ASR_BASE
Change-Id: Icf3719cc0afe3eeb3edc7fa80a2eb5199ca9dda1
diff --git a/marvell/linux/kernel/livepatch/core.c b/marvell/linux/kernel/livepatch/core.c
new file mode 100644
index 0000000..1a9827a
--- /dev/null
+++ b/marvell/linux/kernel/livepatch/core.c
@@ -0,0 +1,1213 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * core.c - Kernel Live Patching Core
+ *
+ * Copyright (C) 2014 Seth Jennings <sjenning@redhat.com>
+ * Copyright (C) 2014 SUSE
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/mutex.h>
+#include <linux/slab.h>
+#include <linux/list.h>
+#include <linux/kallsyms.h>
+#include <linux/livepatch.h>
+#include <linux/elf.h>
+#include <linux/moduleloader.h>
+#include <linux/completion.h>
+#include <linux/memory.h>
+#include <asm/cacheflush.h>
+#include "core.h"
+#include "patch.h"
+#include "transition.h"
+
+/*
+ * klp_mutex is a coarse lock which serializes access to klp data. All
+ * accesses to klp-related variables and structures must have mutex protection,
+ * except within the following functions which carefully avoid the need for it:
+ *
+ * - klp_ftrace_handler()
+ * - klp_update_patch_state()
+ */
+DEFINE_MUTEX(klp_mutex);
+
+/*
+ * Actively used patches: enabled or in transition. Note that replaced
+ * or disabled patches are not listed even though the related kernel
+ * module still can be loaded.
+ */
+LIST_HEAD(klp_patches);
+
+static struct kobject *klp_root_kobj;
+
+static bool klp_is_module(struct klp_object *obj)
+{
+ return obj->name;
+}
+
+/* sets obj->mod if object is not vmlinux and module is found */
+static void klp_find_object_module(struct klp_object *obj)
+{
+ struct module *mod;
+
+ if (!klp_is_module(obj))
+ return;
+
+ mutex_lock(&module_mutex);
+ /*
+ * We do not want to block removal of patched modules and therefore
+ * we do not take a reference here. The patches are removed by
+ * klp_module_going() instead.
+ */
+ mod = find_module(obj->name);
+ /*
+ * Do not mess work of klp_module_coming() and klp_module_going().
+ * Note that the patch might still be needed before klp_module_going()
+ * is called. Module functions can be called even in the GOING state
+ * until mod->exit() finishes. This is especially important for
+ * patches that modify semantic of the functions.
+ */
+ if (mod && mod->klp_alive)
+ obj->mod = mod;
+
+ mutex_unlock(&module_mutex);
+}
+
+static bool klp_initialized(void)
+{
+ return !!klp_root_kobj;
+}
+
+static struct klp_func *klp_find_func(struct klp_object *obj,
+ struct klp_func *old_func)
+{
+ struct klp_func *func;
+
+ klp_for_each_func(obj, func) {
+ if ((strcmp(old_func->old_name, func->old_name) == 0) &&
+ (old_func->old_sympos == func->old_sympos)) {
+ return func;
+ }
+ }
+
+ return NULL;
+}
+
+static struct klp_object *klp_find_object(struct klp_patch *patch,
+ struct klp_object *old_obj)
+{
+ struct klp_object *obj;
+
+ klp_for_each_object(patch, obj) {
+ if (klp_is_module(old_obj)) {
+ if (klp_is_module(obj) &&
+ strcmp(old_obj->name, obj->name) == 0) {
+ return obj;
+ }
+ } else if (!klp_is_module(obj)) {
+ return obj;
+ }
+ }
+
+ return NULL;
+}
+
+struct klp_find_arg {
+ const char *objname;
+ const char *name;
+ unsigned long addr;
+ unsigned long count;
+ unsigned long pos;
+};
+
+static int klp_find_callback(void *data, const char *name,
+ struct module *mod, unsigned long addr)
+{
+ struct klp_find_arg *args = data;
+
+ if ((mod && !args->objname) || (!mod && args->objname))
+ return 0;
+
+ if (strcmp(args->name, name))
+ return 0;
+
+ if (args->objname && strcmp(args->objname, mod->name))
+ return 0;
+
+ args->addr = addr;
+ args->count++;
+
+ /*
+ * Finish the search when the symbol is found for the desired position
+ * or the position is not defined for a non-unique symbol.
