drivers/firmware/efi/fake_mem.c

   1 /*
   2  * fake_mem.c
   3  *
   4  * Copyright (C) 2015 FUJITSU LIMITED
   5  * Author: Taku Izumi <izumi.taku@jp.fujitsu.com>
   6  *
   7  * This code introduces new boot option named "efi_fake_mem"
   8  * By specifying this parameter, you can add arbitrary attribute to
   9  * specific memory range by updating original (firmware provided) EFI
  10  * memmap.
  11  *
  12  *  This program is free software; you can redistribute it and/or modify it
  13  *  under the terms and conditions of the GNU General Public License,
  14  *  version 2, as published by the Free Software Foundation.
  15  *
  16  *  This program is distributed in the hope it will be useful, but WITHOUT
  17  *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  18  *  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  19  *  more details.
  20  *
  21  *  You should have received a copy of the GNU General Public License along with
  22  *  this program; if not, see <http://www.gnu.org/licenses/>.
  23  *
  24  *  The full GNU General Public License is included in this distribution in
  25  *  the file called "COPYING".
  26  */
  27
  28 #include <linux/kernel.h>
  29 #include <linux/efi.h>
  30 #include <linux/init.h>
  31 #include <linux/memblock.h>
  32 #include <linux/types.h>
  33 #include <linux/sort.h>
  34 #include <asm/efi.h>
  35
  36 #define EFI_MAX_FAKEMEM CONFIG_EFI_MAX_FAKE_MEM
  37
  38 struct fake_mem {
  39         struct range range;
  40         u64 attribute;
  41 };
  42 static struct fake_mem fake_mems[EFI_MAX_FAKEMEM];
  43 static int nr_fake_mem;
  44
  45 static int __init cmp_fake_mem(const void *x1, const void *x2)
  46 {
  47         const struct fake_mem *m1 = x1;
  48         const struct fake_mem *m2 = x2;
  49
  50         if (m1->range.start < m2->range.start)
  51                 return -1;
  52         if (m1->range.start > m2->range.start)
  53                 return 1;
  54         return 0;
  55 }
  56
  57 void __init efi_fake_memmap(void)
  58 {
  59         u64 start, end, m_start, m_end, m_attr;
  60         int new_nr_map = memmap.nr_map;
  61         efi_memory_desc_t *md;
  62         phys_addr_t new_memmap_phy;
  63         void *new_memmap;
  64         void *old, *new;
  65         int i;
  66
  67         if (!nr_fake_mem || !efi_enabled(EFI_MEMMAP))
  68                 return;
  69
  70         /* count up the number of EFI memory descriptor */
  71         for (old = memmap.map; old < memmap.map_end; old += memmap.desc_size) {
  72                 md = old;
  73                 start = md->phys_addr;
  74                 end = start + (md->num_pages << EFI_PAGE_SHIFT) - 1;
  75
  76                 for (i = 0; i < nr_fake_mem; i++) {
  77                         /* modifying range */
  78                         m_start = fake_mems[i].range.start;
  79                         m_end = fake_mems[i].range.end;
  80
  81                         if (m_start <= start) {
  82                                 /* split into 2 parts */
  83                                 if (start < m_end && m_end < end)
  84                                         new_nr_map++;
  85                         }
  86                         if (start < m_start && m_start < end) {
  87                                 /* split into 3 parts */
  88                                 if (m_end < end)
  89                                         new_nr_map += 2;
  90                                 /* split into 2 parts */
  91                                 if (end <= m_end)
  92                                         new_nr_map++;
  93                         }
  94                 }
  95         }
  96
  97         /* allocate memory for new EFI memmap */
  98         new_memmap_phy = memblock_alloc(memmap.desc_size * new_nr_map,
  99                                         PAGE_SIZE);
 100         if (!new_memmap_phy)
 101                 return;
 102
 103         /* create new EFI memmap */
 104         new_memmap = early_memremap(new_memmap_phy,
 105                                     memmap.desc_size * new_nr_map);
 106         if (!new_memmap) {
 107                 memblock_free(new_memmap_phy, memmap.desc_size * new_nr_map);
 108                 return;
 109         }
 110
 111         for (old = memmap.map, new = new_memmap;
 112              old < memmap.map_end;
 113              old += memmap.desc_size, new += memmap.desc_size) {
 114
 115                 /* copy original EFI memory descriptor */
 116                 memcpy(new, old, memmap.desc_size);
 117                 md = new;
 118                 start = md->phys_addr;
 119                 end = md->phys_addr + (md->num_pages << EFI_PAGE_SHIFT) - 1;
 120
 121                 for (i = 0; i < nr_fake_mem; i++) {
 122                         /* modifying range */
 123                         m_start = fake_mems[i].range.start;
 124                         m_end = fake_mems[i].range.end;
 125                         m_attr = fake_mems[i].attribute;
 126
