15 files changed, 5534 insertions, 0 deletions

diff --git a/kernel/module/Makefile b/kernel/module/Makefile
new file mode 100644
index 000000000000..948efea81e85
--- /dev/null
+++ b/kernel/module/Makefile
@@ -0,0 +1,21 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Makefile for linux kernel module support
+#
+
+# These are called from save_stack_trace() on slub debug path,
+# and produce insane amounts of uninteresting coverage.
+KCOV_INSTRUMENT_module.o := n
+
+obj-y += main.o strict_rwx.o
+obj-$(CONFIG_MODULE_DECOMPRESS) += decompress.o
+obj-$(CONFIG_MODULE_SIG) += signing.o
+obj-$(CONFIG_LIVEPATCH) += livepatch.o
+obj-$(CONFIG_MODULES_TREE_LOOKUP) += tree_lookup.o
+obj-$(CONFIG_DEBUG_KMEMLEAK) += debug_kmemleak.o
+obj-$(CONFIG_KALLSYMS) += kallsyms.o
+obj-$(CONFIG_PROC_FS) += procfs.o
+obj-$(CONFIG_SYSFS) += sysfs.o
+obj-$(CONFIG_KGDB_KDB) += kdb.o
+obj-$(CONFIG_MODVERSIONS) += version.o
+obj-$(CONFIG_MODULE_UNLOAD_TAINT_TRACKING) += tracking.o
diff --git a/kernel/module/debug_kmemleak.c b/kernel/module/debug_kmemleak.c
new file mode 100644
index 000000000000..12a569d361e8
--- /dev/null
+++ b/kernel/module/debug_kmemleak.c
@@ -0,0 +1,30 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Module kmemleak support
+ *
+ * Copyright (C) 2009 Catalin Marinas
+ */
+
+#include <linux/module.h>
+#include <linux/kmemleak.h>
+#include "internal.h"
+
+void kmemleak_load_module(const struct module *mod,
+			  const struct load_info *info)
+{
+	unsigned int i;
+
+	/* only scan the sections containing data */
+	kmemleak_scan_area(mod, sizeof(struct module), GFP_KERNEL);
+
+	for (i = 1; i < info->hdr->e_shnum; i++) {
+		/* Scan all writable sections that's not executable */
+		if (!(info->sechdrs[i].sh_flags & SHF_ALLOC) ||
+		    !(info->sechdrs[i].sh_flags & SHF_WRITE) ||
+		    (info->sechdrs[i].sh_flags & SHF_EXECINSTR))
+			continue;
+
+		kmemleak_scan_area((void *)info->sechdrs[i].sh_addr,
+				   info->sechdrs[i].sh_size, GFP_KERNEL);
+	}
+}
diff --git a/kernel/module/decompress.c b/kernel/module/decompress.c
new file mode 100644
index 000000000000..2fc7081dd7c1
--- /dev/null
+++ b/kernel/module/decompress.c
@@ -0,0 +1,276 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright 2021 Google LLC.
+ */
+
+#include <linux/init.h>
+#include <linux/highmem.h>
+#include <linux/kobject.h>
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/sysfs.h>
+#include <linux/vmalloc.h>
+
+#include "internal.h"
+
+static int module_extend_max_pages(struct load_info *info, unsigned int extent)
+{
+	struct page **new_pages;
+
+	new_pages = kvmalloc_array(info->max_pages + extent,
+				   sizeof(info->pages), GFP_KERNEL);
+	if (!new_pages)
+		return -ENOMEM;
+
+	memcpy(new_pages, info->pages, info->max_pages * sizeof(info->pages));
+	kvfree(info->pages);
+	info->pages = new_pages;
+	info->max_pages += extent;
+
+	return 0;
+}
+
+static struct page *module_get_next_page(struct load_info *info)
+{
+	struct page *page;
+	int error;
+
+	if (info->max_pages == info->used_pages) {
+		error = module_extend_max_pages(info, info->used_pages);
+		if (error)
+			return ERR_PTR(error);
+	}
+
+	page = alloc_page(GFP_KERNEL | __GFP_HIGHMEM);
+	if (!page)
+		return ERR_PTR(-ENOMEM);
+
+	info->pages[info->used_pages++] = page;
+	return page;
+}
+
+#ifdef CONFIG_MODULE_COMPRESS_GZIP
+#include <linux/zlib.h>
+#define MODULE_COMPRESSION	gzip
+#define MODULE_DECOMPRESS_FN	module_gzip_decompress
+
+/*
+ * Calculate length of the header which consists of signature, header
+ * flags, time stamp and operating system ID (10 bytes total), plus
+ * an optional filename.