+ */
+ if ((args->pos && (args->count == args->pos)) ||
+ (!args->pos && (args->count > 1)))
+ return 1;
+
+ return 0;
+}
+
+static int klp_find_object_symbol(const char *objname, const char *name,
+ unsigned long sympos, unsigned long *addr)
+{
+ struct klp_find_arg args = {
+ .objname = objname,
+ .name = name,
+ .addr = 0,
+ .count = 0,
+ .pos = sympos,
+ };
+
+ mutex_lock(&module_mutex);
+ if (objname)
+ module_kallsyms_on_each_symbol(klp_find_callback, &args);
+ else
+ kallsyms_on_each_symbol(klp_find_callback, &args);
+ mutex_unlock(&module_mutex);
+
+ /*
+ * Ensure an address was found. If sympos is 0, ensure symbol is unique;
+ * otherwise ensure the symbol position count matches sympos.
+ */
+ if (args.addr == 0)
+ pr_err("symbol '%s' not found in symbol table\n", name);
+ else if (args.count > 1 && sympos == 0) {
+ pr_err("unresolvable ambiguity for symbol '%s' in object '%s'\n",
+ name, objname);
+ } else if (sympos != args.count && sympos > 0) {
+ pr_err("symbol position %lu for symbol '%s' in object '%s' not found\n",
+ sympos, name, objname ? objname : "vmlinux");
+ } else {
+ *addr = args.addr;
+ return 0;
+ }
+
+ *addr = 0;
+ return -EINVAL;
+}
+
+static int klp_resolve_symbols(Elf_Shdr *relasec, struct module *pmod)
+{
+ int i, cnt, vmlinux, ret;
+ char objname[MODULE_NAME_LEN];
+ char symname[KSYM_NAME_LEN];
+ char *strtab = pmod->core_kallsyms.strtab;
+ Elf_Rela *relas;
+ Elf_Sym *sym;
+ unsigned long sympos, addr;
+
+ /*
+ * Since the field widths for objname and symname in the sscanf()
+ * call are hard-coded and correspond to MODULE_NAME_LEN and
+ * KSYM_NAME_LEN respectively, we must make sure that MODULE_NAME_LEN
+ * and KSYM_NAME_LEN have the values we expect them to have.
+ *
+ * Because the value of MODULE_NAME_LEN can differ among architectures,
+ * we use the smallest/strictest upper bound possible (56, based on
+ * the current definition of MODULE_NAME_LEN) to prevent overflows.
+ */
+ BUILD_BUG_ON(MODULE_NAME_LEN < 56 || KSYM_NAME_LEN != 192);
+
+ relas = (Elf_Rela *) relasec->sh_addr;
+ /* For each rela in this klp relocation section */
+ for (i = 0; i < relasec->sh_size / sizeof(Elf_Rela); i++) {
+ sym = pmod->core_kallsyms.symtab + ELF_R_SYM(relas[i].r_info);
+ if (sym->st_shndx != SHN_LIVEPATCH) {
+ pr_err("symbol %s is not marked as a livepatch symbol\n",
+ strtab + sym->st_name);
+ return -EINVAL;
+ }
+
+ /* Format: .klp.sym.objname.symname,sympos */
+ cnt = sscanf(strtab + sym->st_name,
+ ".klp.sym.%55[^.].%191[^,],%lu",
+ objname, symname, &sympos);
+ if (cnt != 3) {
+ pr_err("symbol %s has an incorrectly formatted name\n",
+ strtab + sym->st_name);
+ return -EINVAL;
+ }
+
+ /* klp_find_object_symbol() treats a NULL objname as vmlinux */
+ vmlinux = !strcmp(objname, "vmlinux");
+ ret = klp_find_object_symbol(vmlinux ? NULL : objname,
+ symname, sympos, &addr);
+ if (ret)
+ return ret;
+
+ sym->st_value = addr;
+ }
+
+ return 0;
+}
+
+static int klp_write_object_relocations(struct module *pmod,
+ struct klp_object *obj)
+{
+ int i, cnt, ret = 0;
+ const char *objname, *secname;
+ char sec_objname[MODULE_NAME_LEN];
+ Elf_Shdr *sec;
+
+ if (WARN_ON(!klp_is_object_loaded(obj)))
+ return -EINVAL;
+
+ objname = klp_is_module(obj) ? obj->name : "vmlinux";
+
+ /* For each klp relocation section */
+ for (i = 1; i < pmod->klp_info->hdr.e_shnum; i++) {
+ sec = pmod->klp_info->sechdrs + i;
+ secname = pmod->klp_info->secstrings + sec->sh_name;
+ if (!(sec->sh_flags & SHF_RELA_LIVEPATCH))
+ continue;
+
+ /*
+ * Format: .klp.rela.sec_objname.section_name
+ * See comment in klp_resolve_symbols() for an explanation
+ * of the selected field width value.
