Commit 7c4146e8 authored by Michael Roth's avatar Michael Roth Committed by Borislav Petkov
Browse files

x86/compressed/acpi: Move EFI detection to helper 



Future patches for SEV-SNP-validated CPUID will also require early
parsing of the EFI configuration. Incrementally move the related code
into a set of helpers that can be re-used for that purpose.

First, carve out the functionality which determines the EFI environment
type the machine is booting on.

  [ bp: Massage commit message. ]

Signed-off-by: default avatarMichael Roth <michael.roth@amd.com>
Signed-off-by: default avatarBrijesh Singh <brijesh.singh@amd.com>
Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20220307213356.2797205-25-brijesh.singh@amd.com
parent 469693d8

arch/x86/boot/compressed/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -103,6 +103,7 @@ endif 
vmlinux-objs-$(CONFIG_ACPI) += $(obj)/acpi.o



vmlinux-objs-$(CONFIG_EFI_MIXED) += $(obj)/efi_thunk_$(BITS).o

vmlinux-objs-$(CONFIG_EFI) += $(obj)/efi.o

efi-obj-$(CONFIG_EFI_STUB) = $(objtree)/drivers/firmware/efi/libstub/lib.a



$(obj)/vmlinux: $(vmlinux-objs-y) $(efi-obj-y) FORCE

arch/x86/boot/compressed/acpi.c

+10 −18
Original line number Diff line number Diff line
@@ -87,7 +87,7 @@ static acpi_physical_address kexec_get_rsdp_addr(void) 
	efi_system_table_64_t *systab;

	struct efi_setup_data *esd;

	struct efi_info *ei;

	char *sig;

	enum efi_type et;



	esd = (struct efi_setup_data *)get_kexec_setup_data_addr();

	if (!esd)
@@ -98,10 +98,9 @@ static acpi_physical_address kexec_get_rsdp_addr(void) 
		return 0;

	}



	ei = &boot_params->efi_info;

	sig = (char *)&ei->efi_loader_signature;

	if (strncmp(sig, EFI64_LOADER_SIGNATURE, 4)) {

		debug_putstr("Wrong kexec EFI loader signature.\n");

	et = efi_get_type(boot_params);

	if (et != EFI_TYPE_64) {

		debug_putstr("Unexpected kexec EFI environment (expected 64-bit EFI).\n");

		return 0;

	}
@@ -122,29 +121,22 @@ static acpi_physical_address efi_get_rsdp_addr(void) 
	unsigned long systab, config_tables;

	unsigned int nr_tables;

	struct efi_info *ei;

	enum efi_type et;

	bool efi_64;

	char *sig;



	ei = &boot_params->efi_info;

	sig = (char *)&ei->efi_loader_signature;



	if (!strncmp(sig, EFI64_LOADER_SIGNATURE, 4)) {

	et = efi_get_type(boot_params);

	if (et == EFI_TYPE_64)

		efi_64 = true;

	} else if (!strncmp(sig, EFI32_LOADER_SIGNATURE, 4)) {

	else if (et == EFI_TYPE_32)

		efi_64 = false;

	} else {

		debug_putstr("Wrong EFI loader signature.\n");

	else

		return 0;

	}



	/* Get systab from boot params. */

	ei = &boot_params->efi_info;

#ifdef CONFIG_X86_64

	systab = ei->efi_systab | ((__u64)ei->efi_systab_hi << 32);

#else

	if (ei->efi_systab_hi || ei->efi_memmap_hi) {

		debug_putstr("Error getting RSDP address: EFI system table located above 4GB.\n");

		return 0;

	}

	systab = ei->efi_systab;

#endif

	if (!systab)

arch/x86/boot/compressed/efi.c

0 → 100644
+50 −0
Original line number Diff line number Diff line 
// 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;

}

arch/x86/boot/compressed/misc.h

+16 −0
Original line number Diff line number Diff line
@@ -176,4 +176,20 @@ void boot_stage2_vc(void); 


unsigned long sev_verify_cbit(unsigned long cr3);



enum efi_type {

	EFI_TYPE_64,

	EFI_TYPE_32,

	EFI_TYPE_NONE,

};



#ifdef CONFIG_EFI

/* helpers for early EFI config table access */

enum efi_type efi_get_type(struct boot_params *bp);

#else

static inline enum efi_type efi_get_type(struct boot_params *bp)

{

	return EFI_TYPE_NONE;

}

#endif /* CONFIG_EFI */



#endif /* BOOT_COMPRESSED_MISC_H */