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    SubjectRe: [RFC PATCH 6/9] livepatch: create per-task consistency model
    (2015/02/10 2:31), Josh Poimboeuf wrote:
    > Add a basic per-task consistency model. This is the foundation which
    > will eventually enable us to patch those ~10% of security patches which
    > change function prototypes and/or data semantics.
    >
    > When a patch is enabled, livepatch enters into a transition state where
    > tasks are converging from the old universe to the new universe. If a
    > given task isn't using any of the patched functions, it's switched to
    > the new universe. Once all the tasks have been converged to the new
    > universe, patching is complete.
    >
    > The same sequence occurs when a patch is disabled, except the tasks
    > converge from the new universe to the old universe.
    >
    > The /sys/kernel/livepatch/<patch>/transition file shows whether a patch
    > is in transition. Only a single patch (the topmost patch on the stack)
    > can be in transition at a given time. A patch can remain in the
    > transition state indefinitely, if any of the tasks are stuck in the
    > previous universe.
    >
    > A transition can be reversed and effectively canceled by writing the
    > opposite value to the /sys/kernel/livepatch/<patch>/enabled file while
    > the transition is in progress. Then all the tasks will attempt to
    > converge back to the original universe.
    >
    > Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
    > ---
    > include/linux/livepatch.h | 18 ++-
    > include/linux/sched.h | 3 +
    > kernel/fork.c | 2 +
    > kernel/livepatch/Makefile | 2 +-
    > kernel/livepatch/core.c | 71 ++++++----
    > kernel/livepatch/patch.c | 34 ++++-
    > kernel/livepatch/patch.h | 1 +
    > kernel/livepatch/transition.c | 300 ++++++++++++++++++++++++++++++++++++++++++
    > kernel/livepatch/transition.h | 16 +++
    > kernel/sched/core.c | 2 +
    > 10 files changed, 423 insertions(+), 26 deletions(-)
    > create mode 100644 kernel/livepatch/transition.c
    > create mode 100644 kernel/livepatch/transition.h
    >
    > diff --git a/include/linux/livepatch.h b/include/linux/livepatch.h
    > index 0e65b4d..b8c2f15 100644
    > --- a/include/linux/livepatch.h
    > +++ b/include/linux/livepatch.h
    > @@ -40,6 +40,7 @@
    > * @old_size: size of the old function
    > * @new_size: size of the new function
    > * @patched: the func has been added to the klp_ops list
    > + * @transition: the func is currently being applied or reverted
    > */
    > struct klp_func {
    > /* external */
    > @@ -60,6 +61,7 @@ struct klp_func {
    > struct list_head stack_node;
    > unsigned long old_size, new_size;
    > int patched;
    > + int transition;
    > };
    >
    > /**
    > @@ -128,6 +130,20 @@ extern int klp_unregister_patch(struct klp_patch *);
    > extern int klp_enable_patch(struct klp_patch *);
    > extern int klp_disable_patch(struct klp_patch *);
    >
    > -#endif /* CONFIG_LIVEPATCH */
    > +extern int klp_universe_goal;
    > +
    > +static inline void klp_update_task_universe(struct task_struct *t)
    > +{
    > + /* corresponding smp_wmb() is in klp_set_universe_goal() */
    > + smp_rmb();
    > +
    > + t->klp_universe = klp_universe_goal;
    > +}
    > +
    > +#else /* !CONFIG_LIVEPATCH */
    > +
    > +static inline void klp_update_task_universe(struct task_struct *t) {}
    > +
    > +#endif /* !CONFIG_LIVEPATCH */
    >
    > #endif /* _LINUX_LIVEPATCH_H_ */
    > diff --git a/include/linux/sched.h b/include/linux/sched.h
    > index 8db31ef..a95e59a 100644
    > --- a/include/linux/sched.h
    > +++ b/include/linux/sched.h
