arch/arm/mm/vmregion.c

   1 #include <linux/spinlock.h>
   2 #include <linux/list.h>
   3 #include <linux/slab.h>
   4
   5 #include "vmregion.h"
   6
   7 /*
   8  * VM region handling support.
   9  *
  10  * This should become something generic, handling VM region allocations for
  11  * vmalloc and similar (ioremap, module space, etc).
  12  *
  13  * I envisage vmalloc()'s supporting vm_struct becoming:
  14  *
  15  *  struct vm_struct {
  16  *    struct vmregion   region;
  17  *    unsigned long     flags;
  18  *    struct page       **pages;
  19  *    unsigned int      nr_pages;
  20  *    unsigned long     phys_addr;
  21  *  };
  22  *
  23  * get_vm_area() would then call vmregion_alloc with an appropriate
  24  * struct vmregion head (eg):
  25  *
  26  *  struct vmregion vmalloc_head = {
  27  *      .vm_list        = LIST_HEAD_INIT(vmalloc_head.vm_list),
  28  *      .vm_start       = VMALLOC_START,
  29  *      .vm_end         = VMALLOC_END,
  30  *  };
  31  *
  32  * However, vmalloc_head.vm_start is variable (typically, it is dependent on
  33  * the amount of RAM found at boot time.)  I would imagine that get_vm_area()
  34  * would have to initialise this each time prior to calling vmregion_alloc().
  35  */
  36
  37 struct arm_vmregion *
  38 arm_vmregion_alloc(struct arm_vmregion_head *head, size_t size, gfp_t gfp)
  39 {
  40         unsigned long addr = head->vm_start, end = head->vm_end - size;
  41         unsigned long flags;
  42         struct arm_vmregion *c, *new;
  43
  44         if (head->vm_end - head->vm_start < size) {
  45                 printk(KERN_WARNING "%s: allocation too big (requested %#x)\n",
  46                         __func__, size);
  47                 goto out;
  48         }
  49
  50         new = kmalloc(sizeof(struct arm_vmregion), gfp);
  51         if (!new)
  52                 goto out;
  53
  54         spin_lock_irqsave(&head->vm_lock, flags);
  55
  56         list_for_each_entry(c, &head->vm_list, vm_list) {
  57                 if ((addr + size) < addr)
  58                         goto nospc;
  59                 if ((addr + size) <= c->vm_start)
  60                         goto found;
  61                 addr = c->vm_end;
  62                 if (addr > end)
  63                         goto nospc;
  64         }
  65
  66  found:
  67         /*
  68          * Insert this entry _before_ the one we found.
  69          */
  70         list_add_tail(&new->vm_list, &c->vm_list);
  71         new->vm_start = addr;
  72         new->vm_end = addr + size;
  73         new->vm_active = 1;
  74
  75         spin_unlock_irqrestore(&head->vm_lock, flags);
  76         return new;
  77
  78  nospc:
  79         spin_unlock_irqrestore(&head->vm_lock, flags);
  80         kfree(new);
  81  out:
  82         return NULL;
  83 }
  84
  85 static struct arm_vmregion *__arm_vmregion_find(struct arm_vmregion_head *head, unsigned long addr)
  86 {
  87         struct arm_vmregion *c;
  88
  89         list_for_each_entry(c, &head->vm_list, vm_list) {
  90                 if (c->vm_active && c->vm_start == addr)
  91                         goto out;
  92         }
  93         c = NULL;
  94  out:
  95         return c;
  96 }
  97
  98 struct arm_vmregion *arm_vmregion_find(struct arm_vmregion_head *head, unsigned long addr)
  99 {
 100         struct arm_vmregion *c;
 101         unsigned long flags;
 102
 103         spin_lock_irqsave(&head->vm_lock, flags);
 104         c = __arm_vmregion_find(head, addr);
 105         spin_unlock_irqrestore(&head->vm_lock, flags);
 106         return c;
 107 }
 108
 109 struct arm_vmregion *arm_vmregion_find_remove(struct arm_vmregion_head *head, unsigned long addr)
 110 {
 111         struct arm_vmregion *c;
 112         unsigned long flags;
 113
 114         spin_lock_irqsave(&head->vm_lock, flags);
 115         c = __arm_vmregion_find(head, addr);
 116         if (c)
 117                 c->vm_active = 0;
 118         spin_unlock_irqrestore(&head->vm_lock, flags);
 119         return c;
 120 }
 121
 122 void arm_vmregion_free(struct arm_vmregion_head *head, struct arm_vmregion *c)
 123 {
 124         unsigned long flags;
 125
 126         spin_lock_irqsave(&head->vm_lock, flags);
 127         list_del(&c->vm_list);
 128         spin_unlock_irqrestore(&head->vm_lock, flags);
 129
 130         kfree(c);
 131 }