feat(arm64): init system, proper heap allocator, TTBR0 and ERET fixes#165
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feat(arm64): init system, proper heap allocator, TTBR0 and ERET fixes#165
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…0 on syscall resume Implement ARM64 init system (/sbin/init) that spawns telnetd and init_shell, replacing direct init_shell boot. Fix three critical bugs discovered during testing: 1. Heap exhaustion (OOM): Replace bump allocator with linked_list_allocator. The bump allocator never reclaimed freed memory, exhausting the 32MB heap within seconds of boot as temporary Vec/String/BTreeMap allocations permanently consumed space. Also remove unnecessary Box::leak calls in exec syscall paths (ARM64 and x86_64) that leaked entire ELF binaries. 2. TTBR0 stale after blocking syscall: When a userspace thread blocked in a syscall (e.g., read() on stdin) was context-switched back in, setup_kernel_thread_return_arm64 did not restore the process's page table. TTBR0 retained the previously-running process's value, causing instruction abort permission faults when the thread returned to EL0 with the wrong address space. 3. Register clobber fixes in ERET paths: Use per-CPU eret_scratch field to save/restore registers across SP switches in both syscall and IRQ return paths, preventing x0/x1 corruption (syscall) and x16 corruption (IRQ). 4. TTBR0 restoration after exec: Update saved_process_cr3 after exec switches to the new program's page table, preventing the assembly ERET path from restoring the old (freed) page table. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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Summary
/sbin/initbinary that spawns telnetd and init_shell, with zombie reaping and service respawnlinked_list_allocator— the bump allocator never reclaimed freed memory, causing OOM within seconds of bootBox::leakof ELF data and program names in exec syscall paths (ARM64 + x86_64)Test plan
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