/* SPDX-License-Identifier: GPL-2.0 */#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. */ #define sizeof_mbr(type, member) ({ sizeof(((type *)0)->member); }) #define BOOT_PARAM_PRESERVE(struct_member)				\	{								\		.start = offsetof(struct boot_params, struct_member),	\		.len   = sizeof_mbr(struct boot_params, struct_member),	\	} struct boot_params_to_save {	unsigned int start;	unsigned int len;}; 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/arch/x86/boot.rst .  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) {		static struct boot_params scratch;		char *bp_base = (char *)boot_params;		char *save_base = (char *)&scratch;		int i; 		const struct boot_params_to_save to_save[] = {			BOOT_PARAM_PRESERVE(screen_info),			BOOT_PARAM_PRESERVE(apm_bios_info),			BOOT_PARAM_PRESERVE(tboot_addr),			BOOT_PARAM_PRESERVE(ist_info),			BOOT_PARAM_PRESERVE(hd0_info),			BOOT_PARAM_PRESERVE(hd1_info),			BOOT_PARAM_PRESERVE(sys_desc_table),			BOOT_PARAM_PRESERVE(olpc_ofw_header),			BOOT_PARAM_PRESERVE(efi_info),			BOOT_PARAM_PRESERVE(alt_mem_k),			BOOT_PARAM_PRESERVE(scratch),			BOOT_PARAM_PRESERVE(e820_entries),			BOOT_PARAM_PRESERVE(eddbuf_entries),			BOOT_PARAM_PRESERVE(edd_mbr_sig_buf_entries),			BOOT_PARAM_PRESERVE(edd_mbr_sig_buffer),			BOOT_PARAM_PRESERVE(secure_boot),			BOOT_PARAM_PRESERVE(hdr),			BOOT_PARAM_PRESERVE(e820_table),			BOOT_PARAM_PRESERVE(eddbuf),			BOOT_PARAM_PRESERVE(cc_blob_address),		}; 		memset(&scratch, 0, sizeof(scratch)); 		for (i = 0; i < ARRAY_SIZE(to_save); i++) {			memcpy(save_base + to_save[i].start,			       bp_base + to_save[i].start, to_save[i].len);		} 		memcpy(boot_params, save_base, sizeof(*boot_params));	}} #endif /* _ASM_X86_BOOTPARAM_UTILS_H */