driver/us_slot_manager.c

   1 #include <linux/slab.h>
   2 #include <linux/hardirq.h>
   3 #include <linux/sched.h>
   4 #include <linux/mm.h>
   5 #include <linux/mman.h>
   6 #include <linux/list.h>
   7 #include <dbi_insn_slots.h>
   8 #include <asm/dbi_kprobes.h>
   9
  10 static unsigned long alloc_user_pages(struct task_struct *task, unsigned long len, unsigned long prot, unsigned long flags)
  11 {
  12         unsigned long ret = 0;
  13         struct task_struct *otask = current;
  14         struct mm_struct *mm;
  15         int atomic = in_atomic();
  16
  17         mm = atomic ? task->active_mm : get_task_mm(task);
  18         if (mm) {
  19                 if (!atomic) {
  20                         if (!down_write_trylock(&mm->mmap_sem)) {
  21                                 rcu_read_lock();
  22
  23                                 up_read(&mm->mmap_sem);
  24                                 down_write(&mm->mmap_sem);
  25
  26                                 rcu_read_unlock();
  27                         }
  28                 }
  29                 // FIXME: its seems to be bad decision to replace 'current' pointer temporarily
  30                 current_thread_info()->task = task;
  31                 ret = do_mmap_pgoff(NULL, 0, len, prot, flags, 0);
  32                 current_thread_info()->task = otask;
  33                 if (!atomic) {
  34                         downgrade_write (&mm->mmap_sem);
  35                         mmput(mm);
  36                 }
  37         } else {
  38                 printk("proc %d has no mm", task->tgid);
  39         }
  40
  41         return ret;
  42 }
  43
  44 static void *sm_alloc_us(struct slot_manager *sm)
  45 {
  46         struct task_struct *task = sm->data;
  47
  48         return (void *)alloc_user_pages(task, PAGE_SIZE,
  49                                         PROT_EXEC|PROT_READ|PROT_WRITE,
  50                                         MAP_ANONYMOUS|MAP_PRIVATE);
  51 }
  52
  53 static void sm_free_us(struct slot_manager *sm, void *ptr)
  54 {
  55         struct task_struct *task = sm->data;
  56
  57         /*
  58          * E. G.: This code provides kernel dump because of rescheduling while atomic.
  59          * As workaround, this code was commented. In this case we will have memory leaks
  60          * for instrumented process, but instrumentation process should functionate correctly.
  61          * Planned that good solution for this problem will be done during redesigning KProbe
  62          * for improving supportability and performance.
  63          */
  64 #if 0
  65         mm = get_task_mm(task);
  66         if (mm) {
  67                 down_write(&mm->mmap_sem);
  68                 do_munmap(mm, (unsigned long)(ptr), PAGE_SIZE);
  69                 up_write(&mm->mmap_sem);
  70                 mmput(mm);
  71         }
  72 #endif
  73         /* FIXME: implement the removal of memory for task */
  74 }
  75
  76 struct slot_manager *create_sm_us(struct task_struct *task)
  77 {
  78         struct slot_manager *sm = kmalloc(sizeof(*sm), GFP_ATOMIC);
  79         sm->slot_size = UPROBES_TRAMP_LEN;
  80         sm->alloc = sm_alloc_us;
  81         sm->free = sm_free_us;
  82         INIT_HLIST_NODE(&sm->page_list);
  83         sm->data = task;
  84
  85         return sm;
  86 }
  87
  88 void free_sm_us(struct slot_manager *sm)
  89 {
  90         /* FIXME: free */
  91 }