Remove old code

Signed-off-by: Richard Qin <richard.qin.x@gmail.com>

1 files changed, 0 insertions, 780 deletions

diff --git a/kernel/task.cc b/kernel/task.cc
deleted file mode 100644
index 9f9b043..0000000
--- a/kernel/task.cc
+++ /dev/null
@@ -1,780 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0-or-later */
-/* Copyright (C) 2026 Richard Qin */
-
-/*
- * Task Management — create, exit, destroy, kthread
- *
- * Implements task lifecycle management: kernel thread creation,
- * task exit (zombie transition), and resource reclamation.
- *
- * Reference: docs/specs/task.md §4-§6
- */
-
-#include <lume/task.h>
-#include <lume/sched.h>
-#include <lume/pmm.h>
-#include <lume/addr.h>
-#include <lume/new.h>
-#include <lume/kprintf.h>
-#include <lume/klog.h>
-#include <lume/vmm.h>
-#include <lume/errno.h>
-#include <lume/pid.h>
-#include <lume/wait.h>
-#include <lume/clone.h>
-#include <lume/signal_nr.h>
-#include <arch/cpu.h>
-#include <arch/context.h>
-#include <lume/uaccess.h>
-#include <lume/fs_struct.h>
-#include <lume/fdtable.h>
-#include <lume/signal.h>
-#include <lume/signal_types.h>
-#include <lume/pgrp.h>
-#include <arch/pmap.h>
-#include <kernel/sync/spinlock.h>
-
-/* ======================================================================
- * Forward declarations
- * ====================================================================== */
-
-extern "C" void kthread_entry_trampoline();
-extern "C" void ret_from_fork();
-
-/* ======================================================================
- * Global task list
- * ====================================================================== */
-
-list_node g_all_tasks;
-Spinlock g_task_list_lock;
-int32 g_nr_tasks = 0;
-
-/* Special tasks */
-TaskControlBlock* g_kernel_task = nullptr;  /* PID 0 container */
-TaskControlBlock* g_init_task = nullptr;    /* PID 1 (future) */
-
-/* ======================================================================
- * task_init() — called once from kernel_main before sched_init
- * ====================================================================== */
-
-void task_init()
-{
-    g_all_tasks.init();
-    g_task_list_lock.init("task_list");
-    g_pid_alloc.init();
-
-    printk(KERN_INFO "init: task_init done (pid_alloc ready)\n");
-}
-
-/* ======================================================================
- * alloc_task — allocate TCB + kernel stack
- *
- * This is the SINGLE canonical TCB initializer. Both kthread_create
- * (task.cc) and sched_init (sched_core.cc) must use this function.
- * NEVER duplicate this logic — adding fields to TaskControlBlock
- * requires updating only this function.
- * ====================================================================== */
-
-TaskControlBlock* alloc_task(const char* name, uint8 priority,
-                             uint8 flags, uint8 cpu)
-{
-    auto* task = new TaskControlBlock;
-    if (!task) return nullptr;
-
-    task->context = {};
-
-    /* Allocate 8KB kernel stack (order-1 = 2 pages) */
-    Page* stack_page = pmm_alloc_pages(1);
-    if (!stack_page) {
-        delete task;
-        return nullptr;
-    }
-    task->kstack_pa = page_to_pa(stack_page).raw;
-    task->kstack_va = pa_to_va(phys_addr(task->kstack_pa)).raw;
-
-    /* Write stack canary at bottom */
-    *reinterpret_cast<uint64*>(task->kstack_va) = kStackCanary;
-
-    /* Place TrapFrame at the top of the kernel stack (like Linux pt_regs).
-     * ALL tasks — kernel threads and user processes — have a TrapFrame
-     * here. kthread_create sets the initial SP below the TrapFrame so
-     * the kthread function never touches this reserved area.
