wireguard-linux/arch/um/include/shared/skas, branch update-toolchain

um: refactor TLB update handling

2024-07-03T15:09:50Z

Conceptually, we want the memory mappings to always be up to date and represent whatever is in the TLB. To ensure that, we need to sync them over in the userspace case and for the kernel we need to process the mappings. The kernel will call flush_tlb_* if page table entries that were valid before become invalid. Unfortunately, this is not the case if entries are added. As such, change both flush_tlb_* and set_ptes to track the memory range that has to be synchronized. For the kernel, we need to execute a flush_tlb_kern_* immediately but we can wait for the first page fault in case of set_ptes. For userspace in contrast we only store that a range of memory needs to be synced and do so whenever we switch to that process. Signed-off-by: Benjamin Berg Link: https://patch.msgid.link/20240703134536.1161108-13-benjamin@sipsolutions.net Signed-off-by: Johannes Berg

um: Delay flushing syscalls until the thread is restarted

2024-07-03T15:09:49Z

As running the syscalls is expensive due to context switches, we should do so as late as possible in case more syscalls need to be queued later on. This will also benefit a later move to a SECCOMP enabled userspace as in that case the need for extra context switches is removed entirely. Signed-off-by: Benjamin Berg Link: https://patch.msgid.link/20240703134536.1161108-9-benjamin@sipsolutions.net Signed-off-by: Johannes Berg

um: remove copy_context_skas0

2024-07-03T15:09:49Z

The kernel flushes the memory ranges anyway for CoW and does not assume that the userspace process has anything set up already. So, start with a fresh process for the new mm context. Signed-off-by: Benjamin Berg Link: https://patch.msgid.link/20240703134536.1161108-8-benjamin@sipsolutions.net Signed-off-by: Johannes Berg

um: remove LDT support

2024-07-03T15:09:49Z

The current LDT code has a few issues that mean it should be redone in a different way once we always start with a fresh MM even when cloning. In a new and better world, the kernel would just ensure its own LDT is clear at startup. At that point, all that is needed is a simple function to populate the LDT from another MM in arch_dup_mmap combined with some tracking of the installed LDT entries for each MM. Note that the old implementation was even incorrect with regard to reading, as it copied out the LDT entries in the internal format rather than converting them to the userspace structure. Removal should be fine as the LDT is not used for thread-local storage anymore. Signed-off-by: Benjamin Berg Link: https://patch.msgid.link/20240703134536.1161108-7-benjamin@sipsolutions.net Signed-off-by: Johannes Berg

um: Rework syscall handling

2024-07-03T15:09:49Z

Rework syscall handling to be platform independent. Also create a clean split between queueing of syscalls and flushing them out, removing the need to keep state in the code that triggers the syscalls. The code adds syscall_data_len to the global mm_id structure. This will be used later to allow surrounding code to track whether syscalls still need to run and if errors occurred. Signed-off-by: Benjamin Berg Link: https://patch.msgid.link/20240703134536.1161108-5-benjamin@sipsolutions.net Signed-off-by: Johannes Berg

um: Create signal stack memory assignment in stub_data

2024-07-03T15:09:48Z

When we switch to use seccomp, we need both the signal stack and other data (i.e. syscall information) to co-exist in the stub data. To facilitate this, start by defining separate memory areas for the stack and syscall data. This moves the signal stack onto a new page as the memory area is not sufficient to hold both signal stack and syscall information. Only change the signal stack setup for now, as the syscall code will be reworked later. Signed-off-by: Benjamin Berg Link: https://patch.msgid.link/20240703134536.1161108-3-benjamin@sipsolutions.net Signed-off-by: Johannes Berg

um: Fix the -Wmissing-prototypes warning for __switch_mm

2024-04-30T12:14:08Z

The __switch_mm function is defined in the user code, and is called by the kernel code. It should be declared in a shared header. Fixes: 4dc706c2f292 ("um: take um_mmu.h to asm/mmu.h, clean asm/mmu_context.h a bit") Signed-off-by: Tiwei Bie Signed-off-by: Richard Weinberger

um: separate child and parent errors in clone stub

2021-02-12T20:34:33Z

If the two are mixed up, then it looks as though the parent returned an error if the child failed (before) the mmap(), and then the resulting process never gets killed. Fix this by splitting the child and parent errors, reporting and using them appropriately. Signed-off-by: Johannes Berg Signed-off-by: Richard Weinberger

um: defer killing userspace on page table update failures

2021-02-12T20:32:04Z

In some cases we can get to fix_range_common() with mmap_sem held, and in others we get there without it being held. For example, we get there with it held from sys_mprotect(), and without it held from fork_handler(). Avoid any issues in this and simply defer killing the task until it runs the next time. Do it on the mm so that another task that shares the same mm can't continue running afterwards. Cc: stable@vger.kernel.org Fixes: 468f65976a8d ("um: Fix hung task in fix_range_common()") Signed-off-by: Johannes Berg Signed-off-by: Richard Weinberger

um: Add SPDX headers for files in arch/um/include

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