cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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efi-stub.c (11026B)


      1// SPDX-License-Identifier: GPL-2.0-only
      2/*
      3 * EFI stub implementation that is shared by arm and arm64 architectures.
      4 * This should be #included by the EFI stub implementation files.
      5 *
      6 * Copyright (C) 2013,2014 Linaro Limited
      7 *     Roy Franz <roy.franz@linaro.org
      8 * Copyright (C) 2013 Red Hat, Inc.
      9 *     Mark Salter <msalter@redhat.com>
     10 */
     11
     12#include <linux/efi.h>
     13#include <linux/libfdt.h>
     14#include <asm/efi.h>
     15
     16#include "efistub.h"
     17
     18/*
     19 * This is the base address at which to start allocating virtual memory ranges
     20 * for UEFI Runtime Services.
     21 *
     22 * For ARM/ARM64:
     23 * This is in the low TTBR0 range so that we can use
     24 * any allocation we choose, and eliminate the risk of a conflict after kexec.
     25 * The value chosen is the largest non-zero power of 2 suitable for this purpose
     26 * both on 32-bit and 64-bit ARM CPUs, to maximize the likelihood that it can
     27 * be mapped efficiently.
     28 * Since 32-bit ARM could potentially execute with a 1G/3G user/kernel split,
     29 * map everything below 1 GB. (512 MB is a reasonable upper bound for the
     30 * entire footprint of the UEFI runtime services memory regions)
     31 *
     32 * For RISC-V:
     33 * There is no specific reason for which, this address (512MB) can't be used
     34 * EFI runtime virtual address for RISC-V. It also helps to use EFI runtime
     35 * services on both RV32/RV64. Keep the same runtime virtual address for RISC-V
     36 * as well to minimize the code churn.
     37 */
     38#define EFI_RT_VIRTUAL_BASE	SZ_512M
     39#define EFI_RT_VIRTUAL_SIZE	SZ_512M
     40
     41#ifdef CONFIG_ARM64
     42# define EFI_RT_VIRTUAL_LIMIT	DEFAULT_MAP_WINDOW_64
     43#elif defined(CONFIG_RISCV)
     44# define EFI_RT_VIRTUAL_LIMIT	TASK_SIZE_MIN
     45#else
     46# define EFI_RT_VIRTUAL_LIMIT	TASK_SIZE
     47#endif
     48
     49static u64 virtmap_base = EFI_RT_VIRTUAL_BASE;
     50static bool flat_va_mapping;
     51
     52const efi_system_table_t *efi_system_table;
     53
     54static struct screen_info *setup_graphics(void)
     55{
     56	efi_guid_t gop_proto = EFI_GRAPHICS_OUTPUT_PROTOCOL_GUID;
     57	efi_status_t status;
     58	unsigned long size;
     59	void **gop_handle = NULL;
     60	struct screen_info *si = NULL;
     61
     62	size = 0;
     63	status = efi_bs_call(locate_handle, EFI_LOCATE_BY_PROTOCOL,
     64			     &gop_proto, NULL, &size, gop_handle);
     65	if (status == EFI_BUFFER_TOO_SMALL) {
     66		si = alloc_screen_info();
     67		if (!si)
     68			return NULL;
     69		status = efi_setup_gop(si, &gop_proto, size);
     70		if (status != EFI_SUCCESS) {
     71			free_screen_info(si);
     72			return NULL;
     73		}
     74	}
     75	return si;
     76}
     77
     78static void install_memreserve_table(void)
     79{
     80	struct linux_efi_memreserve *rsv;
     81	efi_guid_t memreserve_table_guid = LINUX_EFI_MEMRESERVE_TABLE_GUID;
     82	efi_status_t status;
     83
     84	status = efi_bs_call(allocate_pool, EFI_LOADER_DATA, sizeof(*rsv),
     85			     (void **)&rsv);
     86	if (status != EFI_SUCCESS) {
     87		efi_err("Failed to allocate memreserve entry!\n");
     88		return;
     89	}
     90
     91	rsv->next = 0;
     92	rsv->size = 0;
     93	atomic_set(&rsv->count, 0);
     94
     95	status = efi_bs_call(install_configuration_table,
     96			     &memreserve_table_guid, rsv);
     97	if (status != EFI_SUCCESS)
     98		efi_err("Failed to install memreserve config table!\n");
     99}
    100
    101static u32 get_supported_rt_services(void)
    102{
    103	const efi_rt_properties_table_t *rt_prop_table;
    104	u32 supported = EFI_RT_SUPPORTED_ALL;
    105
    106	rt_prop_table = get_efi_config_table(EFI_RT_PROPERTIES_TABLE_GUID);
    107	if (rt_prop_table)
    108		supported &= rt_prop_table->runtime_services_supported;
    109
    110	return supported;
    111}
    112
    113/*
    114 * EFI entry point for the arm/arm64 EFI stubs.  This is the entrypoint
    115 * that is described in the PE/COFF header.  Most of the code is the same
    116 * for both archictectures, with the arch-specific code provided in the
    117 * handle_kernel_image() function.
