refactor: promote new architecture to repository root

Archive the deprecated implementation under lume-legacy, make the new kernel the default root-level build, and update repository entry points without changing kernel behavior.

3 files changed, 951 insertions, 0 deletions

diff --git a/lume-legacy/src/kernel/proc/exec.cc b/lume-legacy/src/kernel/proc/exec.cc
new file mode 100644
index 0000000..8d8c467
--- /dev/null
+++ b/lume-legacy/src/kernel/proc/exec.cc
@@ -0,0 +1,260 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2026 Richard QIn
+ */
+#include "common/types.h"
+#include "kernel/riscv.h"
+#include "kernel/proc.h"
+#include "kernel/mm.h"
+#include "kernel/elf.h"
+#include "fs/fs.h"
+#include "lib/string.h"
+#include "drivers/uart.h"
+#include "kernel/trap.h"
+
+extern char trampoline[];
+
+// RAII: Page Table Resource Management
+class VmGuard
+{
+public:
+    uint64 *pagetable = nullptr;
+    uint64 sz = 0;
+
+    VmGuard() : pagetable(VM::uvmcreate()) {}
+
+    ~VmGuard()
+    {
+        if (pagetable)
+        {
+            VM::uvmfree(pagetable, sz);
+        }
+    }
+
+    // Copying is prohibited
+    VmGuard(const VmGuard &) = delete;
+    VmGuard &operator=(const VmGuard &) = delete;
+
+    // Submit resources: Ownership transfer, destructor no longer releases
+    uint64 *commit()
+    {
+        uint64 *pt = pagetable;
+        pagetable = nullptr;
+        return pt;
+    }
+};
+
+// RAII: Inode Lock Management
+class InodeGuard
+{
+public:
+    Inode *ip;
+    InodeGuard(Inode *i) : ip(i)
+    {
+        if (ip)
+            VFS::ilock(ip);
+    }
+    ~InodeGuard()
+    {
+        if (ip)
+        {
+            VFS::iunlockput(ip); // Automatically unlock and release references
+        }
+    }
+    // Copying is prohibited
+    InodeGuard(const InodeGuard &) = delete;
+    InodeGuard &operator=(const InodeGuard &) = delete;
+};
+
+// laod segment
+static int loadseg(uint64 *pagetable, uint64 va, Inode *ip, uint64 offset, uint64 sz)
+{
+    for (uint64 i = 0; i < sz; i += PGSIZE)
+    {
+        uint64 pa = VM::walkaddr(pagetable, va + i);
+        if (pa == 0)
+        {
+            Drivers::uart_puts("[Exec Debug] loadseg: walkaddr failed\n");
+            return -1;
+        }
+
+        uint64 n = PGSIZE - (va + i) % PGSIZE;
+        if (i + n > sz)
+            n = sz - i;
+
+        // Read physical address (isUser=0)
+        if (ip->read((char *)(pa + (va + i) % PGSIZE), offset + i, n, 0) != (int)n)
+        {
+            Drivers::uart_puts("[Exec Debug] loadseg: read failed\n");
+            return -1;
+        }
+    }
+    return 0;
+}
+
+namespace Exec
+{
+    int exec(char *path, char **argv)
+    {
+        // 1. Get Inode
+        Inode *raw_ip = VFS::namei(path);
+        if (!raw_ip)
+        {
+            Drivers::uart_puts("[Exec Debug] namei failed for path: ");
+            Drivers::uart_puts(path);
+            Drivers::uart_puts("\n");
+            return -1;
+        }
+        InodeGuard iguard(raw_ip);
+
+        // Get ELF head
+        struct elfhdr elf;
+        if (raw_ip->read((char *)&elf, 0, sizeof(elf), 0) != sizeof(elf))
+        {
+            Drivers::uart_puts("[Exec Debug] read elf header failed\n");
+            return -1;
+        }
+        if (elf.magic != ELF_MAGIC)
+        {
+            Drivers::uart_puts("[Exec Debug] invalid elf magic\n");
+            return -1;
+        }
+
+        // Create new pagetable
+        VmGuard vm_guard;
+        if (!vm_guard.pagetable)
+        {
+            Drivers::uart_puts("[Exec Debug] uvmcreate failed\n");
