// SPDX-License-Identifier: GPL-2.0/* * Copyright (C) 2016 Linaro Ltd;  <ard.biesheuvel@linaro.org> */ #include <linux/efi.h>#include <linux/log2.h>#include <asm/efi.h> #include "efistub.h" /* * Return the number of slots covered by this entry, i.e., the number of * addresses it covers that are suitably aligned and supply enough room * for the allocation. */static unsigned long get_entry_num_slots(efi_memory_desc_t *md,					 unsigned long size,					 unsigned long align_shift,					 u64 alloc_min, u64 alloc_max){	unsigned long align = 1UL << align_shift;	u64 first_slot, last_slot, region_end; 	if (md->type != EFI_CONVENTIONAL_MEMORY)		return 0; 	if (md->attribute & EFI_MEMORY_HOT_PLUGGABLE)		return 0; 	if (efi_soft_reserve_enabled() &&	    (md->attribute & EFI_MEMORY_SP))		return 0; 	region_end = min(md->phys_addr + md->num_pages * EFI_PAGE_SIZE - 1,			 alloc_max);	if (region_end < size)		return 0; 	first_slot = round_up(max(md->phys_addr, alloc_min), align);	last_slot = round_down(region_end - size + 1, align); 	if (first_slot > last_slot)		return 0; 	return ((unsigned long)(last_slot - first_slot) >> align_shift) + 1;} /* * The UEFI memory descriptors have a virtual address field that is only used * when installing the virtual mapping using SetVirtualAddressMap(). Since it * is unused here, we can reuse it to keep track of each descriptor's slot * count. */#define MD_NUM_SLOTS(md)	((md)->virt_addr) efi_status_t efi_random_alloc(unsigned long size,			      unsigned long align,			      unsigned long *addr,			      unsigned long random_seed,			      int memory_type,			      unsigned long alloc_min,			      unsigned long alloc_max){	struct efi_boot_memmap *map __free(efi_pool) = NULL;	unsigned long total_slots = 0, target_slot;	unsigned long total_mirrored_slots = 0;	efi_status_t status;	int map_offset; 	status = efi_get_memory_map(&map, false);	if (status != EFI_SUCCESS)		return status; 	if (align < EFI_ALLOC_ALIGN)		align = EFI_ALLOC_ALIGN; 	/* Avoid address 0x0, as it can be mistaken for NULL */	if (alloc_min == 0)		alloc_min = align; 	size = round_up(size, EFI_ALLOC_ALIGN); 	/* count the suitable slots in each memory map entry */	for (map_offset = 0; map_offset < map->map_size; map_offset += map->desc_size) {		efi_memory_desc_t *md = (void *)map->map + map_offset;		unsigned long slots; 		slots = get_entry_num_slots(md, size, ilog2(align), alloc_min,					    alloc_max);		MD_NUM_SLOTS(md) = slots;		total_slots += slots;		if (md->attribute & EFI_MEMORY_MORE_RELIABLE)			total_mirrored_slots += slots;	} 	/* consider only mirrored slots for randomization if any exist */	if (total_mirrored_slots > 0)		total_slots = total_mirrored_slots; 	/* find a random number between 0 and total_slots */	target_slot = (total_slots * (u64)(random_seed & U32_MAX)) >> 32; 	/*	 * target_slot is now a value in the range [0, total_slots), and so	 * it corresponds with exactly one of the suitable slots we recorded	 * when iterating over the memory map the first time around.	 *	 * So iterate over the memory map again, subtracting the number of	 * slots of each entry at each iteration, until we have found the entry	 * that covers our chosen slot. Use the residual value of target_slot	 * to calculate the randomly chosen address, and allocate it directly	 * using EFI_ALLOCATE_ADDRESS.	 */	status = EFI_OUT_OF_RESOURCES;	for (map_offset = 0; map_offset < map->map_size; map_offset += map->desc_size) {		efi_memory_desc_t *md = (void *)map->map + map_offset;		efi_physical_addr_t target;		unsigned long pages; 		if (total_mirrored_slots > 0 &&		    !(md->attribute & EFI_MEMORY_MORE_RELIABLE))			continue; 		if (target_slot >= MD_NUM_SLOTS(md)) {			target_slot -= MD_NUM_SLOTS(md);			continue;		} 		target = round_up(max_t(u64, md->phys_addr, alloc_min), align) + target_slot * align;		pages = size / EFI_PAGE_SIZE; 		status = efi_bs_call(allocate_pages, EFI_ALLOCATE_ADDRESS,				     memory_type, pages, &target);		if (status == EFI_SUCCESS)			*addr = target;		break;	} 	return status;}