+ */
+ cnt = sscanf(secname, ".klp.rela.%55[^.]", sec_objname);
+ if (cnt != 1) {
+ pr_err("section %s has an incorrectly formatted name\n",
+ secname);
+ ret = -EINVAL;
+ break;
+ }
+
+ if (strcmp(objname, sec_objname))
+ continue;
+
+ ret = klp_resolve_symbols(sec, pmod);
+ if (ret)
+ break;
+
+ ret = apply_relocate_add(pmod->klp_info->sechdrs,
+ pmod->core_kallsyms.strtab,
+ pmod->klp_info->symndx, i, pmod);
+ if (ret)
+ break;
+ }
+
+ return ret;
+}
+
+/*
+ * Sysfs Interface
+ *
+ * /sys/kernel/livepatch
+ * /sys/kernel/livepatch/<patch>
+ * /sys/kernel/livepatch/<patch>/enabled
+ * /sys/kernel/livepatch/<patch>/transition
+ * /sys/kernel/livepatch/<patch>/force
+ * /sys/kernel/livepatch/<patch>/<object>
+ * /sys/kernel/livepatch/<patch>/<object>/<function,sympos>
+ */
+static int __klp_disable_patch(struct klp_patch *patch);
+
+static ssize_t enabled_store(struct kobject *kobj, struct kobj_attribute *attr,
+ const char *buf, size_t count)
+{
+ struct klp_patch *patch;
+ int ret;
+ bool enabled;
+
+ ret = kstrtobool(buf, &enabled);
+ if (ret)
+ return ret;
+
+ patch = container_of(kobj, struct klp_patch, kobj);
+
+ mutex_lock(&klp_mutex);
+
+ if (patch->enabled == enabled) {
+ /* already in requested state */
+ ret = -EINVAL;
+ goto out;
+ }
+
+ /*
+ * Allow to reverse a pending transition in both ways. It might be
+ * necessary to complete the transition without forcing and breaking
+ * the system integrity.
+ *
+ * Do not allow to re-enable a disabled patch.
+ */
+ if (patch == klp_transition_patch)
+ klp_reverse_transition();
+ else if (!enabled)
+ ret = __klp_disable_patch(patch);
+ else
+ ret = -EINVAL;
+
+out:
+ mutex_unlock(&klp_mutex);
+
+ if (ret)
+ return ret;
+ return count;
+}
+
+static ssize_t enabled_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf)
+{
+ struct klp_patch *patch;
+
+ patch = container_of(kobj, struct klp_patch, kobj);
+ return snprintf(buf, PAGE_SIZE-1, "%d\n", patch->enabled);
+}
+
+static ssize_t transition_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf)
+{
+ struct klp_patch *patch;
+
+ patch = container_of(kobj, struct klp_patch, kobj);
+ return snprintf(buf, PAGE_SIZE-1, "%d\n",
+ patch == klp_transition_patch);
+}
+
+static ssize_t force_store(struct kobject *kobj, struct kobj_attribute *attr,
+ const char *buf, size_t count)
+{
+ struct klp_patch *patch;
+ int ret;
+ bool val;
+
+ ret = kstrtobool(buf, &val);
+ if (ret)
+ return ret;
+
+ if (!val)
+ return count;
+
+ mutex_lock(&klp_mutex);
+
+ patch = container_of(kobj, struct klp_patch, kobj);
+ if (patch != klp_transition_patch) {
+ mutex_unlock(&klp_mutex);
+ return -EINVAL;
+ }
+
+ klp_force_transition();
+
+ mutex_unlock(&klp_mutex);
+
+ return count;
+}
+
+static struct kobj_attribute enabled_kobj_attr = __ATTR_RW(enabled);
+static struct kobj_attribute transition_kobj_attr = __ATTR_RO(transition);
+static struct kobj_attribute force_kobj_attr = __ATTR_WO(force);
+static struct attribute *klp_patch_attrs[] = {
+ &enabled_kobj_attr.attr,
+ &transition_kobj_attr.attr,
+ &force_kobj_attr.attr,
+ NULL
+};
+ATTRIBUTE_GROUPS(klp_patch);
+
+static void klp_free_object_dynamic(struct klp_object *obj)
+{
+ kfree(obj->name);
+ kfree(obj);
+}
+
+static void klp_init_func_early(struct klp_object *obj,
+ struct klp_func *func);
+static void klp_init_object_early(struct klp_patch *patch,
+ struct klp_object *obj);
+
+static struct klp_object *klp_alloc_object_dynamic(const char *name,
+ struct klp_patch *patch)
+{
+ struct klp_object *obj;
+
+ obj = kzalloc(sizeof(*obj), GFP_KERNEL);
+ if (!obj)
+ return NULL;
+
+ if (name) {
+ obj->name = kstrdup(name, GFP_KERNEL);
+ if (!obj->name) {
+ kfree(obj);
+ return NULL;
+ }
+ }
+
+ klp_init_object_early(patch, obj);
+ obj->dynamic = true;
+
+ return obj;
+}
+
+static void klp_free_func_nop(struct klp_func *func)
+{
+ kfree(func->old_name);
+ kfree(func);
+}
+
+static struct klp_func *klp_alloc_func_nop(struct klp_func *old_func,
+ struct klp_object *obj)
+{
+ struct klp_func *func;
+
+ func = kzalloc(sizeof(*func), GFP_KERNEL);
+ if (!func)
+ return NULL;
+
+ if (old_func->old_name) {
+ func->old_name = kstrdup(old_func->old_name, GFP_KERNEL);
+ if (!func->old_name) {
+ kfree(func);
+ return NULL;
+ }
+ }
+
+ klp_init_func_early(obj, func);
+ /*
+ * func->new_func is same as func->old_func. These addresses are
+ * set when the object is loaded, see klp_init_object_loaded().