+            return -1;
+        }
+
+        // Load Program Segment
+        struct proghdr ph;
+        for (int i = 0; i < elf.phnum; i++)
+        {
+            uint64 off = elf.phoff + i * sizeof(ph);
+            if (raw_ip->read((char *)&ph, off, sizeof(ph), 0) != sizeof(ph))
+            {
+                Drivers::uart_puts("[Exec Debug] read proghdr failed\n");
+                return -1;
+            }
+
+            if (ph.type != ELF_PROG_LOAD)
+                continue;
+            if (ph.memsz < ph.filesz)
+                return -1;
+            if (ph.vaddr + ph.memsz < ph.vaddr)
+                return -1;
+
+            uint64 sz1 = VM::uvmalloc(vm_guard.pagetable, vm_guard.sz, ph.vaddr + ph.memsz, PTE_W | PTE_X | PTE_R | PTE_U);
+            if (sz1 == 0)
+            {
+                Drivers::uart_puts("[Exec Debug] uvmalloc failed (segment)\n");
+                return -1;
+            }
+            vm_guard.sz = sz1;
+
+            if (loadseg(vm_guard.pagetable, ph.vaddr, raw_ip, ph.off, ph.filesz) < 0)
+                return -1;
+        }
+
+        // Prepare user stack
+        uint64 sz = PGROUNDUP(vm_guard.sz);
+
+        const int stack_data_pages = 16;
+        const int stack_total_pages = stack_data_pages + 1;
+
+        uint64 sz1 = VM::uvmalloc(vm_guard.pagetable, sz, sz + stack_total_pages * PGSIZE, PTE_W | PTE_R | PTE_U);
+        if (sz1 == 0)
+        {
+            Drivers::uart_puts("[Exec Debug] uvmalloc failed (stack)\n");
+            return -1;
+        }
+        vm_guard.sz = sz1;
+
+        VM::uvmunmap(vm_guard.pagetable, sz, 1, 0);
+
+        uint64 sp = sz1;
+        uint64 stackbase = sp - stack_data_pages * PGSIZE;
+        uint64 ustack[32];
+        uint64 argc = 0;
+
+        // Push parameter string
+        for (; argv[argc]; argc++)
+        {
+            if (argc >= 31)
+                return -1;
+            sp -= strlen(argv[argc]) + 1;
+            sp -= sp % 16;
+            if (sp < stackbase)
+            {
+                Drivers::uart_puts("[Exec Debug] stack overflow (args)\n");
+                return -1;
+            }
+
+            if (VM::copyout(vm_guard.pagetable, sp, argv[argc], strlen(argv[argc]) + 1) < 0)
+            {
+                Drivers::uart_puts("[Exec Debug] copyout arg string failed\n");
+                return -1;
+            }
+            ustack[argc] = sp;
+        }
+        ustack[argc] = 0;
+
+        // Push into parameter array
+        sp -= (argc + 1) * sizeof(uint64);
+        sp -= sp % 16;
+        if (sp < stackbase)
+        {
+            Drivers::uart_puts("[Exec Debug] stack overflow (argv array)\n");
+            return -1;
+        }
+        if (VM::copyout(vm_guard.pagetable, sp, (char *)ustack, (argc + 1) * sizeof(uint64)) < 0)
+        {
+            Drivers::uart_puts("[Exec Debug] copyout argv array failed\n");
+            return -1;
+        }
+
+        // Commit Changes
+        struct Proc *p = myproc();
+        if (VM::mappages(vm_guard.pagetable, TRAPFRAME, PGSIZE, (uint64)p->tf, PTE_R | PTE_W) < 0)
+        {
+            Drivers::uart_puts("[Exec Debug] mappages TRAPFRAME failed\n");
+            return -1;
+        }
+
+        uint64 oldsz = p->sz;
+        uint64 *oldpagetable = p->pagetable;
+
+        p->tf->a0 = argc;
+        p->tf->a1 = sp;
+        p->tf->sp = sp;
+        p->tf->epc = elf.entry;
+
+        char *s = path, *last = path;
+        while (*s)
+        {
+            if (*s == '/')
+                last = s + 1;
+            s++;
+        }
+