    > @@ -1701,6 +1701,9 @@ struct task_struct {
    > #ifdef CONFIG_DEBUG_ATOMIC_SLEEP
    > unsigned long task_state_change;
    > #endif
    > +#ifdef CONFIG_LIVEPATCH
    > + int klp_universe;
    > +#endif
    > };
    >
    > /* Future-safe accessor for struct task_struct's cpus_allowed. */
    > diff --git a/kernel/fork.c b/kernel/fork.c
    > index 4dc2dda..1dcbebe 100644
    > --- a/kernel/fork.c
    > +++ b/kernel/fork.c
    > @@ -74,6 +74,7 @@
    > #include <linux/uprobes.h>
    > #include <linux/aio.h>
    > #include <linux/compiler.h>
    > +#include <linux/livepatch.h>
    >
    > #include <asm/pgtable.h>
    > #include <asm/pgalloc.h>
    > @@ -1538,6 +1539,7 @@ static struct task_struct *copy_process(unsigned long clone_flags,
    > total_forks++;
    > spin_unlock(&current->sighand->siglock);
    > syscall_tracepoint_update(p);
    > + klp_update_task_universe(p);
    > write_unlock_irq(&tasklist_lock);
    >
    > proc_fork_connector(p);
    > diff --git a/kernel/livepatch/Makefile b/kernel/livepatch/Makefile
    > index e136dad..2b8bdb1 100644
    > --- a/kernel/livepatch/Makefile
    > +++ b/kernel/livepatch/Makefile
    > @@ -1,3 +1,3 @@
    > obj-$(CONFIG_LIVEPATCH) += livepatch.o
    >
    > -livepatch-objs := core.o patch.o
    > +livepatch-objs := core.o patch.o transition.o
    > diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
    > index 85d4ef7..790dc10 100644
    > --- a/kernel/livepatch/core.c
    > +++ b/kernel/livepatch/core.c
    > @@ -28,14 +28,17 @@
    > #include <linux/kallsyms.h>
    >
    > #include "patch.h"
    > +#include "transition.h"
    >
    > /*
    > - * The klp_mutex protects the global lists and state transitions of any
    > - * structure reachable from them. References to any structure must be obtained
    > - * under mutex protection (except in klp_ftrace_handler(), which uses RCU to
    > - * ensure it gets consistent data).
    > + * The 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_task_universe()
    > */
    > -static DEFINE_MUTEX(klp_mutex);
    > +DEFINE_MUTEX(klp_mutex);
    >
    > static LIST_HEAD(klp_patches);
    >
    > @@ -67,7 +70,6 @@ static void klp_find_object_module(struct klp_object *obj)
    > mutex_unlock(&module_mutex);
    > }
    >
    > -/* klp_mutex must be held by caller */
    > static bool klp_is_patch_registered(struct klp_patch *patch)
    > {
    > struct klp_patch *mypatch;
    > @@ -285,18 +287,17 @@ static int klp_write_object_relocations(struct module *pmod,
    >
    > static int __klp_disable_patch(struct klp_patch *patch)
    > {
    > - struct klp_object *obj;
    > + if (klp_transition_patch)
    > + return -EBUSY;
    >
    > /* enforce stacking: only the last enabled patch can be disabled */
    > if (!list_is_last(&patch->list, &klp_patches) &&
    > list_next_entry(patch, list)->enabled)
    > return -EBUSY;
    >
    > - pr_notice("disabling patch '%s'\n", patch->mod->name);
    > -
    > - for (obj = patch->objs; obj->funcs; obj++)
    > - if (obj->patched)
    > - klp_unpatch_object(obj);
    > + klp_init_transition(patch, KLP_UNIVERSE_NEW);
    > + klp_start_transition(KLP_UNIVERSE_OLD);
    > + klp_try_complete_transition();
    >
    > patch->enabled = 0;
    >
    > @@ -340,6 +341,9 @@ 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;
    >
    > @@ -351,7 +355,7 @@ static int __klp_enable_patch(struct klp_patch *patch)
    > pr_notice_once("tainting kernel with TAINT_LIVEPATCH\n");
    > add_taint(TAINT_LIVEPATCH, LOCKDEP_STILL_OK);
    >
    > - pr_notice("enabling patch '%s'\n", patch->mod->name);
    > + klp_init_transition(patch, KLP_UNIVERSE_OLD);
    >
    > for (obj = patch->objs; obj->funcs; obj++) {
    > klp_find_object_module(obj);