    118 */
    119efi_status_t __efiapi efi_pe_entry(efi_handle_t handle,
    120				   efi_system_table_t *sys_table_arg)
    121{
    122	efi_loaded_image_t *image;
    123	efi_status_t status;
    124	unsigned long image_addr;
    125	unsigned long image_size = 0;
    126	/* addr/point and size pairs for memory management*/
    127	unsigned long initrd_addr = 0;
    128	unsigned long initrd_size = 0;
    129	unsigned long fdt_addr = 0;  /* Original DTB */
    130	unsigned long fdt_size = 0;
    131	char *cmdline_ptr = NULL;
    132	int cmdline_size = 0;
    133	efi_guid_t loaded_image_proto = LOADED_IMAGE_PROTOCOL_GUID;
    134	unsigned long reserve_addr = 0;
    135	unsigned long reserve_size = 0;
    136	enum efi_secureboot_mode secure_boot;
    137	struct screen_info *si;
    138	efi_properties_table_t *prop_tbl;
    139
    140	efi_system_table = sys_table_arg;
    141
    142	/* Check if we were booted by the EFI firmware */
    143	if (efi_system_table->hdr.signature != EFI_SYSTEM_TABLE_SIGNATURE) {
    144		status = EFI_INVALID_PARAMETER;
    145		goto fail;
    146	}
    147
    148	status = check_platform_features();
    149	if (status != EFI_SUCCESS)
    150		goto fail;
    151
    152	/*
    153	 * Get a handle to the loaded image protocol.  This is used to get
    154	 * information about the running image, such as size and the command
    155	 * line.
    156	 */
    157	status = efi_system_table->boottime->handle_protocol(handle,
    158					&loaded_image_proto, (void *)&image);
    159	if (status != EFI_SUCCESS) {
    160		efi_err("Failed to get loaded image protocol\n");
    161		goto fail;
    162	}
    163
    164	/*
    165	 * Get the command line from EFI, using the LOADED_IMAGE
    166	 * protocol. We are going to copy the command line into the
    167	 * device tree, so this can be allocated anywhere.