+        size_t len = 0;
+        while (last[len] && len < sizeof(p->name) - 1)
+        {
+            p->name[len] = last[len];
+            len++;
+        }
+        p->name[len] = '\0';
+
+        // change pagetable
+        p->pagetable = vm_guard.commit();
+        p->sz = vm_guard.sz;
+
+        // release old pagetable
+        VM::uvmfree(oldpagetable, oldsz);
+        asm volatile("fence.i");
+
+        return 0; // iguard unlocks and releases IP upon destruction
+    }
+}
\ No newline at end of file
diff --git a/lume-legacy/src/kernel/proc/proc.cc b/lume-legacy/src/kernel/proc/proc.cc
new file mode 100644
index 0000000..3923fe8
--- /dev/null
+++ b/lume-legacy/src/kernel/proc/proc.cc
@@ -0,0 +1,654 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2026 Richard QIn
+ */
+#include "kernel/proc.h"
+#include "kernel/proc_def.h"
+#include "kernel/runqueue.h"
+#include "kernel/cpu.h"
+#include "kernel/spinlock.h"
+#include "kernel/pmm.h"
+#include "kernel/mm.h"
+#include "kernel/trap.h"
+#include "kernel/riscv.h"
+#include "kernel/slab.h"
+#include "drivers/uart.h"
+#include "fs/fs.h"
+#include "fs/file.h"
+#include "lib/string.h"
+
+// #define NPROC 64
+#define NCPU 8
+
+extern "C" void swtch(struct Context *old_ctx, struct Context *new_ctx);
+extern char uservec[], trampoline[];
+extern "C" void usertrap();
+extern "C" void userret(uint64, uint64);
+extern char initcode_start[], initcode_end[];
+
+// struct Proc procs[NPROC];
+struct Proc *proc_list_head = nullptr;
+struct Proc *initproc = nullptr;
+struct Spinlock proc_mem_lock;
+struct cpu cpus[NCPU];
+struct RunQueue runqueues[NCPU];
+
+
+static int nextpid = 1;
+
+
+struct cpu *mycpu()
+{
+    int id = r_tp();
+    return &cpus[id];
+}
+
+
+void RunQueue::init(const char *name)
+{
+    lock.init(name);
+    count = 0;
+    for (int i = 0; i < N_PRIO; i++)
+    {
+        heads[i] = nullptr;
+        tails[i] = nullptr;
+    }
+}
+
+void RunQueue::enqueue(struct Proc *p)
+{
+    if (p->priority < 0 || p->priority >= N_PRIO)
+        p->priority = PRIO_MIN;
+    p->next = nullptr;
+    if (heads[p->priority] == nullptr)
+    {
+        heads[p->priority] = p;
+        tails[p->priority] = p;
+    }
+    else
+    {
+        tails[p->priority]->next = p;
+        tails[p->priority] = p;
+    }
+    count++;
+}
+
+struct Proc *RunQueue::dequeue()
+{
+    for (int i = 0; i < N_PRIO; i++)
+    {
+        if (heads[i])
+        {
+            struct Proc *p = heads[i];
+            heads[i] = p->next;
+            if (!heads[i])
+                tails[i] = nullptr;
+            p->next = nullptr;
+            count--;
+            return p;
+        }
+    }
+    return nullptr;
+}
+
+struct Proc *RunQueue::steal()
+{
+    for (int i = N_PRIO - 1; i >= 0; i--)
+    {
+        if (heads[i])
+        {
+            struct Proc *p = heads[i];
+            heads[i] = p->next;
+            if (!heads[i])
+                tails[i] = nullptr;
+            p->next = nullptr;
+            count--;
+            return p;
+        }
+    }
+    return nullptr;
+}
+
+//  Trap Return Functions
+
+void usertrapret()
+{
+    struct Proc *p = myproc();
+
+    intr_off();
+
+    // Set stvec to point to uservec in the trampoline
+    // When an interrupt occurs in user mode, the CPU will jump here
+    uint64 trampoline_uservec = TRAMPOLINE + (uservec - trampoline);
+    w_stvec(trampoline_uservec);
+
+    // Fill in the Trapframe, used when uservec saves the kernel state
+    p->tf->kernel_satp = r_satp();
+    p->tf->kernel_sp = (uint64)p->kstack + PGSIZE;
