coredump: coredump server support

[etiaro]

Description

Introduces kernel thread that uses messaging to inform coredump server process about crashed processes and provide any data required for creating coredump for post-mortem analysis with GDB.

Motivation and Context

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: ia32-generic-qemu, armv7r5f-zynqmp-qemu, sparcv8leon-generic-qemu

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 (list the PRs, preferably in merge-order).
• !syscalls: move signal handling to kernel #670
• hal/armvXm: use cpu_context_t as exc_context_t  #685
• I will merge this PR by myself when appropriate.

[gemini-code-assist]

Summary of Changes

Hello @etiaro, 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 coredump server functionality to the Phoenix-RTOS kernel. Its primary purpose is to capture the state of a crashed process, including its memory segments, threads, and context, to facilitate post-mortem debugging. This is achieved by integrating the coredump mechanism into the kernel's exception and process management systems, ensuring that fatal errors trigger a coredump rather than just halting the system.

Highlights

• Coredump Server Implementation: A new coredump server is added, capable of enqueuing crashed processes and providing their memory and thread information upon request.
• Enhanced Exception Handling: The kernel's exception handlers across various architectures are updated to initiate a coredump sequence instead of simply halting the CPU on fatal exceptions.
• Process and Thread Management Integration: Core process and thread management routines are modified to support the coredump lifecycle, including marking processes for coredump, handling thread termination during coredump, and managing memory deallocation.
• Build System Updates: The build system is updated to compile and link the new coredump server components into the kernel.
• Context and Relocation Handling: Improvements are made to how CPU contexts are saved and restored, and relocation information for processes (especially for NOMMU builds) is now accessible for coredump purposes.

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[gemini-code-assist]

Code Review

This pull request introduces coredump server support, a significant feature involving extensive changes across exception handling, process management, and thread lifecycle. The core logic is implemented in the new coredump module. While the overall approach is sound, I've identified several critical issues, including potential NULL pointer dereferences and a memory leak in proc_join. I've also provided suggestions to improve robustness and fix bugs in the coredump data handling. Please address these points to ensure the stability of this new functionality.