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-rw-r--r--grub-core/kern/efi/mm.c691
1 files changed, 691 insertions, 0 deletions
diff --git a/grub-core/kern/efi/mm.c b/grub-core/kern/efi/mm.c
new file mode 100644
index 0000000..9838fb2
--- /dev/null
+++ b/grub-core/kern/efi/mm.c
@@ -0,0 +1,691 @@
+/* mm.c - generic EFI memory management */
+/*
+ * GRUB -- GRand Unified Bootloader
+ * Copyright (C) 2006,2007,2008,2009 Free Software Foundation, Inc.
+ *
+ * GRUB is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * GRUB is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with GRUB. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <grub/misc.h>
+#include <grub/mm.h>
+#include <grub/efi/api.h>
+#include <grub/efi/efi.h>
+#include <grub/cpu/efi/memory.h>
+
+#if defined (__i386__) || defined (__x86_64__)
+#include <grub/pci.h>
+#endif
+
+#define NEXT_MEMORY_DESCRIPTOR(desc, size) \
+ ((grub_efi_memory_descriptor_t *) ((char *) (desc) + (size)))
+
+#define BYTES_TO_PAGES(bytes) (((bytes) + 0xfff) >> 12)
+#define BYTES_TO_PAGES_DOWN(bytes) ((bytes) >> 12)
+#define PAGES_TO_BYTES(pages) ((pages) << 12)
+
+/* The size of a memory map obtained from the firmware. This must be
+ a multiplier of 4KB. */
+#define MEMORY_MAP_SIZE 0x3000
+
+/* The minimum and maximum heap size for GRUB itself. */
+#define MIN_HEAP_SIZE 0x100000
+#define MAX_HEAP_SIZE (1600 * 0x100000)
+
+static void *finish_mmap_buf = 0;
+static grub_efi_uintn_t finish_mmap_size = 0;
+static grub_efi_uintn_t finish_key = 0;
+static grub_efi_uintn_t finish_desc_size;
+static grub_efi_uint32_t finish_desc_version;
+int grub_efi_is_finished = 0;
+
+/*
+ * We need to roll back EFI allocations on exit. Remember allocations that
+ * we'll free on exit.
+ */
+struct efi_allocation;
+struct efi_allocation {
+ grub_efi_physical_address_t address;
+ grub_efi_uint64_t pages;
+ struct efi_allocation *next;
+};
+static struct efi_allocation *efi_allocated_memory;
+
+static void
+grub_efi_store_alloc (grub_efi_physical_address_t address,
+ grub_efi_uintn_t pages)
+{
+ grub_efi_boot_services_t *b;
+ struct efi_allocation *alloc;
+ grub_efi_status_t status;
+
+ b = grub_efi_system_table->boot_services;
+ status = efi_call_3 (b->allocate_pool, GRUB_EFI_LOADER_DATA,
+ sizeof(*alloc), (void**)&alloc);
+
+ if (status == GRUB_EFI_SUCCESS)
+ {
+ alloc->next = efi_allocated_memory;
+ alloc->address = address;
+ alloc->pages = pages;
+ efi_allocated_memory = alloc;
+ }
+ else
+ grub_printf ("Could not malloc memory to remember EFI allocation. "
+ "Exiting GRUB won't free all memory.\n");
+}
+
+static void
+grub_efi_drop_alloc (grub_efi_physical_address_t address,
+ grub_efi_uintn_t pages)
+{
+ struct efi_allocation *ea, *eap;
+ grub_efi_boot_services_t *b;
+
+ b = grub_efi_system_table->boot_services;
+
+ for (eap = NULL, ea = efi_allocated_memory; ea; eap = ea, ea = ea->next)
+ {
+ if (ea->address != address || ea->pages != pages)
+ continue;
+
+ /* Remove the current entry from the list. */
+ if (eap)
+ eap->next = ea->next;
+ else
+ efi_allocated_memory = ea->next;
+
+ /* Then free the memory backing it. */
+ efi_call_1 (b->free_pool, ea);
+
+ /* And leave, we're done. */
+ break;
+ }
+}
+
+/* Allocate pages. Return the pointer to the first of allocated pages. */
+void *
