name : bootparam_utils.h /* 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 */