+ */
+static size_t module_gzip_header_len(const u8 *buf, size_t size)
+{
+	const u8 signature[] = { 0x1f, 0x8b, 0x08 };
+	size_t len = 10;
+
+	if (size < len || memcmp(buf, signature, sizeof(signature)))
+		return 0;
+
+	if (buf[3] & 0x08) {
+		do {
+			/*
+			 * If we can't find the end of the file name we must
+			 * be dealing with a corrupted file.
+			 */
+			if (len == size)
+				return 0;
+		} while (buf[len++] != '\0');
+	}
+
+	return len;
+}
+
+static ssize_t module_gzip_decompress(struct load_info *info,
+				      const void *buf, size_t size)
+{
+	struct z_stream_s s = { 0 };
+	size_t new_size = 0;
+	size_t gzip_hdr_len;
+	ssize_t retval;
+	int rc;
+
+	gzip_hdr_len = module_gzip_header_len(buf, size);
+	if (!gzip_hdr_len) {
+		pr_err("not a gzip compressed module\n");
+		return -EINVAL;
+	}
+
+	s.next_in = buf + gzip_hdr_len;
+	s.avail_in = size - gzip_hdr_len;
+
+	s.workspace = kmalloc(zlib_inflate_workspacesize(), GFP_KERNEL);
+	if (!s.workspace)
+		return -ENOMEM;
+
+	rc = zlib_inflateInit2(&s, -MAX_WBITS);
+	if (rc != Z_OK) {
+		pr_err("failed to initialize decompressor: %d\n", rc);
+		retval = -EINVAL;
+		goto out;
+	}
+
+	do {
+		struct page *page = module_get_next_page(info);
+
+		if (!page) {
+			retval = -ENOMEM;
+			goto out_inflate_end;
+		}
+
+		s.next_out = kmap(page);
+		s.avail_out = PAGE_SIZE;
+		rc = zlib_inflate(&s, 0);
+		kunmap(page);
+
+		new_size += PAGE_SIZE - s.avail_out;
+	} while (rc == Z_OK);
+
+	if (rc != Z_STREAM_END) {
+		pr_err("decompression failed with status %d\n", rc);
+		retval = -EINVAL;
+		goto out_inflate_end;
+	}
+
+	retval = new_size;
+
+out_inflate_end:
+	zlib_inflateEnd(&s);
+out:
+	kfree(s.workspace);
+	return retval;
+}
+#elif CONFIG_MODULE_COMPRESS_XZ
+#include <linux/xz.h>
+#define MODULE_COMPRESSION	xz
+#define MODULE_DECOMPRESS_FN	module_xz_decompress
+
+static ssize_t module_xz_decompress(struct load_info *info,
+				    const void *buf, size_t size)
+{
+	static const u8 signature[] = { 0xfd, '7', 'z', 'X', 'Z', 0 };
+	struct xz_dec *xz_dec;
+	struct xz_buf xz_buf;
+	enum xz_ret xz_ret;
+	size_t new_size = 0;
+	ssize_t retval;
+
+	if (size < sizeof(signature) ||
+	    memcmp(buf, signature, sizeof(signature))) {
+		pr_err("not an xz compressed module\n");
+		return -EINVAL;
+	}
+
+	xz_dec = xz_dec_init(XZ_DYNALLOC, (u32)-1);
+	if (!xz_dec)
+		return -ENOMEM;
+
+	xz_buf.in_size = size;
+	xz_buf.in = buf;
+	xz_buf.in_pos = 0;
+
+	do {
+		struct page *page = module_get_next_page(info);
+
+		if (!page) {
+			retval = -ENOMEM;
+			goto out;
+		}
+
+		xz_buf.out = kmap(page);
+		xz_buf.out_pos = 0;
+		xz_buf.out_size = PAGE_SIZE;
+		xz_ret = xz_dec_run(xz_dec, &xz_buf);
+		kunmap(page);
+
+		new_size += xz_buf.out_pos;
+	} while (xz_buf.out_pos == PAGE_SIZE && xz_ret == XZ_OK);
+
+	if (xz_ret != XZ_STREAM_END) {
+		pr_err("decompression failed with status %d\n", xz_ret);
+		retval = -EINVAL;
+		goto out;
+	}
+
+	retval = new_size;
+
+ out:
+	xz_dec_end(xz_dec);
+	return retval;
+}
+#else
+#error "Unexpected configuration for CONFIG_MODULE_DECOMPRESS"
+#endif
+
+int module_decompress(struct load_info *info, const void *buf, size_t size)
+{
+	unsigned int n_pages;
+	ssize_t data_size;
+	int error;
+
+	/*
+	 * Start with number of pages twice as big as needed for
+	 * compressed data.
