efi/libstub/efi-stub.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  * EFI stub implementation that is shared by arm and arm64 architectures.
0004  * This should be #included by the EFI stub implementation files.
0005  *
0006  * Copyright (C) 2013,2014 Linaro Limited
0007  *     Roy Franz <roy.franz@linaro.org
0008  * Copyright (C) 2013 Red Hat, Inc.
0009  *     Mark Salter <msalter@redhat.com>
0010  */
0011
0012 #include <linux/efi.h>
0013 #include <linux/libfdt.h>
0014 #include <asm/efi.h>
0015
0016 #include "efistub.h"
0017
0018 /*
0019  * This is the base address at which to start allocating virtual memory ranges
0020  * for UEFI Runtime Services.
0021  *
0022  * For ARM/ARM64:
0023  * This is in the low TTBR0 range so that we can use
0024  * any allocation we choose, and eliminate the risk of a conflict after kexec.
0025  * The value chosen is the largest non-zero power of 2 suitable for this purpose
0026  * both on 32-bit and 64-bit ARM CPUs, to maximize the likelihood that it can
0027  * be mapped efficiently.
0028  * Since 32-bit ARM could potentially execute with a 1G/3G user/kernel split,
0029  * map everything below 1 GB. (512 MB is a reasonable upper bound for the
0030  * entire footprint of the UEFI runtime services memory regions)
0031  *
0032  * For RISC-V:
0033  * There is no specific reason for which, this address (512MB) can't be used
0034  * EFI runtime virtual address for RISC-V. It also helps to use EFI runtime
0035  * services on both RV32/RV64. Keep the same runtime virtual address for RISC-V
0036  * as well to minimize the code churn.
0037  */
0038 #define EFI_RT_VIRTUAL_BASE SZ_512M
0039 #define EFI_RT_VIRTUAL_SIZE SZ_512M
0040
0041 #ifdef CONFIG_ARM64
0042 # define EFI_RT_VIRTUAL_LIMIT   DEFAULT_MAP_WINDOW_64
0043 #elif defined(CONFIG_RISCV)
0044 # define EFI_RT_VIRTUAL_LIMIT   TASK_SIZE_MIN
0045 #else
0046 # define EFI_RT_VIRTUAL_LIMIT   TASK_SIZE
0047 #endif
0048
0049 static u64 virtmap_base = EFI_RT_VIRTUAL_BASE;
0050 static bool flat_va_mapping;
0051
0052 const efi_system_table_t *efi_system_table;
0053
0054 static struct screen_info *setup_graphics(void)
0055 {
0056     efi_guid_t gop_proto = EFI_GRAPHICS_OUTPUT_PROTOCOL_GUID;
0057     efi_status_t status;
0058     unsigned long size;
0059     void **gop_handle = NULL;
0060     struct screen_info *si = NULL;
0061
0062     size = 0;
0063     status = efi_bs_call(locate_handle, EFI_LOCATE_BY_PROTOCOL,
0064                  &gop_proto, NULL, &size, gop_handle);
0065     if (status == EFI_BUFFER_TOO_SMALL) {
0066         si = alloc_screen_info();
0067         if (!si)
0068             return NULL;
0069         status = efi_setup_gop(si, &gop_proto, size);
0070         if (status != EFI_SUCCESS) {
0071             free_screen_info(si);
0072             return NULL;
0073         }
0074     }
0075     return si;
0076 }
0077
0078 static void install_memreserve_table(void)
0079 {
0080     struct linux_efi_memreserve *rsv;
0081     efi_guid_t memreserve_table_guid = LINUX_EFI_MEMRESERVE_TABLE_GUID;
0082     efi_status_t status;
0083
0084     status = efi_bs_call(allocate_pool, EFI_LOADER_DATA, sizeof(*rsv),
0085                  (void **)&rsv);
0086     if (status != EFI_SUCCESS) {
0087         efi_err("Failed to allocate memreserve entry!\n");
0088         return;
0089     }
0090
0091     rsv->next = 0;
0092     rsv->size = 0;
0093     atomic_set(&rsv->count, 0);
0094
0095     status = efi_bs_call(install_configuration_table,
0096                  &memreserve_table_guid, rsv);
0097     if (status != EFI_SUCCESS)
0098         efi_err("Failed to install memreserve config table!\n");
0099 }
0100
0101 static u32 get_supported_rt_services(void)
0102 {
0103     const efi_rt_properties_table_t *rt_prop_table;
0104     u32 supported = EFI_RT_SUPPORTED_ALL;
0105
0106     rt_prop_table = get_efi_config_table(EFI_RT_PROPERTIES_TABLE_GUID);
0107     if (rt_prop_table)
0108         supported &= rt_prop_table->runtime_services_supported;
0109
0110     return supported;
0111 }
0112
0113 /*
0114  * EFI entry point for the arm/arm64 EFI stubs.  This is the entrypoint
0115  * that is described in the PE/COFF header.  Most of the code is the same
0116  * for both archictectures, with the arch-specific code provided in the
0117  * handle_kernel_image() function.