    > @@ -360,17 +364,24 @@ static int __klp_enable_patch(struct klp_patch *patch)
    > continue;
    >
    > ret = klp_patch_object(obj);
    > - if (ret)
    > - goto unregister;
    > + if (ret) {
    > + pr_warn("failed to enable patch '%s'\n",
    > + patch->mod->name);
    > +
    > + klp_unpatch_objects(patch);
    > + klp_complete_transition();
    > +
    > + return ret;
    > + }
    > }
    >
    > + klp_start_transition(KLP_UNIVERSE_NEW);
    > +
    > + klp_try_complete_transition();
    > +
    > patch->enabled = 1;
    >
    > return 0;
    > -
    > -unregister:
    > - WARN_ON(__klp_disable_patch(patch));
    > - return ret;
    > }
    >
    > /**
    > @@ -407,6 +418,7 @@ EXPORT_SYMBOL_GPL(klp_enable_patch);
    > * /sys/kernel/livepatch
    > * /sys/kernel/livepatch/<patch>
    > * /sys/kernel/livepatch/<patch>/enabled
    > + * /sys/kernel/livepatch/<patch>/transition
    > * /sys/kernel/livepatch/<patch>/<object>
    > * /sys/kernel/livepatch/<patch>/<object>/<func>
    > */
    > @@ -435,7 +447,9 @@ static ssize_t enabled_store(struct kobject *kobj, struct kobj_attribute *attr,
    > goto err;
    > }
    >
    > - if (val) {
    > + if (klp_transition_patch == patch) {
    > + klp_reverse_transition();
    > + } else if (val) {
    > ret = __klp_enable_patch(patch);
    > if (ret)
    > goto err;
    > @@ -463,9 +477,21 @@ static ssize_t enabled_show(struct kobject *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",
    > + klp_transition_patch == patch);
    > +}
    > +
    > static struct kobj_attribute enabled_kobj_attr = __ATTR_RW(enabled);
    > +static struct kobj_attribute transition_kobj_attr = __ATTR_RO(transition);
    > static struct attribute *klp_patch_attrs[] = {
    > &enabled_kobj_attr.attr,
    > + &transition_kobj_attr.attr,
    > NULL
    > };
    >
    > @@ -543,6 +569,7 @@ static int klp_init_func(struct klp_object *obj, struct klp_func *func)
    > {
    > INIT_LIST_HEAD(&func->stack_node);
    > func->patched = 0;
    > + func->transition = 0;
    >
    > return kobject_init_and_add(&func->kobj, &klp_ktype_func,
    > obj->kobj, func->old_name);
    > @@ -725,7 +752,7 @@ static void klp_module_notify_coming(struct klp_patch *patch,
    > if (ret)
    > goto err;
    >
    > - if (!patch->enabled)
    > + if (!patch->enabled && klp_transition_patch != patch)
    > return;
    >
    > pr_notice("applying patch '%s' to loading module '%s'\n",
    > @@ -746,7 +773,7 @@ static void klp_module_notify_going(struct klp_patch *patch,
    > struct module *pmod = patch->mod;
    > struct module *mod = obj->mod;
    >
    > - if (!patch->enabled)
    > + if (!patch->enabled && klp_transition_patch != patch)
    > goto free;
    >
    > pr_notice("reverting patch '%s' on unloading module '%s'\n",
    > diff --git a/kernel/livepatch/patch.c b/kernel/livepatch/patch.c
    > index 281fbca..f12256b 100644
    > --- a/kernel/livepatch/patch.c
    > +++ b/kernel/livepatch/patch.c
    > @@ -24,6 +24,7 @@
    > #include <linux/slab.h>
    >
    > #include "patch.h"
    > +#include "transition.h"
    >
    > static LIST_HEAD(klp_ops);
    >
    > @@ -38,14 +39,34 @@ static void notrace klp_ftrace_handler(unsigned long ip,
    > ops = container_of(fops, struct klp_ops, fops);
    >
    > rcu_read_lock();
    > +
    > func = list_first_or_null_rcu(&ops->func_stack, struct klp_func,
    > stack_node);
    > - rcu_read_unlock();
    >
    > if (WARN_ON_ONCE(!func))
    > - return;
    > + goto unlock;
    > +
    > + if (unlikely(func->transition)) {
    > + /* corresponding smp_wmb() is in klp_init_transition() */
    > + smp_rmb();
    > +
    > + if (current->klp_universe == KLP_UNIVERSE_OLD) {
    > + /*
    > + * Use the previously patched version of the function.