+    p->tf->kernel_trap = (uint64)usertrap;
+    p->tf->kernel_hartid = r_tp();
+
+    // Set SSTATUS
+    // SPP = 0 (return to User Mode)
+    // SPIE = 1 (enable interrupts)
+    unsigned long x = r_sstatus();
+    x &= ~SSTATUS_SPP;
+    x |= SSTATUS_SPIE;
+    w_sstatus(x);
+
+    // Set SEPC to the user program counter
+    w_sepc(p->tf->epc);
+
+    // Prepare user page table SATP
+    uint64 satp = MAKE_SATP(p->pagetable);
+
+    // Calculate the virtual address of userret in the trampoline
+    uint64 fn = TRAMPOLINE + ((uint64)userret - (uint64)trampoline);
+
+    // Jump to userret, with parameters being the TRAPFRAME address and the user page table SATP
+    ((void (*)(uint64, uint64))fn)(TRAPFRAME, satp);
+}
+
+
+void forkret()
+{
+
+    struct cpu *c = mycpu();
+    c->runqueue->lock.release();
+
+    // Debug
+    // Drivers::uart_puts("[Proc] forkret: jumping to user.\n");
+
+    // Enter user mode
+    usertrapret();
+}
+
+//  ProcManager Implementation
+
+static Proc *allocproc()
+{
+    struct Proc *p;
+    proc_mem_lock.acquire();
+
+    p = (struct Proc *)Slab::kmalloc(sizeof(struct Proc));
+
+    if (!p)
+    {
+        proc_mem_lock.release();
+        return 0;
+    }
+
+    memset(p, 0, sizeof(struct Proc));
+
+    p->all_next = proc_list_head;
+    p->all_prev = nullptr;
+    if (proc_list_head)
+        proc_list_head->all_prev = p;
+    proc_list_head = p;
+
+
+    p->state = USED;
+    p->pid = nextpid++;
+    p->priority = 0;
+    p->killed = 0;
+    p->cpu = mycpu();
+    p->cwd = nullptr;
+    for (int i = 0; i < NOFILE; i++)
+        p->ofile[i] = nullptr;
+
+    if ((p->tf = (struct Trapframe *)PMM::alloc_page()) == 0)
+    {
+        p->state = UNUSED;
+        if (p->all_next)
+            p->all_next->all_prev = p->all_prev;
+        if (p->all_prev)
+            p->all_prev->all_next = p->all_next;
+        if (p == proc_list_head)
+            proc_list_head = p->all_next;
+        Slab::kfree(p);
+        proc_mem_lock.release();
+        return 0;
+    }
+
+    if ((p->kstack = PMM::alloc_page()) == 0)
+    {
+        PMM::free_page(p->tf);
+        p->state = UNUSED;
+        if (p->all_next)
+            p->all_next->all_prev = p->all_prev;
+        if (p->all_prev)
+            p->all_prev->all_next = p->all_next;
+        if (p == proc_list_head)
+            proc_list_head = p->all_next;
+        Slab::kfree(p);
+
+        proc_mem_lock.release();
+        return 0;
+    }
+    memset(p->kstack, 0, PGSIZE);
+
+    memset(&p->context, 0, sizeof(p->context));
+
+    // Set the context so that the next time this process is scheduled, it starts executing directly from forkret
+    p->context.ra = (uint64)forkret;
+    p->context.sp = (uint64)p->kstack + PGSIZE;
+    return p;
+}
+
+static void freeproc(struct Proc *p)
+{
+    if (p->tf)
+        PMM::free_page(p->tf);
+    p->tf = 0;
+    if (p->kstack)
+        PMM::free_page(p->kstack);
+    p->kstack = 0;
+    if (p->pagetable)
+        VM::uvmfree(p->pagetable, p->sz);
+    for (int i = 0; i < NOFILE; i++)
+    {
+        if (p->ofile[i])
+        {
+            FileTable::close(p->ofile[i]);
+            p->ofile[i] = nullptr;
+        }
+    }
+    if (p->cwd)
+    {
+        VFS::iput(p->cwd);
+        p->cwd = nullptr;
+    }
+
+    if (p->all_prev)
+        p->all_prev->all_next = p->all_next;
+    else
+        proc_list_head = p->all_next;
+
+    if (p->all_next)
+        p->all_next->all_prev = p->all_prev;
+
+    Slab::kfree(p);
+}
+
+int fork()
+{
+    struct Proc *np;
+    struct Proc *p = myproc();
+
+    if ((np = allocproc()) == 0)