-     * kernel_execve / do_execve can later fill it in for user-mode return. */
-    uint64 tf_addr = task->kstack_va + kKernelStackSize
-                     - sizeof(arch::TrapFrame);
-    task->trapframe = reinterpret_cast<arch::TrapFrame*>(tf_addr);
-    __builtin_memset(task->trapframe, 0, sizeof(arch::TrapFrame));
-
-    /* Basic fields */
-    task->name = name;
-    task->priority = priority;
-    task->time_slice = priority_to_timeslice(priority);
-    task->state = TaskState::Runnable;
-    task->cpu_id = cpu;
-    task->flags = flags;
-    task->exit_code = 0;
-    task->exit_signal = 0;
-    task->preempt_count = 0;
-    task->clear_child_tid = 0;
-    task->stopped_code = 0;
-    task->notify_continued = false;
-    task->parent = nullptr;
-    task->mm = nullptr;
-    task->fpstate = {};
-    task->files = nullptr;
-    task->fs = nullptr;
-    task->pending.init();
-    task->blocked.clear();
-    task->sighand = nullptr;
-    task->signal  = nullptr;
-
-    /* Init all list nodes */
-    task->run_link.init();
-    task->all_link.init();
-    task->children.init();
-    task->sibling.init();
-    task->lock.init("task");
-    task->wait_chld.init("wait_chld");
-
-    /* Default sched class */
-    extern const SchedClass g_sched_class_o1;
-    task->sched_class = &g_sched_class_o1;
-    task->sched_entity = &task->run_link;
-
-    return task;
-}
-
-/* Add task to global task list */
-static void task_list_add(TaskControlBlock* task)
-{
-    LockGuard guard(g_task_list_lock);
-
-    list_node* head = &g_all_tasks;
-    task->all_link.prev = head->prev;
-    task->all_link.next = head;
-    head->prev->next = &task->all_link;
-    head->prev = &task->all_link;
-
-    g_nr_tasks++;
-}
-
-/* Remove task from global task list */
-static void task_list_remove(TaskControlBlock* task)
-{
-    LockGuard guard(g_task_list_lock);
-
-    task->all_link.prev->next = task->all_link.next;
-    task->all_link.next->prev = task->all_link.prev;
-    task->all_link.init();
-
-    if (g_nr_tasks > 0)
-        g_nr_tasks--;
-}
-
-/* ======================================================================
- * kthread_create — create a kernel thread
- * ====================================================================== */
-
-TaskControlBlock* kthread_create(const char* name,
-                                 void (*entry)(void*),
-                                 void* arg,
-                                 uint8 priority)
-{
-    TaskControlBlock* task = alloc_task(name, priority, TF_KTHREAD,
-                                         static_cast<uint8>(arch::cpu::id()));
-    if (!task) return nullptr;
-
-    /* Allocate PID */
-    task->pid = g_pid_alloc.alloc();
-    if (task->pid < 0) {
-        /* PID exhausted — clean up */
-            pmm_free_pages(pa_to_page(phys_addr(task->kstack_pa)), 1);
-        delete task;
-        return nullptr;
-    }
-    task->tgid = task->pid;
-
-    /* Kernel threads: exit_signal = -1 → auto-reap on exit.
-     * Linux: kernel_thread() passes (flags & ~CSIGNAL) → exit_signal = 0,
-     * but kthreads' parent (kthreadd) reaps them.  We have no kthreadd,
-     * so we use -1 which makes exit_notify() call release_task() directly,
-     * identical to Linux's CLONE_THREAD autoreap path. */
-    task->exit_signal = -1;
-
-    /* Set up context for kthread_entry_trampoline.
-     * SP starts BELOW the TrapFrame reserved at the stack top.
