1 files changed, 72 insertions, 0 deletions
diff --git a/arch/x86/purgatory/purgatory.c b/arch/x86/purgatory/purgatory.c
new file mode 100644
index 000000000000..25e068ba3382
--- /dev/null
+++ b/arch/x86/purgatory/purgatory.c
@@ -0,0 +1,72 @@
+/*
+ * purgatory: Runs between two kernels
+ *
+ * Copyright (C) 2014 Red Hat Inc.
+ *
+ * Author:
+ *       Vivek Goyal <vgoyal@redhat.com>
+ *
+ * This source code is licensed under the GNU General Public License,
+ * Version 2.  See the file COPYING for more details.
+ */
+
+#include "sha256.h"
+#include "../boot/string.h"
+
+struct sha_region {
+	unsigned long start;
+	unsigned long len;
+};
+
+unsigned long backup_dest = 0;
+unsigned long backup_src = 0;
+unsigned long backup_sz = 0;
+
+u8 sha256_digest[SHA256_DIGEST_SIZE] = { 0 };
+
+struct sha_region sha_regions[16] = {};
+
+/*
+ * 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 (backup_dest)
+		memcpy((void *)backup_dest, (void *)backup_src, backup_sz);
+
+	return 0;
+}
+
+int verify_sha256_digest(void)
+{
+	struct sha_region *ptr, *end;
+	u8 digest[SHA256_DIGEST_SIZE];
+	struct sha256_state sctx;
+
+	sha256_init(&sctx);
+	end = &sha_regions[sizeof(sha_regions)/sizeof(sha_regions[0])];
+	for (ptr = sha_regions; ptr < end; ptr++)
+		sha256_update(&sctx, (uint8_t *)(ptr->start), ptr->len);
+
+	sha256_final(&sctx, digest);
+
+	if (memcmp(digest, 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();
+}