    168	 */
    169	cmdline_ptr = efi_convert_cmdline(image, &cmdline_size);
    170	if (!cmdline_ptr) {
    171		efi_err("getting command line via LOADED_IMAGE_PROTOCOL\n");
    172		status = EFI_OUT_OF_RESOURCES;
    173		goto fail;
    174	}
    175
    176	if (IS_ENABLED(CONFIG_CMDLINE_EXTEND) ||
    177	    IS_ENABLED(CONFIG_CMDLINE_FORCE) ||
    178	    cmdline_size == 0) {
    179		status = efi_parse_options(CONFIG_CMDLINE);
    180		if (status != EFI_SUCCESS) {
    181			efi_err("Failed to parse options\n");
    182			goto fail_free_cmdline;
    183		}
    184	}
    185
    186	if (!IS_ENABLED(CONFIG_CMDLINE_FORCE) && cmdline_size > 0) {
    187		status = efi_parse_options(cmdline_ptr);
    188		if (status != EFI_SUCCESS) {
    189			efi_err("Failed to parse options\n");
    190			goto fail_free_cmdline;
    191		}
    192	}
    193
    194	efi_info("Booting Linux Kernel...\n");
    195
    196	si = setup_graphics();
    197
    198	status = handle_kernel_image(&image_addr, &image_size,
    199				     &reserve_addr,
    200				     &reserve_size,
    201				     image, handle);
    202	if (status != EFI_SUCCESS) {
    203		efi_err("Failed to relocate kernel\n");
    204		goto fail_free_screeninfo;
    205	}
    206
    207	efi_retrieve_tpm2_eventlog();
    208
    209	/* Ask the firmware to clear memory on unclean shutdown */
    210	efi_enable_reset_attack_mitigation();
    211
    212	secure_boot = efi_get_secureboot();
    213
    214	/*
    215	 * Unauthenticated device tree data is a security hazard, so ignore
    216	 * 'dtb=' unless UEFI Secure Boot is disabled.  We assume that secure
    217	 * boot is enabled if we can't determine its state.
    218	 */
    219	if (!IS_ENABLED(CONFIG_EFI_ARMSTUB_DTB_LOADER) ||
    220	     secure_boot != efi_secureboot_mode_disabled) {
    221		if (strstr(cmdline_ptr, "dtb="))
    222			efi_err("Ignoring DTB from command line.\n");
    223	} else {
    224		status = efi_load_dtb(image, &fdt_addr, &fdt_size);
    225
    226		if (status != EFI_SUCCESS) {
    227			efi_err("Failed to load device tree!\n");
    228			goto fail_free_image;
    229		}
    230	}
    231
    232	if (fdt_addr) {
    233		efi_info("Using DTB from command line\n");
    234	} else {
    235		/* Look for a device tree configuration table entry. */
    236		fdt_addr = (uintptr_t)get_fdt(&fdt_size);
    237		if (fdt_addr)
    238			efi_info("Using DTB from configuration table\n");
    239	}
    240
    241	if (!fdt_addr)
    242		efi_info("Generating empty DTB\n");
    243
    244	efi_load_initrd(image, &initrd_addr, &initrd_size, ULONG_MAX,
    245			efi_get_max_initrd_addr(image_addr));
    246
    247	efi_random_get_seed();
    248
    249	/*
    250	 * If the NX PE data feature is enabled in the properties table, we
    251	 * should take care not to create a virtual mapping that changes the
    252	 * relative placement of runtime services code and data regions, as
    253	 * they may belong to the same PE/COFF executable image in memory.
    254	 * The easiest way to achieve that is to simply use a 1:1 mapping.
    255	 */
    256	prop_tbl = get_efi_config_table(EFI_PROPERTIES_TABLE_GUID);
    257	flat_va_mapping = prop_tbl &&
    258			  (prop_tbl->memory_protection_attribute &
    259			   EFI_PROPERTIES_RUNTIME_MEMORY_PROTECTION_NON_EXECUTABLE_PE_DATA);
    260
    261	/* force efi_novamap if SetVirtualAddressMap() is unsupported */
    262	efi_novamap |= !(get_supported_rt_services() &
    263			 EFI_RT_SUPPORTED_SET_VIRTUAL_ADDRESS_MAP);
    264
    265	/* hibernation expects the runtime regions to stay in the same place */
    266	if (!IS_ENABLED(CONFIG_HIBERNATION) && !efi_nokaslr && !flat_va_mapping) {
    267		/*
    268		 * Randomize the base of the UEFI runtime services region.
    269		 * Preserve the 2 MB alignment of the region by taking a
    270		 * shift of 21 bit positions into account when scaling
    271		 * the headroom value using a 32-bit random value.