+ */
+ func->old_sympos = old_func->old_sympos;
+ func->nop = true;
+
+ return func;
+}
+
+static int klp_add_object_nops(struct klp_patch *patch,
+ struct klp_object *old_obj)
+{
+ struct klp_object *obj;
+ struct klp_func *func, *old_func;
+
+ obj = klp_find_object(patch, old_obj);
+
+ if (!obj) {
+ obj = klp_alloc_object_dynamic(old_obj->name, patch);
+ if (!obj)
+ return -ENOMEM;
+ }
+
+ klp_for_each_func(old_obj, old_func) {
+ func = klp_find_func(obj, old_func);
+ if (func)
+ continue;
+
+ func = klp_alloc_func_nop(old_func, obj);
+ if (!func)
+ return -ENOMEM;
+ }
+
+ return 0;
+}
+
+/*
+ * Add 'nop' functions which simply return to the caller to run
+ * the original function. The 'nop' functions are added to a
+ * patch to facilitate a 'replace' mode.
+ */
+static int klp_add_nops(struct klp_patch *patch)
+{
+ struct klp_patch *old_patch;
+ struct klp_object *old_obj;
+
+ klp_for_each_patch(old_patch) {
+ klp_for_each_object(old_patch, old_obj) {
+ int err;
+
+ err = klp_add_object_nops(patch, old_obj);
+ if (err)
+ return err;
+ }
+ }
+
+ return 0;
+}
+
+static void klp_kobj_release_patch(struct kobject *kobj)
+{
+ struct klp_patch *patch;
+
+ patch = container_of(kobj, struct klp_patch, kobj);
+ complete(&patch->finish);
+}
+
+static struct kobj_type klp_ktype_patch = {
+ .release = klp_kobj_release_patch,
+ .sysfs_ops = &kobj_sysfs_ops,
+ .default_groups = klp_patch_groups,
+};
+
+static void klp_kobj_release_object(struct kobject *kobj)
+{
+ struct klp_object *obj;
+
+ obj = container_of(kobj, struct klp_object, kobj);
+
+ if (obj->dynamic)
+ klp_free_object_dynamic(obj);
+}
+
+static struct kobj_type klp_ktype_object = {
+ .release = klp_kobj_release_object,
+ .sysfs_ops = &kobj_sysfs_ops,
+};
+
+static void klp_kobj_release_func(struct kobject *kobj)
+{
+ struct klp_func *func;
+
+ func = container_of(kobj, struct klp_func, kobj);
+
+ if (func->nop)
+ klp_free_func_nop(func);
+}
+
+static struct kobj_type klp_ktype_func = {
+ .release = klp_kobj_release_func,
+ .sysfs_ops = &kobj_sysfs_ops,
+};
+
+static void __klp_free_funcs(struct klp_object *obj, bool nops_only)
+{
+ struct klp_func *func, *tmp_func;
+
+ klp_for_each_func_safe(obj, func, tmp_func) {
+ if (nops_only && !func->nop)
+ continue;
+
+ list_del(&func->node);
+ kobject_put(&func->kobj);
+ }
+}
+
+/* Clean up when a patched object is unloaded */
+static void klp_free_object_loaded(struct klp_object *obj)
+{
+ struct klp_func *func;
+
+ obj->mod = NULL;
+
+ klp_for_each_func(obj, func) {
+ func->old_func = NULL;
+
+ if (func->nop)
+ func->new_func = NULL;
+ }
+}
+
+static void __klp_free_objects(struct klp_patch *patch, bool nops_only)
+{
+ struct klp_object *obj, *tmp_obj;
+
+ klp_for_each_object_safe(patch, obj, tmp_obj) {
+ __klp_free_funcs(obj, nops_only);
+
+ if (nops_only && !obj->dynamic)
+ continue;
+
+ list_del(&obj->node);
+ kobject_put(&obj->kobj);
+ }
+}
+
+static void klp_free_objects(struct klp_patch *patch)
+{
+ __klp_free_objects(patch, false);
+}
+
+static void klp_free_objects_dynamic(struct klp_patch *patch)
+{
+ __klp_free_objects(patch, true);
+}
+
+/*
+ * This function implements the free operations that can be called safely
+ * under klp_mutex.
