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.
*/
/**
* get_var() - get UEFI variable
*
* It is the caller's duty to free the returned buffer.
*
* @name: name of variable
* @vendor: vendor GUID of variable
* @size: size of allocated buffer
* Return: buffer with variable data or NULL
*/
static void *get_var(u16 *name, const efi_guid_t *vendor,
efi_uintn_t *size)
{
efi_status_t ret;
void *buf = NULL;
*size = 0;
ret = efi_get_variable_int(name, vendor, NULL, size, buf, NULL);
if (ret == EFI_BUFFER_TOO_SMALL) {
buf = malloc(*size);
ret = efi_get_variable_int(name, vendor, NULL, size, buf, NULL);
}
if (ret != EFI_SUCCESS) {
free(buf);
*size = 0;
return NULL;
}
return buf;
}
/**
* 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[] = L"Boot0000";
u16 hexmap[] = L"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 = 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(L"BootCurrent",
&efi_global_variable_guid,
attributes, sizeof(n), &n, false);
if (ret != EFI_SUCCESS) {
if (EFI_CALL(efi_unload_image(*handle))
!= EFI_SUCCESS)
log_err("Unloading image failed\n");
goto error;
}
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);
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(L"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(L"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 = get_var(L"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;
}