From 2c3c1048746a4622d8c89a29670120dc8fab93c4 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sun, 7 Apr 2024 20:49:45 +0200 Subject: Adding upstream version 6.1.76. Signed-off-by: Daniel Baumann --- drivers/firmware/efi/libstub/randomalloc.c | 130 +++++++++++++++++++++++++++++ 1 file changed, 130 insertions(+) create mode 100644 drivers/firmware/efi/libstub/randomalloc.c (limited to 'drivers/firmware/efi/libstub/randomalloc.c') diff --git a/drivers/firmware/efi/libstub/randomalloc.c b/drivers/firmware/efi/libstub/randomalloc.c new file mode 100644 index 000000000..9fb586989 --- /dev/null +++ b/drivers/firmware/efi/libstub/randomalloc.c @@ -0,0 +1,130 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2016 Linaro Ltd; + */ + +#include +#include +#include + +#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) +{ + unsigned long align = 1UL << align_shift; + u64 first_slot, last_slot, region_end; + + if (md->type != EFI_CONVENTIONAL_MEMORY) + 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, + (u64)ULONG_MAX); + if (region_end < size) + return 0; + + first_slot = round_up(md->phys_addr, 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) +{ + unsigned long total_slots = 0, target_slot; + unsigned long total_mirrored_slots = 0; + struct efi_boot_memmap *map; + 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; + + 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)); + 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. + */ + 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(md->phys_addr, align) + target_slot * align; + pages = size / EFI_PAGE_SIZE; + + status = efi_bs_call(allocate_pages, EFI_ALLOCATE_ADDRESS, + EFI_LOADER_DATA, pages, &target); + if (status == EFI_SUCCESS) + *addr = target; + break; + } + + efi_bs_call(free_pool, map); + + return status; +} -- cgit v1.2.3