+grub_efi_allocate_pages_real (grub_efi_physical_address_t address,
+ grub_efi_uintn_t pages,
+ grub_efi_allocate_type_t alloctype,
+ grub_efi_memory_type_t memtype)
+{
+ grub_efi_status_t status;
+ grub_efi_boot_services_t *b;
+
+ /* Limit the memory access to less than 4GB for 32-bit platforms. */
+ if (address > GRUB_EFI_MAX_USABLE_ADDRESS)
+ {
+ char inv_addr[17], max_addr[17]; /* log16(2^64) = 16, plus NUL. */
+
+ grub_snprintf (inv_addr, sizeof (inv_addr) - 1, "%" PRIxGRUB_UINT64_T,
+ address);
+ grub_snprintf (max_addr, sizeof (max_addr) - 1, "%" PRIxGRUB_UINT64_T,
+ (grub_efi_uint64_t) GRUB_EFI_MAX_USABLE_ADDRESS);
+ grub_error (GRUB_ERR_BAD_ARGUMENT,
+ N_("invalid memory address (0x%s > 0x%s)"), inv_addr, max_addr);
+ return NULL;
+ }
+
+ b = grub_efi_system_table->boot_services;
+ status = efi_call_4 (b->allocate_pages, alloctype, memtype, pages, &address);
+ if (status != GRUB_EFI_SUCCESS)
+ {
+ grub_error (GRUB_ERR_OUT_OF_MEMORY, N_("out of memory"));
+ return NULL;
+ }
+
+ if (address == 0)
+ {
+ /* Uggh, the address 0 was allocated... This is too annoying,
+ so reallocate another one. */
+ address = GRUB_EFI_MAX_USABLE_ADDRESS;
+ status = efi_call_4 (b->allocate_pages, alloctype, memtype, pages, &address);
+ grub_efi_free_pages (0, pages);
+ if (status != GRUB_EFI_SUCCESS)
+ {
+ grub_error (GRUB_ERR_OUT_OF_MEMORY, N_("out of memory"));
+ return NULL;
+ }
+ }
+
+ grub_efi_store_alloc (address, pages);
+
+ return (void *) ((grub_addr_t) address);
+}
+
+void *
+grub_efi_allocate_any_pages (grub_efi_uintn_t pages)
+{
+ return grub_efi_allocate_pages_real (GRUB_EFI_MAX_USABLE_ADDRESS,
+ pages, GRUB_EFI_ALLOCATE_MAX_ADDRESS,
+ GRUB_EFI_LOADER_DATA);
+}
+
+void *
+grub_efi_allocate_fixed (grub_efi_physical_address_t address,
+ grub_efi_uintn_t pages)
+{
+ return grub_efi_allocate_pages_real (address, pages,
+ GRUB_EFI_ALLOCATE_ADDRESS,
+ GRUB_EFI_LOADER_DATA);
+}
+
+/* Free pages starting from ADDRESS. */
+void
+grub_efi_free_pages (grub_efi_physical_address_t address,
+ grub_efi_uintn_t pages)
+{
+ grub_efi_boot_services_t *b;
+
+ b = grub_efi_system_table->boot_services;
+ efi_call_2 (b->free_pages, address, pages);
+
+ grub_efi_drop_alloc (address, pages);
+}
+
+#if defined (__i386__) || defined (__x86_64__)
+
+/* Helper for stop_broadcom. */
+static int
+find_card (grub_pci_device_t dev, grub_pci_id_t pciid,
+ void *data __attribute__ ((unused)))
+{
+ grub_pci_address_t addr;
+ grub_uint8_t cap;
+ grub_uint16_t pm_state;
+
+ if ((pciid & 0xffff) != GRUB_PCI_VENDOR_BROADCOM)
+ return 0;
+
+ addr = grub_pci_make_address (dev, GRUB_PCI_REG_CLASS);
+ if (grub_pci_read (addr) >> 24 != GRUB_PCI_CLASS_NETWORK)
+ return 0;
+ cap = grub_pci_find_capability (dev, GRUB_PCI_CAP_POWER_MANAGEMENT);
+ if (!cap)
+ return 0;
+ addr = grub_pci_make_address (dev, cap + 4);
+ pm_state = grub_pci_read_word (addr);
+ pm_state = pm_state | 0x03;
+ grub_pci_write_word (addr, pm_state);
+ grub_pci_read_word (addr);
+ return 0;
+}
+
+static void
+stop_broadcom (void)
+{
+ grub_pci_iterate (find_card, NULL);
+}
+
+#endif
+
+grub_err_t
+grub_efi_finish_boot_services (grub_efi_uintn_t *outbuf_size, void *outbuf,
+ grub_efi_uintn_t *map_key,
+ grub_efi_uintn_t *efi_desc_size,
+ grub_efi_uint32_t *efi_desc_version)
+{
+ grub_efi_boot_services_t *b;
+ grub_efi_status_t status;
+