+	 */
+	n_pages = DIV_ROUND_UP(size, PAGE_SIZE) * 2;
+	error = module_extend_max_pages(info, n_pages);
+
+	data_size = MODULE_DECOMPRESS_FN(info, buf, size);
+	if (data_size < 0) {
+		error = data_size;
+		goto err;
+	}
+
+	info->hdr = vmap(info->pages, info->used_pages, VM_MAP, PAGE_KERNEL);
+	if (!info->hdr) {
+		error = -ENOMEM;
+		goto err;
+	}
+
+	info->len = data_size;
+	return 0;
+
+err:
+	module_decompress_cleanup(info);
+	return error;
+}
+
+void module_decompress_cleanup(struct load_info *info)
+{
+	int i;
+
+	if (info->hdr)
+		vunmap(info->hdr);
+
+	for (i = 0; i < info->used_pages; i++)
+		__free_page(info->pages[i]);
+
+	kvfree(info->pages);
+
+	info->pages = NULL;
+	info->max_pages = info->used_pages = 0;
+}
+
+#ifdef CONFIG_SYSFS
+static ssize_t compression_show(struct kobject *kobj,
+				struct kobj_attribute *attr, char *buf)
+{
+	return sysfs_emit(buf, "%s\n", __stringify(MODULE_COMPRESSION));
+}
+
+static struct kobj_attribute module_compression_attr = __ATTR_RO(compression);
+
+static int __init module_decompress_sysfs_init(void)
+{
+	int error;
+
+	error = sysfs_create_file(&module_kset->kobj,
+				  &module_compression_attr.attr);
+	if (error)
+		pr_warn("Failed to create 'compression' attribute");
+
+	return 0;
+}
+late_initcall(module_decompress_sysfs_init);
+#endif
diff --git a/kernel/module/internal.h b/kernel/module/internal.h
new file mode 100644
index 000000000000..bc5507ab8450
--- /dev/null
+++ b/kernel/module/internal.h
@@ -0,0 +1,302 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/* Module internals
+ *
+ * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ */
+
+#include <linux/elf.h>
+#include <linux/compiler.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/rculist.h>
+#include <linux/rcupdate.h>
+
+#ifndef ARCH_SHF_SMALL
+#define ARCH_SHF_SMALL 0
+#endif
+
+/* If this is set, the section belongs in the init part of the module */
+#define INIT_OFFSET_MASK (1UL << (BITS_PER_LONG - 1))
+/* Maximum number of characters written by module_flags() */
+#define MODULE_FLAGS_BUF_SIZE (TAINT_FLAGS_COUNT + 4)
+
+#ifndef CONFIG_ARCH_WANTS_MODULES_DATA_IN_VMALLOC
+#define	data_layout core_layout
+#endif
+
+/*
+ * Modules' sections will be aligned on page boundaries
+ * to ensure complete separation of code and data, but
+ * only when CONFIG_STRICT_MODULE_RWX=y
+ */
+#ifdef CONFIG_STRICT_MODULE_RWX
+# define strict_align(X) PAGE_ALIGN(X)
+#else
+# define strict_align(X) (X)
+#endif
+
+extern struct mutex module_mutex;
+extern struct list_head modules;
+
+extern struct module_attribute *modinfo_attrs[];
+extern size_t modinfo_attrs_count;
+
+/* Provided by the linker */
+extern const struct kernel_symbol __start___ksymtab[];
+extern const struct kernel_symbol __stop___ksymtab[];
+extern const struct kernel_symbol __start___ksymtab_gpl[];
+extern const struct kernel_symbol __stop___ksymtab_gpl[];
+extern const s32 __start___kcrctab[];
+extern const s32 __start___kcrctab_gpl[];
+
+struct load_info {
+	const char *name;
+	/* pointer to module in temporary copy, freed at end of load_module() */
+	struct module *mod;
+	Elf_Ehdr *hdr;
+	unsigned long len;
+	Elf_Shdr *sechdrs;
+	char *secstrings, *strtab;
+	unsigned long symoffs, stroffs, init_typeoffs, core_typeoffs;
+	struct _ddebug *debug;
+	unsigned int num_debug;
+	bool sig_ok;
+#ifdef CONFIG_KALLSYMS
+	unsigned long mod_kallsyms_init_off;
+#endif
