!syscalls: add portUnregister syscall

[julianuziemblo]

The functionality is there but was previously unused. Its useful with new remove_dev() userspace function that will call it if there's no filesystem.

Description

Motivation and Context

Depends-On: libphoenix:julianuziemblo/remove_dev

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Chore (refactoring, style fixes, git/CI config, submodule management, no code logic changes)

How Has This Been Tested?

• Already covered by automatic testing.
• New test added: (add PR link here).
• Tested by hand on: armv7m7-imxrt117x-evk

Checklist:

• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing linter checks and tests passed.
• My changes generate no new compilation warnings for any of the targets.

Special treatment

• This PR needs additional PRs to work:
  • Add destroy_dev() function as a counterpart to create_dev() libphoenix#466
• I will merge this PR by myself when appropriate.

[gemini-code-assist]

Summary of Changes

Hello, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request introduces a new portUnregister syscall, making previously existing kernel functionality accessible to userspace. This change is crucial for enabling more dynamic device management, specifically for scenarios where devices need to be removed and their associated ports unregistered, such as with the remove_dev() userspace function.

Highlights

• New portUnregister syscall: Exposed the portUnregister functionality as a new syscall, allowing userspace to unregister ports. This is particularly useful for new device removal mechanisms.

Changelog

• include/syscalls.h
  • Added portUnregister to the list of available syscall IDs.
• syscalls.c
  • Implemented the syscalls_portUnregister function, which retrieves the port name from the user stack and calls the proc_portUnregister kernel function.

Activity

• Pull request created by julianuziemblo.
• Identified as a breaking change.
• Tested manually on armv7m7-imxrt117x-evk.
• Depends on libphoenix:julianuziemblo/remove_dev.

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[gemini-code-assist]

Code Review

This pull request introduces a new portUnregister syscall. The implementation contains a critical bug where it reads an argument from an incorrect stack offset, which would cause it to fail. I've provided a fix for this. Additionally, I've pointed out a security vulnerability related to handling strings from userspace and a design issue with the function's return type that prevents error handling. Addressing these would significantly improve the robustness and security of the new syscall.

[github-actions]

Unit Test Results

9 553 tests  ±0   8 961 ✅ ±0   52m 45s ⏱️ -1s
  591 suites ±0     592 💤 ±0 
    1 files   ±0       0 ❌ ±0 

Results for commit d575864. ± Comparison against base commit cbfa5d0.

♻️ This comment has been updated with latest results.

[nalajcie]

please use the same branch name for related changes in different repos - that way you won't need to use Depends-On and it will look sane for the developer checking-out your change locally if needed.

[julianuziemblo]

please use the same branch name for related changes in different repos - that way you won't need to use Depends-On and it will look sane for the developer checking-out your change locally if needed.

Agreed, but these changes are related only one way, same branch names might have been confusing. Next time I'll try to find a matching one tho.

[agkaminski]

Not that sure it will work well, have no problem with addition of syscall

[julianuziemblo]

Not that sure it will work well, has no problem with addition of syscall

I'll add some tests before merging

[nalajcie]

not sure but at https://github.com/phoenix-rtos/phoenix-rtos-kernel/blob/master/proc/name.c#L140 it should probably be entry->next instead of NULL?

I'm also not sure about generic approach - if we would like for the servers to be restartable - it would be better to have the same port number as the previous instance, so actually re-reading port from the dev and reclaiming it might be a better approach (clients doesn't need to re-lookup). Might not matter that much if we switch the message API to explicit open/close connection.

[agkaminski]

I guess usage of len deeper is TODO (what if I lie about len when executing the syscall)?