diff options
Diffstat (limited to 'drivers/firmware/efi/libstub/efi-stub.c')
| -rw-r--r-- | drivers/firmware/efi/libstub/efi-stub.c | 357 |
1 files changed, 357 insertions, 0 deletions
diff --git a/drivers/firmware/efi/libstub/efi-stub.c b/drivers/firmware/efi/libstub/efi-stub.c new file mode 100644 index 000000000..cf474f0dd --- /dev/null +++ b/drivers/firmware/efi/libstub/efi-stub.c @@ -0,0 +1,357 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * EFI stub implementation that is shared by arm and arm64 architectures. + * This should be #included by the EFI stub implementation files. + * + * Copyright (C) 2013,2014 Linaro Limited + * Roy Franz <roy.franz@linaro.org + * Copyright (C) 2013 Red Hat, Inc. + * Mark Salter <msalter@redhat.com> + */ + +#include <linux/efi.h> +#include <asm/efi.h> + +#include "efistub.h" + +/* + * This is the base address at which to start allocating virtual memory ranges + * for UEFI Runtime Services. + * + * For ARM/ARM64: + * This is in the low TTBR0 range so that we can use + * any allocation we choose, and eliminate the risk of a conflict after kexec. + * The value chosen is the largest non-zero power of 2 suitable for this purpose + * both on 32-bit and 64-bit ARM CPUs, to maximize the likelihood that it can + * be mapped efficiently. + * Since 32-bit ARM could potentially execute with a 1G/3G user/kernel split, + * map everything below 1 GB. (512 MB is a reasonable upper bound for the + * entire footprint of the UEFI runtime services memory regions) + * + * For RISC-V: + * There is no specific reason for which, this address (512MB) can't be used + * EFI runtime virtual address for RISC-V. It also helps to use EFI runtime + * services on both RV32/RV64. Keep the same runtime virtual address for RISC-V + * as well to minimize the code churn. + */ +#define EFI_RT_VIRTUAL_BASE SZ_512M +#define EFI_RT_VIRTUAL_SIZE SZ_512M + +#ifdef CONFIG_ARM64 +# define EFI_RT_VIRTUAL_LIMIT DEFAULT_MAP_WINDOW_64 +#elif defined(CONFIG_RISCV) || defined(CONFIG_LOONGARCH) +# define EFI_RT_VIRTUAL_LIMIT TASK_SIZE_MIN +#else /* Only if TASK_SIZE is a constant */ +# define EFI_RT_VIRTUAL_LIMIT TASK_SIZE +#endif + +/* + * Some architectures map the EFI regions into the kernel's linear map using a + * fixed offset. + */ +#ifndef EFI_RT_VIRTUAL_OFFSET +#define EFI_RT_VIRTUAL_OFFSET 0 +#endif + +static u64 virtmap_base = EFI_RT_VIRTUAL_BASE; +static bool flat_va_mapping = (EFI_RT_VIRTUAL_OFFSET != 0); + +static struct screen_info *setup_graphics(void) +{ + efi_guid_t gop_proto = EFI_GRAPHICS_OUTPUT_PROTOCOL_GUID; + efi_status_t status; + unsigned long size; + void **gop_handle = NULL; + struct screen_info *si = NULL; + + size = 0; + status = efi_bs_call(locate_handle, EFI_LOCATE_BY_PROTOCOL, + &gop_proto, NULL, &size, gop_handle); + if (status == EFI_BUFFER_TOO_SMALL) { + si = alloc_screen_info(); + if (!si) + return NULL; + status = efi_setup_gop(si, &gop_proto, size); + if (status != EFI_SUCCESS) { + free_screen_info(si); + return NULL; + } + } + return si; +} + +static void install_memreserve_table(void) +{ + struct linux_efi_memreserve *rsv; + efi_guid_t memreserve_table_guid = LINUX_EFI_MEMRESERVE_TABLE_GUID; + efi_status_t status; + + status = efi_bs_call(allocate_pool, EFI_LOADER_DATA, sizeof(*rsv), + (void **)&rsv); + if (status != EFI_SUCCESS) { + efi_err("Failed to allocate memreserve entry!\n"); + return; + } + + rsv->next = 0; + rsv->size = 0; + atomic_set(&rsv->count, 0); + + status = efi_bs_call(install_configuration_table, + &memreserve_table_guid, rsv); + if (status != EFI_SUCCESS) + efi_err("Failed to install memreserve config table!