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90 lines
2.8 KiB
90 lines
2.8 KiB
/* SPDX-License-Identifier: GPL-2.0 */ |
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#ifndef _ASM_X86_BOOTPARAM_UTILS_H |
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#define _ASM_X86_BOOTPARAM_UTILS_H |
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#include <asm/bootparam.h> |
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/* |
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* This file is included from multiple environments. Do not |
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* add completing #includes to make it standalone. |
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*/ |
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/* |
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* Deal with bootloaders which fail to initialize unknown fields in |
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* boot_params to zero. The list fields in this list are taken from |
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* analysis of kexec-tools; if other broken bootloaders initialize a |
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* different set of fields we will need to figure out how to disambiguate. |
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* |
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* Note: efi_info is commonly left uninitialized, but that field has a |
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* private magic, so it is better to leave it unchanged. |
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*/ |
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#define sizeof_mbr(type, member) ({ sizeof(((type *)0)->member); }) |
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#define BOOT_PARAM_PRESERVE(struct_member) \ |
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{ \ |
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.start = offsetof(struct boot_params, struct_member), \ |
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.len = sizeof_mbr(struct boot_params, struct_member), \ |
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} |
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struct boot_params_to_save { |
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unsigned int start; |
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unsigned int len; |
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}; |
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static void sanitize_boot_params(struct boot_params *boot_params) |
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{ |
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/* |
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* IMPORTANT NOTE TO BOOTLOADER AUTHORS: do not simply clear |
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* this field. The purpose of this field is to guarantee |
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* compliance with the x86 boot spec located in |
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* Documentation/x86/boot.rst . That spec says that the |
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* *whole* structure should be cleared, after which only the |
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* portion defined by struct setup_header (boot_params->hdr) |
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* should be copied in. |
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* |
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* If you're having an issue because the sentinel is set, you |
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* need to change the whole structure to be cleared, not this |
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* (or any other) individual field, or you will soon have |
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* problems again. |
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*/ |
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if (boot_params->sentinel) { |
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static struct boot_params scratch; |
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char *bp_base = (char *)boot_params; |
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char *save_base = (char *)&scratch; |
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int i; |
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const struct boot_params_to_save to_save[] = { |
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BOOT_PARAM_PRESERVE(screen_info), |
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BOOT_PARAM_PRESERVE(apm_bios_info), |
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BOOT_PARAM_PRESERVE(tboot_addr), |
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BOOT_PARAM_PRESERVE(ist_info), |
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BOOT_PARAM_PRESERVE(hd0_info), |
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BOOT_PARAM_PRESERVE(hd1_info), |
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BOOT_PARAM_PRESERVE(sys_desc_table), |
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BOOT_PARAM_PRESERVE(olpc_ofw_header), |
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BOOT_PARAM_PRESERVE(efi_info), |
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BOOT_PARAM_PRESERVE(alt_mem_k), |
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BOOT_PARAM_PRESERVE(scratch), |
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BOOT_PARAM_PRESERVE(e820_entries), |
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BOOT_PARAM_PRESERVE(eddbuf_entries), |
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BOOT_PARAM_PRESERVE(edd_mbr_sig_buf_entries), |
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BOOT_PARAM_PRESERVE(edd_mbr_sig_buffer), |
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BOOT_PARAM_PRESERVE(secure_boot), |
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BOOT_PARAM_PRESERVE(hdr), |
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BOOT_PARAM_PRESERVE(e820_table), |
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BOOT_PARAM_PRESERVE(eddbuf), |
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}; |
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memset(&scratch, 0, sizeof(scratch)); |
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for (i = 0; i < ARRAY_SIZE(to_save); i++) { |
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memcpy(save_base + to_save[i].start, |
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bp_base + to_save[i].start, to_save[i].len); |
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} |
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memcpy(boot_params, save_base, sizeof(*boot_params)); |
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} |
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} |
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#endif /* _ASM_X86_BOOTPARAM_UTILS_H */
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