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https://gitee.com/bianbu-linux/linux-6.6
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0b1d9debe3
The logic in efi_random_alloc() will iterate over the memory map twice, once to count the number of candidate slots, and another time to locate the chosen slot after randomization. If there is insufficient memory to do the allocation, the second loop will run to completion without actually having located a slot, but we currently return EFI_SUCCESS in this case, as we fail to initialize status to the appropriate error value of EFI_OUT_OF_RESOURCES. Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
132 lines
3.7 KiB
C
132 lines
3.7 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (C) 2016 Linaro Ltd; <ard.biesheuvel@linaro.org>
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*/
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#include <linux/efi.h>
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#include <linux/log2.h>
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#include <asm/efi.h>
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#include "efistub.h"
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/*
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* Return the number of slots covered by this entry, i.e., the number of
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* addresses it covers that are suitably aligned and supply enough room
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* for the allocation.
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*/
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static unsigned long get_entry_num_slots(efi_memory_desc_t *md,
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unsigned long size,
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unsigned long align_shift)
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{
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unsigned long align = 1UL << align_shift;
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u64 first_slot, last_slot, region_end;
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if (md->type != EFI_CONVENTIONAL_MEMORY)
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return 0;
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if (efi_soft_reserve_enabled() &&
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(md->attribute & EFI_MEMORY_SP))
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return 0;
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region_end = min(md->phys_addr + md->num_pages * EFI_PAGE_SIZE - 1,
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(u64)EFI_ALLOC_LIMIT);
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if (region_end < size)
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return 0;
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first_slot = round_up(md->phys_addr, align);
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last_slot = round_down(region_end - size + 1, align);
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if (first_slot > last_slot)
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return 0;
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return ((unsigned long)(last_slot - first_slot) >> align_shift) + 1;
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}
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/*
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* The UEFI memory descriptors have a virtual address field that is only used
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* when installing the virtual mapping using SetVirtualAddressMap(). Since it
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* is unused here, we can reuse it to keep track of each descriptor's slot
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* count.
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*/
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#define MD_NUM_SLOTS(md) ((md)->virt_addr)
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efi_status_t efi_random_alloc(unsigned long size,
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unsigned long align,
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unsigned long *addr,
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unsigned long random_seed,
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int memory_type)
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{
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unsigned long total_slots = 0, target_slot;
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unsigned long total_mirrored_slots = 0;
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struct efi_boot_memmap *map;
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efi_status_t status;
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int map_offset;
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status = efi_get_memory_map(&map, false);
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if (status != EFI_SUCCESS)
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return status;
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if (align < EFI_ALLOC_ALIGN)
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align = EFI_ALLOC_ALIGN;
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size = round_up(size, EFI_ALLOC_ALIGN);
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/* count the suitable slots in each memory map entry */
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for (map_offset = 0; map_offset < map->map_size; map_offset += map->desc_size) {
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efi_memory_desc_t *md = (void *)map->map + map_offset;
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unsigned long slots;
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slots = get_entry_num_slots(md, size, ilog2(align));
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MD_NUM_SLOTS(md) = slots;
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total_slots += slots;
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if (md->attribute & EFI_MEMORY_MORE_RELIABLE)
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total_mirrored_slots += slots;
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}
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/* consider only mirrored slots for randomization if any exist */
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if (total_mirrored_slots > 0)
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total_slots = total_mirrored_slots;
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/* find a random number between 0 and total_slots */
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target_slot = (total_slots * (u64)(random_seed & U32_MAX)) >> 32;
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/*
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* target_slot is now a value in the range [0, total_slots), and so
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* it corresponds with exactly one of the suitable slots we recorded
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* when iterating over the memory map the first time around.
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*
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* So iterate over the memory map again, subtracting the number of
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* slots of each entry at each iteration, until we have found the entry
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* that covers our chosen slot. Use the residual value of target_slot
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* to calculate the randomly chosen address, and allocate it directly
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* using EFI_ALLOCATE_ADDRESS.
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*/
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status = EFI_OUT_OF_RESOURCES;
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for (map_offset = 0; map_offset < map->map_size; map_offset += map->desc_size) {
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efi_memory_desc_t *md = (void *)map->map + map_offset;
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efi_physical_addr_t target;
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unsigned long pages;
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if (total_mirrored_slots > 0 &&
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!(md->attribute & EFI_MEMORY_MORE_RELIABLE))
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continue;
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if (target_slot >= MD_NUM_SLOTS(md)) {
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target_slot -= MD_NUM_SLOTS(md);
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continue;
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}
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target = round_up(md->phys_addr, align) + target_slot * align;
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pages = size / EFI_PAGE_SIZE;
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status = efi_bs_call(allocate_pages, EFI_ALLOCATE_ADDRESS,
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memory_type, pages, &target);
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if (status == EFI_SUCCESS)
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*addr = target;
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break;
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}
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efi_bs_call(free_pool, map);
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return status;
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}
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