+#if defined (__i386__) || defined (__x86_64__)
+ const grub_uint16_t apple[] = { 'A', 'p', 'p', 'l', 'e' };
+ int is_apple;
+
+ is_apple = (grub_memcmp (grub_efi_system_table->firmware_vendor,
+ apple, sizeof (apple)) == 0);
+#endif
+
+ while (1)
+ {
+ if (grub_efi_get_memory_map (&finish_mmap_size, finish_mmap_buf, &finish_key,
+ &finish_desc_size, &finish_desc_version) < 0)
+ return grub_error (GRUB_ERR_IO, "couldn't retrieve memory map");
+
+ if (outbuf && *outbuf_size < finish_mmap_size)
+ return grub_error (GRUB_ERR_IO, "memory map buffer is too small");
+
+ finish_mmap_buf = grub_malloc (finish_mmap_size);
+ if (!finish_mmap_buf)
+ return grub_errno;
+
+ if (grub_efi_get_memory_map (&finish_mmap_size, finish_mmap_buf, &finish_key,
+ &finish_desc_size, &finish_desc_version) <= 0)
+ {
+ grub_free (finish_mmap_buf);
+ return grub_error (GRUB_ERR_IO, "couldn't retrieve memory map");
+ }
+
+ b = grub_efi_system_table->boot_services;
+ status = efi_call_2 (b->exit_boot_services, grub_efi_image_handle,
+ finish_key);
+ if (status == GRUB_EFI_SUCCESS)
+ break;
+
+ if (status != GRUB_EFI_INVALID_PARAMETER)
+ {
+ grub_free (finish_mmap_buf);
+ return grub_error (GRUB_ERR_IO, "couldn't terminate EFI services");
+ }
+
+ grub_free (finish_mmap_buf);
+ grub_printf ("Trying to terminate EFI services again\n");
+ }
+ grub_efi_is_finished = 1;
+ if (outbuf_size)
+ *outbuf_size = finish_mmap_size;
+ if (outbuf)
+ grub_memcpy (outbuf, finish_mmap_buf, finish_mmap_size);
+ if (map_key)
+ *map_key = finish_key;
+ if (efi_desc_size)
+ *efi_desc_size = finish_desc_size;
+ if (efi_desc_version)
+ *efi_desc_version = finish_desc_version;
+
+#if defined (__i386__) || defined (__x86_64__)
+ if (is_apple)
+ stop_broadcom ();
+#endif
+
+ return GRUB_ERR_NONE;
+}
+
+/*
+ * To obtain the UEFI memory map, we must pass a buffer of sufficient size
+ * to hold the entire map. This function returns a sane start value for
+ * buffer size.
+ */
+grub_efi_uintn_t
+grub_efi_find_mmap_size (void)
+{
+ grub_efi_uintn_t mmap_size = 0;
+ grub_efi_uintn_t desc_size;
+
+ if (grub_efi_get_memory_map (&mmap_size, NULL, NULL, &desc_size, 0) < 0)
+ {
+ grub_error (GRUB_ERR_IO, "cannot get EFI memory map size");
+ return 0;
+ }
+
+ /*
+ * Add an extra page, since UEFI can alter the memory map itself on
+ * callbacks or explicit calls, including console output.
+ */
+ return ALIGN_UP (mmap_size + GRUB_EFI_PAGE_SIZE, GRUB_EFI_PAGE_SIZE);
+}
+
+/* Get the memory map as defined in the EFI spec. Return 1 if successful,
+ return 0 if partial, or return -1 if an error occurs. */
+int
+grub_efi_get_memory_map (grub_efi_uintn_t *memory_map_size,
+ grub_efi_memory_descriptor_t *memory_map,
+ grub_efi_uintn_t *map_key,
+ grub_efi_uintn_t *descriptor_size,
+ grub_efi_uint32_t *descriptor_version)
+{
+ grub_efi_status_t status;
+ grub_efi_boot_services_t *b;
+ grub_efi_uintn_t key;
+ grub_efi_uint32_t version;
+ grub_efi_uintn_t size;
+
+ if (grub_efi_is_finished)
+ {
+ int ret = 1;
+
+ if (memory_map != NULL)
+ {
+ if (*memory_map_size < finish_mmap_size)
+ {
+ grub_memcpy (memory_map, finish_mmap_buf, *memory_map_size);
+ ret = 0;
+ }
+ else
+ grub_memcpy (memory_map, finish_mmap_buf, finish_mmap_size);
+ }
+ else
+ {
+ /*
+ * Incomplete, no buffer to copy into, same as
+ * GRUB_EFI_BUFFER_TOO_SMALL below.
