X-Git-Url: https://scm.lunaixsky.com/lunaix-os.git/blobdiff_plain/48b4a227035048fdebcd32532deb7a857c6199ac..0067bc210e621ccda286092d081a7890d65e1c18:/lunaix-os/kernel/process.c

diff --git a/lunaix-os/kernel/process.c b/lunaix-os/kernel/process.c
index be7d423..29cff62 100644
--- a/lunaix-os/kernel/process.c
+++ b/lunaix-os/kernel/process.c
@@ -1,17 +1,18 @@
 #include <lunaix/process.h>
 #include <lunaix/mm/vmm.h>
+#include <lunaix/mm/region.h>
 #include <lunaix/clock.h>
 #include <lunaix/syslog.h>
 #include <lunaix/common.h>
+#include <lunaix/syscall.h>
+#include <lunaix/spike.h>
 
 LOG_MODULE("PROC")
 
-void dup_proc() {
-    pid_t pid = alloc_pid();
-
+void* __dup_pagetable(pid_t pid, uintptr_t mount_point) {
     void* ptd_pp = pmm_alloc_page(pid, PP_FGPERSIST);
     x86_page_table* ptd = vmm_fmap_page(pid, PG_MOUNT_1, ptd_pp, PG_PREM_RW);
-    x86_page_table* pptd = (x86_page_table*) L1_BASE_VADDR;
+    x86_page_table* pptd = (x86_page_table*) (mount_point | (0x3FF << 12));
 
     for (size_t i = 0; i < PG_MAX_ENTRIES - 1; i++)
     {
@@ -21,28 +22,15 @@ void dup_proc() {
             continue;
         }
         
-        x86_page_table* ppt = (x86_page_table*) L2_VADDR(i);
+        x86_page_table* ppt = (x86_page_table*) (mount_point | (i << 12));
         void* pt_pp = pmm_alloc_page(pid, PP_FGPERSIST);
         x86_page_table* pt = vmm_fmap_page(pid, PG_MOUNT_2, pt_pp, PG_PREM_RW);
 
         for (size_t j = 0; j < PG_MAX_ENTRIES; j++)
         {
-            uintptr_t va = ((i << 10) | j) << 12;
-            x86_pte_t ppte = ppt->entry[j];
-            if (!ppte || !(ppte & PG_PRESENT)) {
-                pt->entry[j] = ppte;
-                continue;
-            }
-
-            // FIXME: 根据 mm_region 将读共享的页（如堆）标为只读，而私有的页（如栈），则复制；而写共享的页则无需更改flags
-            if (va >= KSTACK_START) {
-                void* ppa = vmm_dup_page(va);
-                ppte = ppte & 0xfff | (uintptr_t)ppa;
-            }
-            pt->entry[j] = ppte;
-            // ppte = ppte & ~PG_WRITE;
-            // pt->entry[j] = ppte;
-            // ppt->entry[j] = ppte;
+            x86_pte_t pte = ppt->entry[j];
+            pmm_ref_page(pid, pte & ~0xfff);
+            pt->entry[j] = pte;
         }
 
         ptd->entry[i] = (uintptr_t)pt_pp | PG_PREM_RW;
@@ -50,19 +38,103 @@ void dup_proc() {
     
     ptd->entry[PG_MAX_ENTRIES - 1] = NEW_L1_ENTRY(T_SELF_REF_PERM, ptd_pp);
 
+    return ptd_pp;
+}
+
+void* dup_pagetable(pid_t pid) {
+    return __dup_pagetable(pid, PD_REFERENCED);
+}
+
+__DEFINE_LXSYSCALL(void, fork) {
+    dup_proc();
+}
+
+__DEFINE_LXSYSCALL(pid_t, getpid) {
+    return __current->pid;
+}
+
+__DEFINE_LXSYSCALL(pid_t, getppid) {
+    return __current->parent->pid;
+}
+
+void dup_proc() {
+    pid_t pid = alloc_pid();
+
     struct proc_info pcb = (struct proc_info) {
         .created = clock_systime(),
         .pid = pid,
         .mm = __current->mm,
-        .page_table = ptd_pp,
         .intr_ctx = __current->intr_ctx,
-        .parent_created = __current->created
+        .parent = __current
     };
 
