1 files changed, 54 insertions, 0 deletions
diff --git a/arch/x86/include/asm/bootparam_utils.h b/arch/x86/include/asm/bootparam_utils.h
new file mode 100644
index 000000000..4a8cb8d7c
--- /dev/null
+++ b/arch/x86/include/asm/bootparam_utils.h
@@ -0,0 +1,54 @@
+#ifndef _ASM_X86_BOOTPARAM_UTILS_H
+#define _ASM_X86_BOOTPARAM_UTILS_H
+
+#include <asm/bootparam.h>
+
+/*
+ * This file is included from multiple environments.  Do not
+ * add completing #includes to make it standalone.
+ */
+
+/*
+ * Deal with bootloaders which fail to initialize unknown fields in
+ * boot_params to zero.  The list fields in this list are taken from
+ * analysis of kexec-tools; if other broken bootloaders initialize a
+ * different set of fields we will need to figure out how to disambiguate.
+ *
+ * Note: efi_info is commonly left uninitialized, but that field has a
+ * private magic, so it is better to leave it unchanged.
+ */
+static void sanitize_boot_params(struct boot_params *boot_params)
+{
+	/* 
+	 * IMPORTANT NOTE TO BOOTLOADER AUTHORS: do not simply clear
+	 * this field.  The purpose of this field is to guarantee
+	 * compliance with the x86 boot spec located in
+	 * Documentation/x86/boot.txt .  That spec says that the
+	 * *whole* structure should be cleared, after which only the
+	 * portion defined by struct setup_header (boot_params->hdr)
+	 * should be copied in.
+	 *
+	 * If you're having an issue because the sentinel is set, you
+	 * need to change the whole structure to be cleared, not this
+	 * (or any other) individual field, or you will soon have
+	 * problems again.
+	 */
+	if (boot_params->sentinel) {
+		/* fields in boot_params are left uninitialized, clear them */
+		memset(&boot_params->ext_ramdisk_image, 0,
+		       (char *)&boot_params->efi_info -
+			(char *)&boot_params->ext_ramdisk_image);
+		memset(&boot_params->kbd_status, 0,
+		       (char *)&boot_params->hdr -
+		       (char *)&boot_params->kbd_status);
+		memset(&boot_params->_pad7[0], 0,
+		       (char *)&boot_params->edd_mbr_sig_buffer[0] -
+			(char *)&boot_params->_pad7[0]);
+		memset(&boot_params->_pad8[0], 0,
+		       (char *)&boot_params->eddbuf[0] -
+			(char *)&boot_params->_pad8[0]);
+		memset(&boot_params->_pad9[0], 0, sizeof(boot_params->_pad9));
+	}
+}
+
+#endif /* _ASM_X86_BOOTPARAM_UTILS_H */