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>

4 files changed, 228 insertions, 0 deletions

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index e2f89a7495d2..eaf84759482e 100644
--- a/arch/x86/Kconfig
+++ b/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
diff --git a/arch/x86/include/asm/efi.h b/arch/x86/include/asm/efi.h
index f29d1450edf4..a63154e049d7 100644
--- a/arch/x86/include/asm/efi.h
+++ b/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 */
diff --git a/arch/x86/platform/efi/Makefile b/arch/x86/platform/efi/Makefile
index ed5502a5185d..543df9a1379d 100644
--- a/arch/x86/platform/efi/Makefile
+++ b/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
diff --git a/arch/x86/platform/efi/runtime-map.c b/arch/x86/platform/efi/runtime-map.c
new file mode 100644
index 000000000000..bbee682ef8cd
--- /dev/null
+++ b/arch/x86/platform/efi/runtime-map.c
@@ -0,0 +1,194 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2013 Red Hat, Inc., Dave Young <dyoung@redhat.com>
+ */
+
+#include <linux/string.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/efi.h>
+#include <linux/slab.h>
+
+#include <asm/efi.h>
+#include <asm/setup.h>
+
+struct efi_runtime_map_entry {
+	efi_memory_desc_t md;
+	struct kobject kobj;   /* kobject for each entry */
+};
+
+static struct efi_runtime_map_entry **map_entries;
+
+struct map_attribute {
+	struct attribute attr;
+	ssize_t (*show)(struct efi_runtime_map_entry *entry, char *buf);
+};
+
+static inline struct map_attribute *to_map_attr(struct attribute *attr)
+{
+	return container_of(attr, struct map_attribute, attr);
+}
+
+static ssize_t type_show(struct efi_runtime_map_entry *entry, char *buf)
+{
+	return snprintf(buf, PAGE_SIZE, "0x%x\n", entry->md.type);
+}
+
+#define EFI_RUNTIME_FIELD(var) entry->md.var
+
+#define EFI_RUNTIME_U64_ATTR_SHOW(name) \
+static ssize_t name##_show(struct efi_runtime_map_entry *entry, char *buf) \
+{ \
+	return snprintf(buf, PAGE_SIZE, "0x%llx\n", EFI_RUNTIME_FIELD(name)); \
+}
+
+EFI_RUNTIME_U64_ATTR_SHOW(phys_addr);
+EFI_RUNTIME_U64_ATTR_SHOW(virt_addr);
+EFI_RUNTIME_U64_ATTR_SHOW(num_pages);
+EFI_RUNTIME_U64_ATTR_SHOW(attribute);
+
+static inline struct efi_runtime_map_entry *to_map_entry(struct kobject *kobj)
+{
+	return container_of(kobj, struct efi_runtime_map_entry, kobj);
+}
+
+static ssize_t map_attr_show(struct kobject *kobj, struct attribute *attr,
+			      char *buf)
+{
+	struct efi_runtime_map_entry *entry = to_map_entry(kobj);
+	struct map_attribute *map_attr = to_map_attr(attr);
+
+	return map_attr->show(entry, buf);
+}
+
+static struct map_attribute map_type_attr = __ATTR_RO_MODE(type, 0400);
+static struct map_attribute map_phys_addr_attr = __ATTR_RO_MODE(phys_addr, 0400);
+static struct map_attribute map_virt_addr_attr = __ATTR_RO_MODE(virt_addr, 0400);
+static struct map_attribute map_num_pages_attr = __ATTR_RO_MODE(num_pages, 0400);
+static struct map_attribute map_attribute_attr = __ATTR_RO_MODE(attribute, 0400);
+
+/*
+ * These are default attributes that are added for every memmap entry.
+ */
+static struct attribute *def_attrs[] = {
+	&map_type_attr.attr,
+	&map_phys_addr_attr.attr,
+	&map_virt_addr_attr.attr,
+	&map_num_pages_attr.attr,
+	&map_attribute_attr.attr,
+	NULL
+};
+ATTRIBUTE_GROUPS(def);
+
+static const struct sysfs_ops map_attr_ops = {
+	.show = map_attr_show,
+};
+
+static void map_release(struct kobject *kobj)
+{
+	struct efi_runtime_map_entry *entry;
+
+	entry = to_map_entry(kobj);
+	kfree(entry);
+}
+
+static struct kobj_type __refdata map_ktype = {
+	.sysfs_ops	= &map_attr_ops,
+	.default_groups	= def_groups,
+	.release	= map_release,
+};
+
+static struct kset *map_kset;
+
+static struct efi_runtime_map_entry *
+add_sysfs_runtime_map_entry(struct kobject *kobj, int nr,
+			    efi_memory_desc_t *md)
+{
+	int ret;
+	struct efi_runtime_map_entry *entry;
+
+	if (!map_kset) {
+		map_kset = kset_create_and_add("runtime-map", NULL, kobj);
+		if (!map_kset)
+			return ERR_PTR(-ENOMEM);
+	}
+
+	entry = kzalloc(sizeof(*entry), GFP_KERNEL);
+	if (!entry) {
+		kset_unregister(map_kset);
+		map_kset = NULL;
+		return ERR_PTR(-ENOMEM);
+	}
+
+	memcpy(&entry->md, md, sizeof(efi_memory_desc_t));
+
+	kobject_init(&entry->kobj, &map_ktype);
+	entry->kobj.kset = map_kset;
+	ret = kobject_add(&entry->kobj, NULL, "%d", nr);
+	if (ret) {
+		kobject_put(&entry->kobj);
+		kset_unregister(map_kset);
+		map_kset = NULL;
+		return ERR_PTR(ret);
+	}
+
+	return entry;
+}
+
+int efi_get_runtime_map_size(void)
+{
+	return efi.memmap.nr_map * efi.memmap.desc_size;
+}
+
+int efi_get_runtime_map_desc_size(void)
+{
+	return efi.memmap.desc_size;
+}
+
+int efi_runtime_map_copy(void *buf, size_t bufsz)
+{
+	size_t sz = efi_get_runtime_map_size();
+
+	if (sz > bufsz)
+		sz = bufsz;
+
+	memcpy(buf, efi.memmap.map, sz);
+	return 0;
+}
+
+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) || !efi_kobj)
+		return 0;
+
+	map_entries = kcalloc(efi.memmap.nr_map, sizeof(entry), GFP_KERNEL);
+	if (!map_entries) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	i = 0;
+	for_each_efi_memory_desc(md) {
+		entry = add_sysfs_runtime_map_entry(efi_kobj, i, md);
+		if (IS_ERR(entry)) {
+			ret = PTR_ERR(entry);
+			goto out_add_entry;
+		}
+		*(map_entries + i++) = entry;
+	}
+
+	return 0;
+out_add_entry:
+	for (j = i - 1; j >= 0; j--) {
+		entry = *(map_entries + j);
+		kobject_put(&entry->kobj);
+	}
+out:
+	return ret;
+}
+subsys_initcall_sync(efi_runtime_map_init);