+        return -1;
+
+    np->pagetable = VM::uvmcreate();
+    np->sz = p->sz;
+    if (VM::uvmcopy(p->pagetable, np->pagetable, p->sz) < 0)
+    {
+        freeproc(np);
+        proc_mem_lock.release();
+        return -1;
+    }
+    
+
+    if (VM::mappages(np->pagetable, TRAPFRAME, PGSIZE, (uint64)np->tf, PTE_R | PTE_W) < 0)
+    {
+        freeproc(np);
+        proc_mem_lock.release();
+        return -1;
+    }
+
+    *(np->tf) = *(p->tf);
+    np->tf->a0 = 0;
+    strcpy(np->name, p->name);
+    np->parent = p;
+    np->priority = p->priority;
+
+    for (int i = 0; i < NOFILE; i++)
+    {
+        if (p->ofile[i])
+        {
+            np->ofile[i] = FileTable::dup(p->ofile[i]);
+        }
+    }
+
+    if (p->cwd)
+    {
+        np->cwd = VFS::idup(p->cwd);
+    }
+
+    proc_mem_lock.release();
+
+    struct cpu *c = mycpu();
+    c->runqueue->lock.acquire();
+    np->state = RUNNABLE;
+    c->runqueue->enqueue(np);
+    c->runqueue->lock.release();
+
+    return np->pid;
+}
+
+namespace ProcManager
+{
+
+    void init()
+    {
+        proc_mem_lock.init("proc_mem");
+
+        proc_list_head = nullptr;
+
+        for (int i = 0; i < NCPU; i++)
+        {
+            cpus[i].runqueue = &runqueues[i];
+            cpus[i].runqueue->init("runqueue");
+        }
+    }
+
+    void scheduler()
+    {
+        struct Proc *p;
+        struct cpu *c = mycpu();
+        c->proc = 0;
+        Drivers::uart_puts("[Proc] Scheduler started (Per-CPU).\n");
+
+        for (;;)
+        {
+            intr_on();
+
+            // Get from the local queue
+            c->runqueue->lock.acquire();
+            p = c->runqueue->dequeue();
+            c->runqueue->lock.release();
+
+            // Work Stealing
+            if (!p)
+            {
+                for (int i = 0; i < NCPU; i++)
+                {
+                    if ((uint64)i == r_tp())
+                        continue;
+
+                    struct cpu *victim = &cpus[i];
+                    victim->runqueue->lock.acquire();
+                    if (victim->runqueue->count > 0)
+                        p = victim->runqueue->steal();
+                    victim->runqueue->lock.release();
+                    if (p)
+                        break;
+                }
+            }
+
+            if (p)
+            {
+                p->state = RUNNING;
+                c->proc = p;
+
+                c->runqueue->lock.acquire();
+                swtch(&c->context, &p->context);
+                c->runqueue->lock.release();
+
+                c->proc = 0;
+            }
+        }
+    }
+
+    void yield()
+    {
+        struct Proc *p = myproc();
+        struct cpu *c = mycpu();
+        c->runqueue->lock.acquire();
+        if (p && p->state == RUNNING)
+        {
+            p->state = RUNNABLE;
+            if (p->priority < PRIO_MIN)
+                p->priority++;
+            c->runqueue->enqueue(p);
+            swtch(&p->context, &c->context);
+        }
+        c->runqueue->lock.release();
+    }
+
+    void user_init()
+    {
+        struct Proc *p = allocproc();
+        if (!p)
+            return;
+
+        initproc = p;
+
+        p->pagetable = VM::uvmcreate();
+
+        uint64 initcode_sz = initcode_end - initcode_start;
+        Drivers::uart_puts("[Proc] initcode size: ");
+        Drivers::uart_put_int(initcode_sz);
+        Drivers::uart_puts(" bytes\n");
+
+        uint64 code_pages = PGROUNDUP(initcode_sz) / PGSIZE;
+
+        for (uint64 i = 0; i < code_pages; i++)
+        {
