backup_default_smm.c

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/* SPDX-License-Identifier: GPL-2.0-only */
 
#include <string.h>
#include <acpi/acpi.h>
#include <console/console.h>
#include <cbmem.h>
#include <cpu/x86/smm.h>
 
void *backup_default_smm_area(void)
{
        void *save_area;
        const void *default_smm = (void *)SMM_DEFAULT_BASE;
 
        if (!CONFIG(HAVE_ACPI_RESUME))
                return NULL;
 
        /*
         * The buffer needs to be preallocated regardless. In the non-resume
         * path it will be allocated for handling resume. Note that cbmem_add()
         * does a find before the addition.
         */
        save_area = cbmem_add(CBMEM_ID_SMM_SAVE_SPACE, SMM_DEFAULT_SIZE);
 
        if (save_area == NULL) {
                printk(BIOS_DEBUG, "SMM save area not added.\n");
                return NULL;
        }
 
        /* Only back up the area on S3 resume. */
        if (acpi_is_wakeup_s3()) {
                memcpy(save_area, default_smm, SMM_DEFAULT_SIZE);
                return save_area;
        }
 
        /*
         * Not the S3 resume path. No need to restore memory contents after
         * SMM relocation.
         */
        return NULL;
}
 
void restore_default_smm_area(void *smm_save_area)
{
        void *default_smm = (void *)SMM_DEFAULT_BASE;
 
        if (smm_save_area == NULL)
                return;
 
        memcpy(default_smm, smm_save_area, SMM_DEFAULT_SIZE);
}