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x86/compressed/acpi: Move EFI detection to helper

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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: Michael Roth <michael.roth@amd.com>
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20220307213356.2797205-25-brijesh.singh@amd.com
This commit is contained in:
Michael Roth 2022-02-09 12:10:18 -06:00 committed by Borislav Petkov
parent 469693d8f6
commit 7c4146e888
4 changed files with 77 additions and 18 deletions
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1
arch/x86/boot/compressed/Makefile
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@ -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

28
arch/x86/boot/compressed/acpi.c
View File

@ -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)

50
arch/x86/boot/compressed/efi.c Normal file
View File

@ -0,0 +1,50 @@
// 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;
}

16
arch/x86/boot/compressed/misc.h
View File

@ -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 */