-     * This ensures the kthread function never clobbers the TrapFrame area. */
-    uint64 stack_top = task->kstack_va + kKernelStackSize
-                       - sizeof(arch::TrapFrame);
-    task->context = {};
-    task->context.ra = reinterpret_cast<uint64>(kthread_entry_trampoline);
-    task->context.sp = stack_top;
-    task->context.s[0] = reinterpret_cast<uint64>(entry);
-    task->context.s[1] = reinterpret_cast<uint64>(arg);
-
-    /* Parent is kernel_task (PID 0) or current caller */
-    TaskControlBlock* parent = g_kernel_task ? g_kernel_task : current_task();
-    task->parent = parent;
-    if (parent) {
-        LockGuard guard(parent->lock);
-        list_node* head = &parent->children;
-        task->sibling.prev = head->prev;
-        task->sibling.next = head;
-        head->prev->next = &task->sibling;
-        head->prev = &task->sibling;
-    }
-
-    /* Add to global list and enqueue */
-    task_list_add(task);
-    sched_enqueue(task);
-
-    return task;
-}
-
-/* ======================================================================
- * task_exit — transition current task to Zombie
- * ====================================================================== */
-
-void task_exit(int code)
-{
-    TaskControlBlock* curr = current_task();
-    if (!curr) kernel_panic("task_exit: no current task");
-
-    /* Linux ABI: normal exit encodes status as (code & 0xFF) << 8 */
-    curr->exit_code = (code & 0xFF) << 8;
-
-    /* CLONE_CHILD_CLEARTID / set_tid_address: write 0 to user tidptr.
-     * This is how pthread_join detects thread termination.
-     * TODO: futex_wake(clear_child_tid, 1) after writing 0. */
-    if (curr->clear_child_tid != 0 && curr->mm != nullptr) {
-        int32 zero = 0;
-        copy_to_user(curr->clear_child_tid, &zero, sizeof(zero));
-        curr->clear_child_tid = 0;
-    }
-
-    /* Release user address space (refcount-safe).
-     * MUST switch to kernel page table FIRST — otherwise we're running
-     * on a freed page table after put() deallocates it. */
-    if (curr->mm != nullptr) {
-        extern uint64 g_kernel_pgtbl;
-        pmap::activate(g_kernel_pgtbl);
-        curr->mm->put();
-        curr->mm = nullptr;
-    }
-
-    /* Reparent children to init (or kernel_task if no init yet) */
-    TaskControlBlock* foster = g_init_task ? g_init_task : g_kernel_task;
-    if (foster && !curr->children.is_empty()) {
-        LockGuard guard(curr->lock);
-
-        list_node* child_node = curr->children.next;
-        while (child_node != &curr->children) {
-            list_node* next_sib = child_node->next;
-            auto* child = list_entry<TaskControlBlock,
-                                     &TaskControlBlock::sibling>(child_node);
-            child->parent = foster;
-
-            /* Move sibling link to foster's children */
-            child_node->prev->next = child_node->next;
-            child_node->next->prev = child_node->prev;
-
-            list_node* fhead = &foster->children;
-            child_node->prev = fhead->prev;
-            child_node->next = fhead;
-            fhead->prev->next = child_node;
-            fhead->prev = child_node;
-
-            child_node = next_sib;
-        }
-        curr->children.init();
-    }
-
-
-    /* ---- exit_notify: Linux kernel/exit.c:exit_notify() ----
-     * Determine whether this task should be auto-reaped or become zombie.
-     *
-     * Linux logic (simplified):
-     *   - exit_signal == -1 (kthreads, sub-threads): autoreap = true
-     *   - exit_signal >= 1 (user processes): notify parent, become zombie
-     *
-     * If autoreap, we call release_task() equivalent inline:
-     * free PID, remove from task list, then deschedule to Dead. */
-    bool autoreap = (curr->exit_signal <= 0);
-
-    if (autoreap) {
-        /* Auto-reap: release resources immediately (no zombie state).
-         * Linux: exit_notify() → tsk->exit_state = EXIT_DEAD → release_task() */
-        task_list_remove(curr);
-        g_pid_alloc.free(curr->pid);
-
-        /* Remove from parent's children list */
-        curr->sibling.prev->next = curr->sibling.next;
-        curr->sibling.next->prev = curr->sibling.prev;
-        curr->sibling.init();
-
-        /* Drop signal_struct ref: last task in the thread group also
-         * detaches us from the pgrp hash. */
-        if (curr->signal) {
-            put_signal_struct(curr->signal);
-            curr->signal = nullptr;
-        }
-        if (curr->sighand) {
-            put_sighand(curr->sighand);
-            curr->sighand = nullptr;
-        }
-
-        curr->state = TaskState::Dead;
-        schedule();
-        __builtin_unreachable();
-    }
-
-    /* User process path: become Zombie for parent wait() */
-    curr->state = TaskState::Zombie;
-
-    /* Wake parent->wait_chld queue */
-    if (curr->parent) {
-        curr->parent->wait_chld.wake_all();
-    }
-
-    /* Yield CPU — never returns */
-    schedule();
-
-    __builtin_unreachable();
-}
-
-void task_kill_current(int sig)
-{
-    TaskControlBlock* curr = current_task();
-    if (!curr) kernel_panic("task_kill_current: no current task");
-
-    /* Linux ABI: signal-killed encodes status as (signo & 0x7F) */
-    curr->exit_code = sig & 0x7F;
-
-    /* Release user address space (refcount-safe).