-    // 正如同fork一样，返回两次。
+    setup_proc_mem(&pcb, PD_MOUNT_1);    //挂载点#1是当前进程的页表
+
+    // 根据 mm_region 进一步配置页表
+    if (__current->mm.regions) {
+        struct mm_region *pos, *n;
+        llist_for_each(pos, n, &__current->mm.regions->head, head) {
+            region_add(&pcb, pos->start, pos->end, pos->attr);
+
+            // 如果写共享，则不作处理。
+            if ((pos->attr & REGION_WSHARED)) {
+                continue;
+            }
+
+            uintptr_t start_vpn = PG_ALIGN(pos->start) >> 12;
+            uintptr_t end_vpn = PG_ALIGN(pos->end) >> 12;
+            for (size_t i = start_vpn; i < end_vpn; i++)
+            {
+                x86_pte_t *curproc = &((x86_page_table*)(PD_MOUNT_1 | ((i & 0xffc00) << 2)))->entry[i & 0x3ff];
+                x86_pte_t *newproc = &((x86_page_table*)(PD_MOUNT_2 | ((i & 0xffc00) << 2)))->entry[i & 0x3ff];
+
+                if (pos->attr == REGION_RSHARED) {
+                    // 如果读共享，则将两者的都标注为只读，那么任何写入都将会应用COW策略。
+                    *curproc = *curproc & ~PG_WRITE;
+                    *newproc = *newproc & ~PG_WRITE;
+                }
+                else {
+                    // 如果是私有页，则将该页从新进程中移除。
+                    *newproc = 0;
+                }
+            }
+        }
+    }
+    
+    vmm_unmount_pd(PD_MOUNT_2);
+
+    // 正如同fork，返回两次。
     pcb.intr_ctx.registers.eax = 0;
     __current->intr_ctx.registers.eax = pid;
 
     push_process(&pcb);
+}
+
+extern void __kernel_end;
+
+void setup_proc_mem(struct proc_info* proc, uintptr_t usedMnt) {
+    // copy the entire kernel page table
+    pid_t pid = proc->pid;
+    void* pt_copy = __dup_pagetable(pid, usedMnt);
+
+    vmm_mount_pd(PD_MOUNT_2, pt_copy);   // 将新进程的页表挂载到挂载点#2
+
+    // copy the kernel stack
+    for (size_t i = KSTACK_START >> 12; i <= KSTACK_TOP >> 12; i++)
+    {
+        x86_pte_t *ppte = &((x86_page_table*)(PD_MOUNT_2 | ((i & 0xffc00) << 2)))->entry[i & 0x3ff];
+        void* ppa = vmm_dup_page(pid, PG_ENTRY_ADDR(*ppte));
+        *ppte = (*ppte & 0xfff) | (uintptr_t)ppa;
+    }
+
+    // 我们不需要分配内核的区域，因为所有的内核代码和数据段只能通过系统调用来访问，任何非法的访问
+    // 都会导致eip落在区域外面，从而segmentation fault.
     
+    // 定义用户栈区域，但是不分配实际的物理页。我们会在Page fault handler里面实现动态分配物理页的逻辑。（虚拟内存的好处！）
+    // FIXME: 这里应该放到spawn_proc里面。
+    // region_add(proc, USTACK_END, USTACK_SIZE, REGION_PRIVATE | REGION_RW);
+
+    // 至于其他的区域我们暂时没有办法知道，因为那需要知道用户程序的信息。我们留到之后在处理。
+
+    proc->page_table = pt_copy;
 }
\ No newline at end of file