 127                         if (m_start <= start && end <= m_end)
 128                                 md->attribute |= m_attr;
 129
 130                         if (m_start <= start &&
 131                             (start < m_end && m_end < end)) {
 132                                 /* first part */
 133                                 md->attribute |= m_attr;
 134                                 md->num_pages = (m_end - md->phys_addr + 1) >>
 135                                         EFI_PAGE_SHIFT;
 136                                 /* latter part */
 137                                 new += memmap.desc_size;
 138                                 memcpy(new, old, memmap.desc_size);
 139                                 md = new;
 140                                 md->phys_addr = m_end + 1;
 141                                 md->num_pages = (end - md->phys_addr + 1) >>
 142                                         EFI_PAGE_SHIFT;
 143                         }
 144
 145                         if ((start < m_start && m_start < end) && m_end < end) {
 146                                 /* first part */
 147                                 md->num_pages = (m_start - md->phys_addr) >>
 148                                         EFI_PAGE_SHIFT;
 149                                 /* middle part */
 150                                 new += memmap.desc_size;
 151                                 memcpy(new, old, memmap.desc_size);
 152                                 md = new;
 153                                 md->attribute |= m_attr;
 154                                 md->phys_addr = m_start;
 155                                 md->num_pages = (m_end - m_start + 1) >>
 156                                         EFI_PAGE_SHIFT;
 157                                 /* last part */
 158                                 new += memmap.desc_size;
 159                                 memcpy(new, old, memmap.desc_size);
 160                                 md = new;
 161                                 md->phys_addr = m_end + 1;
 162                                 md->num_pages = (end - m_end) >>
 163                                         EFI_PAGE_SHIFT;
 164                         }
 165
 166                         if ((start < m_start && m_start < end) &&
 167                             (end <= m_end)) {
 168                                 /* first part */
 169                                 md->num_pages = (m_start - md->phys_addr) >>
 170                                         EFI_PAGE_SHIFT;
 171                                 /* latter part */
 172                                 new += memmap.desc_size;
 173                                 memcpy(new, old, memmap.desc_size);
 174                                 md = new;
 175                                 md->phys_addr = m_start;
 176                                 md->num_pages = (end - md->phys_addr + 1) >>
 177                                         EFI_PAGE_SHIFT;
 178                                 md->attribute |= m_attr;
 179                         }
 180                 }
 181         }
 182
 183         /* swap into new EFI memmap */
 184         efi_unmap_memmap();
 185         memmap.map = new_memmap;
 186         memmap.phys_map = new_memmap_phy;
 187         memmap.nr_map = new_nr_map;
 188         memmap.map_end = memmap.map + memmap.nr_map * memmap.desc_size;
 189         set_bit(EFI_MEMMAP, &efi.flags);
 190
 191         /* print new EFI memmap */
 192         efi_print_memmap();
 193 }
 194
 195 static int __init setup_fake_mem(char *p)
 196 {
 197         u64 start = 0, mem_size = 0, attribute = 0;
 198         int i;
 199
 200         if (!p)
 201                 return -EINVAL;
 202
 203         while (*p != '\0') {
 204                 mem_size = memparse(p, &p);
 205                 if (*p == '@')
 206                         start = memparse(p+1, &p);
 207                 else
 208                         break;
 209
 210                 if (*p == ':')
 211                         attribute = simple_strtoull(p+1, &p, 0);
 212                 else
 213                         break;
 214
 215                 if (nr_fake_mem >= EFI_MAX_FAKEMEM)
 216                         break;
 217
 218                 fake_mems[nr_fake_mem].range.start = start;
 219                 fake_mems[nr_fake_mem].range.end = start + mem_size - 1;
 220                 fake_mems[nr_fake_mem].attribute = attribute;
 221                 nr_fake_mem++;
 222
 223                 if (*p == ',')
 224                         p++;
 225         }
 226
 227         sort(fake_mems, nr_fake_mem, sizeof(struct fake_mem),
 228              cmp_fake_mem, NULL);
 229
 230         for (i = 0; i < nr_fake_mem; i++)
 231                 pr_info("efi_fake_mem: add attr=0x%016llx to [mem 0x%016llx-0x%016llx]",
 232                         fake_mems[i].attribute, fake_mems[i].range.start,
 233                         fake_mems[i].range.end);
 234
 235         return *p == '\0' ? 0 : -EINVAL;
 236 }
 237
 238 early_param("efi_fake_mem", setup_fake_mem);