-     * Switch to kernel page table first (same as task_exit). */
-    if (curr->mm) {
-        extern uint64 g_kernel_pgtbl;
-        pmap::activate(g_kernel_pgtbl);
-        curr->mm->put();
-        curr->mm = nullptr;
-    }
-
-    /* Reparent children (same as task_exit) */
-    TaskControlBlock* foster = g_init_task ? g_init_task : g_kernel_task;
-    if (foster && !curr->children.is_empty()) {
-        LockGuard guard(curr->lock);
-
-        list_node* child_node = curr->children.next;
-        while (child_node != &curr->children) {
-            list_node* next_sib = child_node->next;
-            auto* child = list_entry<TaskControlBlock,
-                                     &TaskControlBlock::sibling>(child_node);
-            child->parent = foster;
-
-            child_node->prev->next = child_node->next;
-            child_node->next->prev = child_node->prev;
-
-            list_node* fhead = &foster->children;
-            child_node->prev = fhead->prev;
-            child_node->next = fhead;
-            fhead->prev->next = child_node;
-            fhead->prev = child_node;
-
-            child_node = next_sib;
-        }
-        curr->children.init();
-    }
-
-    curr->state = TaskState::Zombie;
-
-    if (curr->parent) {
-        curr->parent->wait_chld.wake_all();
-    }
-
-    schedule();
-    __builtin_unreachable();
-}
-
-/* ======================================================================
- * task_destroy — fully reclaim a Zombie task (called by waitpid)
- * ====================================================================== */
-
-void task_destroy(TaskControlBlock* task)
-{
-    /* Remove from global list */
-    task_list_remove(task);
-
-    /* Remove from parent's children */
-    task->sibling.prev->next = task->sibling.next;
-    task->sibling.next->prev = task->sibling.prev;
-    task->sibling.init();
-
-    /* Free PID */
-    g_pid_alloc.free(task->pid);
-
-    /* Drop signal_struct + sighand refs.  For zombies these are delayed
-     * until reap (here) so a waitpid() walker can still inspect
-     * pgid/sid; Linux defers __exit_signal/__cleanup_sighand to
-     * release_task() for the same reason. */
-    if (task->signal) {
-        put_signal_struct(task->signal);
-        task->signal = nullptr;
-    }
-    if (task->sighand) {
-        put_sighand(task->sighand);
-        task->sighand = nullptr;
-    }
-
-    /* Free kernel stack */
-    if (task->kstack_pa != 0) {
-           pmm_free_pages(pa_to_page(phys_addr(task->kstack_pa)), 1);
-    }
-
-    /* Free TCB */
-    delete task;
-}
-
-/* ======================================================================
- * do_wait4 — wait for a child to exit (Linux-compatible)
- *
- * @wait_pid: >0  = specific child PID
- *            -1  = any child
- *            0   = any child in same process group (TODO)
- *            <-1 = any child in specific process group (TODO)
- * @options:  WNOHANG = return immediately if no zombie
- * @exit_code: output parameter (already in Linux wstatus format)
- *
- * Returns: PID of exited child, -ECHILD, or -EAGAIN (WNOHANG).