+            void *mem = PMM::alloc_page();
+            if (!mem)
+            {
+                Drivers::uart_puts("user_init: out of memory for code\n");
+                return;
+            }
+            memset(mem, 0, PGSIZE);
+
+            uint64 src_offset = i * PGSIZE;
+            uint64 copy_len = PGSIZE;
+            if (src_offset + copy_len > initcode_sz)
+            {
+                copy_len = initcode_sz - src_offset;
+            }
+            memmove(mem, (void *)(initcode_start + src_offset), copy_len);
+
+            if (VM::mappages(p->pagetable, i * PGSIZE, PGSIZE, (uint64)mem, PTE_R | PTE_W | PTE_X | PTE_U) < 0)
+            {
+                Drivers::uart_puts("user_init: mappages code failed\n");
+                return;
+            }
+        }
+
+        uint64 stack_va = (code_pages + 1) * PGSIZE;
+
+        void *stack = PMM::alloc_page();
+        if (!stack)
+            return;
+        memset(stack, 0, PGSIZE);
+
+        if (VM::mappages(p->pagetable, stack_va, PGSIZE, (uint64)stack, PTE_R | PTE_W | PTE_U) < 0)
+            return;
+
+        if (VM::mappages(p->pagetable, TRAPFRAME, PGSIZE, (uint64)p->tf, PTE_R | PTE_W) < 0)
+            return;
+
+        p->tf->epc = 0;
+        p->tf->sp = stack_va + PGSIZE;
+        p->sz = stack_va + PGSIZE;
+        strcpy(p->name, "initcode");
+
+        p->cwd = nullptr;
+
+        proc_mem_lock.release();
+
+        struct cpu *c = &cpus[0];
+        c->runqueue->lock.acquire();
+        p->state = RUNNABLE;
+        c->runqueue->enqueue(p);
+        c->runqueue->lock.release();
+
+        Drivers::uart_puts("[Proc] user_init success. PID: 1\n");
+        asm volatile("fence.i");
+    }
+
+    void sleep(void *chan, Spinlock *lk)
+    {
+        struct Proc *p = myproc();
+        struct cpu *c = mycpu();
+
+        if (lk && lk != &proc_mem_lock)
+            lk->release();
+
+        c->runqueue->lock.acquire();
+        p->chan = chan;
+        p->state = SLEEPING;
+        swtch(&p->context, &c->context);
+        p->chan = 0;
+        c->runqueue->lock.release();
+
+        if (lk && lk != &proc_mem_lock)
+            lk->acquire();
+    }
+
+    void wakeup(void *chan)
+    {
+        for (struct Proc *p = proc_list_head; p != nullptr; p = p->all_next)
+        {
+            if (p->state == SLEEPING && p->chan == chan)
+            {
+                struct cpu *c = mycpu();
+                c->runqueue->lock.acquire();
+                p->state = RUNNABLE;
+                c->runqueue->enqueue(p);
+                c->runqueue->lock.release();
+            }
+        }
+    }
+
+    void exit(int status)
+    {
+        struct Proc *p = myproc();
+        if (p == initproc)
+            while (1)
+                ;
+
+        wakeup(p->parent);
+
+        proc_mem_lock.acquire();
+
+        for (struct Proc *pp = proc_list_head; pp != nullptr; pp = pp->all_next)
+        {
+            if (pp->parent == p)
+            {
+                pp->parent = initproc;
+                wakeup(initproc);
+            }
+        }
+
+        proc_mem_lock.release();
+
+        p->xstate = status;
+
+        struct cpu *c = mycpu();
+        c->runqueue->lock.acquire();
+        p->state = ZOMBIE;
+        swtch(&p->context, &c->context);
+        while (1)
+            ;
+    }
+
+    int wait(uint64 addr)
+    {
+
+        struct Proc *np;
+        int havekids, pid;
+        struct Proc *p = myproc();
+        for (;;)
+        {
+            havekids = 0;
+            proc_mem_lock.acquire();
+
+            for (np = proc_list_head; np != nullptr; np = np->all_next)