+#ifdef CONFIG_MODULE_DECOMPRESS
+	struct page **pages;
+	unsigned int max_pages;
+	unsigned int used_pages;
+#endif
+	struct {
+		unsigned int sym, str, mod, vers, info, pcpu;
+	} index;
+};
+
+enum mod_license {
+	NOT_GPL_ONLY,
+	GPL_ONLY,
+};
+
+struct find_symbol_arg {
+	/* Input */
+	const char *name;
+	bool gplok;
+	bool warn;
+
+	/* Output */
+	struct module *owner;
+	const s32 *crc;
+	const struct kernel_symbol *sym;
+	enum mod_license license;
+};
+
+int mod_verify_sig(const void *mod, struct load_info *info);
+int try_to_force_load(struct module *mod, const char *reason);
+bool find_symbol(struct find_symbol_arg *fsa);
+struct module *find_module_all(const char *name, size_t len, bool even_unformed);
+int cmp_name(const void *name, const void *sym);
+long module_get_offset(struct module *mod, unsigned int *size, Elf_Shdr *sechdr,
+		       unsigned int section);
+char *module_flags(struct module *mod, char *buf);
+size_t module_flags_taint(unsigned long taints, char *buf);
+
+static inline void module_assert_mutex_or_preempt(void)
+{
+#ifdef CONFIG_LOCKDEP
+	if (unlikely(!debug_locks))
+		return;
+
+	WARN_ON_ONCE(!rcu_read_lock_sched_held() &&
+		     !lockdep_is_held(&module_mutex));
+#endif
+}
+
+static inline unsigned long kernel_symbol_value(const struct kernel_symbol *sym)
+{
+#ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
+	return (unsigned long)offset_to_ptr(&sym->value_offset);
+#else
+	return sym->value;
+#endif
+}
+
+#ifdef CONFIG_LIVEPATCH
+int copy_module_elf(struct module *mod, struct load_info *info);
+void free_module_elf(struct module *mod);
+#else /* !CONFIG_LIVEPATCH */
+static inline int copy_module_elf(struct module *mod, struct load_info *info)
+{
+	return 0;
+}
+
+static inline void free_module_elf(struct module *mod) { }
+#endif /* CONFIG_LIVEPATCH */
+
+static inline bool set_livepatch_module(struct module *mod)
+{
+#ifdef CONFIG_LIVEPATCH
+	mod->klp = true;
+	return true;
+#else
+	return false;
+#endif
+}
+
+#ifdef CONFIG_MODULE_UNLOAD_TAINT_TRACKING
+struct mod_unload_taint {
+	struct list_head list;
+	char name[MODULE_NAME_LEN];
+	unsigned long taints;
+	u64 count;
+};
+
+int try_add_tainted_module(struct module *mod);
+void print_unloaded_tainted_modules(void);
+#else /* !CONFIG_MODULE_UNLOAD_TAINT_TRACKING */
+static inline int try_add_tainted_module(struct module *mod)
+{
+	return 0;
+}
+
+static inline void print_unloaded_tainted_modules(void)
+{
+}
+#endif /* CONFIG_MODULE_UNLOAD_TAINT_TRACKING */
+
+#ifdef CONFIG_MODULE_DECOMPRESS
+int module_decompress(struct load_info *info, const void *buf, size_t size);
+void module_decompress_cleanup(struct load_info *info);
+#else
+static inline int module_decompress(struct load_info *info,
+				    const void *buf, size_t size)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline void module_decompress_cleanup(struct load_info *info)
+{
+}
+#endif
+
+struct mod_tree_root {
+#ifdef CONFIG_MODULES_TREE_LOOKUP
+	struct latch_tree_root root;
+#endif
+	unsigned long addr_min;
+	unsigned long addr_max;
+};
+
+extern struct mod_tree_root mod_tree;
+extern struct mod_tree_root mod_data_tree;
+
+#ifdef CONFIG_MODULES_TREE_LOOKUP
+void mod_tree_insert(struct module *mod);
+void mod_tree_remove_init(struct module *mod);
+void mod_tree_remove(struct module *mod);
+struct module *mod_find(unsigned long addr, struct mod_tree_root *tree);
+#else /* !CONFIG_MODULES_TREE_LOOKUP */
