mm/cma_debug.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * CMA DebugFS Interface
   4  *
   5  * Copyright (c) 2015 Sasha Levin <sasha.levin@oracle.com>
   6  */
   7
   8
   9 #include <linux/debugfs.h>
  10 #include <linux/cma.h>
  11 #include <linux/list.h>
  12 #include <linux/kernel.h>
  13 #include <linux/slab.h>
  14 #include <linux/mm_types.h>
  15
  16 #include "cma.h"
  17
  18 struct cma_mem {
  19         struct hlist_node node;
  20         struct page *p;
  21         unsigned long n;
  22 };
  23
  24 static struct dentry *cma_debugfs_root;
  25
  26 static int cma_debugfs_get(void *data, u64 *val)
  27 {
  28         unsigned long *p = data;
  29
  30         *val = *p;
  31
  32         return 0;
  33 }
  34 DEFINE_SIMPLE_ATTRIBUTE(cma_debugfs_fops, cma_debugfs_get, NULL, "%llu\n");
  35
  36 static int cma_used_get(void *data, u64 *val)
  37 {
  38         struct cma *cma = data;
  39         unsigned long used;
  40
  41         mutex_lock(&cma->lock);
  42         /* pages counter is smaller than sizeof(int) */
  43         used = bitmap_weight(cma->bitmap, (int)cma_bitmap_maxno(cma));
  44         mutex_unlock(&cma->lock);
  45         *val = (u64)used << cma->order_per_bit;
  46
  47         return 0;
  48 }
  49 DEFINE_SIMPLE_ATTRIBUTE(cma_used_fops, cma_used_get, NULL, "%llu\n");
  50
  51 static int cma_maxchunk_get(void *data, u64 *val)
  52 {
  53         struct cma *cma = data;
  54         unsigned long maxchunk = 0;
  55         unsigned long start, end = 0;
  56         unsigned long bitmap_maxno = cma_bitmap_maxno(cma);
  57
  58         mutex_lock(&cma->lock);
  59         for (;;) {
  60                 start = find_next_zero_bit(cma->bitmap, bitmap_maxno, end);
  61                 if (start >= cma->count)
  62                         break;
  63                 end = find_next_bit(cma->bitmap, bitmap_maxno, start);
  64                 maxchunk = max(end - start, maxchunk);
  65         }
  66         mutex_unlock(&cma->lock);
  67         *val = (u64)maxchunk << cma->order_per_bit;
  68
  69         return 0;
  70 }
  71 DEFINE_SIMPLE_ATTRIBUTE(cma_maxchunk_fops, cma_maxchunk_get, NULL, "%llu\n");
  72
  73 static void cma_add_to_cma_mem_list(struct cma *cma, struct cma_mem *mem)
  74 {
  75         spin_lock(&cma->mem_head_lock);
  76         hlist_add_head(&mem->node, &cma->mem_head);
  77         spin_unlock(&cma->mem_head_lock);
  78 }
  79
  80 static struct cma_mem *cma_get_entry_from_list(struct cma *cma)
  81 {
  82         struct cma_mem *mem = NULL;
  83
  84         spin_lock(&cma->mem_head_lock);
  85         if (!hlist_empty(&cma->mem_head)) {
  86                 mem = hlist_entry(cma->mem_head.first, struct cma_mem, node);
  87                 hlist_del_init(&mem->node);
  88         }
  89         spin_unlock(&cma->mem_head_lock);
  90
  91         return mem;
  92 }
  93
  94 static int cma_free_mem(struct cma *cma, int count)
  95 {
  96         struct cma_mem *mem = NULL;
  97
  98         while (count) {
  99                 mem = cma_get_entry_from_list(cma);
 100                 if (mem == NULL)
 101                         return 0;
 102
 103                 if (mem->n <= count) {
 104                         cma_release(cma, mem->p, mem->n);
 105                         count -= mem->n;
 106                         kfree(mem);
 107                 } else if (cma->order_per_bit == 0) {
 108                         cma_release(cma, mem->p, count);
 109                         mem->p += count;
 110                         mem->n -= count;
 111                         count = 0;
 112                         cma_add_to_cma_mem_list(cma, mem);
 113                 } else {
 114                         pr_debug("cma: cannot release partial block when order_per_bit != 0\n");
 115                         cma_add_to_cma_mem_list(cma, mem);
 116                         break;
 117                 }
 118         }
 119
 120         return 0;
 121
 122 }
 123
 124 static int cma_free_write(void *data, u64 val)
 125 {
 126         int pages = val;
 127         struct cma *cma = data;
 128
 129         return cma_free_mem(cma, pages);
 130 }
 131 DEFINE_SIMPLE_ATTRIBUTE(cma_free_fops, NULL, cma_free_write, "%llu\n");
 132
 133 static int cma_alloc_mem(struct cma *cma, int count)
 134 {
 135         struct cma_mem *mem;
 136         struct page *p;
 137
 138         mem = kzalloc(sizeof(*mem), GFP_KERNEL);
 139         if (!mem)
 140                 return -ENOMEM;
 141
 142         p = cma_alloc(cma, count, 0, false);
 143         if (!p) {
 144                 kfree(mem);
 145                 return -ENOMEM;
 146         }
 147
 148         mem->p = p;
 149         mem->n = count;
 150
 151         cma_add_to_cma_mem_list(cma, mem);
 152
 153         return 0;
 154 }
 155
 156 static int cma_alloc_write(void *data, u64 val)
 157 {
 158         int pages = val;
 159         struct cma *cma = data;
 160
 161         return cma_alloc_mem(cma, pages);
 162 }
 163 DEFINE_SIMPLE_ATTRIBUTE(cma_alloc_fops, NULL, cma_alloc_write, "%llu\n");
 164
 165 static void cma_debugfs_add_one(struct cma *cma, int idx)
 166 {
 167         struct dentry *tmp;
 168         char name[16];
 169         int u32s;
 170
 171         scnprintf(name, sizeof(name), "cma-%s", cma->name);
 172
 173         tmp = debugfs_create_dir(name, cma_debugfs_root);
 174
 175         debugfs_create_file("alloc", 0200, tmp, cma, &cma_alloc_fops);
 176         debugfs_create_file("free", 0200, tmp, cma, &cma_free_fops);
 177         debugfs_create_file("base_pfn", 0444, tmp,
 178                             &cma->base_pfn, &cma_debugfs_fops);
 179         debugfs_create_file("count", 0444, tmp, &cma->count, &cma_debugfs_fops);
 180         debugfs_create_file("order_per_bit", 0444, tmp,
 181                             &cma->order_per_bit, &cma_debugfs_fops);
 182         debugfs_create_file("used", 0444, tmp, cma, &cma_used_fops);
 183         debugfs_create_file("maxchunk", 0444, tmp, cma, &cma_maxchunk_fops);
 184
 185         u32s = DIV_ROUND_UP(cma_bitmap_maxno(cma), BITS_PER_BYTE * sizeof(u32));
 186         debugfs_create_u32_array("bitmap", 0444, tmp, (u32 *)cma->bitmap, u32s);
 187 }
 188
 189 static int __init cma_debugfs_init(void)
 190 {
 191         int i;
 192
 193         cma_debugfs_root = debugfs_create_dir("cma", NULL);
 194         if (!cma_debugfs_root)
 195                 return -ENOMEM;
 196
 197         for (i = 0; i < cma_area_count; i++)
 198                 cma_debugfs_add_one(&cma_areas[i], i);
 199
 200         return 0;
 201 }
 202 late_initcall(cma_debugfs_init);