u-boot/lib/efi_loader/efi_bootmgr.c

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// SPDX-License-Identifier: GPL-2.0+
/*
* EFI boot manager
*
* Copyright (c) 2017 Rob Clark
*/
#define LOG_CATEGORY LOGC_EFI
#include <common.h>
#include <charset.h>
#include <log.h>
#include <malloc.h>
#include <efi_loader.h>
#include <efi_variable.h>
#include <asm/unaligned.h>
static const struct efi_boot_services *bs;
static const struct efi_runtime_services *rs;
/*
* bootmgr implements the logic of trying to find a payload to boot
* based on the BootOrder + BootXXXX variables, and then loading it.
*
* TODO detecting a special key held (f9?) and displaying a boot menu
* like you would get on a PC would be clever.
*
* TODO if we had a way to write and persist variables after the OS
* has started, we'd also want to check OsIndications to see if we
* should do normal or recovery boot.
*/
/**
* try_load_entry() - try to load image for boot option
*
* Attempt to load load-option number 'n', returning device_path and file_path
* if successful. This checks that the EFI_LOAD_OPTION is active (enabled)
* and that the specified file to boot exists.
*
* @n: number of the boot option, e.g. 0x0a13 for Boot0A13
* @handle: on return handle for the newly installed image
* @load_options: load options set on the loaded image protocol
* Return: status code
*/
static efi_status_t try_load_entry(u16 n, efi_handle_t *handle,
void **load_options)
{
struct efi_load_option lo;
u16 varname[] = u"Boot0000";
u16 hexmap[] = u"0123456789ABCDEF";
void *load_option;
efi_uintn_t size;
efi_status_t ret;
varname[4] = hexmap[(n & 0xf000) >> 12];
varname[5] = hexmap[(n & 0x0f00) >> 8];
varname[6] = hexmap[(n & 0x00f0) >> 4];
varname[7] = hexmap[(n & 0x000f) >> 0];
load_option = efi_get_var(varname, &efi_global_variable_guid, &size);
if (!load_option)
return EFI_LOAD_ERROR;
ret = efi_deserialize_load_option(&lo, load_option, &size);
if (ret != EFI_SUCCESS) {
log_warning("Invalid load option for %ls\n", varname);
goto error;
}
if (lo.attributes & LOAD_OPTION_ACTIVE) {
u32 attributes;
log_debug("%s: trying to load \"%ls\" from %pD\n",
__func__, lo.label, lo.file_path);
ret = EFI_CALL(efi_load_image(true, efi_root, lo.file_path,
NULL, 0, handle));
if (ret != EFI_SUCCESS) {
log_warning("Loading %ls '%ls' failed\n",
varname, lo.label);
goto error;
}
attributes = EFI_VARIABLE_BOOTSERVICE_ACCESS |
EFI_VARIABLE_RUNTIME_ACCESS;
ret = efi_set_variable_int(u"BootCurrent",
&efi_global_variable_guid,
attributes, sizeof(n), &n, false);
efi_loader: Replace config option for initrd loading Up to now we install EFI_LOAD_FILE2_PROTOCOL to load an initrd unconditionally. Although we correctly return various EFI exit codes depending on the file status (i.e EFI_NO_MEDIA, EFI_NOT_FOUND etc), the kernel loader, only falls back to the cmdline interpreted initrd if the protocol is not installed. This creates a problem for EFI installers, since they won't be able to load their own initrd and continue the installation. It also makes the feature hard to use, since we can either have a single initrd or we have to recompile u-boot if the filename changes. So let's introduce a different logic that will decouple the initrd path from the config option we currently have. When defining a UEFI BootXXXX we can use the filepathlist and store a file path pointing to our initrd. Specifically the EFI spec describes: "The first element of the array is a device path that describes the device and location of the Image for this load option. Other device paths may optionally exist in the FilePathList, but their usage is OSV specific" When the EFI application is launched through the bootmgr, we'll try to interpret the extra device path. If that points to a file that exists on our disk, we'll now install the load_file2 and the efi-stub will be able to use it. This opens up another path using U-Boot and defines a new boot flow. A user will be able to control the kernel/initrd pairs without explicit cmdline args or GRUB. Signed-off-by: Ilias Apalodimas <ilias.apalodimas@linaro.org> Reviewed-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