\n"); +} + +static u32 get_supported_rt_services(void) +{ + const efi_rt_properties_table_t *rt_prop_table; + u32 supported = EFI_RT_SUPPORTED_ALL; + + rt_prop_table = get_efi_config_table(EFI_RT_PROPERTIES_TABLE_GUID); + if (rt_prop_table) + supported &= rt_prop_table->runtime_services_supported; + + return supported; +} + +/* + * EFI entry point for the arm/arm64 EFI stubs. This is the entrypoint + * that is described in the PE/COFF header. Most of the code is the same + * for both archictectures, with the arch-specific code provided in the + * handle_kernel_image() function. + */ +efi_status_t __efiapi efi_pe_entry(efi_handle_t handle, + efi_system_table_t *sys_table_arg) +{ + efi_loaded_image_t *image; + efi_status_t status; + unsigned long image_addr; + unsigned long image_size = 0; + /* addr/point and size pairs for memory management*/ + char *cmdline_ptr = NULL; + int cmdline_size = 0; + efi_guid_t loaded_image_proto = LOADED_IMAGE_PROTOCOL_GUID; + unsigned long reserve_addr = 0; + unsigned long reserve_size = 0; + struct screen_info *si; + efi_properties_table_t *prop_tbl; + + efi_system_table = sys_table_arg; + + /* Check if we were booted by the EFI firmware */ + if (efi_system_table->hdr.signature != EFI_SYSTEM_TABLE_SIGNATURE) { + status = EFI_INVALID_PARAMETER; + goto fail; + } + + status = check_platform_features(); + if (status != EFI_SUCCESS) + goto fail; + + /* + * Get a handle to the loaded image protocol. This is used to get + * information about the running image, such as size and the command + * line. + */ + status = efi_bs_call(handle_protocol, handle, &loaded_image_proto, + (void *)&image); + if (status != EFI_SUCCESS) { + efi_err("Failed to get loaded image protocol\n"); + goto fail; + } + + /* + * Get the command line from EFI, using the LOADED_IMAGE + * protocol. We are going to copy the command line into the + * device tree, so this can be allocated anywhere. + */ + cmdline_ptr = efi_convert_cmdline(image, &cmdline_size); + if (!cmdline_ptr) { + efi_err("getting command line via LOADED_IMAGE_PROTOCOL\n"); + status = EFI_OUT_OF_RESOURCES; + goto fail; + } + + if (IS_ENABLED(CONFIG_CMDLINE_EXTEND) || + IS_ENABLED(CONFIG_CMDLINE_FORCE) || + cmdline_size == 0) { + status = efi_parse_options(CONFIG_CMDLINE); + if (status != EFI_SUCCESS) { + efi_err("Failed to parse options\n"); + goto fail_free_cmdline; + } + } + + if (!IS_ENABLED(CONFIG_CMDLINE_FORCE) && cmdline_size > 0) { + status = efi_parse_options(cmdline_ptr); + if (status != EFI_SUCCESS) { + efi_err("Failed to parse options\n"); + goto fail_free_cmdline; + } + } + + efi_info("Booting Linux Kernel...\n"); + + si = setup_graphics(); + + status = handle_kernel_image(&image_addr, &image_size, + &reserve_addr, + &reserve_size, + image, handle); + if (status != EFI_SUCCESS) { + efi_err("Failed to relocate kernel\n"); + goto fail_free_screeninfo; + } + + efi_retrieve_tpm2_eventlog(); + + /* Ask the firmware to clear memory on unclean shutdown */ + efi_enable_reset_attack_mitigation(); + + efi_load_initrd(image, ULONG_MAX, efi_get_max_initrd_addr(image_addr), + NULL); + + efi_random_get_seed(); + + /* + * If the NX PE data feature is enabled in the properties table, we + * should take care not to create a virtual mapping that changes the + * relative placement of runtime services code and data regions, as + * they may belong to the same PE/COFF executable image in memory. + * The easiest way to achieve that is to simply use a 1:1 mapping. + */ + prop_tbl = get_efi_config_table(EFI_PROPERTIES_TABLE_GUID); + flat_va_mapping |= prop_tbl && + (prop_tbl->memory_protection_attribute & + EFI_PROPERTIES_RUNTIME_MEMORY_PROTECTION_NON_EXECUTABLE_PE_DATA); + + /* force efi_novamap if SetVirtualAddressMap() is unsupported */ + efi_novamap |= !