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 align,
  39                    size_t size, gfp_t gfp)
  40 {
  41         unsigned long addr = head->vm_start, end = head->vm_end - size;
  42         unsigned long flags;
  43         struct arm_vmregion *c, *new;
  44
  45         if (head->vm_end - head->vm_start < size) {
  46                 printk(KERN_WARNING "%s: allocation too big (requested %#x)\n",
  47                         __func__, size);
  48                 goto out;
  49         }
  50
  51         new = kmalloc(sizeof(struct arm_vmregion), gfp);
  52         if (!new)
  53                 goto out;
  54
  55         spin_lock_irqsave(&head->vm_lock, flags);
  56
  57         list_for_each_entry(c, &head->vm_list, vm_list) {
  58                 if ((addr + size) < addr)
  59                         goto nospc;
  60                 if ((addr + size) <= c->vm_start)
  61                         goto found;
  62                 addr = ALIGN(c->vm_end, align);
  63                 if (addr > end)
  64                         goto nospc;
  65         }
  66
  67  found:
  68         /*
  69          * Insert this entry _before_ the one we found.
  70          */
  71         list_add_tail(&new->vm_list, &c->vm_list);
  72         new->vm_start = addr;
  73         new->vm_end = addr + size;
  74         new->vm_active = 1;
  75
  76         spin_unlock_irqrestore(&head->vm_lock, flags);
  77         return new;
  78
  79  nospc:
  80         spin_unlock_irqrestore(&head->vm_lock, flags);
  81         kfree(new);
  82  out:
  83         return NULL;
  84 }
  85
  86 static struct arm_vmregion *__arm_vmregion_find(struct arm_vmregion_head *head, unsigned long addr)
  87 {
  88         struct arm_vmregion *c;
  89
  90         list_for_each_entry(c, &head->vm_list, vm_list) {
  91                 if (c->vm_active && c->vm_start == addr)
  92                         goto out;
  93         }
  94         c = NULL;
  95  out:
  96         return c;
  97 }
  98
  99 struct arm_vmregion *arm_vmregion_find(struct arm_vmregion_head *head, unsigned long addr)
 100 {
 101         struct arm_vmregion *c;
 102         unsigned long flags;
 103
 104         spin_lock_irqsave(&head->vm_lock, flags);
 105         c = __arm_vmregion_find(head, addr);
 106         spin_unlock_irqrestore(&head->vm_lock, flags);
 107         return c;
 108 }
 109
 110 struct arm_vmregion *arm_vmregion_find_remove(struct arm_vmregion_head *head, unsigned long addr)
 111 {
 112         struct arm_vmregion *c;
 113         unsigned long flags;
 114
 115         spin_lock_irqsave(&head->vm_lock, flags);
 116         c = __arm_vmregion_find(head, addr);
 117         if (c)
 118                 c->vm_active = 0;
 119         spin_unlock_irqrestore(&head->vm_lock, flags);
 120         return c;
 121 }
 122
 123 void arm_vmregion_free(struct arm_vmregion_head *head, struct arm_vmregion *c)
 124 {
 125         unsigned long flags;
 126
 127         spin_lock_irqsave(&head->vm_lock, flags);
 128         list_del(&c->vm_list);
 129         spin_unlock_irqrestore(&head->vm_lock, flags);
 130
 131         kfree(c);
 132 }