    272		 */
    273		static const u64 headroom = EFI_RT_VIRTUAL_LIMIT -
    274					    EFI_RT_VIRTUAL_BASE -
    275					    EFI_RT_VIRTUAL_SIZE;
    276		u32 rnd;
    277
    278		status = efi_get_random_bytes(sizeof(rnd), (u8 *)&rnd);
    279		if (status == EFI_SUCCESS) {
    280			virtmap_base = EFI_RT_VIRTUAL_BASE +
    281				       (((headroom >> 21) * rnd) >> (32 - 21));
    282		}
    283	}
    284
    285	install_memreserve_table();
    286
    287	status = allocate_new_fdt_and_exit_boot(handle, &fdt_addr,
    288						initrd_addr, initrd_size,
    289						cmdline_ptr, fdt_addr, fdt_size);
    290	if (status != EFI_SUCCESS)
    291		goto fail_free_initrd;
    292
    293	if (IS_ENABLED(CONFIG_ARM))
    294		efi_handle_post_ebs_state();
    295
    296	efi_enter_kernel(image_addr, fdt_addr, fdt_totalsize((void *)fdt_addr));
    297	/* not reached */
    298
    299fail_free_initrd:
    300	efi_err("Failed to update FDT and exit boot services\n");
    301
    302	efi_free(initrd_size, initrd_addr);
    303	efi_free(fdt_size, fdt_addr);
    304
    305fail_free_image:
    306	efi_free(image_size, image_addr);
    307	efi_free(reserve_size, reserve_addr);
    308fail_free_screeninfo:
    309	free_screen_info(si);
    310fail_free_cmdline:
    311	efi_bs_call(free_pool, cmdline_ptr);
    312fail:
    313	return status;
    314}
    315
    316/*
    317 * efi_get_virtmap() - create a virtual mapping for the EFI memory map
    318 *
    319 * This function populates the virt_addr fields of all memory region descriptors
    320 * in @memory_map whose EFI_MEMORY_RUNTIME attribute is set. Those descriptors
    321 * are also copied to @runtime_map, and their total count is returned in @count.
    322 */
    323void efi_get_virtmap(efi_memory_desc_t *memory_map, unsigned long map_size,
    324		     unsigned long desc_size, efi_memory_desc_t *runtime_map,
    325		     int *count)
    326{
    327	u64 efi_virt_base = virtmap_base;
    328	efi_memory_desc_t *in, *out = runtime_map;
    329	int l;
    330
    331	for (l = 0; l < map_size; l += desc_size) {
    332		u64 paddr, size;
    333
    334		in = (void *)memory_map + l;
    335		if (!(in->attribute & EFI_MEMORY_RUNTIME))
    336			continue;
    337
    338		paddr = in->phys_addr;
    339		size = in->num_pages * EFI_PAGE_SIZE;
    340
    341		in->virt_addr = in->phys_addr;
    342		if (efi_novamap) {
    343			continue;
    344		}
    345
    346		/*
    347		 * Make the mapping compatible with 64k pages: this allows
    348		 * a 4k page size kernel to kexec a 64k page size kernel and
    349		 * vice versa.
    350		 */
    351		if (!flat_va_mapping) {
    352
    353			paddr = round_down(in->phys_addr, SZ_64K);
    354			size += in->phys_addr - paddr;
    355
    356			/*
    357			 * Avoid wasting memory on PTEs by choosing a virtual
    358			 * base that is compatible with section mappings if this
    359			 * region has the appropriate size and physical
    360			 * alignment. (Sections are 2 MB on 4k granule kernels)
    361			 */
    362			if (IS_ALIGNED(in->phys_addr, SZ_2M) && size >= SZ_2M)
    363				efi_virt_base = round_up(efi_virt_base, SZ_2M);
    364			else
    365				efi_virt_base = round_up(efi_virt_base, SZ_64K);
    366
    367			in->virt_addr += efi_virt_base - paddr;
    368			efi_virt_base += size;
    369		}
    370
    371		memcpy(out, in, desc_size);
    372		out = (void *)out + desc_size;
    373		++*count;
    374	}
    375}