+ *
+ * The operation must be completed by calling klp_free_patch_finish()
+ * outside klp_mutex.
+ */
+void klp_free_patch_start(struct klp_patch *patch)
+{
+ if (!list_empty(&patch->list))
+ list_del(&patch->list);
+
+ klp_free_objects(patch);
+}
+
+/*
+ * This function implements the free part that must be called outside
+ * klp_mutex.
+ *
+ * It must be called after klp_free_patch_start(). And it has to be
+ * the last function accessing the livepatch structures when the patch
+ * gets disabled.
+ */
+static void klp_free_patch_finish(struct klp_patch *patch)
+{
+ /*
+ * Avoid deadlock with enabled_store() sysfs callback by
+ * calling this outside klp_mutex. It is safe because
+ * this is called when the patch gets disabled and it
+ * cannot get enabled again.
+ */
+ kobject_put(&patch->kobj);
+ wait_for_completion(&patch->finish);
+
+ /* Put the module after the last access to struct klp_patch. */
+ if (!patch->forced)
+ module_put(patch->mod);
+}
+
+/*
+ * The livepatch might be freed from sysfs interface created by the patch.
+ * This work allows to wait until the interface is destroyed in a separate
+ * context.
+ */
+static void klp_free_patch_work_fn(struct work_struct *work)
+{
+ struct klp_patch *patch =
+ container_of(work, struct klp_patch, free_work);
+
+ klp_free_patch_finish(patch);
+}
+
+static int klp_init_func(struct klp_object *obj, struct klp_func *func)
+{
+ if (!func->old_name)
+ return -EINVAL;
+
+ /*
+ * NOPs get the address later. The patched module must be loaded,
+ * see klp_init_object_loaded().
+ */
+ if (!func->new_func && !func->nop)
+ return -EINVAL;
+
+ if (strlen(func->old_name) >= KSYM_NAME_LEN)
+ return -EINVAL;
+
+ INIT_LIST_HEAD(&func->stack_node);
+ func->patched = false;
+ func->transition = false;
+
+ /* The format for the sysfs directory is <function,sympos> where sympos
+ * is the nth occurrence of this symbol in kallsyms for the patched
+ * object. If the user selects 0 for old_sympos, then 1 will be used
+ * since a unique symbol will be the first occurrence.
+ */
+ return kobject_add(&func->kobj, &obj->kobj, "%s,%lu",
+ func->old_name,
+ func->old_sympos ? func->old_sympos : 1);
+}
+
+/* Arches may override this to finish any remaining arch-specific tasks */
+void __weak arch_klp_init_object_loaded(struct klp_patch *patch,
+ struct klp_object *obj)
+{
+}
+
+/* parts of the initialization that is done only when the object is loaded */
+static int klp_init_object_loaded(struct klp_patch *patch,
+ struct klp_object *obj)
+{
+ struct klp_func *func;
+ int ret;
+
+ mutex_lock(&text_mutex);
+
+ module_disable_ro(patch->mod);
+ ret = klp_write_object_relocations(patch->mod, obj);
+ if (ret) {
+ module_enable_ro(patch->mod, true);
+ mutex_unlock(&text_mutex);
+ return ret;
+ }
+
+ arch_klp_init_object_loaded(patch, obj);
+ module_enable_ro(patch->mod, true);
+
+ mutex_unlock(&text_mutex);
+
+ klp_for_each_func(obj, func) {
+ ret = klp_find_object_symbol(obj->name, func->old_name,
+ func->old_sympos,
+ (unsigned long *)&func->old_func);
+ if (ret)
+ return ret;
+
+ ret = kallsyms_lookup_size_offset((unsigned long)func->old_func,
+ &func->old_size, NULL);
+ if (!ret) {
+ pr_err("kallsyms size lookup failed for '%s'\n",
