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// SPDX-License-Identifier: GPL-2.0
/*
* Helpers for early access to EFI configuration table.
*
* Originally derived from arch/x86/boot/compressed/acpi.c
*/
#include "misc.h"
#include <linux/efi.h>
#include <asm/efi.h>
/**
* efi_get_type - Given a pointer to boot_params, determine the type of EFI environment.
*
* @bp: pointer to boot_params
*
* Return: EFI_TYPE_{32,64} for valid EFI environments, EFI_TYPE_NONE otherwise.
*/
enum efi_type efi_get_type(struct boot_params *bp)
{
struct efi_info *ei;
enum efi_type et;
const char *sig;
ei = &bp->efi_info;
sig = (char *)&ei->efi_loader_signature;
if (!strncmp(sig, EFI64_LOADER_SIGNATURE, 4)) {
et = EFI_TYPE_64;
} else if (!strncmp(sig, EFI32_LOADER_SIGNATURE, 4)) {
et = EFI_TYPE_32;
} else {
debug_putstr("No EFI environment detected.\n");
et = EFI_TYPE_NONE;
}
#ifndef CONFIG_X86_64
/*
* Existing callers like acpi.c treat this case as an indicator to
* fall-through to non-EFI, rather than an error, so maintain that
* functionality here as well.
*/
if (ei->efi_systab_hi || ei->efi_memmap_hi) {
debug_putstr("EFI system table is located above 4GB and cannot be accessed.\n");
et = EFI_TYPE_NONE;
}
#endif
return et;
}
/**
* efi_get_system_table - Given a pointer to boot_params, retrieve the physical address
* of the EFI system table.
*
* @bp: pointer to boot_params
*
* Return: EFI system table address on success. On error, return 0.
*/
unsigned long efi_get_system_table(struct boot_params *bp)
{
unsigned long sys_tbl_pa;
struct efi_info *ei;
enum efi_type et;
/* Get systab from boot params. */
ei = &bp->efi_info;
#ifdef CONFIG_X86_64
sys_tbl_pa = ei->efi_systab | ((__u64)ei->efi_systab_hi << 32);
#else
sys_tbl_pa = ei->efi_systab;
#endif
if (!sys_tbl_pa) {
debug_putstr("EFI system table not found.");
return 0;
}
return sys_tbl_pa;
}
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