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// SPDX-License-Identifier: GPL-2.0-only
/*
* purgatory: Runs between two kernels
*
* Copyright (C) 2014 Red Hat Inc.
*
* Author:
* Vivek Goyal <vgoyal@redhat.com>
*/
#include <linux/bug.h>
#include <linux/sha256.h>
#include <asm/purgatory.h>
#include "../boot/string.h"
unsigned long purgatory_backup_dest __section(.kexec-purgatory);
unsigned long purgatory_backup_src __section(.kexec-purgatory);
unsigned long purgatory_backup_sz __section(.kexec-purgatory);
u8 purgatory_sha256_digest[SHA256_DIGEST_SIZE] __section(.kexec-purgatory);
struct kexec_sha_region purgatory_sha_regions[KEXEC_SEGMENT_MAX] __section(.kexec-purgatory);
/*
* On x86, second kernel requries first 640K of memory to boot. Copy
* first 640K to a backup region in reserved memory range so that second
* kernel can use first 640K.
*/
static int copy_backup_region(void)
{
if (purgatory_backup_dest) {
memcpy((void *)purgatory_backup_dest,
(void *)purgatory_backup_src, purgatory_backup_sz);
}
return 0;
}
static int verify_sha256_digest(void)
{
struct kexec_sha_region *ptr, *end;
u8 digest[SHA256_DIGEST_SIZE];
struct sha256_state sctx;
sha256_init(&sctx);
end = purgatory_sha_regions + ARRAY_SIZE(purgatory_sha_regions);
for (ptr = purgatory_sha_regions; ptr < end; ptr++)
sha256_update(&sctx, (uint8_t *)(ptr->start), ptr->len);
sha256_final(&sctx, digest);
if (memcmp(digest, purgatory_sha256_digest, sizeof(digest)))
return 1;
return 0;
}
void purgatory(void)
{
int ret;
ret = verify_sha256_digest();
if (ret) {
/* loop forever */
for (;;)
;
}
copy_backup_region();
}
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