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.

1 files changed, 185 insertions, 0 deletions

diff --git a/kernel/sys_process.cc b/kernel/sys_process.cc
new file mode 100644
index 0000000..438ad1b
--- /dev/null
+++ b/kernel/sys_process.cc
@@ -0,0 +1,185 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/* Copyright (C) 2026 Richard Qin */
+
+/*
+ * Process Control System Calls
+ *
+ * Implements: exit, exit_group, getpid, gettid, getppid,
+ *             sched_yield, clone (stub), wait4 (stub),
+ *             set_tid_address, getuid, getgid.
+ *
+ * Reference: docs/specs/syscall.md §7.1
+ */
+
+#include "lume/klog.h"
+#include <lume/types.h>
+#include <lume/task.h>
+#include <lume/sched.h>
+#include <lume/errno.h>
+#include <lume/uaccess.h>
+#include <lume/wait.h>
+
+/* External: task lifecycle (kernel/task.cc) */
+extern void task_exit(int code);
+extern int32 do_wait4(int32 wait_pid, int options, int32* exit_code);
+extern int32 task_clone(arch::TrapFrame* tf, uint64 clone_flags,
+                        uint64 child_stack, uint64 parent_tidptr,
+                        uint64 child_tidptr, uint64 tls);
+extern int32 task_fork(arch::TrapFrame* tf);
+
+/* ======================================================================
+ * sys_exit / sys_exit_group
+ * ====================================================================== */
+
+int64 sys_exit(uint64 code, uint64, uint64, uint64, uint64, uint64)
+{
+    task_exit(static_cast<int>(code & 0xFF));
+    __builtin_unreachable();
+}
+
+int64 sys_exit_group(uint64 code, uint64, uint64, uint64, uint64, uint64)
+{
+    /* Phase 2: single-threaded, equivalent to sys_exit.
+     * Phase 3: kill all threads in tgid then exit. */
+    task_exit(static_cast<int>(code & 0xFF));
+    __builtin_unreachable();
+}
+
+/* ======================================================================
+ * sys_getpid / sys_gettid / sys_getppid
+ * ====================================================================== */
+
+int64 sys_getpid(uint64, uint64, uint64, uint64, uint64, uint64)
+{
+    return current_task()->tgid;  /* Linux: getpid() returns tgid */
+}
+
+int64 sys_gettid(uint64, uint64, uint64, uint64, uint64, uint64)
+{
+    return current_task()->pid;   /* Linux: gettid() returns real tid */
+}
+
+int64 sys_getppid(uint64, uint64, uint64, uint64, uint64, uint64)
+{
+    TaskControlBlock* parent = current_task()->parent;
+    return parent ? parent->tgid : 0;
+}
+
+/* ======================================================================
+ * sys_sched_yield
+ * ====================================================================== */
+
+int64 sys_sched_yield_wrapper(uint64, uint64, uint64, uint64, uint64, uint64)
+{
+    sched_yield();
+    return 0;
+}
+
+int64 sys_clone_wrapper(uint64 flags, uint64 child_stack,
+                        uint64 ptid, uint64 ctid, uint64 tls, uint64)
+{
+    arch::TrapFrame* tf = current_task()->trapframe;
+    if (!tf) return -EINVAL;
+
+    return task_clone(tf, flags, child_stack, ptid, ctid, tls);
+}
+
+/* ========================================================================
+ * sys_wait4 — Wait for child to exit
+ * ======================================================================== */
+
+int64 sys_wait4_wrapper(uint64 pid, uint64 wstatus_ptr,
+                        uint64 options, uint64, uint64, uint64)
+{
+    int32 exit_code = 0;
+    int32 child_pid = do_wait4(static_cast<int32>(pid),
+                               static_cast<int>(options),
+                               &exit_code);
+
+    if (child_pid < 0) return child_pid;
+
+    /* exit_code is already in Linux wstatus format */
+    if (wstatus_ptr != 0) {
+        if (copy_to_user(wstatus_ptr, &exit_code, sizeof(int)) < 0)
+            return -EFAULT;
+    }
+
+    return child_pid;
+}
+
+/* ======================================================================
+ * sys_set_tid_address — musl libc calls this very early
+ * ====================================================================== */
+
+int64 sys_set_tid_address(uint64 tidptr, uint64, uint64,
+                          uint64, uint64, uint64)
+{
+    /* Store clear_child_tid pointer — on exit, kernel writes 0 here
+     * and does futex_wake (enables pthread_join). */
+    current_task()->clear_child_tid = tidptr;
+    return current_task()->pid;
+}
+
+/* ======================================================================
+ * sys_getuid / sys_getgid — Phase 2: always root
+ * ====================================================================== */
+
+int64 sys_getuid(uint64, uint64, uint64, uint64, uint64, uint64)
+{
+    return 0; /* root */
+}
+
+int64 sys_getgid(uint64, uint64, uint64, uint64, uint64, uint64)
+{
+    return 0; /* root */
+}
+
+/* ======================================================================
+ * sys_nanosleep (SYS_nanosleep = 101)
+ * ====================================================================== */
+#include <lume/wait.h>
+#include <lume/kprintf.h>
+#include <lume/timer.h>
+
+struct linux_timespec {
+    int64 tv_sec;
+    int64 tv_nsec;
+};
+
+static void nanosleep_wakeup(TimerList* t) {
+    TaskControlBlock* task = static_cast<TaskControlBlock*>(t->data);
+    task->state = TaskState::Runnable;
+    sched_enqueue(task);
+}
+
+int64 sys_nanosleep(uint64 req_ptr, uint64 rem_ptr, uint64, uint64, uint64, uint64) {
+    if (req_ptr == 0) return -EINVAL;
+
+    linux_timespec req;
+    if (copy_from_user(&req, req_ptr, sizeof(req)) != 0) {
+        return -EFAULT;
+    }
+
+    uint64 target = *(volatile uint64*)&g_jiffies + (req.tv_sec * 100) + (req.tv_nsec / 10000000);
+    
+    TaskControlBlock* curr = current_task();
+    curr->state = TaskState::Sleeping;
+    
+    TimerList t;
+    t.init(nanosleep_wakeup);
+    t.expires = target;
+    t.data = curr;
+    
+    add_timer(&t);
+    
+    if (*(volatile uint64*)&g_jiffies < target) {
+        schedule();
+    } else {
+        curr->state = TaskState::Running;
+    }
+    
+    
+    del_timer(&t);
+
+    return 0;
+}