1 files changed, 132 insertions, 0 deletions
diff --git a/drivers/firmware/efi/libstub/mem.c b/drivers/firmware/efi/libstub/mem.c
new file mode 100644
index 000000000..feef8d4be
--- /dev/null
+++ b/drivers/firmware/efi/libstub/mem.c
@@ -0,0 +1,132 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/efi.h>
+#include <asm/efi.h>
+
+#include "efistub.h"
+
+static inline bool mmap_has_headroom(unsigned long buff_size,
+				     unsigned long map_size,
+				     unsigned long desc_size)
+{
+	unsigned long slack = buff_size - map_size;
+
+	return slack / desc_size >= EFI_MMAP_NR_SLACK_SLOTS;
+}
+
+/**
+ * efi_get_memory_map() - get memory map
+ * @map:	on return pointer to memory map
+ *
+ * Retrieve the UEFI memory map. The allocated memory leaves room for
+ * up to EFI_MMAP_NR_SLACK_SLOTS additional memory map entries.
+ *
+ * Return:	status code
+ */
+efi_status_t efi_get_memory_map(struct efi_boot_memmap *map)
+{
+	efi_memory_desc_t *m = NULL;
+	efi_status_t status;
+	unsigned long key;
+	u32 desc_version;
+
+	*map->desc_size =	sizeof(*m);
+	*map->map_size =	*map->desc_size * 32;
+	*map->buff_size =	*map->map_size;
+again:
+	status = efi_bs_call(allocate_pool, EFI_LOADER_DATA,
+			     *map->map_size, (void **)&m);
+	if (status != EFI_SUCCESS)
+		goto fail;
+
+	*map->desc_size = 0;
+	key = 0;
+	status = efi_bs_call(get_memory_map, map->map_size, m,
+			     &key, map->desc_size, &desc_version);
+	if (status == EFI_BUFFER_TOO_SMALL ||
+	    !mmap_has_headroom(*map->buff_size, *map->map_size,
+			       *map->desc_size)) {
+		efi_bs_call(free_pool, m);
+		/*
+		 * Make sure there is some entries of headroom so that the
+		 * buffer can be reused for a new map after allocations are
+		 * no longer permitted.  Its unlikely that the map will grow to
+		 * exceed this headroom once we are ready to trigger
+		 * ExitBootServices()
+		 */
+		*map->map_size += *map->desc_size * EFI_MMAP_NR_SLACK_SLOTS;
+		*map->buff_size = *map->map_size;
+		goto again;
+	}
+
+	if (status == EFI_SUCCESS) {
+		if (map->key_ptr)
+			*map->key_ptr = key;
+		if (map->desc_ver)
+			*map->desc_ver = desc_version;
+	} else {
+		efi_bs_call(free_pool, m);
+	}
+
+fail:
+	*map->map = m;
+	return status;
+}
+
+/**
+ * efi_allocate_pages() - Allocate memory pages
+ * @size:	minimum number of bytes to allocate
+ * @addr:	On return the address of the first allocated page. The first
+ *		allocated page has alignment EFI_ALLOC_ALIGN which is an
+ *		architecture dependent multiple of the page size.
+ * @max:	the address that the last allocated memory page shall not
+ *		exceed
+ *
+ * Allocate pages as EFI_LOADER_DATA. The allocated pages are aligned according
+ * to EFI_ALLOC_ALIGN. The last allocated page will not exceed the address
+ * given by @max.
+ *
+ * Return:	status code
+ */
+efi_status_t efi_allocate_pages(unsigned long size, unsigned long *addr,
+				unsigned long max)
+{
+	efi_physical_addr_t alloc_addr;
+	efi_status_t status;
+
+	if (EFI_ALLOC_ALIGN > EFI_PAGE_SIZE)
+		return efi_allocate_pages_aligned(size, addr, max,
+						  EFI_ALLOC_ALIGN);
+
+	alloc_addr = ALIGN_DOWN(max + 1, EFI_ALLOC_ALIGN) - 1;
+	status = efi_bs_call(allocate_pages, EFI_ALLOCATE_MAX_ADDRESS,
+			     EFI_LOADER_DATA, DIV_ROUND_UP(size, EFI_PAGE_SIZE),
+			     &alloc_addr);
+	if (status != EFI_SUCCESS)
+		return status;
+
+	*addr = alloc_addr;
+	return EFI_SUCCESS;
+}
+
+/**
+ * efi_free() - free memory pages
+ * @size:	size of the memory area to free in bytes
+ * @addr:	start of the memory area to free (must be EFI_PAGE_SIZE
+ *		aligned)
+ *
+ * @size is rounded up to a multiple of EFI_ALLOC_ALIGN which is an
+ * architecture specific multiple of EFI_PAGE_SIZE. So this function should
+ * only be used to return pages allocated with efi_allocate_pages() or
+ * efi_low_alloc_above().
+ */
+void efi_free(unsigned long size, unsigned long addr)
+{
+	unsigned long nr_pages;
+
+	if (!size)
+		return;
+
+	nr_pages = round_up(size, EFI_ALLOC_ALIGN) / EFI_PAGE_SIZE;
+	efi_bs_call(free_pages, addr, nr_pages);
+}