+ func->old_name);
+ return -ENOENT;
+ }
+
+ if (func->nop)
+ func->new_func = func->old_func;
+
+ ret = kallsyms_lookup_size_offset((unsigned long)func->new_func,
+ &func->new_size, NULL);
+ if (!ret) {
+ pr_err("kallsyms size lookup failed for '%s' replacement\n",
+ func->old_name);
+ return -ENOENT;
+ }
+ }
+
+ return 0;
+}
+
+static int klp_init_object(struct klp_patch *patch, struct klp_object *obj)
+{
+ struct klp_func *func;
+ int ret;
+ const char *name;
+
+ if (klp_is_module(obj) && strlen(obj->name) >= MODULE_NAME_LEN)
+ return -EINVAL;
+
+ obj->patched = false;
+ obj->mod = NULL;
+
+ klp_find_object_module(obj);
+
+ name = klp_is_module(obj) ? obj->name : "vmlinux";
+ ret = kobject_add(&obj->kobj, &patch->kobj, "%s", name);
+ if (ret)
+ return ret;
+
+ klp_for_each_func(obj, func) {
+ ret = klp_init_func(obj, func);
+ if (ret)
+ return ret;
+ }
+
+ if (klp_is_object_loaded(obj))
+ ret = klp_init_object_loaded(patch, obj);
+
+ return ret;
+}
+
+static void klp_init_func_early(struct klp_object *obj,
+ struct klp_func *func)
+{
+ kobject_init(&func->kobj, &klp_ktype_func);
+ list_add_tail(&func->node, &obj->func_list);
+}
+
+static void klp_init_object_early(struct klp_patch *patch,
+ struct klp_object *obj)
+{
+ INIT_LIST_HEAD(&obj->func_list);
+ kobject_init(&obj->kobj, &klp_ktype_object);
+ list_add_tail(&obj->node, &patch->obj_list);
+}
+
+static int klp_init_patch_early(struct klp_patch *patch)
+{
+ struct klp_object *obj;
+ struct klp_func *func;
+
+ if (!patch->objs)
+ return -EINVAL;
+
+ INIT_LIST_HEAD(&patch->list);
+ INIT_LIST_HEAD(&patch->obj_list);
+ kobject_init(&patch->kobj, &klp_ktype_patch);
+ patch->enabled = false;
+ patch->forced = false;
+ INIT_WORK(&patch->free_work, klp_free_patch_work_fn);
+ init_completion(&patch->finish);
+
+ klp_for_each_object_static(patch, obj) {
+ if (!obj->funcs)
+ return -EINVAL;
+
+ klp_init_object_early(patch, obj);
+
+ klp_for_each_func_static(obj, func) {
+ klp_init_func_early(obj, func);
+ }
+ }
+
+ if (!try_module_get(patch->mod))
+ return -ENODEV;
+
+ return 0;
+}
+
+static int klp_init_patch(struct klp_patch *patch)
+{
+ struct klp_object *obj;
+ int ret;
+
+ ret = kobject_add(&patch->kobj, klp_root_kobj, "%s", patch->mod->name);
+ if (ret)
+ return ret;
+
+ if (patch->replace) {
+ ret = klp_add_nops(patch);
+ if (ret)
+ return ret;
+ }
+
+ klp_for_each_object(patch, obj) {
+ ret = klp_init_object(patch, obj);
+ if (ret)
+ return ret;
+ }
+
+ list_add_tail(&patch->list, &klp_patches);
+
+ return 0;
+}
+
+static int __klp_disable_patch(struct klp_patch *patch)
+{
+ struct klp_object *obj;
+
+ if (WARN_ON(!patch->enabled))
+ return -EINVAL;
+
+ if (klp_transition_patch)
+ return -EBUSY;
+
+ klp_init_transition(patch, KLP_UNPATCHED);
+
+ klp_for_each_object(patch, obj)
+ if (obj->patched)
+ klp_pre_unpatch_callback(obj);
+
+ /*
+ * Enforce the order of the func->transition writes in
+ * klp_init_transition() and the TIF_PATCH_PENDING writes in
+ * klp_start_transition(). In the rare case where klp_ftrace_handler()
+ * is called shortly after klp_update_patch_state() switches the task,
+ * this ensures the handler sees that func->transition is set.