+
+static inline void mod_tree_insert(struct module *mod) { }
+static inline void mod_tree_remove_init(struct module *mod) { }
+static inline void mod_tree_remove(struct module *mod) { }
+static inline struct module *mod_find(unsigned long addr, struct mod_tree_root *tree)
+{
+	struct module *mod;
+
+	list_for_each_entry_rcu(mod, &modules, list,
+				lockdep_is_held(&module_mutex)) {
+		if (within_module(addr, mod))
+			return mod;
+	}
+
+	return NULL;
+}
+#endif /* CONFIG_MODULES_TREE_LOOKUP */
+
+void module_enable_ro(const struct module *mod, bool after_init);
+void module_enable_nx(const struct module *mod);
+void module_enable_x(const struct module *mod);
+int module_enforce_rwx_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs,
+				char *secstrings, struct module *mod);
+bool module_check_misalignment(const struct module *mod);
+
+#ifdef CONFIG_MODULE_SIG
+int module_sig_check(struct load_info *info, int flags);
+#else /* !CONFIG_MODULE_SIG */
+static inline int module_sig_check(struct load_info *info, int flags)
+{
+	return 0;
+}
+#endif /* !CONFIG_MODULE_SIG */
+
+#ifdef CONFIG_DEBUG_KMEMLEAK
+void kmemleak_load_module(const struct module *mod, const struct load_info *info);
+#else /* !CONFIG_DEBUG_KMEMLEAK */
+static inline void kmemleak_load_module(const struct module *mod,
+					const struct load_info *info) { }
+#endif /* CONFIG_DEBUG_KMEMLEAK */
+
+#ifdef CONFIG_KALLSYMS
+void init_build_id(struct module *mod, const struct load_info *info);
+void layout_symtab(struct module *mod, struct load_info *info);
+void add_kallsyms(struct module *mod, const struct load_info *info);
+unsigned long find_kallsyms_symbol_value(struct module *mod, const char *name);
+
+static inline bool sect_empty(const Elf_Shdr *sect)
+{
+	return !(sect->sh_flags & SHF_ALLOC) || sect->sh_size == 0;
+}
+#else /* !CONFIG_KALLSYMS */
+static inline void init_build_id(struct module *mod, const struct load_info *info) { }
+static inline void layout_symtab(struct module *mod, struct load_info *info) { }
+static inline void add_kallsyms(struct module *mod, const struct load_info *info) { }
+#endif /* CONFIG_KALLSYMS */
+
+#ifdef CONFIG_SYSFS
+int mod_sysfs_setup(struct module *mod, const struct load_info *info,
+		    struct kernel_param *kparam, unsigned int num_params);
+void mod_sysfs_teardown(struct module *mod);
+void init_param_lock(struct module *mod);
+#else /* !CONFIG_SYSFS */
+static inline int mod_sysfs_setup(struct module *mod,
+			   	  const struct load_info *info,
+			   	  struct kernel_param *kparam,
+			   	  unsigned int num_params)
+{
+	return 0;
+}
+
+static inline void mod_sysfs_teardown(struct module *mod) { }
+static inline void init_param_lock(struct module *mod) { }
+#endif /* CONFIG_SYSFS */
+
+#ifdef CONFIG_MODVERSIONS
+int check_version(const struct load_info *info,
+		  const char *symname, struct module *mod, const s32 *crc);
+void module_layout(struct module *mod, struct modversion_info *ver, struct kernel_param *kp,
+		   struct kernel_symbol *ks, struct tracepoint * const *tp);
+int check_modstruct_version(const struct load_info *info, struct module *mod);
+int same_magic(const char *amagic, const char *bmagic, bool has_crcs);
+#else /* !CONFIG_MODVERSIONS */
+static inline int check_version(const struct load_info *info,
+				const char *symname,
+				struct module *mod,
+				const s32 *crc)
+{
