efi: x86: Move EFI runtime map sysfs code to arch/x86

The EFI runtime map code is only wired up on x86, which is the only
architecture that has a need for it in its implementation of kexec.

So let's move this code under arch/x86 and drop all references to it
from generic code. To ensure that the efi_runtime_map_init() is invoked
at the appropriate time use a 'sync' subsys_initcall() that will be
called right after the EFI initcall made from generic code where the
original invocation of efi_runtime_map_init() resided.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Dave Young <dyoung@redhat.com>

arch/x86/Kconfig

@@ -2014,6 +2014,17 @@ config EFI_MAX_FAKE_MEM
 	  Ranges can be set up to this value using comma-separated list.
 	  The default value is 8.
 
+config EFI_RUNTIME_MAP
+	bool "Export EFI runtime maps to sysfs" if EXPERT
+	depends on EFI
+	default KEXEC_CORE
+	help
+	  Export EFI runtime memory regions to /sys/firmware/efi/runtime-map.
+	  That memory map is required by the 2nd kernel to set up EFI virtual
+	  mappings after kexec, but can also be used for debugging purposes.
+
+	  See also Documentation/ABI/testing/sysfs-firmware-efi-runtime-map.
+
 source "kernel/Kconfig.hz"
 
 config KEXEC

arch/x86/include/asm/efi.h

@@ -432,4 +432,26 @@ extern void __init efi_memmap_insert(struct efi_memory_map *old_memmap,
 #define arch_ima_efi_boot_mode	\
 	({ extern struct boot_params boot_params; boot_params.secure_boot; })
 
+#ifdef CONFIG_EFI_RUNTIME_MAP
+int efi_get_runtime_map_size(void);
+int efi_get_runtime_map_desc_size(void);
+int efi_runtime_map_copy(void *buf, size_t bufsz);
+#else
+static inline int efi_get_runtime_map_size(void)
+{
+	return 0;
+}
+
+static inline int efi_get_runtime_map_desc_size(void)
+{
+	return 0;
+}
+
+static inline int efi_runtime_map_copy(void *buf, size_t bufsz)
+{
+	return 0;
+}
+
+#endif
+
 #endif /* _ASM_X86_EFI_H */

arch/x86/platform/efi/Makefile

@@ -6,3 +6,4 @@ obj-$(CONFIG_EFI) 		+= memmap.o quirks.o efi.o efi_$(BITS).o \
 				   efi_stub_$(BITS).o
 obj-$(CONFIG_EFI_MIXED)		+= efi_thunk_$(BITS).o
 obj-$(CONFIG_EFI_FAKE_MEMMAP)	+= fake_mem.o
+obj-$(CONFIG_EFI_RUNTIME_MAP)	+= runtime-map.o

arch/x86/platform/efi/runtime-map.c

@@ -1,6 +1,5 @@
 // SPDX-License-Identifier: GPL-2.0
 /*
- * linux/drivers/efi/runtime-map.c
  * Copyright (C) 2013 Red Hat, Inc., Dave Young <dyoung@redhat.com>
  */
 
@@ -11,6 +10,7 @@
 #include <linux/efi.h>
 #include <linux/slab.h>
 
+#include <asm/efi.h>
 #include <asm/setup.h>
 
 struct efi_runtime_map_entry {
@@ -157,13 +157,13 @@ int efi_runtime_map_copy(void *buf, size_t bufsz)
 	return 0;
 }
 
-int __init efi_runtime_map_init(struct kobject *efi_kobj)
+static int __init efi_runtime_map_init(void)
 {
 	int i, j, ret = 0;
 	struct efi_runtime_map_entry *entry;
 	efi_memory_desc_t *md;
 
-	if (!efi_enabled(EFI_MEMMAP))
+	if (!efi_enabled(EFI_MEMMAP) || !efi_kobj)
 		return 0;
 
 	map_entries = kcalloc(efi.memmap.nr_map, sizeof(entry), GFP_KERNEL);
@@ -191,3 +191,4 @@ int __init efi_runtime_map_init(struct kobject *efi_kobj)
 out:
 	return ret;
 }
+subsys_initcall_sync(efi_runtime_map_init);

drivers/firmware/efi/Kconfig

@@ -26,17 +26,6 @@ config EFI_VARS_PSTORE_DEFAULT_DISABLE
 	  backend for pstore by default. This setting can be overridden
 	  using the efivars module's pstore_disable parameter.
 
-config EFI_RUNTIME_MAP
-	bool "Export EFI runtime maps to sysfs" if EXPERT
-	depends on X86 && EFI
-	default KEXEC_CORE
-	help
-	  Export EFI runtime memory regions to /sys/firmware/efi/runtime-map.
-	  That memory map is required by the 2nd kernel to set up EFI virtual
-	  mappings after kexec, but can also be used for debugging purposes.
-
-	  See also Documentation/ABI/testing/sysfs-firmware-efi-runtime-map.
-
 config EFI_SOFT_RESERVE
 	bool "Reserve EFI Specific Purpose Memory"
 	depends on EFI && EFI_STUB && ACPI_HMAT

drivers/firmware/efi/Makefile

@@ -20,7 +20,6 @@ obj-$(CONFIG_EFI_PARAMS_FROM_FDT)	+= fdtparams.o
 obj-$(CONFIG_EFI_ESRT)			+= esrt.o
 obj-$(CONFIG_EFI_VARS_PSTORE)		+= efi-pstore.o
 obj-$(CONFIG_UEFI_CPER)			+= cper.o
-obj-$(CONFIG_EFI_RUNTIME_MAP)		+= runtime-map.o
 obj-$(CONFIG_EFI_RUNTIME_WRAPPERS)	+= runtime-wrappers.o
 subdir-$(CONFIG_EFI_STUB)		+= libstub
 obj-$(CONFIG_EFI_BOOTLOADER_CONTROL)	+= efibc.o

drivers/firmware/efi/efi.c

@@ -396,10 +396,6 @@ static int __init efisubsys_init(void)
 		goto err_unregister;
 	}
 
-	error = efi_runtime_map_init(efi_kobj);
-	if (error)
-		goto err_remove_group;
-
 	/* and the standard mountpoint for efivarfs */
 	error = sysfs_create_mount_point(efi_kobj, "efivars");
 	if (error) {
@@ -425,6 +421,7 @@ static int __init efisubsys_init(void)
 		generic_ops_unregister();
 err_put:
 	kobject_put(efi_kobj);
+	efi_kobj = NULL;
 	destroy_workqueue(efi_rts_wq);
 	return error;
 }

include/linux/efi.h

@@ -1089,34 +1089,6 @@ extern int efi_capsule_update(efi_capsule_header_t *capsule,
 static inline bool efi_capsule_pending(int *reset_type) { return false; }
 #endif
 
-#ifdef CONFIG_EFI_RUNTIME_MAP
-int efi_runtime_map_init(struct kobject *);
-int efi_get_runtime_map_size(void);
-int efi_get_runtime_map_desc_size(void);
-int efi_runtime_map_copy(void *buf, size_t bufsz);
-#else
-static inline int efi_runtime_map_init(struct kobject *kobj)
-{
-	return 0;
-}
-
-static inline int efi_get_runtime_map_size(void)
-{
-	return 0;
-}
-
-static inline int efi_get_runtime_map_desc_size(void)
-{
-	return 0;
-}
-
-static inline int efi_runtime_map_copy(void *buf, size_t bufsz)
-{
-	return 0;
-}
-
-#endif
-
 #ifdef CONFIG_EFI
 extern bool efi_runtime_disabled(void);
 #else