+ */
+ ret = 0;
+ }
+ *memory_map_size = finish_mmap_size;
+ if (map_key)
+ *map_key = finish_key;
+ if (descriptor_size)
+ *descriptor_size = finish_desc_size;
+ if (descriptor_version)
+ *descriptor_version = finish_desc_version;
+ return ret;
+ }
+
+ /* Allow some parameters to be missing. */
+ if (! map_key)
+ map_key = &key;
+ if (! descriptor_version)
+ descriptor_version = &version;
+ if (! descriptor_size)
+ descriptor_size = &size;
+
+ b = grub_efi_system_table->boot_services;
+ status = efi_call_5 (b->get_memory_map, memory_map_size, memory_map, map_key,
+ descriptor_size, descriptor_version);
+ if (*descriptor_size == 0)
+ *descriptor_size = sizeof (grub_efi_memory_descriptor_t);
+ if (status == GRUB_EFI_SUCCESS)
+ return 1;
+ else if (status == GRUB_EFI_BUFFER_TOO_SMALL)
+ return 0;
+ else
+ return -1;
+}
+
+/* Sort the memory map in place. */
+static void
+sort_memory_map (grub_efi_memory_descriptor_t *memory_map,
+ grub_efi_uintn_t desc_size,
+ grub_efi_memory_descriptor_t *memory_map_end)
+{
+ grub_efi_memory_descriptor_t *d1;
+ grub_efi_memory_descriptor_t *d2;
+
+ for (d1 = memory_map;
+ d1 < memory_map_end;
+ d1 = NEXT_MEMORY_DESCRIPTOR (d1, desc_size))
+ {
+ grub_efi_memory_descriptor_t *max_desc = d1;
+
+ for (d2 = NEXT_MEMORY_DESCRIPTOR (d1, desc_size);
+ d2 < memory_map_end;
+ d2 = NEXT_MEMORY_DESCRIPTOR (d2, desc_size))
+ {
+ if (max_desc->num_pages < d2->num_pages)
+ max_desc = d2;
+ }
+
+ if (max_desc != d1)
+ {
+ grub_efi_memory_descriptor_t tmp;
+
+ tmp = *d1;
+ *d1 = *max_desc;
+ *max_desc = tmp;
+ }
+ }
+}
+
+/* Filter the descriptors. GRUB needs only available memory. */
+static grub_efi_memory_descriptor_t *
+filter_memory_map (grub_efi_memory_descriptor_t *memory_map,
+ grub_efi_memory_descriptor_t *filtered_memory_map,
+ grub_efi_uintn_t desc_size,
+ grub_efi_memory_descriptor_t *memory_map_end)
+{
+ grub_efi_memory_descriptor_t *desc;
+ grub_efi_memory_descriptor_t *filtered_desc;
+
+ for (desc = memory_map, filtered_desc = filtered_memory_map;
+ desc < memory_map_end;
+ desc = NEXT_MEMORY_DESCRIPTOR (desc, desc_size))
+ {
+ if (desc->type == GRUB_EFI_CONVENTIONAL_MEMORY
+#if 1
+ && desc->physical_start <= GRUB_EFI_MAX_USABLE_ADDRESS
+#endif
+ && desc->physical_start + PAGES_TO_BYTES (desc->num_pages) > 0x100000
+ && desc->num_pages != 0)
+ {
+ grub_memcpy (filtered_desc, desc, desc_size);
+
+ /* Avoid less than 1MB, because some loaders seem to be confused. */
+ if (desc->physical_start < 0x100000)
+ {
+ desc->num_pages -= BYTES_TO_PAGES (0x100000
+ - desc->physical_start);
+ desc->physical_start = 0x100000;
+ }
+
+#if 1
+ if (BYTES_TO_PAGES (filtered_desc->physical_start)
+ + filtered_desc->num_pages
+ > BYTES_TO_PAGES_DOWN (GRUB_EFI_MAX_USABLE_ADDRESS))
+ filtered_desc->num_pages
+ = (BYTES_TO_PAGES_DOWN (GRUB_EFI_MAX_USABLE_ADDRESS)
+ - BYTES_TO_PAGES (filtered_desc->physical_start));
+#endif
+
+ if (filtered_desc->num_pages == 0)
+ continue;
+
+ filtered_desc = NEXT_MEMORY_DESCRIPTOR (filtered_desc, desc_size);
+ }
+ }
+
+ return filtered_desc;
+}
