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 */
 33int __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! phys_map=%pa, size=0x%lx\n",
 47			&phys_map, data->size);
 48		return -ENOMEM;
 49	}
 50
 51	map.phys_map = data->phys_map;
 52	map.nr_map = data->size / data->desc_size;
 53	map.map_end = map.map + data->size;
 54
 55	map.desc_version = data->desc_version;
 56	map.desc_size = data->desc_size;
 57	map.flags = data->flags;
 58
 59	set_bit(EFI_MEMMAP, &efi.flags);
 60
 61	efi.memmap = map;
 62
 63	return 0;
 64}
 65
 66/**
 67 * efi_memmap_init_early - Map the EFI memory map data structure
 68 * @data: EFI memory map data
 69 *
 70 * Use early_memremap() to map the passed in EFI memory map and assign
 71 * it to efi.memmap.
 72 *
 73 * Returns: zero on success, a negative error code on failure.
 74 */
 75int __init efi_memmap_init_early(struct efi_memory_map_data *data)
 76{
 77	/* Cannot go backwards */
 78	WARN_ON(efi.memmap.flags & EFI_MEMMAP_LATE);
 79
 80	data->flags = 0;
 81	return __efi_memmap_init(data);
 82}
 83
 84void __init efi_memmap_unmap(void)
 85{
 86	if (!efi_enabled(EFI_MEMMAP))
 87		return;
 88
 89	if (!(efi.memmap.flags & EFI_MEMMAP_LATE)) {
 90		unsigned long size;
 91
 92		size = efi.memmap.desc_size * efi.memmap.nr_map;
 93		early_memunmap(efi.memmap.map, size);
 94	} else {
 95		memunmap(efi.memmap.map);
 96	}
 97
 98	efi.memmap.map = NULL;
 99	clear_bit(EFI_MEMMAP, &efi.flags);
100}
101
102/**
103 * efi_memmap_init_late - Map efi.memmap with memremap()
104 * @addr: Physical address of the new EFI memory map
105 * @size: Size in bytes of the new EFI memory map
106 *
107 * Setup a mapping of the EFI memory map using ioremap_cache(). This
108 * function should only be called once the vmalloc space has been
109 * setup and is therefore not suitable for calling during early EFI
110 * initialise, e.g. in efi_init(). Additionally, it expects
111 * efi_memmap_init_early() to have already been called.
112 *
113 * The reason there are two EFI memmap initialisation
114 * (efi_memmap_init_early() and this late version) is because the
115 * early EFI memmap should be explicitly unmapped once EFI
116 * initialisation is complete as the fixmap space used to map the EFI
117 * memmap (via early_memremap()) is a scarce resource.
118 *
119 * This late mapping is intended to persist for the duration of
120 * runtime so that things like efi_mem_desc_lookup() and
121 * efi_mem_attributes() always work.
122 *
123 * Returns: zero on success, a negative error code on failure.
124 */
125int __init efi_memmap_init_late(phys_addr_t addr, unsigned long size)
126{
127	struct efi_memory_map_data data = {
128		.phys_map = addr,
129		.size = size,
130		.flags = EFI_MEMMAP_LATE,
131	};
132
133	/* Did we forget to unmap the early EFI memmap? */
134	WARN_ON(efi.memmap.map);
135
136	/* Were we already called? */
137	WARN_ON(efi.memmap.flags & EFI_MEMMAP_LATE);
138
139	/*
140	 * It makes no sense to allow callers to register different
141	 * values for the following fields. Copy them out of the
142	 * existing early EFI memmap.
143	 */
144	data.desc_version = efi.memmap.desc_version;
145	data.desc_size = efi.memmap.desc_size;
146
147	return __efi_memmap_init(&data);
148}