2021-03-17 19:55:00 +00:00
if (ret != EFI_SUCCESS)
goto unload;
/* try to register load file2 for initrd's */
if (IS_ENABLED(CONFIG_EFI_LOAD_FILE2_INITRD)) {
ret = efi_initrd_register();
if (ret != EFI_SUCCESS)
goto unload;
}
log_info("Booting: %ls\n", lo.label);
} else {
ret = EFI_LOAD_ERROR;
}
/* Set load options */
if (size) {
*load_options = malloc(size);
if (!*load_options) {
ret = EFI_OUT_OF_RESOURCES;
goto error;
}
memcpy(*load_options, lo.optional_data, size);
ret = efi_set_load_options(*handle, size, *load_options);
} else {
*load_options = NULL;
}
error:
free(load_option);
efi_loader: Replace config option for initrd loading Up to now we install EFI_LOAD_FILE2_PROTOCOL to load an initrd unconditionally. Although we correctly return various EFI exit codes depending on the file status (i.e EFI_NO_MEDIA, EFI_NOT_FOUND etc), the kernel loader, only falls back to the cmdline interpreted initrd if the protocol is not installed. This creates a problem for EFI installers, since they won't be able to load their own initrd and continue the installation. It also makes the feature hard to use, since we can either have a single initrd or we have to recompile u-boot if the filename changes. So let's introduce a different logic that will decouple the initrd path from the config option we currently have. When defining a UEFI BootXXXX we can use the filepathlist and store a file path pointing to our initrd. Specifically the EFI spec describes: "The first element of the array is a device path that describes the device and location of the Image for this load option. Other device paths may optionally exist in the FilePathList, but their usage is OSV specific" When the EFI application is launched through the bootmgr, we'll try to interpret the extra device path. If that points to a file that exists on our disk, we'll now install the load_file2 and the efi-stub will be able to use it. This opens up another path using U-Boot and defines a new boot flow. A user will be able to control the kernel/initrd pairs without explicit cmdline args or GRUB. Signed-off-by: Ilias Apalodimas <ilias.apalodimas@linaro.org> Reviewed-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
2021-03-17 19:55:00 +00:00
return ret;
unload:
if (EFI_CALL(efi_unload_image(*handle)) != EFI_SUCCESS)
log_err("Unloading image failed\n");
free(load_option);
return ret;
}
/**
* efi_bootmgr_load() - try to load from BootNext or BootOrder
*
* Attempt to load from BootNext or in the order specified by BootOrder
* EFI variable, the available load-options, finding and returning
* the first one that can be loaded successfully.
*
* @handle: on return handle for the newly installed image
* @load_options: load options set on the loaded image protocol
* Return: status code
*/
efi_status_t efi_bootmgr_load(efi_handle_t *handle, void **load_options)
{
u16 bootnext, *bootorder;
efi_uintn_t size;
int i, num;
efi_status_t ret;
bs = systab.boottime;
rs = systab.runtime;
/* BootNext */
size = sizeof(bootnext);
ret = efi_get_variable_int(u"BootNext",
&efi_global_variable_guid,
NULL, &size, &bootnext, NULL);
if (ret == EFI_SUCCESS || ret == EFI_BUFFER_TOO_SMALL) {
/* BootNext does exist here */
if (ret == EFI_BUFFER_TOO_SMALL || size != sizeof(u16))
log_err("BootNext must be 16-bit integer\n");
/* delete BootNext */
ret = efi_set_variable_int(u"BootNext",
&efi_global_variable_guid,
0, 0, NULL, false);
/* load BootNext */
if (ret == EFI_SUCCESS) {
if (size == sizeof(u16)) {
ret = try_load_entry(bootnext, handle,
load_options);
if (ret == EFI_SUCCESS)
return ret;
log_warning(
"Loading from BootNext failed, falling back to BootOrder\n");
}
} else {
log_err("Deleting BootNext failed\n");
}
}
/* BootOrder */
bootorder = efi_get_var(u"BootOrder", &efi_global_variable_guid, &size);
if (!bootorder) {
log_info("BootOrder not defined\n");
ret = EFI_NOT_FOUND;
goto error;
}
num = size / sizeof(uint16_t);
for (i = 0; i < num; i++) {
log_debug("%s trying to load Boot%04X\n", __func__,
bootorder[i]);
ret = try_load_entry(bootorder[i], handle, load_options);
if (ret == EFI_SUCCESS)
break;
}
free(bootorder);
error:
return ret;
}