    > + * If no previous patches exist, use the original
    > + * function.
    > + */
    > + func = list_entry_rcu(func->stack_node.next,
    > + struct klp_func, stack_node);
    > +
    > + if (&func->stack_node == &ops->func_stack)
    > + goto unlock;
    > + }
    > + }
    >
    > klp_arch_set_pc(regs, (unsigned long)func->new_func);
    > +unlock:
    > + rcu_read_unlock();
    > }
    >
    > struct klp_ops *klp_find_ops(unsigned long old_addr)
    > @@ -174,3 +195,12 @@ int klp_patch_object(struct klp_object *obj)
    >
    > return 0;
    > }
    > +
    > +void klp_unpatch_objects(struct klp_patch *patch)
    > +{
    > + struct klp_object *obj;
    > +
    > + for (obj = patch->objs; obj->funcs; obj++)
    > + if (obj->patched)
    > + klp_unpatch_object(obj);
    > +}
    > diff --git a/kernel/livepatch/patch.h b/kernel/livepatch/patch.h
    > index bb34bd3..1648259 100644
    > --- a/kernel/livepatch/patch.h
    > +++ b/kernel/livepatch/patch.h
    > @@ -23,3 +23,4 @@ struct klp_ops *klp_find_ops(unsigned long old_addr);
    >
    > extern int klp_patch_object(struct klp_object *obj);
    > extern void klp_unpatch_object(struct klp_object *obj);
    > +extern void klp_unpatch_objects(struct klp_patch *patch);
    > diff --git a/kernel/livepatch/transition.c b/kernel/livepatch/transition.c
    > new file mode 100644
    > index 0000000..2630296
    > --- /dev/null
    > +++ b/kernel/livepatch/transition.c
    > @@ -0,0 +1,300 @@
    > +/*
    > + * transition.c - Kernel Live Patching transition functions
    > + *
    > + * Copyright (C) 2015 Josh Poimboeuf <jpoimboe@redhat.com>
    > + *
    > + * This program is free software; you can redistribute it and/or
    > + * modify it under the terms of the GNU General Public License
    > + * as published by the Free Software Foundation; either version 2
    > + * of the License, or (at your option) any later version.
    > + *
    > + * This program is distributed in the hope that it will be useful,
    > + * but WITHOUT ANY WARRANTY; without even the implied warranty of
    > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    > + * GNU General Public License for more details.
    > + *
    > + * You should have received a copy of the GNU General Public License
    > + * along with this program; if not, see <http://www.gnu.org/licenses/>.
    > + */
    > +
    > +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
    > +
    > +#include <linux/cpu.h>
    > +#include <asm/stacktrace.h>
    > +#include "../sched/sched.h"
    > +
    > +#include "patch.h"
    > +#include "transition.h"
    > +
    > +static void klp_transition_work_fn(struct work_struct *);
    > +static DECLARE_DELAYED_WORK(klp_transition_work, klp_transition_work_fn);
    > +
    > +struct klp_patch *klp_transition_patch;
    > +
    > +int klp_universe_goal = KLP_UNIVERSE_UNDEFINED;
    > +
    > +static void klp_set_universe_goal(int universe)
    > +{
    > + klp_universe_goal = universe;
    > +
    > + /* corresponding smp_rmb() is in klp_update_task_universe() */
    > + smp_wmb();
    > +}
    > +
    > +/*
    > + * The transition to the universe goal is complete. Clean up the data
    > + * structures.
