1 files changed, 309 insertions, 0 deletions
diff --git a/drivers/firmware/efi/libstub/mem.c b/drivers/firmware/efi/libstub/mem.c
new file mode 100644
index 000000000000..869a79c8946f
--- /dev/null
+++ b/drivers/firmware/efi/libstub/mem.c
@@ -0,0 +1,309 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/efi.h>
+#include <asm/efi.h>
+
+#include "efistub.h"
+
+#define EFI_MMAP_NR_SLACK_SLOTS	8
+
+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 = ALIGN_DOWN(max + 1, EFI_ALLOC_ALIGN) - 1;
+	int slack = EFI_ALLOC_ALIGN / EFI_PAGE_SIZE - 1;
+	efi_status_t status;
+
+	size = round_up(size, EFI_ALLOC_ALIGN);
+	status = efi_bs_call(allocate_pages, EFI_ALLOCATE_MAX_ADDRESS,
+			     EFI_LOADER_DATA, size / EFI_PAGE_SIZE + slack,
+			     &alloc_addr);
+	if (status != EFI_SUCCESS)
+		return status;
+
+	*addr = ALIGN((unsigned long)alloc_addr, EFI_ALLOC_ALIGN);
+
+	if (slack > 0) {
+		int l = (alloc_addr % EFI_ALLOC_ALIGN) / EFI_PAGE_SIZE;
+
+		if (l) {
+			efi_bs_call(free_pages, alloc_addr, slack - l + 1);
+			slack = l - 1;
+		}
+		if (slack)
+			efi_bs_call(free_pages, *addr + size, slack);
+	}
+	return EFI_SUCCESS;
+}
+/**
+ * efi_low_alloc_above() - allocate pages at or above given address
+ * @size:	size of the memory area to allocate
+ * @align:	minimum alignment of the allocated memory area. It should
+ *		a power of two.
+ * @addr:	on exit the address of the allocated memory
+ * @min:	minimum address to used for the memory allocation
+ *
+ * Allocate at the lowest possible address that is not below @min as
+ * EFI_LOADER_DATA. The allocated pages are aligned according to @align but at
+ * least EFI_ALLOC_ALIGN. The first allocated page will not below the address
+ * given by @min.
+ *
+ * Return:	status code
+ */
+efi_status_t efi_low_alloc_above(unsigned long size, unsigned long align,
+				 unsigned long *addr, unsigned long min)
+{
+	unsigned long map_size, desc_size, buff_size;
+	efi_memory_desc_t *map;
+	efi_status_t status;
+	unsigned long nr_pages;
+	int i;
+	struct efi_boot_memmap boot_map;
+
+	boot_map.map		= &map;
+	boot_map.map_size	= &map_size;
+	boot_map.desc_size	= &desc_size;
+	boot_map.desc_ver	= NULL;
+	boot_map.key_ptr	= NULL;
+	boot_map.buff_size	= &buff_size;
+
+	status = efi_get_memory_map(&boot_map);
+	if (status != EFI_SUCCESS)
+		goto fail;
+
+	/*
+	 * Enforce minimum alignment that EFI or Linux requires when
+	 * requesting a specific address.  We are doing page-based (or
+	 * larger) allocations, and both the address and size must meet
+	 * alignment constraints.