(get_supported_rt_services() & + EFI_RT_SUPPORTED_SET_VIRTUAL_ADDRESS_MAP); + + /* hibernation expects the runtime regions to stay in the same place */ + if (!IS_ENABLED(CONFIG_HIBERNATION) && !efi_nokaslr && !flat_va_mapping) { + /* + * Randomize the base of the UEFI runtime services region. + * Preserve the 2 MB alignment of the region by taking a + * shift of 21 bit positions into account when scaling + * the headroom value using a 32-bit random value. + */ + static const u64 headroom = EFI_RT_VIRTUAL_LIMIT - + EFI_RT_VIRTUAL_BASE - + EFI_RT_VIRTUAL_SIZE; + u32 rnd; + + status = efi_get_random_bytes(sizeof(rnd), (u8 *)&rnd); + if (status == EFI_SUCCESS) { + virtmap_base = EFI_RT_VIRTUAL_BASE + + (((headroom >> 21) * rnd) >> (32 - 21)); + } + } + + install_memreserve_table(); + + status = efi_boot_kernel(handle, image, image_addr, cmdline_ptr); + + efi_free(image_size, image_addr); + efi_free(reserve_size, reserve_addr); +fail_free_screeninfo: + free_screen_info(si); +fail_free_cmdline: + efi_bs_call(free_pool, cmdline_ptr); +fail: + return status; +} + +/* + * efi_allocate_virtmap() - create a pool allocation for the virtmap + * + * Create an allocation that is of sufficient size to hold all the memory + * descriptors that will be passed to SetVirtualAddressMap() to inform the + * firmware about the virtual mapping that will be used under the OS to call + * into the firmware. + */ +efi_status_t efi_alloc_virtmap(efi_memory_desc_t **virtmap, + unsigned long *desc_size, u32 *desc_ver) +{ + unsigned long size, mmap_key; + efi_status_t status; + + /* + * Use the size of the current memory map as an upper bound for the + * size of the buffer we need to pass to SetVirtualAddressMap() to + * cover all EFI_MEMORY_RUNTIME regions. + */ + size = 0; + status = efi_bs_call(get_memory_map, &size, NULL, &mmap_key, desc_size, + desc_ver); + if (status != EFI_BUFFER_TOO_SMALL) + return EFI_LOAD_ERROR; + + return efi_bs_call(allocate_pool, EFI_LOADER_DATA, size, + (void **)virtmap); +} + +/* + * efi_get_virtmap() - create a virtual mapping for the EFI memory map + * + * This function populates the virt_addr fields of all memory region descriptors + * in @memory_map whose EFI_MEMORY_RUNTIME attribute is set. Those descriptors + * are also copied to @runtime_map, and their total count is returned in @count. + */ +void efi_get_virtmap(efi_memory_desc_t *memory_map, unsigned long map_size, + unsigned long desc_size, efi_memory_desc_t *runtime_map, + int *count) +{ + u64 efi_virt_base = virtmap_base; + efi_memory_desc_t *in, *out = runtime_map; + int l; + + *count = 0; + + for (l = 0; l < map_size; l += desc_size) { + u64 paddr, size; + + in = (void *)memory_map + l; + if (!(in->attribute & EFI_MEMORY_RUNTIME)) + continue; + + paddr = in->phys_addr; + size = in->num_pages * EFI_PAGE_SIZE; + + in->virt_addr = in->phys_addr + EFI_RT_VIRTUAL_OFFSET; + if (efi_novamap) { + continue; + } + + /* + * Make the mapping compatible with 64k pages: this allows + * a 4k page size kernel to kexec a 64k page size kernel and + * vice versa. + */ + if (!flat_va_mapping) { + + paddr = round_down(in->phys_addr, SZ_64K); + size += in->phys_addr - paddr; + + /* + * Avoid wasting memory on PTEs by choosing a virtual + * base that is compatible with section mappings if this + * region has the appropriate size and physical + * alignment. (Sections are 2 MB on 4k granule kernels) + */ + if (IS_ALIGNED(in->phys_addr, SZ_2M) && size >= SZ_2M) + efi_virt_base = round_up(efi_virt_base, SZ_2M); + else + efi_virt_base = round_up(efi_virt_base, SZ_64K); + + in->virt_addr += efi_virt_base - paddr; + efi_virt_base += size; + } + + memcpy(out, in, desc_size); + out = (void *)out + desc_size; + ++*count; + } +} |