drivers/android/binder_alloc.h

   1 /*
   2  * Copyright (C) 2017 Google, Inc.
   3  *
   4  * This software is licensed under the terms of the GNU General Public
   5  * License version 2, as published by the Free Software Foundation, and
   6  * may be copied, distributed, and modified under those terms.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11  * GNU General Public License for more details.
  12  *
  13  */
  14
  15 #ifndef _LINUX_BINDER_ALLOC_H
  16 #define _LINUX_BINDER_ALLOC_H
  17
  18 #include <linux/rbtree.h>
  19 #include <linux/list.h>
  20 #include <linux/mm.h>
  21 #include <linux/rtmutex.h>
  22 #include <linux/vmalloc.h>
  23 #include <linux/slab.h>
  24
  25 struct binder_transaction;
  26
  27 /**
  28  * struct binder_buffer - buffer used for binder transactions
  29  * @entry:              entry alloc->buffers
  30  * @rb_node:            node for allocated_buffers/free_buffers rb trees
  31  * @free:               true if buffer is free
  32  * @allow_user_free:    describe the second member of struct blah,
  33  * @async_transaction:  describe the second member of struct blah,
  34  * @debug_id:           describe the second member of struct blah,
  35  * @transaction:        describe the second member of struct blah,
  36  * @target_node:        describe the second member of struct blah,
  37  * @data_size:          describe the second member of struct blah,
  38  * @offsets_size:       describe the second member of struct blah,
  39  * @extra_buffers_size: describe the second member of struct blah,
  40  * @data:i              describe the second member of struct blah,
  41  *
  42  * Bookkeeping structure for binder transaction buffers
  43  */
  44 struct binder_buffer {
  45         struct list_head entry; /* free and allocated entries by address */
  46         struct rb_node rb_node; /* free entry by size or allocated entry */
  47                                 /* by address */
  48         unsigned free:1;
  49         unsigned allow_user_free:1;
  50         unsigned async_transaction:1;
  51         unsigned free_in_progress:1;
  52         unsigned debug_id:28;
  53
  54         struct binder_transaction *transaction;
  55
  56         struct binder_node *target_node;
  57         size_t data_size;
  58         size_t offsets_size;
  59         size_t extra_buffers_size;
  60         uint8_t data[0];
  61 };
  62
  63 /**
  64  * struct binder_alloc - per-binder proc state for binder allocator
  65  * @vma:                vm_area_struct passed to mmap_handler
  66  *                      (invarient after mmap)
  67  * @tsk:                tid for task that called init for this proc
  68  *                      (invariant after init)
  69  * @vma_vm_mm:          copy of vma->vm_mm (invarient after mmap)
  70  * @buffer:             base of per-proc address space mapped via mmap
  71  * @user_buffer_offset: offset between user and kernel VAs for buffer
  72  * @buffers:            list of all buffers for this proc
  73  * @free_buffers:       rb tree of buffers available for allocation
  74  *                      sorted by size
  75  * @allocated_buffers:  rb tree of allocated buffers sorted by address
  76  * @free_async_space:   VA space available for async buffers. This is
  77  *                      initialized at mmap time to 1/2 the full VA space
  78  * @pages:              array of physical page addresses for each
  79  *                      page of mmap'd space
  80  * @buffer_size:        size of address space specified via mmap
  81  * @pid:                pid for associated binder_proc (invariant after init)
  82  *
  83  * Bookkeeping structure for per-proc address space management for binder
  84  * buffers. It is normally initialized during binder_init() and binder_mmap()
  85  * calls. The address space is used for both user-visible buffers and for
  86  * struct binder_buffer objects used to track the user buffers
  87  */
  88 struct binder_alloc {
  89         struct mutex mutex;
  90         struct task_struct *tsk;
  91         struct vm_area_struct *vma;
  92         struct mm_struct *vma_vm_mm;
  93         void *buffer;
  94         ptrdiff_t user_buffer_offset;
  95         struct list_head buffers;
  96         struct rb_root free_buffers;
  97         struct rb_root allocated_buffers;
  98         size_t free_async_space;
  99         struct page **pages;
 100         size_t buffer_size;
 101         uint32_t buffer_free;
 102         int pid;
 103 };
 104
 105 extern struct binder_buffer *binder_alloc_new_buf(struct binder_alloc *alloc,
 106                                                   size_t data_size,
 107                                                   size_t offsets_size,
 108                                                   size_t extra_buffers_size,
 109                                                   int is_async);
 110 extern void binder_alloc_init(struct binder_alloc *alloc);
 111 extern void binder_alloc_vma_close(struct binder_alloc *alloc);
 112 extern struct binder_buffer *
 113 binder_alloc_prepare_to_free(struct binder_alloc *alloc,
 114                              uintptr_t user_ptr);
 115 extern void binder_alloc_free_buf(struct binder_alloc *alloc,
 116                                   struct binder_buffer *buffer);
 117 extern int binder_alloc_mmap_handler(struct binder_alloc *alloc,
 118                                      struct vm_area_struct *vma);
 119 extern void binder_alloc_deferred_release(struct binder_alloc *alloc);
 120 extern int binder_alloc_get_allocated_count(struct binder_alloc *alloc);
 121 extern void binder_alloc_print_allocated(struct seq_file *m,
 122                                          struct binder_alloc *alloc);
 123
 124 /**
 125  * binder_alloc_get_free_async_space() - get free space available for async
 126  * @alloc:      binder_alloc for this proc
 127  *
 128  * Return:      the bytes remaining in the address-space for async transactions
 129  */
 130 static inline size_t
 131 binder_alloc_get_free_async_space(struct binder_alloc *alloc)
 132 {
 133         size_t free_async_space;
 134
 135         mutex_lock(&alloc->mutex);
 136         free_async_space = alloc->free_async_space;
 137         mutex_unlock(&alloc->mutex);
 138         return free_async_space;
 139 }
 140
 141 /**
 142  * binder_alloc_get_user_buffer_offset() - get offset between kernel/user addrs
 143  * @alloc:      binder_alloc for this proc
 144  *
 145  * Return:      the offset between kernel and user-space addresses to use for
 146  * virtual address conversion
 147  */
 148 static inline ptrdiff_t
 149 binder_alloc_get_user_buffer_offset(struct binder_alloc *alloc)
 150 {
 151         /*
 152          * user_buffer_offset is constant if vma is set and
 153          * undefined if vma is not set. It is possible to
 154          * get here with !alloc->vma if the target process
 155          * is dying while a transaction is being initiated.
 156          * Returning the old value is ok in this case and
 157          * the transaction will fail.
 158          */
 159         return alloc->user_buffer_offset;
 160 }
 161
 162 #endif /* _LINUX_BINDER_ALLOC_H */