drivers/firmware/efi/fake_mem.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * fake_mem.c
   4  *
   5  * Copyright (C) 2015 FUJITSU LIMITED
   6  * Author: Taku Izumi <izumi.taku@jp.fujitsu.com>
   7  *
   8  * This code introduces new boot option named "efi_fake_mem"
   9  * By specifying this parameter, you can add arbitrary attribute to
  10  * specific memory range by updating original (firmware provided) EFI
  11  * memmap.
  12  */
  13
  14 #include <linux/kernel.h>
  15 #include <linux/efi.h>
  16 #include <linux/init.h>
  17 #include <linux/memblock.h>
  18 #include <linux/types.h>
  19 #include <linux/sort.h>
  20 #include "fake_mem.h"
  21
  22 struct efi_mem_range efi_fake_mems[EFI_MAX_FAKEMEM];
  23 int nr_fake_mem;
  24
  25 static int __init cmp_fake_mem(const void *x1, const void *x2)
  26 {
  27         const struct efi_mem_range *m1 = x1;
  28         const struct efi_mem_range *m2 = x2;
  29
  30         if (m1->range.start < m2->range.start)
  31                 return -1;
  32         if (m1->range.start > m2->range.start)
  33                 return 1;
  34         return 0;
  35 }
  36
  37 static void __init efi_fake_range(struct efi_mem_range *efi_range)
  38 {
  39         struct efi_memory_map_data data = { 0 };
  40         int new_nr_map = efi.memmap.nr_map;
  41         efi_memory_desc_t *md;
  42         void *new_memmap;
  43
  44         /* count up the number of EFI memory descriptor */
  45         for_each_efi_memory_desc(md)
  46                 new_nr_map += efi_memmap_split_count(md, &efi_range->range);
  47
  48         /* allocate memory for new EFI memmap */
  49         if (efi_memmap_alloc(new_nr_map, &data) != 0)
  50                 return;
  51
  52         /* create new EFI memmap */
  53         new_memmap = early_memremap(data.phys_map, data.size);
  54         if (!new_memmap) {
  55                 __efi_memmap_free(data.phys_map, data.size, data.flags);
  56                 return;
  57         }
  58
  59         efi_memmap_insert(&efi.memmap, new_memmap, efi_range);
  60
  61         /* swap into new EFI memmap */
  62         early_memunmap(new_memmap, data.size);
  63
  64         efi_memmap_install(&data);
  65 }
  66
  67 void __init efi_fake_memmap(void)
  68 {
  69         int i;
  70
  71         if (!efi_enabled(EFI_MEMMAP) || !nr_fake_mem)
  72                 return;
  73
  74         for (i = 0; i < nr_fake_mem; i++)
  75                 efi_fake_range(&efi_fake_mems[i]);
  76
  77         /* print new EFI memmap */
  78         efi_print_memmap();
  79 }
  80
  81 static int __init setup_fake_mem(char *p)
  82 {
  83         u64 start = 0, mem_size = 0, attribute = 0;
  84         int i;
  85
  86         if (!p)
  87                 return -EINVAL;
  88
  89         while (*p != '\0') {
  90                 mem_size = memparse(p, &p);
  91                 if (*p == '@')
  92                         start = memparse(p+1, &p);
  93                 else
  94                         break;
  95
  96                 if (*p == ':')
  97                         attribute = simple_strtoull(p+1, &p, 0);
  98                 else
  99                         break;
 100
 101                 if (nr_fake_mem >= EFI_MAX_FAKEMEM)
 102                         break;
 103
 104                 efi_fake_mems[nr_fake_mem].range.start = start;
 105                 efi_fake_mems[nr_fake_mem].range.end = start + mem_size - 1;
 106                 efi_fake_mems[nr_fake_mem].attribute = attribute;
 107                 nr_fake_mem++;
 108
 109                 if (*p == ',')
 110                         p++;
 111         }
 112
 113         sort(efi_fake_mems, nr_fake_mem, sizeof(struct efi_mem_range),
 114              cmp_fake_mem, NULL);
 115
 116         for (i = 0; i < nr_fake_mem; i++)
 117                 pr_info("efi_fake_mem: add attr=0x%016llx to [mem 0x%016llx-0x%016llx]",
 118                         efi_fake_mems[i].attribute, efi_fake_mems[i].range.start,
 119                         efi_fake_mems[i].range.end);
 120
 121         return *p == '\0' ? 0 : -EINVAL;
 122 }
 123
 124 early_param("efi_fake_mem", setup_fake_mem);