+            {
+                if (np->parent == p)
+                {
+                    havekids = 1;
+                    if (np->state == ZOMBIE)
+                    {
+
+                        struct cpu *child_cpu = np->cpu;
+                        if (child_cpu)
+                        {
+                            proc_mem_lock.release();
+                            child_cpu->runqueue->lock.acquire();
+                            child_cpu->runqueue->lock.release();
+                            proc_mem_lock.acquire();
+                        }
+
+                        pid = np->pid;
+                        if (addr != 0 && VM::copyout(p->pagetable, addr, (char *)&np->xstate, sizeof(np->xstate)) < 0)
+                        {
+                            proc_mem_lock.release();
+                            return -1;
+                        }
+                        freeproc(np);
+                        proc_mem_lock.release();
+                        return pid;
+                    }
+                }
+            }
+            proc_mem_lock.release();
+
+            if (!havekids || p->state == ZOMBIE)
+                return -1;
+            sleep(p, &proc_mem_lock);
+        }
+    }
+
+    int kill(int pid)
+    {
+        Proc* p;
+        proc_mem_lock.acquire();
+        for (p = proc_list_head; p != nullptr; p = p->all_next)
+        {
+            if (p->pid == pid)
+            {
+                p->killed = 1;
+
+                if (p->state == SLEEPING)
+                {
+                    p->state = RUNNABLE;
+
+                    struct cpu *c = mycpu();
+                    c->runqueue->lock.acquire();
+                    c->runqueue->enqueue(p);
+                    c->runqueue->lock.release();
+                }
+
+                proc_mem_lock.release();
+                return 0;
+            }
+        }
+        proc_mem_lock.release();
+        return -1;
+    }
+
+    int growproc(int n)
+    {
+        uint64 sz;
+        struct Proc *p = myproc();
+
+        sz = p->sz;
+
+        if (n > 0)
+        {
+            // Call VM::uvmalloc to allocate memory
+            // Parameters: page table, old size, new size, permissions (PTE_W)
+            if ((sz = VM::uvmalloc(p->pagetable, sz, sz + n, PTE_W | PTE_R | PTE_U)) == 0)
+            {
+                return -1;
+            }
+        }
+        else if (n < 0)
+        {
+            sz = VM::uvmdealloc(p->pagetable, sz, sz + n);
+        }
+
+        p->sz = sz;
+        return 0;
+    }
+
+    void create_kernel_thread(void (*func)(), const char *name)
+    {
+        (void)func;
+        (void)name;
+    }
+}
\ No newline at end of file
diff --git a/lume-legacy/src/kernel/proc/swtch.S b/lume-legacy/src/kernel/proc/swtch.S
new file mode 100644
index 0000000..d55c03e
--- /dev/null
+++ b/lume-legacy/src/kernel/proc/swtch.S
@@ -0,0 +1,37 @@
+# SPDX-License-Identifier: GPL-2.0-or-later
+# Copyright (C) 2026 Richard Qin
+
+.global swtch
+
+swtch:
+    sd ra, 0(a0)
+    sd sp, 8(a0)
+    sd s0, 16(a0)
+    sd s1, 24(a0)
+    sd s2, 32(a0)
+    sd s3, 40(a0)
+    sd s4, 48(a0)
+    sd s5, 56(a0)
+    sd s6, 64(a0)
+    sd s7, 72(a0)
+    sd s8, 80(a0)
+    sd s9, 88(a0)
+    sd s10, 96(a0)
+    sd s11, 104(a0)
+
+    ld ra, 0(a1)
+    ld sp, 8(a1)
+    ld s0, 16(a1)
+    ld s1, 24(a1)
+    ld s2, 32(a1)
+    ld s3, 40(a1)
+    ld s4, 48(a1)
+    ld s5, 56(a1)
+    ld s6, 64(a1)
+    ld s7, 72(a1)
+    ld s8, 80(a1)
+    ld s9, 88(a1)
+    ld s10, 96(a1)
+    ld s11, 104(a1)
+
+    ret