0118  */
0119 efi_status_t __efiapi efi_pe_entry(efi_handle_t handle,
0120                    efi_system_table_t *sys_table_arg)
0121 {
0122     efi_loaded_image_t *image;
0123     efi_status_t status;
0124     unsigned long image_addr;
0125     unsigned long image_size = 0;
0126     /* addr/point and size pairs for memory management*/
0127     unsigned long initrd_addr = 0;
0128     unsigned long initrd_size = 0;
0129     unsigned long fdt_addr = 0;  /* Original DTB */
0130     unsigned long fdt_size = 0;
0131     char *cmdline_ptr = NULL;
0132     int cmdline_size = 0;
0133     efi_guid_t loaded_image_proto = LOADED_IMAGE_PROTOCOL_GUID;
0134     unsigned long reserve_addr = 0;
0135     unsigned long reserve_size = 0;
0136     enum efi_secureboot_mode secure_boot;
0137     struct screen_info *si;
0138     efi_properties_table_t *prop_tbl;
0139
0140     efi_system_table = sys_table_arg;
0141
0142     /* Check if we were booted by the EFI firmware */
0143     if (efi_system_table->hdr.signature != EFI_SYSTEM_TABLE_SIGNATURE) {
0144         status = EFI_INVALID_PARAMETER;
0145         goto fail;
0146     }
0147
0148     status = check_platform_features();
0149     if (status != EFI_SUCCESS)
0150         goto fail;
0151
0152     /*
0153      * Get a handle to the loaded image protocol.  This is used to get
0154      * information about the running image, such as size and the command
0155      * line.
0156      */
0157     status = efi_system_table->boottime->handle_protocol(handle,
0158                     &loaded_image_proto, (void *)&image);
0159     if (status != EFI_SUCCESS) {
0160         efi_err("Failed to get loaded image protocol\n");
0161         goto fail;
0162     }
0163
0164     /*
0165      * Get the command line from EFI, using the LOADED_IMAGE
0166      * protocol. We are going to copy the command line into the
0167      * device tree, so this can be allocated anywhere.
