Similar to a "real" UEFI implementation, the bootmgr looks at the BootOrder and BootXXXX variables to try to find an EFI payload to load and boot. This is added as a sub-command of bootefi. The idea is that the distro bootcmd would first try loading a payload via the bootmgr, and then if that fails (ie. first boot or corrupted EFI variables) it would fallback to loading bootaa64.efi. (Which would then load fallback.efi which would look for \EFI\*\boot.csv and populate BootOrder and BootXXXX based on what it found.) Signed-off-by: Rob Clark <robdclark@gmail.com> Signed-off-by: Alexander Graf <agraf@suse.de>master
Rob Clark
7 years ago
committed by
Alexander Graf
parent
ad644e7c18
commit
9975fe96b6
@ -0,0 +1,180 @@ |
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/*
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* EFI utils |
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* |
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* Copyright (c) 2017 Rob Clark |
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* |
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* SPDX-License-Identifier: GPL-2.0+ |
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*/ |
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#include <common.h> |
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#include <charset.h> |
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#include <malloc.h> |
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#include <efi_loader.h> |
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static const struct efi_boot_services *bs; |
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static const struct efi_runtime_services *rs; |
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#define LOAD_OPTION_ACTIVE 0x00000001 |
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#define LOAD_OPTION_FORCE_RECONNECT 0x00000002 |
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#define LOAD_OPTION_HIDDEN 0x00000008 |
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/*
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* bootmgr implements the logic of trying to find a payload to boot |
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* based on the BootOrder + BootXXXX variables, and then loading it. |
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* |
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* TODO detecting a special key held (f9?) and displaying a boot menu |
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* like you would get on a PC would be clever. |
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* |
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* TODO if we had a way to write and persist variables after the OS |
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* has started, we'd also want to check OsIndications to see if we |
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* should do normal or recovery boot. |
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*/ |
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/*
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* See section 3.1.3 in the v2.7 UEFI spec for more details on |
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* the layout of EFI_LOAD_OPTION. In short it is: |
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* |
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* typedef struct _EFI_LOAD_OPTION { |
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* UINT32 Attributes; |
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* UINT16 FilePathListLength; |
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* // CHAR16 Description[]; <-- variable length, NULL terminated
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* // EFI_DEVICE_PATH_PROTOCOL FilePathList[]; <-- FilePathListLength bytes
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* // UINT8 OptionalData[];
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* } EFI_LOAD_OPTION; |
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*/ |
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struct load_option { |
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u32 attributes; |
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u16 file_path_length; |
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u16 *label; |
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struct efi_device_path *file_path; |
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u8 *optional_data; |
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}; |
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/* parse an EFI_LOAD_OPTION, as described above */ |
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static void parse_load_option(struct load_option *lo, void *ptr) |
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{ |
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lo->attributes = *(u32 *)ptr; |
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ptr += sizeof(u32); |
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lo->file_path_length = *(u16 *)ptr; |
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ptr += sizeof(u16); |
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lo->label = ptr; |
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ptr += (utf16_strlen(lo->label) + 1) * 2; |
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lo->file_path = ptr; |
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ptr += lo->file_path_length; |
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lo->optional_data = ptr; |
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} |
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/* free() the result */ |
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static void *get_var(u16 *name, const efi_guid_t *vendor, |
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unsigned long *size) |
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{ |
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efi_guid_t *v = (efi_guid_t *)vendor; |
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efi_status_t ret; |
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void *buf = NULL; |
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*size = 0; |
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EFI_CALL(ret = rs->get_variable((s16 *)name, v, NULL, size, buf)); |
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if (ret == EFI_BUFFER_TOO_SMALL) { |
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buf = malloc(*size); |
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EFI_CALL(ret = rs->get_variable((s16 *)name, v, NULL, size, buf)); |
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} |
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if (ret != EFI_SUCCESS) { |
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free(buf); |
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*size = 0; |
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return NULL; |
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} |
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return buf; |
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} |
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/*
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* Attempt to load load-option number 'n', returning device_path and file_path |
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* if successful. This checks that the EFI_LOAD_OPTION is active (enabled) |
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* and that the specified file to boot exists. |
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*/ |
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static void *try_load_entry(uint16_t n, struct efi_device_path **device_path, |
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struct efi_device_path **file_path) |
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{ |
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struct load_option lo; |
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u16 varname[] = L"Boot0000"; |
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u16 hexmap[] = L"0123456789ABCDEF"; |
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void *load_option, *image = NULL; |
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unsigned long size; |
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varname[4] = hexmap[(n & 0xf000) >> 12]; |
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varname[5] = hexmap[(n & 0x0f00) >> 8]; |
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varname[6] = hexmap[(n & 0x00f0) >> 4]; |
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varname[7] = hexmap[(n & 0x000f) >> 0]; |
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load_option = get_var(varname, &efi_global_variable_guid, &size); |
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if (!load_option) |
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return NULL; |
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parse_load_option(&lo, load_option); |
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if (lo.attributes & LOAD_OPTION_ACTIVE) { |
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efi_status_t ret; |
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u16 *str = NULL; |
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debug("%s: trying to load \"%ls\" from: %ls\n", __func__, |
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lo.label, (str = efi_dp_str(lo.file_path))); |
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efi_free_pool(str); |
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ret = efi_load_image_from_path(lo.file_path, &image); |
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if (ret != EFI_SUCCESS) |
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goto error; |
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printf("Booting: %ls\n", lo.label); |
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efi_dp_split_file_path(lo.file_path, device_path, file_path); |
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} |
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error: |
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free(load_option); |
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return image; |
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} |
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/*
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* Attempt to load, in the order specified by BootOrder EFI variable, the |
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* available load-options, finding and returning the first one that can |
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* be loaded successfully. |
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*/ |
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void *efi_bootmgr_load(struct efi_device_path **device_path, |
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struct efi_device_path **file_path) |
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{ |
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uint16_t *bootorder; |
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unsigned long size; |
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void *image = NULL; |
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int i, num; |
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__efi_entry_check(); |
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bs = systab.boottime; |
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rs = systab.runtime; |
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bootorder = get_var(L"BootOrder", &efi_global_variable_guid, &size); |
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if (!bootorder) |
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goto error; |
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num = size / sizeof(uint16_t); |
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for (i = 0; i < num; i++) { |
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debug("%s: trying to load Boot%04X\n", __func__, bootorder[i]); |
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image = try_load_entry(bootorder[i], device_path, file_path); |
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if (image) |
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break; |
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} |
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free(bootorder); |
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error: |
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__efi_exit_check(); |
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return image; |
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} |
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