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![Heinrich Schuchardt](/assets/img/avatar_default.png)
The function names utf16_strlen() and utf16_strnlen() are misnomers. The functions do not count utf-16 characters but non-zero words. So let's rename them to u16_strlen and u16_strnlen(). In utf16_dup() avoid assignment in if clause. Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de> Signed-off-by: Alexander Graf <agraf@suse.de>
178 lines
4.2 KiB
C
178 lines
4.2 KiB
C
// SPDX-License-Identifier: GPL-2.0+
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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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#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 += (u16_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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efi_uintn_t *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(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(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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efi_uintn_t 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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debug("%s: trying to load \"%ls\" from %pD\n",
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__func__, lo.label, lo.file_path);
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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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efi_uintn_t 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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