0168      */
0169     cmdline_ptr = efi_convert_cmdline(image, &cmdline_size);
0170     if (!cmdline_ptr) {
0171         efi_err("getting command line via LOADED_IMAGE_PROTOCOL\n");
0172         status = EFI_OUT_OF_RESOURCES;
0173         goto fail;
0174     }
0175
0176     if (IS_ENABLED(CONFIG_CMDLINE_EXTEND) ||
0177         IS_ENABLED(CONFIG_CMDLINE_FORCE) ||
0178         cmdline_size == 0) {
0179         status = efi_parse_options(CONFIG_CMDLINE);
0180         if (status != EFI_SUCCESS) {
0181             efi_err("Failed to parse options\n");
0182             goto fail_free_cmdline;
0183         }
0184     }
0185
0186     if (!IS_ENABLED(CONFIG_CMDLINE_FORCE) && cmdline_size > 0) {
0187         status = efi_parse_options(cmdline_ptr);
0188         if (status != EFI_SUCCESS) {
0189             efi_err("Failed to parse options\n");
0190             goto fail_free_cmdline;
0191         }
0192     }
0193
0194     efi_info("Booting Linux Kernel...\n");
0195
0196     si = setup_graphics();
0197
0198     status = handle_kernel_image(&image_addr, &image_size,
0199                      &reserve_addr,
0200                      &reserve_size,
0201                      image, handle);
0202     if (status != EFI_SUCCESS) {
0203         efi_err("Failed to relocate kernel\n");
0204         goto fail_free_screeninfo;
0205     }
0206
0207     efi_retrieve_tpm2_eventlog();
0208
0209     /* Ask the firmware to clear memory on unclean shutdown */
0210     efi_enable_reset_attack_mitigation();
0211
0212     secure_boot = efi_get_secureboot();
0213
0214     /*
0215      * Unauthenticated device tree data is a security hazard, so ignore
0216      * 'dtb=' unless UEFI Secure Boot is disabled.  We assume that secure
0217      * boot is enabled if we can't determine its state.
0218      */
0219     if (!IS_ENABLED(CONFIG_EFI_ARMSTUB_DTB_LOADER) ||
0220          secure_boot != efi_secureboot_mode_disabled) {
0221         if (strstr(cmdline_ptr, "dtb="))
0222             efi_err("Ignoring DTB from command line.\n");
0223     } else {
0224         status = efi_load_dtb(image, &fdt_addr, &fdt_size);
0225
0226         if (status != EFI_SUCCESS) {
0227             efi_err("Failed to load device tree!\n");
0228             goto fail_free_image;
0229         }
0230     }
0231
0232     if (fdt_addr) {
0233         efi_info("Using DTB from command line\n");
0234     } else {
0235         /* Look for a device tree configuration table entry. */
0236         fdt_addr = (uintptr_t)get_fdt(&fdt_size);
0237         if (fdt_addr)
0238             efi_info("Using DTB from configuration table\n");
0239     }
0240
0241     if (!fdt_addr)
0242         efi_info("Generating empty DTB\n");
0243
0244     efi_load_initrd(image, &initrd_addr, &initrd_size, ULONG_MAX,
0245             efi_get_max_initrd_addr(image_addr));
0246
0247     efi_random_get_seed();
0248
0249     /*
0250      * If the NX PE data feature is enabled in the properties table, we
0251      * should take care not to create a virtual mapping that changes the
0252      * relative placement of runtime services code and data regions, as
0253      * they may belong to the same PE/COFF executable image in memory.
0254      * The easiest way to achieve that is to simply use a 1:1 mapping.
0255      */
0256     prop_tbl = get_efi_config_table(EFI_PROPERTIES_TABLE_GUID);
0257     flat_va_mapping = prop_tbl &&
0258               (prop_tbl->memory_protection_attribute &
0259                EFI_PROPERTIES_RUNTIME_MEMORY_PROTECTION_NON_EXECUTABLE_PE_DATA);
0260
0261     /* force efi_novamap if SetVirtualAddressMap() is unsupported */
0262     efi_novamap |= !(get_supported_rt_services() &
0263              EFI_RT_SUPPORTED_SET_VIRTUAL_ADDRESS_MAP);
0264
0265     /* hibernation expects the runtime regions to stay in the same place */
0266     if (!IS_ENABLED(CONFIG_HIBERNATION) && !efi_nokaslr && !flat_va_mapping) {
0267         /*
0268          * Randomize the base of the UEFI runtime services region.
0269          * Preserve the 2 MB alignment of the region by taking a
0270          * shift of 21 bit positions into account when scaling
0271          * the headroom value using a 32-bit random value.