+	return 1;
+}
+
+static inline int check_modstruct_version(const struct load_info *info,
+					  struct module *mod)
+{
+	return 1;
+}
+
+static inline int same_magic(const char *amagic, const char *bmagic, bool has_crcs)
+{
+	return strcmp(amagic, bmagic) == 0;
+}
+#endif /* CONFIG_MODVERSIONS */
diff --git a/kernel/module/kallsyms.c b/kernel/module/kallsyms.c
new file mode 100644
index 000000000000..3e11523bc6f6
--- /dev/null
+++ b/kernel/module/kallsyms.c
@@ -0,0 +1,512 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Module kallsyms support
+ *
+ * Copyright (C) 2010 Rusty Russell
+ */
+
+#include <linux/module.h>
+#include <linux/kallsyms.h>
+#include <linux/buildid.h>
+#include <linux/bsearch.h>
+#include "internal.h"
+
+/* Lookup exported symbol in given range of kernel_symbols */
+static const struct kernel_symbol *lookup_exported_symbol(const char *name,
+							  const struct kernel_symbol *start,
+							  const struct kernel_symbol *stop)
+{
+	return bsearch(name, start, stop - start,
+			sizeof(struct kernel_symbol), cmp_name);
+}
+
+static int is_exported(const char *name, unsigned long value,
+		       const struct module *mod)
+{
+	const struct kernel_symbol *ks;
+
+	if (!mod)
+		ks = lookup_exported_symbol(name, __start___ksymtab, __stop___ksymtab);
+	else
+		ks = lookup_exported_symbol(name, mod->syms, mod->syms + mod->num_syms);
+
+	return ks && kernel_symbol_value(ks) == value;
+}
+
+/* As per nm */
+static char elf_type(const Elf_Sym *sym, const struct load_info *info)
+{
+	const Elf_Shdr *sechdrs = info->sechdrs;
+
+	if (ELF_ST_BIND(sym->st_info) == STB_WEAK) {
+		if (ELF_ST_TYPE(sym->st_info) == STT_OBJECT)
+			return 'v';
+		else
+			return 'w';
+	}
+	if (sym->st_shndx == SHN_UNDEF)
+		return 'U';
+	if (sym->st_shndx == SHN_ABS || sym->st_shndx == info->index.pcpu)
+		return 'a';
+	if (sym->st_shndx >= SHN_LORESERVE)
+		return '?';
+	if (sechdrs[sym->st_shndx].sh_flags & SHF_EXECINSTR)
+		return 't';
+	if (sechdrs[sym->st_shndx].sh_flags & SHF_ALLOC &&
+	    sechdrs[sym->st_shndx].sh_type != SHT_NOBITS) {
+		if (!(sechdrs[sym->st_shndx].sh_flags & SHF_WRITE))
+			return 'r';
+		else if (sechdrs[sym->st_shndx].sh_flags & ARCH_SHF_SMALL)
+			return 'g';
+		else
+			return 'd';
+	}
+	if (sechdrs[sym->st_shndx].sh_type == SHT_NOBITS) {
+		if (sechdrs[sym->st_shndx].sh_flags & ARCH_SHF_SMALL)
+			return 's';
+		else
+			return 'b';
+	}
+	if (strstarts(info->secstrings + sechdrs[sym->st_shndx].sh_name,
+		      ".debug")) {
+		return 'n';
+	}
+	return '?';
+}
+
+static bool is_core_symbol(const Elf_Sym *src, const Elf_Shdr *sechdrs,
+			   unsigned int shnum, unsigned int pcpundx)
+{
+	const Elf_Shdr *sec;
+
+	if (src->st_shndx == SHN_UNDEF ||
+	    src->st_shndx >= shnum ||
+	    !src->st_name)
+		return false;
+
+#ifdef CONFIG_KALLSYMS_ALL
+	if (src->st_shndx == pcpundx)
+		return true;
+#endif
+
+	sec = sechdrs + src->st_shndx;
+	if (!(sec->sh_flags & SHF_ALLOC)
+#ifndef CONFIG_KALLSYMS_ALL
+	    || !(sec->sh_flags & SHF_EXECINSTR)
+#endif
+	    || (sec->sh_entsize & INIT_OFFSET_MASK))
+		return false;
+
+	return true;
+}
+
+/*
+ * We only allocate and copy the strings needed by the parts of symtab
+ * we keep.  This is simple, but has the effect of making multiple
+ * copies of duplicates.  We could be more sophisticated, see
+ * linux-kernel thread starting with
+ * <73defb5e4bca04a6431392cc341112b1@localhost>.