+
+/* Return the total number of pages. */
+static grub_efi_uint64_t
+get_total_pages (grub_efi_memory_descriptor_t *memory_map,
+ grub_efi_uintn_t desc_size,
+ grub_efi_memory_descriptor_t *memory_map_end)
+{
+ grub_efi_memory_descriptor_t *desc;
+ grub_efi_uint64_t total = 0;
+
+ for (desc = memory_map;
+ desc < memory_map_end;
+ desc = NEXT_MEMORY_DESCRIPTOR (desc, desc_size))
+ total += desc->num_pages;
+
+ return total;
+}
+
+/* Add memory regions. */
+static void
+add_memory_regions (grub_efi_memory_descriptor_t *memory_map,
+ grub_efi_uintn_t desc_size,
+ grub_efi_memory_descriptor_t *memory_map_end,
+ grub_efi_uint64_t required_pages)
+{
+ grub_efi_memory_descriptor_t *desc;
+
+ for (desc = memory_map;
+ desc < memory_map_end;
+ desc = NEXT_MEMORY_DESCRIPTOR (desc, desc_size))
+ {
+ grub_efi_uint64_t pages;
+ grub_efi_physical_address_t start;
+ void *addr;
+
+ start = desc->physical_start;
+ pages = desc->num_pages;
+ if (pages > required_pages)
+ {
+ start += PAGES_TO_BYTES (pages - required_pages);
+ pages = required_pages;
+ }
+
+ addr = grub_efi_allocate_pages_real (start, pages,
+ GRUB_EFI_ALLOCATE_ADDRESS,
+ GRUB_EFI_LOADER_CODE);
+ if (! addr)
+ grub_fatal ("cannot allocate conventional memory %p with %u pages",
+ (void *) ((grub_addr_t) start),
+ (unsigned) pages);
+
+ grub_mm_init_region (addr, PAGES_TO_BYTES (pages));
+
+ required_pages -= pages;
+ if (required_pages == 0)
+ break;
+ }
+
+ if (required_pages > 0)
+ grub_fatal ("too little memory");
+}
+
+void
+grub_efi_memory_fini (void)
+{
+ /*
+ * Free all stale allocations. grub_efi_free_pages() will remove
+ * the found entry from the list and it will always find the first
+ * list entry (efi_allocated_memory is the list start). Hence we
+ * remove all entries from the list until none is left altogether.
+ */
+ while (efi_allocated_memory)
+ grub_efi_free_pages (efi_allocated_memory->address,
+ efi_allocated_memory->pages);
+}
+
+#if 0
+/* Print the memory map. */
+static void
+print_memory_map (grub_efi_memory_descriptor_t *memory_map,
+ grub_efi_uintn_t desc_size,
+ grub_efi_memory_descriptor_t *memory_map_end)
+{
+ grub_efi_memory_descriptor_t *desc;
+ int i;
+
+ for (desc = memory_map, i = 0;
+ desc < memory_map_end;
+ desc = NEXT_MEMORY_DESCRIPTOR (desc, desc_size), i++)
+ {
+ grub_printf ("MD: t=%x, p=%llx, v=%llx, n=%llx, a=%llx\n",
+ desc->type, desc->physical_start, desc->virtual_start,
+ desc->num_pages, desc->attribute);
+ }
+}
+#endif
+
+void
+grub_efi_mm_init (void)
+{
+ grub_efi_memory_descriptor_t *memory_map;
+ grub_efi_memory_descriptor_t *memory_map_end;
+ grub_efi_memory_descriptor_t *filtered_memory_map;
+ grub_efi_memory_descriptor_t *filtered_memory_map_end;
+ grub_efi_uintn_t map_size;
+ grub_efi_uintn_t desc_size;
+ grub_efi_uint64_t total_pages;
+ grub_efi_uint64_t required_pages;
+ int mm_status;
+
+ /* Prepare a memory region to store two memory maps. */
+ memory_map = grub_efi_allocate_any_pages (2 * BYTES_TO_PAGES (MEMORY_MAP_SIZE));
+ if (! memory_map)
+ grub_fatal ("cannot allocate memory");
