lunaix-os/kernel/process.c

   1 #include <lunaix/process.h>
   2 #include <lunaix/mm/vmm.h>
   3 #include <lunaix/clock.h>
   4 #include <lunaix/syslog.h>
   5 #include <lunaix/common.h>
   6
   7 LOG_MODULE("PROC")
   8
   9 void* __dup_pagetable(pid_t pid, uintptr_t mount_point) {
  10     void* ptd_pp = pmm_alloc_page(pid, PP_FGPERSIST);
  11     x86_page_table* ptd = vmm_fmap_page(pid, PG_MOUNT_1, ptd_pp, PG_PREM_RW);
  12     x86_page_table* pptd = (x86_page_table*) (mount_point | (0x3FF << 12));
  13
  14     for (size_t i = 0; i < PG_MAX_ENTRIES - 1; i++)
  15     {
  16         x86_pte_t ptde = pptd->entry[i];
  17         if (!ptde || !(ptde & PG_PRESENT)) {
  18             ptd->entry[i] = ptde;
  19             continue;
  20         }
  21
  22         x86_page_table* ppt = (x86_page_table*) (mount_point | (i << 12));
  23         void* pt_pp = pmm_alloc_page(pid, PP_FGPERSIST);
  24         x86_page_table* pt = vmm_fmap_page(pid, PG_MOUNT_2, pt_pp, PG_PREM_RW);
  25
  26         for (size_t j = 0; j < PG_MAX_ENTRIES; j++)
  27         {
  28             uintptr_t va = ((i << 10) | j) << 12;
  29             x86_pte_t ppte = ppt->entry[j];
  30             if (!ppte || !(ppte & PG_PRESENT)) {
  31                 pt->entry[j] = ppte;
  32                 continue;
  33             }
  34
  35             // 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
  36             if (va >= KSTACK_START) {
  37                 void* ppa = vmm_dup_page(pid, PG_ENTRY_ADDR(ppte));
  38                 ppte = ppte & 0xfff | (uintptr_t)ppa;
  39             }
  40             pt->entry[j] = ppte;
  41             // ppte = ppte & ~PG_WRITE;
  42             // pt->entry[j] = ppte;
  43             // ppt->entry[j] = ppte;
  44         }
  45
  46         ptd->entry[i] = (uintptr_t)pt_pp | PG_PREM_RW;
  47     }
  48
  49     ptd->entry[PG_MAX_ENTRIES - 1] = NEW_L1_ENTRY(T_SELF_REF_PERM, ptd_pp);
  50
  51     return ptd_pp;
  52 }
  53
  54 void* dup_pagetable(pid_t pid) {
  55     return __dup_pagetable(pid, L2_BASE_VADDR);
  56 }
  57
  58 void dup_proc() {
  59     pid_t pid = alloc_pid();
  60
  61     /*
  62         FIXME: Problematic! It should mount the page table of process then copy it.
  63         The current implementation copy the CURRENTLY loaded pgt.
  64         However, dup_pagetable is designed to copy current loaded pgt.
  65
  66     */
  67
  68     void* mnt_pt = vmm_mount_pd(__current->page_table);
  69
  70     void* pg = __dup_pagetable(pid, mnt_pt);
  71
  72     vmm_unmount_pd();
  73
  74     struct proc_info pcb = (struct proc_info) {
  75         .created = clock_systime(),
  76         .pid = pid,
  77         .mm = __current->mm,
  78         .page_table = pg,
  79         .intr_ctx = __current->intr_ctx,
  80         .parent_created = __current->created
  81     };
  82
  83     // 正如同fork，返回两次。
  84     pcb.intr_ctx.registers.eax = 0;
  85     __current->intr_ctx.registers.eax = pid;
  86
  87     push_process(&pcb);
  88
  89 }