+ */
+void layout_symtab(struct module *mod, struct load_info *info)
+{
+	Elf_Shdr *symsect = info->sechdrs + info->index.sym;
+	Elf_Shdr *strsect = info->sechdrs + info->index.str;
+	const Elf_Sym *src;
+	unsigned int i, nsrc, ndst, strtab_size = 0;
+
+	/* Put symbol section at end of init part of module. */
+	symsect->sh_flags |= SHF_ALLOC;
+	symsect->sh_entsize = module_get_offset(mod, &mod->init_layout.size, symsect,
+						info->index.sym) | INIT_OFFSET_MASK;
+	pr_debug("\t%s\n", info->secstrings + symsect->sh_name);
+
+	src = (void *)info->hdr + symsect->sh_offset;
+	nsrc = symsect->sh_size / sizeof(*src);
+
+	/* Compute total space required for the core symbols' strtab. */
+	for (ndst = i = 0; i < nsrc; i++) {
+		if (i == 0 || is_livepatch_module(mod) ||
+		    is_core_symbol(src + i, info->sechdrs, info->hdr->e_shnum,
+				   info->index.pcpu)) {
+			strtab_size += strlen(&info->strtab[src[i].st_name]) + 1;
+			ndst++;
+		}
+	}
+
+	/* Append room for core symbols at end of core part. */
+	info->symoffs = ALIGN(mod->data_layout.size, symsect->sh_addralign ?: 1);
+	info->stroffs = mod->data_layout.size = info->symoffs + ndst * sizeof(Elf_Sym);
+	mod->data_layout.size += strtab_size;
+	info->core_typeoffs = mod->data_layout.size;
+	mod->data_layout.size += ndst * sizeof(char);
+	mod->data_layout.size = strict_align(mod->data_layout.size);
+
+	/* Put string table section at end of init part of module. */
+	strsect->sh_flags |= SHF_ALLOC;
+	strsect->sh_entsize = module_get_offset(mod, &mod->init_layout.size, strsect,
+						info->index.str) | INIT_OFFSET_MASK;
+	pr_debug("\t%s\n", info->secstrings + strsect->sh_name);
+
+	/* We'll tack temporary mod_kallsyms on the end. */
+	mod->init_layout.size = ALIGN(mod->init_layout.size,
+				      __alignof__(struct mod_kallsyms));
+	info->mod_kallsyms_init_off = mod->init_layout.size;
+	mod->init_layout.size += sizeof(struct mod_kallsyms);
+	info->init_typeoffs = mod->init_layout.size;
+	mod->init_layout.size += nsrc * sizeof(char);
+	mod->init_layout.size = strict_align(mod->init_layout.size);
+}
+
+/*
+ * We use the full symtab and strtab which layout_symtab arranged to
+ * be appended to the init section.  Later we switch to the cut-down
+ * core-only ones.
+ */
+void add_kallsyms(struct module *mod, const struct load_info *info)
+{
+	unsigned int i, ndst;
+	const Elf_Sym *src;
+	Elf_Sym *dst;
+	char *s;
+	Elf_Shdr *symsec = &info->sechdrs[info->index.sym];
+
+	/* Set up to point into init section. */
+	mod->kallsyms = (void __rcu *)mod->init_layout.base +
+		info->mod_kallsyms_init_off;
+
+	preempt_disable();
+	/* The following is safe since this pointer cannot change */
+	rcu_dereference_sched(mod->kallsyms)->symtab = (void *)symsec->sh_addr;
+	rcu_dereference_sched(mod->kallsyms)->num_symtab = symsec->sh_size / sizeof(Elf_Sym);
+	/* Make sure we get permanent strtab: don't use info->strtab. */
+	rcu_dereference_sched(mod->kallsyms)->strtab =
+		(void *)info->sechdrs[info->index.str].sh_addr;
+	rcu_dereference_sched(mod->kallsyms)->typetab = mod->init_layout.base + info->init_typeoffs;
+
+	/*
+	 * Now populate the cut down core kallsyms for after init
+	 * and set types up while we still have access to sections.
+	 */
+	mod->core_kallsyms.symtab = dst = mod->data_layout.base + info->symoffs;
+	mod->core_kallsyms.strtab = s = mod->data_layout.base + info->stroffs;
+	mod->core_kallsyms.typetab = mod->data_layout.base + info->core_typeoffs;
+	src = rcu_dereference_sched(mod->kallsyms)->symtab;
+	for (ndst = i = 0; i < rcu_dereference_sched(mod->kallsyms)->num_symtab; i++) {
+		rcu_dereference_sched(mod->kallsyms)->typetab[i] = elf_type(src + i, info);
+		if (i == 0 || is_livepatch_module(mod) ||
+		    is_core_symbol(src + i, info->sechdrs, info->hdr->e_shnum,
+				   info->index.pcpu)) {
+			mod->core_kallsyms.typetab[ndst] =
+			    rcu_dereference_sched(mod->kallsyms)->typetab[i];
+			dst[ndst] = src[i];
+			dst[ndst++].st_name = s - mod->core_kallsyms.strtab;
+			s += strscpy(s,
+				     &rcu_dereference_sched(mod->kallsyms)->strtab[src[i].st_name],
+				     KSYM_NAME_LEN) + 1;
+		}
+	}
+	preempt_enable();
+	mod->core_kallsyms.num_symtab = ndst;
+}
+
+#if IS_ENABLED(CONFIG_STACKTRACE_BUILD_ID)
+void init_build_id(struct module *mod, const struct load_info *info)
+{
+	const Elf_Shdr *sechdr;
+	unsigned int i;
+
+	for (i = 0; i < info->hdr->e_shnum; i++) {
+		sechdr = &info->sechdrs[i];
+		if (!sect_empty(sechdr) && sechdr->sh_type == SHT_NOTE &&
+		    !build_id_parse_buf((void *)sechdr->sh_addr, mod->build_id,
+					sechdr->sh_size))
+			break;
+	}
+}
+#else
+void init_build_id(struct module *mod, const struct load_info *info)
+{
+}
+#endif
+
+/*
+ * This ignores the intensely annoying "mapping symbols" found
+ * in ARM ELF files: $a, $t and $d.