+
+ /* Obtain descriptors for available memory. */
+ map_size = MEMORY_MAP_SIZE;
+
+ mm_status = grub_efi_get_memory_map (&map_size, memory_map, 0, &desc_size, 0);
+
+ if (mm_status == 0)
+ {
+ grub_efi_free_pages
+ ((grub_efi_physical_address_t) ((grub_addr_t) memory_map),
+ 2 * BYTES_TO_PAGES (MEMORY_MAP_SIZE));
+
+ /* Freeing/allocating operations may increase memory map size. */
+ map_size += desc_size * 32;
+
+ memory_map = grub_efi_allocate_any_pages (2 * BYTES_TO_PAGES (map_size));
+ if (! memory_map)
+ grub_fatal ("cannot allocate memory");
+
+ mm_status = grub_efi_get_memory_map (&map_size, memory_map, 0,
+ &desc_size, 0);
+ }
+
+ if (mm_status < 0)
+ grub_fatal ("cannot get memory map");
+
+ memory_map_end = NEXT_MEMORY_DESCRIPTOR (memory_map, map_size);
+
+ filtered_memory_map = memory_map_end;
+
+ filtered_memory_map_end = filter_memory_map (memory_map, filtered_memory_map,
+ desc_size, memory_map_end);
+
+ /* By default, request a quarter of the available memory. */
+ total_pages = get_total_pages (filtered_memory_map, desc_size,
+ filtered_memory_map_end);
+ required_pages = (total_pages >> 2);
+ if (required_pages < BYTES_TO_PAGES (MIN_HEAP_SIZE))
+ required_pages = BYTES_TO_PAGES (MIN_HEAP_SIZE);
+ else if (required_pages > BYTES_TO_PAGES (MAX_HEAP_SIZE))
+ required_pages = BYTES_TO_PAGES (MAX_HEAP_SIZE);
+
+ /* Sort the filtered descriptors, so that GRUB can allocate pages
+ from smaller regions. */
+ sort_memory_map (filtered_memory_map, desc_size, filtered_memory_map_end);
+
+ /* Allocate memory regions for GRUB's memory management. */
+ add_memory_regions (filtered_memory_map, desc_size,
+ filtered_memory_map_end, required_pages);
+
+#if 0
+ /* For debug. */
+ map_size = MEMORY_MAP_SIZE;
+
+ if (grub_efi_get_memory_map (&map_size, memory_map, 0, &desc_size, 0) < 0)
+ grub_fatal ("cannot get memory map");
+
+ grub_printf ("printing memory map\n");
+ print_memory_map (memory_map, desc_size,
+ NEXT_MEMORY_DESCRIPTOR (memory_map, map_size));
+ grub_fatal ("Debug. ");
+#endif
+
+ /* Release the memory maps. */
+ grub_efi_free_pages ((grub_addr_t) memory_map,
+ 2 * BYTES_TO_PAGES (MEMORY_MAP_SIZE));
+}
+
+#if defined (__aarch64__) || defined (__arm__) || defined (__riscv)
+grub_err_t
+grub_efi_get_ram_base(grub_addr_t *base_addr)
+{
+ grub_efi_memory_descriptor_t *memory_map, *desc;
+ grub_efi_uintn_t memory_map_size, desc_size;
+ int ret;
+
+ memory_map_size = grub_efi_find_mmap_size();
+
+ memory_map = grub_malloc (memory_map_size);
+ if (! memory_map)
+ return GRUB_ERR_OUT_OF_MEMORY;
+ ret = grub_efi_get_memory_map (&memory_map_size, memory_map, NULL,
+ &desc_size, NULL);
+
+ if (ret < 1)
+ return GRUB_ERR_BUG;
+
+ for (desc = memory_map, *base_addr = GRUB_EFI_MAX_USABLE_ADDRESS;
+ (grub_addr_t) desc < ((grub_addr_t) memory_map + memory_map_size);
+ desc = NEXT_MEMORY_DESCRIPTOR (desc, desc_size))
+ if (desc->attribute & GRUB_EFI_MEMORY_WB)
+ *base_addr = grub_min (*base_addr, desc->physical_start);
+
+ grub_free(memory_map);
+
+ return GRUB_ERR_NONE;
+}
+#endif