Something went wrong. Try again.
Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
Something went wrong. Try again.
123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142// 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;}