+ */
+static inline int is_arm_mapping_symbol(const char *str)
+{
+	if (str[0] == '.' && str[1] == 'L')
+		return true;
+	return str[0] == '$' && strchr("axtd", str[1]) &&
+	       (str[2] == '\0' || str[2] == '.');
+}
+
+static const char *kallsyms_symbol_name(struct mod_kallsyms *kallsyms, unsigned int symnum)
+{
+	return kallsyms->strtab + kallsyms->symtab[symnum].st_name;
+}
+
+/*
+ * Given a module and address, find the corresponding symbol and return its name
+ * while providing its size and offset if needed.
+ */
+static const char *find_kallsyms_symbol(struct module *mod,
+					unsigned long addr,
+					unsigned long *size,
+					unsigned long *offset)
+{
+	unsigned int i, best = 0;
+	unsigned long nextval, bestval;
+	struct mod_kallsyms *kallsyms = rcu_dereference_sched(mod->kallsyms);
+
+	/* At worse, next value is at end of module */
+	if (within_module_init(addr, mod))
+		nextval = (unsigned long)mod->init_layout.base + mod->init_layout.text_size;
+	else
+		nextval = (unsigned long)mod->core_layout.base + mod->core_layout.text_size;
+
+	bestval = kallsyms_symbol_value(&kallsyms->symtab[best]);
+
+	/*
+	 * Scan for closest preceding symbol, and next symbol. (ELF
+	 * starts real symbols at 1).
+	 */
+	for (i = 1; i < kallsyms->num_symtab; i++) {
+		const Elf_Sym *sym = &kallsyms->symtab[i];
+		unsigned long thisval = kallsyms_symbol_value(sym);
+
+		if (sym->st_shndx == SHN_UNDEF)
+			continue;
+
+		/*
+		 * We ignore unnamed symbols: they're uninformative
+		 * and inserted at a whim.
+		 */
+		if (*kallsyms_symbol_name(kallsyms, i) == '\0' ||
+		    is_arm_mapping_symbol(kallsyms_symbol_name(kallsyms, i)))
+			continue;
+
+		if (thisval <= addr && thisval > bestval) {
+			best = i;
+			bestval = thisval;
+		}
+		if (thisval > addr && thisval < nextval)
+			nextval = thisval;
+	}
+
+	if (!best)
+		return NULL;
+
+	if (size)
+		*size = nextval - bestval;
+	if (offset)
+		*offset = addr - bestval;
+
+	return kallsyms_symbol_name(kallsyms, best);
+}
+
+void * __weak dereference_module_function_descriptor(struct module *mod,
+						     void *ptr)
+{
+	return ptr;
+}
+
+/*
+ * For kallsyms to ask for address resolution.  NULL means not found.  Careful
+ * not to lock to avoid deadlock on oopses, simply disable preemption.
+ */
+const char *module_address_lookup(unsigned long addr,
+				  unsigned long *size,
+			    unsigned long *offset,
+			    char **modname,
+			    const unsigned char **modbuildid,
+			    char *namebuf)
+{
+	const char *ret = NULL;
+	struct module *mod;
+
+	preempt_disable();
+	mod = __module_address(addr);
+	if (mod) {
+		if (modname)
+			*modname = mod->name;
+		if (modbuildid) {
+#if IS_ENABLED(CONFIG_STACKTRACE_BUILD_ID)
+			*modbuildid = mod->build_id;
+#else
+			*modbuildid = NULL;
+#endif
+		}
+
+		ret = find_kallsyms_symbol(mod, addr, size, offset);
+	}
+	/* Make a copy in here where it's safe */
+	if (ret) {
+		strncpy(namebuf, ret, KSYM_NAME_LEN - 1);
+		ret = namebuf;
+	}
+	preempt_enable();
+
+	return ret;
+}
+
+int lookup_module_symbol_name(unsigned long addr, char *symname)
+{
+	struct module *mod;
+
+	preempt_disable();
+	list_for_each_entry_rcu(mod, &modules, list) {
+		if (mod->state == MODULE_STATE_UNFORMED)
+			continue;
+		if (within_module(addr, mod)) {
+			const char *sym;
+
+			sym = find_kallsyms_symbol(mod, addr, NULL, NULL);
+			if (!sym)