drivers/firmware/efi/memmap.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Common EFI memory map functions.
   4  */
   5
   6 #define pr_fmt(fmt) "efi: " fmt
   7
   8 #include <linux/init.h>
   9 #include <linux/kernel.h>
  10 #include <linux/efi.h>
  11 #include <linux/io.h>
  12 #include <linux/memblock.h>
  13 #include <linux/slab.h>
  14
  15 #include <asm/early_ioremap.h>
  16 #include <asm/efi.h>
  17
  18 /**
  19  * __efi_memmap_init - Common code for mapping the EFI memory map
  20  * @data: EFI memory map data
  21  *
  22  * This function takes care of figuring out which function to use to
  23  * map the EFI memory map in efi.memmap based on how far into the boot
  24  * we are.
  25  *
  26  * During bootup EFI_MEMMAP_LATE in data->flags should be clear since we
  27  * only have access to the early_memremap*() functions as the vmalloc
  28  * space isn't setup.  Once the kernel is fully booted we can fallback
  29  * to the more robust memremap*() API.
  30  *
  31  * Returns: zero on success, a negative error code on failure.
  32  */
  33 int __init __efi_memmap_init(struct efi_memory_map_data *data)
  34 {
  35         struct efi_memory_map map;
  36         phys_addr_t phys_map;
  37
  38         phys_map = data->phys_map;
  39
  40         if (data->flags & EFI_MEMMAP_LATE)
  41                 map.map = memremap(phys_map, data->size, MEMREMAP_WB);
  42         else
  43                 map.map = early_memremap(phys_map, data->size);
  44
  45         if (!map.map) {
  46                 pr_err("Could not map the memory map!\n");
  47                 return -ENOMEM;
  48         }
  49
  50         map.phys_map = data->phys_map;
  51         map.nr_map = data->size / data->desc_size;
  52         map.map_end = map.map + data->size;
  53
  54         map.desc_version = data->desc_version;
  55         map.desc_size = data->desc_size;
  56         map.flags = data->flags;
  57
  58         set_bit(EFI_MEMMAP, &efi.flags);
  59
  60         efi.memmap = map;
  61
  62         return 0;
  63 }
  64
  65 /**
  66  * efi_memmap_init_early - Map the EFI memory map data structure
  67  * @data: EFI memory map data
  68  *
  69  * Use early_memremap() to map the passed in EFI memory map and assign
  70  * it to efi.memmap.
  71  *
  72  * Returns: zero on success, a negative error code on failure.
  73  */
  74 int __init efi_memmap_init_early(struct efi_memory_map_data *data)
  75 {
  76         /* Cannot go backwards */
  77         WARN_ON(efi.memmap.flags & EFI_MEMMAP_LATE);
  78
  79         data->flags = 0;
  80         return __efi_memmap_init(data);
  81 }
  82
  83 void __init efi_memmap_unmap(void)
  84 {
  85         if (!efi_enabled(EFI_MEMMAP))
  86                 return;
  87
  88         if (!(efi.memmap.flags & EFI_MEMMAP_LATE)) {
  89                 unsigned long size;
  90
  91                 size = efi.memmap.desc_size * efi.memmap.nr_map;
  92                 early_memunmap(efi.memmap.map, size);
  93         } else {
  94                 memunmap(efi.memmap.map);
  95         }
  96
  97         efi.memmap.map = NULL;
  98         clear_bit(EFI_MEMMAP, &efi.flags);
  99 }
 100
 101 /**
 102  * efi_memmap_init_late - Map efi.memmap with memremap()
 103  * @addr: Physical address of the new EFI memory map
 104  * @size: Size in bytes of the new EFI memory map
 105  *
 106  * Setup a mapping of the EFI memory map using ioremap_cache(). This
 107  * function should only be called once the vmalloc space has been
 108  * setup and is therefore not suitable for calling during early EFI
 109  * initialise, e.g. in efi_init(). Additionally, it expects
 110  * efi_memmap_init_early() to have already been called.
 111  *
 112  * The reason there are two EFI memmap initialisation
 113  * (efi_memmap_init_early() and this late version) is because the
 114  * early EFI memmap should be explicitly unmapped once EFI
 115  * initialisation is complete as the fixmap space used to map the EFI
 116  * memmap (via early_memremap()) is a scarce resource.
 117  *
 118  * This late mapping is intended to persist for the duration of
 119  * runtime so that things like efi_mem_desc_lookup() and
 120  * efi_mem_attributes() always work.
 121  *
 122  * Returns: zero on success, a negative error code on failure.
 123  */
 124 int __init efi_memmap_init_late(phys_addr_t addr, unsigned long size)
 125 {
 126         struct efi_memory_map_data data = {
 127                 .phys_map = addr,
 128                 .size = size,
 129                 .flags = EFI_MEMMAP_LATE,
 130         };
 131
 132         /* Did we forget to unmap the early EFI memmap? */
 133         WARN_ON(efi.memmap.map);
 134
 135         /* Were we already called? */
 136         WARN_ON(efi.memmap.flags & EFI_MEMMAP_LATE);
 137
 138         /*
 139          * It makes no sense to allow callers to register different
 140          * values for the following fields. Copy them out of the
 141          * existing early EFI memmap.
 142          */
 143         data.desc_version = efi.memmap.desc_version;
 144         data.desc_size = efi.memmap.desc_size;
 145
 146         return __efi_memmap_init(&data);
 147 }