src/cpu/x86/smm/backup_default_smm.c

   1 /*
   2  * This file is part of the coreboot project.
   3  *
   4  * Copyright (C) 2014 Google Inc
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License as
   8  * published by the Free Software Foundation; version 2 of
   9  * the License.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, write to the Free Software
  18  * Foundation, Inc.
  19  */
  20
  21 #include <string.h>
  22 #include <arch/acpi.h>
  23 #include <console/console.h>
  24 #include <cbmem.h>
  25 #include <cpu/x86/smm.h>
  26
  27 void *backup_default_smm_area(void)
  28 {
  29         void *save_area;
  30         const void *default_smm = (void *)SMM_DEFAULT_BASE;
  31
  32         if (!IS_ENABLED(CONFIG_HAVE_ACPI_RESUME))
  33                 return NULL;
  34
  35         /*
  36          * The buffer needs to be preallocated regardless. In the non-resume
  37          * path it will be allocated for handling resume. Note that cbmem_add()
  38          * does a find before the addition.
  39          */
  40         save_area = cbmem_add(CBMEM_ID_SMM_SAVE_SPACE, SMM_DEFAULT_SIZE);
  41
  42         if (save_area == NULL) {
  43                 printk(BIOS_DEBUG, "SMM save area not added.\n");
  44                 return NULL;
  45         }
  46
  47         /* Only back up the area on S3 resume. */
  48         if (acpi_is_wakeup_s3()) {
  49                 memcpy(save_area, default_smm, SMM_DEFAULT_SIZE);
  50                 return save_area;
  51         }
  52
  53         /*
  54          * Not the S3 resume path. No need to restore memory contents after
  55          * SMM relocation.
  56          */
  57         return NULL;
  58 }
  59
  60 void restore_default_smm_area(void *smm_save_area)
  61 {
  62         void *default_smm = (void *)SMM_DEFAULT_BASE;
  63
  64         if (smm_save_area == NULL)
  65                 return;
  66
  67         memcpy(default_smm, smm_save_area, SMM_DEFAULT_SIZE);
  68 }