- * ====================================================================== */
-
-int32 do_wait4(int32 wait_pid, int options, int32* exit_code)
-{
-    TaskControlBlock* curr = current_task();
-    if (!curr) return -EINVAL;
-
-    while (true) {
-        TaskControlBlock* zombie = nullptr;
-        TaskControlBlock* report = nullptr;   /* Stopped/Continued report */
-        int32 report_status = 0;
-        bool has_children = false;
-
-        /*
-         * Two-phase wait: put ourselves on the wait queue BEFORE
-         * checking the condition. This closes the race window where
-         * a child exits between our check and schedule().
-         *
-         * If a child exits and calls wake_all() while we're checking,
-         * our state will be flipped back to Runnable, and schedule()
-         * will simply return immediately.
-         */
-        curr->wait_chld.prepare_to_wait(curr, TaskState::Sleeping);
-
-        /* Scan children */
-        curr->lock.acquire();
-
-        if (curr->children.is_empty()) {
-            curr->lock.release();
-            curr->wait_chld.finish_wait(curr);
-            return -ECHILD;
-        }
-        has_children = true;
-
-        list_node* node = curr->children.next;
-        while (node != &curr->children) {
-            auto* child = list_entry<TaskControlBlock, &TaskControlBlock::sibling>(node);
-            bool matches = (wait_pid == -1) || (wait_pid == child->pid);
-            if (!matches) {
-                node = node->next;
-                continue;
-            }
-
-            /* Zombie reaping has priority — it frees resources. */
-            if (child->state == TaskState::Zombie) {
-                zombie = child;
-                break;
-            }
-
-            /* WUNTRACED: report Stopped child once per stop event. */
-            if ((options & WUNTRACED) && child->stopped_code != 0) {
-                report = child;
-                report_status = child->stopped_code;
-                break;
-            }
-
-            /* WCONTINUED: report a one-shot SIGCONT resume. */
-            if ((options & WCONTINUED) && child->notify_continued) {
-                report = child;
-                report_status = W_CONTINUED();
-                break;
-            }
-
-            node = node->next;
-        }
-        curr->lock.release();
-
-        if (zombie) {
-            curr->wait_chld.finish_wait(curr);
-            int32 pid = zombie->pid;
-            if (exit_code) *exit_code = zombie->exit_code;
-            task_destroy(zombie);
-            return pid;
-        }
-
-        if (report) {
-            /* Status-only report: clear the one-shot flag, leave the
-             * child alive.  WNOWAIT (peek) would skip the clear, but
-             * we don't yet honour it. */
-            curr->wait_chld.finish_wait(curr);
-            int32 pid = report->pid;
-            if (exit_code) *exit_code = report_status;
-            if (W_CONTINUED() == report_status) {
-                report->notify_continued = false;
-            } else {
-                report->stopped_code = 0;
-            }
-            return pid;
-        }
-
-        /* No event to report */
-        if (!has_children) {
-            curr->wait_chld.finish_wait(curr);
-            return -ECHILD;
-        }
-        if (options & WNOHANG) {
-            curr->wait_chld.finish_wait(curr);
-            return 0;
-        }
-
-        /* Condition still false — deschedule.
-         * We are already on the wait queue and marked Sleeping. */
-        schedule();
-
-        /* Woken up — finish_wait removes us from queue, restores Runnable */
-        curr->wait_chld.finish_wait(curr);
-
-        /* Loop back to re-check the condition */
-    }
-}
-
-/* Legacy wrapper for internal callers */
-int32 task_wait(int32* exit_code)
-{
-    return do_wait4(-1, 0, exit_code);
-}
-
-/* ======================================================================
- * task_clone — clone current task with Linux-compatible flags
- *
- * @tf:          trap frame to copy to child
- * @clone_flags: CLONE_VM | CLONE_THREAD | CSIGNAL etc.
- * @child_stack: if non-zero, set as child's user SP (for pthread)
- * @parent_tidptr: write child tid here in parent (CLONE_PARENT_SETTID)
- * @child_tidptr:  write child tid here in child  (CLONE_CHILD_SETTID)
- * @tls:         TLS pointer (CLONE_SETTLS → tp register)
- *
- * Returns: child PID in parent, 0 in child, or negative errno.