+ */
+ smp_wmb();
+
+ klp_start_transition();
+ patch->enabled = false;
+ klp_try_complete_transition();
+
+ return 0;
+}
+
+static int __klp_enable_patch(struct klp_patch *patch)
+{
+ struct klp_object *obj;
+ int ret;
+
+ if (klp_transition_patch)
+ return -EBUSY;
+
+ if (WARN_ON(patch->enabled))
+ return -EINVAL;
+
+ pr_notice("enabling patch '%s'\n", patch->mod->name);
+
+ klp_init_transition(patch, KLP_PATCHED);
+
+ /*
+ * Enforce the order of the func->transition writes in
+ * klp_init_transition() and the ops->func_stack writes in
+ * klp_patch_object(), so that klp_ftrace_handler() will see the
+ * func->transition updates before the handler is registered and the
+ * new funcs become visible to the handler.
+ */
+ smp_wmb();
+
+ klp_for_each_object(patch, obj) {
+ if (!klp_is_object_loaded(obj))
+ continue;
+
+ ret = klp_pre_patch_callback(obj);
+ if (ret) {
+ pr_warn("pre-patch callback failed for object '%s'\n",
+ klp_is_module(obj) ? obj->name : "vmlinux");
+ goto err;
+ }
+
+ ret = klp_patch_object(obj);
+ if (ret) {
+ pr_warn("failed to patch object '%s'\n",
+ klp_is_module(obj) ? obj->name : "vmlinux");
+ goto err;
+ }
+ }
+
+ klp_start_transition();
+ patch->enabled = true;
+ klp_try_complete_transition();
+
+ return 0;
+err:
+ pr_warn("failed to enable patch '%s'\n", patch->mod->name);
+
+ klp_cancel_transition();
+ return ret;
+}
+
+/**
+ * klp_enable_patch() - enable the livepatch
+ * @patch: patch to be enabled
+ *
+ * Initializes the data structure associated with the patch, creates the sysfs
+ * interface, performs the needed symbol lookups and code relocations,
+ * registers the patched functions with ftrace.
+ *
+ * This function is supposed to be called from the livepatch module_init()
+ * callback.
+ *
+ * Return: 0 on success, otherwise error
+ */
+int klp_enable_patch(struct klp_patch *patch)
+{
+ int ret;
+
+ if (!patch || !patch->mod)
+ return -EINVAL;
+
+ if (!is_livepatch_module(patch->mod)) {
+ pr_err("module %s is not marked as a livepatch module\n",
+ patch->mod->name);
+ return -EINVAL;
+ }
+
+ if (!klp_initialized())
+ return -ENODEV;
+
+ if (!klp_have_reliable_stack()) {
+ pr_warn("This architecture doesn't have support for the livepatch consistency model.\n");
+ pr_warn("The livepatch transition may never complete.\n");
+ }
+
+ mutex_lock(&klp_mutex);
+
+ ret = klp_init_patch_early(patch);
+ if (ret) {
+ mutex_unlock(&klp_mutex);
+ return ret;
+ }
+
+ ret = klp_init_patch(patch);
+ if (ret)
+ goto err;
+
+ ret = __klp_enable_patch(patch);
+ if (ret)
+ goto err;
+
+ mutex_unlock(&klp_mutex);
+
+ return 0;
+
+err:
+ klp_free_patch_start(patch);
+
+ mutex_unlock(&klp_mutex);
+
+ klp_free_patch_finish(patch);
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(klp_enable_patch);
+
+/*
+ * This function removes replaced patches.
+ *
+ * We could be pretty aggressive here. It is called in the situation where
+ * these structures are no longer accessible. All functions are redirected
+ * by the klp_transition_patch. They use either a new code or they are in
+ * the original code because of the special nop function patches.
+ *
+ * The only exception is when the transition was forced. In this case,
+ * klp_ftrace_handler() might still see the replaced patch on the stack.
+ * Fortunately, it is carefully designed to work with removed functions
+ * thanks to RCU. We only have to keep the patches on the system. Also
+ * this is handled transparently by patch->module_put.
+ */
+void klp_discard_replaced_patches(struct klp_patch *new_patch)
+{
+ struct klp_patch *old_patch, *tmp_patch;
+
+ klp_for_each_patch_safe(old_patch, tmp_patch) {
+ if (old_patch == new_patch)
+ return;
+
+ old_patch->enabled = false;
+ klp_unpatch_objects(old_patch);
+ klp_free_patch_start(old_patch);
+ schedule_work(&old_patch->free_work);
+ }
+}
+
+/*
+ * This function removes the dynamically allocated 'nop' functions.
+ *
+ * We could be pretty aggressive. NOPs do not change the existing
+ * behavior except for adding unnecessary delay by the ftrace handler.
+ *
+ * It is safe even when the transition was forced. The ftrace handler
+ * will see a valid ops->func_stack entry thanks to RCU.
