscalls with error return take time (and then schedule after) so we cannot hang in such a loop forever. Signed-off-by: Johannes Berg Signed-off-by: Richard Weinberger

x86/syscalls: Use __NR_syscalls instead of __NR_syscall_max

2021-05-20T13:03:59Z

__NR_syscall_max is only used by x86 and UML. In contrast, __NR_syscalls is widely used by all the architectures. Convert __NR_syscall_max to __NR_syscalls and adjust the usage sites. This prepares x86 to switch to the generic syscallhdr.sh script. Signed-off-by: Masahiro Yamada Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/r/20210517073815.97426-6-masahiroy@kernel.org

um: syscall.c: include

2020-04-29T19:22:04Z

Without CONFIG_SECCOMP, we don't get this include recursively through the existing includes, thus failing the build on not having __NR_syscall_max defined. Add the necessary include to fix this. Signed-off-by: Johannes Berg Acked-By: Anton Ivanov Signed-off-by: Richard Weinberger

um: Implement time-travel=ext

2020-03-29T21:29:08Z

This implements synchronized time-travel mode which - using a special application on a unix socket - lets multiple machines take part in a time-travelling simulation together. The protocol for the unix domain socket is defined in the new file include/uapi/linux/um_timetravel.h. Signed-off-by: Johannes Berg Signed-off-by: Richard Weinberger

um: Move timer-internal.h to non-shared

2020-03-29T21:28:43Z

This file isn't really shared, it's only used on the kernel side, not on the user side. Remove the include from the user-side and move the file to a better place. While at it, rename it to time-internal.h, it's not really just timers but all kinds of things related to timekeeping. Signed-off-by: Johannes Berg Signed-off-by: Richard Weinberger

seccomp: simplify secure_computing()

2019-10-10T21:55:24Z

Afaict, the struct seccomp_data argument to secure_computing() is unused by all current callers. So let's remove it. The argument was added in [1]. It was added because having the arch supply the syscall arguments used to be faster than having it done by secure_computing() (cf. Andy's comment in [2]). This is not true anymore though. /* References */ [1]: 2f275de5d1ed ("seccomp: Add a seccomp_data parameter secure_computing()") [2]: https://lore.kernel.org/r/CALCETrU_fs_At-hTpr231kpaAd0z7xJN4ku-DvzhRU6cvcJA_w@mail.gmail.com Signed-off-by: Christian Brauner Cc: Andy Lutomirski Cc: Thomas Gleixner Cc: Will Drewry Cc: Oleg Nesterov Cc: linux-arm-kernel@lists.infradead.org Cc: linux-parisc@vger.kernel.org Cc: linux-s390@vger.kernel.org Cc: linux-um@lists.infradead.org Cc: x86@kernel.org Acked-by: Borislav Petkov Acked-by: Andy Lutomirski Link: https://lore.kernel.org/r/20190924064420.6353-1-christian.brauner@ubuntu.com Signed-off-by: Kees Cook

um: Add SPDX headers to files in arch/um/kernel/

2019-09-15T19:37:17Z

Convert files to use SPDX header. All files are licensed under the GPLv2. Signed-off-by: Alex Dewar Signed-off-by: Richard Weinberger

um: Support time travel mode

2019-07-02T21:27:36Z

Sometimes it can be useful to run with "time travel" inside the UML instance, for example for testing. For example, some tests for the wireless subsystem and userspace are based on hwsim, a virtual wireless adapter. Some tests can take a long time to run because they e.g. wait for 120 seconds to elapse for some regulatory checks. This obviously goes faster if it need not actually wait that long, but time inside the test environment just "bumps up" when there's nothing to do. Add CONFIG_UML_TIME_TRAVEL_SUPPORT to enable code to support such modes at runtime, selected on the command line: * just "time-travel", in which time inside the UML instance can move faster than real time, if there's nothing to do * "time-travel=inf-cpu" in which time also moves slower and any CPU processing takes no time at all, which allows to implement consistent behaviour regardless of host CPU load (or speed) or debug overhead. An additional "time-travel-start=" parameter is also supported in this case to start the wall clock at this time (in unix epoch). With this enabled, the test mentioned above goes from a runtime of about 140 seconds (with startup overhead and all) to being CPU bound and finishing in 15 seconds (on my slow laptop). Signed-off-by: Johannes Berg Signed-off-by: Richard Weinberger