+	 */
+	if (align < EFI_ALLOC_ALIGN)
+		align = EFI_ALLOC_ALIGN;
+
+	size = round_up(size, EFI_ALLOC_ALIGN);
+	nr_pages = size / EFI_PAGE_SIZE;
+	for (i = 0; i < map_size / desc_size; i++) {
+		efi_memory_desc_t *desc;
+		unsigned long m = (unsigned long)map;
+		u64 start, end;
+
+		desc = efi_early_memdesc_ptr(m, desc_size, i);
+
+		if (desc->type != EFI_CONVENTIONAL_MEMORY)
+			continue;
+
+		if (efi_soft_reserve_enabled() &&
+		    (desc->attribute & EFI_MEMORY_SP))
+			continue;
+
+		if (desc->num_pages < nr_pages)
+			continue;
+
+		start = desc->phys_addr;
+		end = start + desc->num_pages * EFI_PAGE_SIZE;
+
+		if (start < min)
+			start = min;
+
+		start = round_up(start, align);
+		if ((start + size) > end)
+			continue;
+
+		status = efi_bs_call(allocate_pages, EFI_ALLOCATE_ADDRESS,
+				     EFI_LOADER_DATA, nr_pages, &start);
+		if (status == EFI_SUCCESS) {
+			*addr = start;
+			break;
+		}
+	}
+
+	if (i == map_size / desc_size)
+		status = EFI_NOT_FOUND;
+
+	efi_bs_call(free_pool, map);
+fail:
+	return status;
+}
+
+/**
+ * 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);
+}
+
+/**
+ * efi_relocate_kernel() - copy memory area
+ * @image_addr:		pointer to address of memory area to copy
+ * @image_size:		size of memory area to copy
+ * @alloc_size:		minimum size of memory to allocate, must be greater or
+ *			equal to image_size
+ * @preferred_addr:	preferred target address
+ * @alignment:		minimum alignment of the allocated memory area. It
+ *			should be a power of two.
+ * @min_addr:		minimum target address
+ *
+ * Copy a memory area to a newly allocated memory area aligned according
+ * to @alignment but at least EFI_ALLOC_ALIGN. If the preferred address
+ * is not available, the allocated address will not be below @min_addr.
+ * On exit, @image_addr is updated to the target copy address that was used.
+ *
+ * This function is used to copy the Linux kernel verbatim. It does not apply
+ * any relocation changes.
+ *
+ * Return:		status code
+ */
+efi_status_t efi_relocate_kernel(unsigned long *image_addr,
+				 unsigned long image_size,
+				 unsigned long alloc_size,
+				 unsigned long preferred_addr,
+				 unsigned long alignment,
+				 unsigned long min_addr)
+{
+	unsigned long cur_image_addr;
+	unsigned long new_addr = 0;
+	efi_status_t status;
+	unsigned long nr_pages;
+	efi_physical_addr_t efi_addr = preferred_addr;
+
+	if (!image_addr || !image_size || !alloc_size)
+		return EFI_INVALID_PARAMETER;
+	if (alloc_size < image_size)
+		return EFI_INVALID_PARAMETER;
+
+	cur_image_addr = *image_addr;
+
+	/*
+	 * The EFI firmware loader could have placed the kernel image
+	 * anywhere in memory, but the kernel has restrictions on the
+	 * max physical address it can run at.  Some architectures
+	 * also have a prefered address, so first try to relocate
+	 * to the preferred address.  If that fails, allocate as low
+	 * as possible while respecting the required alignment.
+	 */
+	nr_pages = round_up(alloc_size, EFI_ALLOC_ALIGN) / EFI_PAGE_SIZE;
+	status = efi_bs_call(allocate_pages, EFI_ALLOCATE_ADDRESS,
+			     EFI_LOADER_DATA, nr_pages, &efi_addr);
+	new_addr = efi_addr;
+	/*
+	 * If preferred address allocation failed allocate as low as
+	 * possible.
+	 */
+	if (status != EFI_SUCCESS) {
+		status = efi_low_alloc_above(alloc_size, alignment, &new_addr,
+					     min_addr);
+	}
+	if (status != EFI_SUCCESS) {
+		pr_efi_err("Failed to allocate usable memory for kernel.\n");
+		return status;
+	}
+
+	/*
+	 * We know source/dest won't overlap since both memory ranges
+	 * have been allocated by UEFI, so we can safely use memcpy.
+	 */
+	memcpy((void *)new_addr, (void *)cur_image_addr, image_size);
+
+	/* Return the new address of the relocated image. */
+	*image_addr = new_addr;
+
+	return status;
+}