- * ====================================================================== */
-
-int32 task_clone(arch::TrapFrame* tf, uint64 clone_flags,
-                 uint64 child_stack, uint64 parent_tidptr,
-                 uint64 child_tidptr, uint64 tls)
-{
-    TaskControlBlock* curr = current_task();
-    if (!curr) return -EINVAL;
-
-    TaskControlBlock* child = alloc_task("cloned", curr->priority, 0,
-                                          static_cast<uint8>(arch::cpu::id()));
-    if (!child) return -ENOMEM;
-
-    /* Allocate PID */
-    child->pid = g_pid_alloc.alloc();
-    if (child->pid < 0) {
-           pmm_free_pages(pa_to_page(phys_addr(child->kstack_pa)), 1);
-        delete child;
-        return -ENOMEM;
-    }
-
-    /* exit_signal + tgid: from clone_flags.
-     * Linux: fork.c line 2418/2424 */
-    if (clone_flags & CLONE_THREAD) {
-        child->tgid = curr->tgid;
-        child->exit_signal = -1;     /* Linux: sub-threads auto-reap */
-    } else {
-        child->tgid = child->pid;
-        child->exit_signal = static_cast<int32>(clone_flags & 0xFF);  /* CSIGNAL */
-        if (child->exit_signal == 0) {
-            child->exit_signal = SIGCHLD;  /* default for fork() */
-        }
-    }
-
-    /* Address space: CLONE_VM shares, otherwise deep copy */
-    if (clone_flags & CLONE_VM) {
-        if (curr->mm) {
-            curr->mm->incref();
-            child->mm = curr->mm;
-        }
-    } else {
-        if (curr->mm) {
-            child->mm = vmm_clone(curr->mm);
-            if (!child->mm) {
-                g_pid_alloc.free(child->pid);
-                pmm_free_pages(pa_to_page(phys_addr(child->kstack_pa)), 1);
-                delete child;
-                return -ENOMEM;
-            }
-        }
-    }
-
-    /* Copy TrapFrame to the child's kernel stack */
-    uint64 tf_addr = child->kstack_va + kKernelStackSize - sizeof(arch::TrapFrame);
-    child->trapframe = reinterpret_cast<arch::TrapFrame*>(tf_addr);
-    *child->trapframe = *tf;
-
-    /* Set Kernel SP */
-    child->trapframe->kernel_sp = reinterpret_cast<uint64>(child->trapframe);
-    child->trapframe->kernel_cpu_id = child->cpu_id;
-
-    /* Child returns 0 from fork/clone */
-    child->trapframe->a[0] = 0;
-
-    /* If caller specified a child stack, use it (pthread_create) */
-    if (child_stack != 0) {
-        child->trapframe->sp = child_stack;
-    }
-
-    /* CLONE_SETTLS: set thread pointer register */
-    if (clone_flags & CLONE_SETTLS) {
-        child->trapframe->tp = tls;
-    }
-
-    /* Set up context for ret_from_fork */
-    uint64 stack_top = tf_addr;
-    child->context = {};
-    child->context.ra = reinterpret_cast<uint64>(ret_from_fork);
-    child->context.sp = stack_top;
-    child->context.s[0] = tf_addr;
-
-    /* ---- Copy fs_struct (Linux: copy_fs in fork.c) ----
-     * CLONE_FS: share the same fs_struct (increment refcount).
-     * Otherwise: allocate a new fs_struct copying root/pwd. */
-    if (curr->fs != nullptr) {
-        if (clone_flags & CLONE_FS) {
-            curr->fs->count.fetch_add(1, __ATOMIC_RELAXED);
-            child->fs = curr->fs;
-        } else {
-            child->fs = copy_fs_struct(curr->fs);
-        }
-    }
-
-    /* ---- Copy files_struct (Linux: copy_files in fork.c) ----
-     * CLONE_FILES: share the same fd table.
-     * Otherwise: duplicate the fd table. */
-    if (curr->files != nullptr) {
-        if (clone_flags & CLONE_FILES) {
-            curr->files->count.fetch_add(1, __ATOMIC_RELAXED);
-            child->files = curr->files;
-        } else {
-            child->files = dup_fd(curr->files);
-        }
-    }
-
-    /* ---- Copy sighand (Linux kernel/fork.c:copy_sighand) ----
-     * CLONE_SIGHAND: share signal handlers (incref parent's).
