a37dac5c5d
The UEFI spec does not mention or reason about the configured size of the virtual address space at all, but it does mention that all memory should be identity mapped using a page size of 4 KiB. This means that a LPA2 capable system that has any system memory outside of the 48-bit addressable physical range and follows the spec to the letter may serve page allocation requests from regions of memory that the kernel cannot access unless it was built with LPA2 support and enables it at runtime. So let's ensure that all page allocations are limited to the 48-bit range. Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
130 lines
3.7 KiB
C
130 lines
3.7 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#include <linux/efi.h>
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#include <asm/efi.h>
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#include "efistub.h"
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/**
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* efi_get_memory_map() - get memory map
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* @map: pointer to memory map pointer to which to assign the
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* newly allocated memory map
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* @install_cfg_tbl: whether or not to install the boot memory map as a
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* configuration table
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*
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* Retrieve the UEFI memory map. The allocated memory leaves room for
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* up to EFI_MMAP_NR_SLACK_SLOTS additional memory map entries.
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*
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* Return: status code
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*/
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efi_status_t efi_get_memory_map(struct efi_boot_memmap **map,
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bool install_cfg_tbl)
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{
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int memtype = install_cfg_tbl ? EFI_ACPI_RECLAIM_MEMORY
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: EFI_LOADER_DATA;
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efi_guid_t tbl_guid = LINUX_EFI_BOOT_MEMMAP_GUID;
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struct efi_boot_memmap *m, tmp;
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efi_status_t status;
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unsigned long size;
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tmp.map_size = 0;
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status = efi_bs_call(get_memory_map, &tmp.map_size, NULL, &tmp.map_key,
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&tmp.desc_size, &tmp.desc_ver);
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if (status != EFI_BUFFER_TOO_SMALL)
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return EFI_LOAD_ERROR;
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size = tmp.map_size + tmp.desc_size * EFI_MMAP_NR_SLACK_SLOTS;
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status = efi_bs_call(allocate_pool, memtype, sizeof(*m) + size,
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(void **)&m);
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if (status != EFI_SUCCESS)
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return status;
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if (install_cfg_tbl) {
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/*
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* Installing a configuration table might allocate memory, and
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* this may modify the memory map. This means we should install
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* the configuration table first, and re-install or delete it
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* as needed.
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*/
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status = efi_bs_call(install_configuration_table, &tbl_guid, m);
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if (status != EFI_SUCCESS)
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goto free_map;
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}
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m->buff_size = m->map_size = size;
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status = efi_bs_call(get_memory_map, &m->map_size, m->map, &m->map_key,
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&m->desc_size, &m->desc_ver);
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if (status != EFI_SUCCESS)
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goto uninstall_table;
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*map = m;
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return EFI_SUCCESS;
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uninstall_table:
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if (install_cfg_tbl)
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efi_bs_call(install_configuration_table, &tbl_guid, NULL);
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free_map:
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efi_bs_call(free_pool, m);
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return status;
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}
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/**
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* efi_allocate_pages() - Allocate memory pages
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* @size: minimum number of bytes to allocate
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* @addr: On return the address of the first allocated page. The first
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* allocated page has alignment EFI_ALLOC_ALIGN which is an
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* architecture dependent multiple of the page size.
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* @max: the address that the last allocated memory page shall not
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* exceed
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*
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* Allocate pages as EFI_LOADER_DATA. The allocated pages are aligned according
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* to EFI_ALLOC_ALIGN. The last allocated page will not exceed the address
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* given by @max.
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*
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* Return: status code
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*/
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efi_status_t efi_allocate_pages(unsigned long size, unsigned long *addr,
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unsigned long max)
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{
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efi_physical_addr_t alloc_addr;
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efi_status_t status;
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max = min(max, EFI_ALLOC_LIMIT);
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if (EFI_ALLOC_ALIGN > EFI_PAGE_SIZE)
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return efi_allocate_pages_aligned(size, addr, max,
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EFI_ALLOC_ALIGN,
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EFI_LOADER_DATA);
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alloc_addr = ALIGN_DOWN(max + 1, EFI_ALLOC_ALIGN) - 1;
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status = efi_bs_call(allocate_pages, EFI_ALLOCATE_MAX_ADDRESS,
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EFI_LOADER_DATA, DIV_ROUND_UP(size, EFI_PAGE_SIZE),
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&alloc_addr);
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if (status != EFI_SUCCESS)
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return status;
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*addr = alloc_addr;
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return EFI_SUCCESS;
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}
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/**
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* efi_free() - free memory pages
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* @size: size of the memory area to free in bytes
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* @addr: start of the memory area to free (must be EFI_PAGE_SIZE
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* aligned)
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*
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* @size is rounded up to a multiple of EFI_ALLOC_ALIGN which is an
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* architecture specific multiple of EFI_PAGE_SIZE. So this function should
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* only be used to return pages allocated with efi_allocate_pages() or
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* efi_low_alloc_above().
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*/
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void efi_free(unsigned long size, unsigned long addr)
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{
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unsigned long nr_pages;
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if (!size)
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return;
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nr_pages = round_up(size, EFI_ALLOC_ALIGN) / EFI_PAGE_SIZE;
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efi_bs_call(free_pages, addr, nr_pages);
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}
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