+ *
+ * We could even free the NOPs structures. They must be the last entry
+ * in ops->func_stack. Therefore unregister_ftrace_function() is called.
+ * It does the same as klp_synchronize_transition() to make sure that
+ * nobody is inside the ftrace handler once the operation finishes.
+ *
+ * IMPORTANT: It must be called right after removing the replaced patches!
+ */
+void klp_discard_nops(struct klp_patch *new_patch)
+{
+ klp_unpatch_objects_dynamic(klp_transition_patch);
+ klp_free_objects_dynamic(klp_transition_patch);
+}
+
+/*
+ * Remove parts of patches that touch a given kernel module. The list of
+ * patches processed might be limited. When limit is NULL, all patches
+ * will be handled.
+ */
+static void klp_cleanup_module_patches_limited(struct module *mod,
+ struct klp_patch *limit)
+{
+ struct klp_patch *patch;
+ struct klp_object *obj;
+
+ klp_for_each_patch(patch) {
+ if (patch == limit)
+ break;
+
+ klp_for_each_object(patch, obj) {
+ if (!klp_is_module(obj) || strcmp(obj->name, mod->name))
+ continue;
+
+ if (patch != klp_transition_patch)
+ klp_pre_unpatch_callback(obj);
+
+ pr_notice("reverting patch '%s' on unloading module '%s'\n",
+ patch->mod->name, obj->mod->name);
+ klp_unpatch_object(obj);
+
+ klp_post_unpatch_callback(obj);
+
+ klp_free_object_loaded(obj);
+ break;
+ }
+ }
+}
+
+int klp_module_coming(struct module *mod)
+{
+ int ret;
+ struct klp_patch *patch;
+ struct klp_object *obj;
+
+ if (WARN_ON(mod->state != MODULE_STATE_COMING))
+ return -EINVAL;
+
+ mutex_lock(&klp_mutex);
+ /*
+ * Each module has to know that klp_module_coming()
+ * has been called. We never know what module will
+ * get patched by a new patch.
+ */
+ mod->klp_alive = true;
+
+ klp_for_each_patch(patch) {
+ klp_for_each_object(patch, obj) {
+ if (!klp_is_module(obj) || strcmp(obj->name, mod->name))
+ continue;
+
+ obj->mod = mod;
+
+ ret = klp_init_object_loaded(patch, obj);
+ if (ret) {
+ pr_warn("failed to initialize patch '%s' for module '%s' (%d)\n",
+ patch->mod->name, obj->mod->name, ret);
+ goto err;
+ }
+
+ pr_notice("applying patch '%s' to loading module '%s'\n",
+ patch->mod->name, obj->mod->name);
+
+ ret = klp_pre_patch_callback(obj);
+ if (ret) {
+ pr_warn("pre-patch callback failed for object '%s'\n",
+ obj->name);
+ goto err;
+ }
+
+ ret = klp_patch_object(obj);
+ if (ret) {
+ pr_warn("failed to apply patch '%s' to module '%s' (%d)\n",
+ patch->mod->name, obj->mod->name, ret);
+
+ klp_post_unpatch_callback(obj);
+ goto err;
+ }
+
+ if (patch != klp_transition_patch)
+ klp_post_patch_callback(obj);
+
+ break;
+ }
+ }
+
+ mutex_unlock(&klp_mutex);
+
+ return 0;
+
+err:
+ /*
+ * If a patch is unsuccessfully applied, return
+ * error to the module loader.
+ */
+ pr_warn("patch '%s' failed for module '%s', refusing to load module '%s'\n",
+ patch->mod->name, obj->mod->name, obj->mod->name);
+ mod->klp_alive = false;
+ obj->mod = NULL;
+ klp_cleanup_module_patches_limited(mod, patch);
+ mutex_unlock(&klp_mutex);
+
+ return ret;
+}
+
+void klp_module_going(struct module *mod)
+{
+ if (WARN_ON(mod->state != MODULE_STATE_GOING &&
+ mod->state != MODULE_STATE_COMING))
+ return;
+
+ mutex_lock(&klp_mutex);
+ /*
+ * Each module has to know that klp_module_going()
+ * has been called. We never know what module will
+ * get patched by a new patch.
+ */
+ mod->klp_alive = false;
+
+ klp_cleanup_module_patches_limited(mod, NULL);
+
+ mutex_unlock(&klp_mutex);
+}
+
+static int __init klp_init(void)
+{
+ klp_root_kobj = kobject_create_and_add("livepatch", kernel_kobj);
+ if (!klp_root_kobj)
+ return -ENOMEM;
+
+ return 0;
+}
+
+module_init(klp_init);