-     * Otherwise: deep copy of the action table; child gets its own
-     * sighand_struct (and its own siglock).  Both branches MUST yield
-     * a non-null sighand — every user task needs one so signal paths
-     * can take the siglock without lazy-allocation races. */
-    if (clone_flags & CLONE_SIGHAND) {
-        if (!curr->sighand) {
-            /* CLONE_SIGHAND requires the parent to have a sighand. */
-            return -EINVAL;
-        }
-        get_sighand(curr->sighand);
-        child->sighand = curr->sighand;
-    } else {
-        child->sighand = copy_sighand(curr->sighand);
-        if (!child->sighand) {
-            /* OOM — same best-effort policy as fs/files/signal above.
-             * A separate cleanup-on-OOM pass is on the to-do list. */
-        }
-    }
-
-    /* ---- Copy signal_struct (Linux: copy_signal in fork.c) ----
-     * CLONE_THREAD shares the parent's signal_struct (incref).
-     * Otherwise allocate a new one that inherits pgid/sid/tty from the
-     * parent so the child stays in the same process group and session —
-     * this is what makes fork() participate in the existing job-control
-     * identity without explicit setpgid() calls. */
-    if (curr->signal != nullptr) {
-        if (clone_flags & CLONE_THREAD) {
-            get_signal_struct(curr->signal);
-            child->signal = curr->signal;
-        } else {
-            child->signal = fork_signal_struct(curr->signal, child);
-        }
-    }
-
-    /* Add to task tree */
-    child->parent = curr;
-    {
-        LockGuard guard(curr->lock);
-        list_node* head = &curr->children;
-        child->sibling.prev = head->prev;
-        child->sibling.next = head;
-        head->prev->next = &child->sibling;
-        head->prev = &child->sibling;
-    }
-
-    /* Add to global list and enqueue */
-    task_list_add(child);
-    sched_enqueue(child);
-
-    /* CLONE_PARENT_SETTID: write child tid to parent's user address */
-    if ((clone_flags & CLONE_PARENT_SETTID) && parent_tidptr != 0) {
-        copy_to_user(parent_tidptr, &child->pid, sizeof(child->pid));
-    }
-
-    /* CLONE_CHILD_SETTID: write child tid into child's user address.
-     * Note: this runs in parent context, but the address is in the
-     * child's mm. For CLONE_VM (threads), parent and child share mm
-     * so this works directly. For fork, the page was just CoW-copied. */
-    if ((clone_flags & CLONE_CHILD_SETTID) && child_tidptr != 0) {
-        if (clone_flags & CLONE_VM) {
-            /* Same address space — write directly */
-            copy_to_user(child_tidptr, &child->pid, sizeof(child->pid));
-        }
-        /* For non-CLONE_VM fork, the child's mm is separate.
-         * The write would need to go into the child's pagetable.
-         * Linux handles this in the child's first schedule via
-         * a special flag. For now, threads (CLONE_VM) are the
-         * primary consumer. */
-    }
-
-    /* CLONE_CHILD_CLEARTID: kernel writes 0 to child_tidptr on exit */
-    if (clone_flags & CLONE_CHILD_CLEARTID) {
-        child->clear_child_tid = child_tidptr;
-    }
-
-    return child->pid;
-}
-
-/* Legacy wrapper — plain fork() semantics */
-int32 task_fork(arch::TrapFrame* tf)
-{
-    return task_clone(tf, SIGCHLD, 0, 0, 0, 0);
-}
-
-
-/* ======================================================================
- * task_check_stack_canary
- * ====================================================================== */
-
-void task_check_stack_canary(TaskControlBlock* task)
-{
-    if (!task || task->kstack_va == 0) return;
-
-    auto* canary = reinterpret_cast<uint64*>(task->kstack_va);
-    if (*canary != kStackCanary) {
-        kernel_panic("kernel stack overflow detected");
-    }
-}