0272          */
0273         static const u64 headroom = EFI_RT_VIRTUAL_LIMIT -
0274                         EFI_RT_VIRTUAL_BASE -
0275                         EFI_RT_VIRTUAL_SIZE;
0276         u32 rnd;
0277
0278         status = efi_get_random_bytes(sizeof(rnd), (u8 *)&rnd);
0279         if (status == EFI_SUCCESS) {
0280             virtmap_base = EFI_RT_VIRTUAL_BASE +
0281                        (((headroom >> 21) * rnd) >> (32 - 21));
0282         }
0283     }
0284
0285     install_memreserve_table();
0286
0287     status = allocate_new_fdt_and_exit_boot(handle, &fdt_addr,
0288                         initrd_addr, initrd_size,
0289                         cmdline_ptr, fdt_addr, fdt_size);
0290     if (status != EFI_SUCCESS)
0291         goto fail_free_initrd;
0292
0293     if (IS_ENABLED(CONFIG_ARM))
0294         efi_handle_post_ebs_state();
0295
0296     efi_enter_kernel(image_addr, fdt_addr, fdt_totalsize((void *)fdt_addr));
0297     /* not reached */
0298
0299 fail_free_initrd:
0300     efi_err("Failed to update FDT and exit boot services\n");
0301
0302     efi_free(initrd_size, initrd_addr);
0303     efi_free(fdt_size, fdt_addr);
0304
0305 fail_free_image:
0306     efi_free(image_size, image_addr);
0307     efi_free(reserve_size, reserve_addr);
0308 fail_free_screeninfo:
0309     free_screen_info(si);
0310 fail_free_cmdline:
0311     efi_bs_call(free_pool, cmdline_ptr);
0312 fail:
0313     return status;
0314 }
0315
0316 /*
0317  * efi_get_virtmap() - create a virtual mapping for the EFI memory map
0318  *
0319  * This function populates the virt_addr fields of all memory region descriptors
0320  * in @memory_map whose EFI_MEMORY_RUNTIME attribute is set. Those descriptors
0321  * are also copied to @runtime_map, and their total count is returned in @count.
0322  */
0323 void efi_get_virtmap(efi_memory_desc_t *memory_map, unsigned long map_size,
0324              unsigned long desc_size, efi_memory_desc_t *runtime_map,
0325              int *count)
0326 {
0327     u64 efi_virt_base = virtmap_base;
0328     efi_memory_desc_t *in, *out = runtime_map;
0329     int l;
0330
0331     for (l = 0; l < map_size; l += desc_size) {
0332         u64 paddr, size;
0333
0334         in = (void *)memory_map + l;
0335         if (!(in->attribute & EFI_MEMORY_RUNTIME))
0336             continue;
0337
0338         paddr = in->phys_addr;
0339         size = in->num_pages * EFI_PAGE_SIZE;
0340
0341         in->virt_addr = in->phys_addr;
0342         if (efi_novamap) {
0343             continue;
0344         }
0345
0346         /*
0347          * Make the mapping compatible with 64k pages: this allows
0348          * a 4k page size kernel to kexec a 64k page size kernel and
0349          * vice versa.
0350          */
0351         if (!flat_va_mapping) {
0352
0353             paddr = round_down(in->phys_addr, SZ_64K);
0354             size += in->phys_addr - paddr;
0355
0356             /*
0357              * Avoid wasting memory on PTEs by choosing a virtual
0358              * base that is compatible with section mappings if this
0359              * region has the appropriate size and physical
0360              * alignment. (Sections are 2 MB on 4k granule kernels)
0361              */
0362             if (IS_ALIGNED(in->phys_addr, SZ_2M) && size >= SZ_2M)
0363                 efi_virt_base = round_up(efi_virt_base, SZ_2M);
0364             else
0365                 efi_virt_base = round_up(efi_virt_base, SZ_64K);
0366
0367             in->virt_addr += efi_virt_base - paddr;
0368             efi_virt_base += size;
0369         }
0370
0371         memcpy(out, in, desc_size);
0372         out = (void *)out + desc_size;
0373         ++*count;
0374     }
0375 }