    > + */
    > +void klp_complete_transition(void)
    > +{
    > + struct klp_object *obj;
    > + struct klp_func *func;
    > +
    > + for (obj = klp_transition_patch->objs; obj->funcs; obj++)
    > + for (func = obj->funcs; func->old_name; func++)
    > + func->transition = 0;
    > +
    > + klp_transition_patch = NULL;
    > +}
    > +
    > +static int klp_stacktrace_address_verify_func(struct klp_func *func,
    > + unsigned long address)
    > +{
    > + unsigned long func_addr, func_size;
    > +
    > + if (klp_universe_goal == KLP_UNIVERSE_OLD) {
    > + /* check the to-be-unpatched function (the func itself) */
    > + func_addr = (unsigned long)func->new_func;
    > + func_size = func->new_size;
    > + } else {
    > + /* check the to-be-patched function (previous func) */
    > + struct klp_ops *ops;
    > +
    > + ops = klp_find_ops(func->old_addr);
    > +
    > + if (list_is_singular(&ops->func_stack)) {
    > + /* original function */
    > + func_addr = func->old_addr;
    > + func_size = func->old_size;
    > + } else {
    > + /* previously patched function */
    > + struct klp_func *prev;
    > +
    > + prev = list_next_entry(func, stack_node);
    > + func_addr = (unsigned long)prev->new_func;
    > + func_size = prev->new_size;
    > + }
    > + }
    > +
    > + if (address >= func_addr && address < func_addr + func_size)
    > + return -1;
    > +
    > + return 0;
    > +}
    > +
    > +/*
    > + * Determine whether the given return address on the stack is within a
    > + * to-be-patched or to-be-unpatched function.
    > + */
    > +static void klp_stacktrace_address_verify(void *data, unsigned long address,
    > + int reliable)
    > +{
    > + struct klp_object *obj;
    > + struct klp_func *func;
    > + int *ret = data;
    > +
    > + if (*ret)
    > + return;
    > +
    > + for (obj = klp_transition_patch->objs; obj->funcs; obj++) {
    > + if (!obj->patched)
    > + continue;
    > + for (func = obj->funcs; func->old_name; func++) {
    > + if (klp_stacktrace_address_verify_func(func, address)) {
    > + *ret = -1;
    > + return;
    > + }
    > + }
    > + }
    > +}
    > +
    > +static int klp_stacktrace_stack(void *data, char *name)
    > +{
    > + return 0;
    > +}
    > +
    > +static const struct stacktrace_ops klp_stacktrace_ops = {
    > + .address = klp_stacktrace_address_verify,
    > + .stack = klp_stacktrace_stack,
    > + .walk_stack = print_context_stack_bp,
    > +};
    > +
    > +/*
    > + * Try to safely transition a task to the universe goal. If the task is
    > + * currently running or is sleeping on a to-be-patched or to-be-unpatched
    > + * function, return false.
    > + */
    > +static bool klp_transition_task(struct task_struct *t)
    > +{
    > + struct rq *rq;
    > + unsigned long flags;
    > + int ret;
    > + bool success = false;
    > +
    > + if (t->klp_universe == klp_universe_goal)
    > + return true;
    > +
    > + rq = task_rq_lock(t, &flags);
    > +
    > + if (task_running(rq, t) && t != current) {
    > + pr_debug("%s: pid %d (%s) is running\n", __func__, t->pid,
    > + t->comm);
    > + goto done;
    > + }

    Let me confirm that this always skips running tasks, and klp retries
    checking by using delayed worker, correct?

    Indeed, this can work if we retries enough long...

    Thank you,

    > +
    > + ret = 0;
    > + dump_trace(t, NULL, NULL, 0, &klp_stacktrace_ops, &ret);
    > + if (ret) {
    > + pr_debug("%s: pid %d (%s) is sleeping on a patched function\n",
    > + __func__, t->pid, t->comm);
    > + goto done;
    > + }
    > +
    > + klp_update_task_universe(t);
    > +
    > + success = true;
    > +done:
    > + task_rq_unlock(rq, t, &flags);
    > + return success;
    > +}
    > +
    > +/*
    > + * Try to transition all tasks to the universe goal. If any tasks are still
    > + * stuck in the original universe, schedule a retry.
    > + */
    > +void klp_try_complete_transition(void)
    > +{
    > + unsigned int cpu;
    > + struct task_struct *g, *t;
    > + bool complete = true;
    > +
    > + /* try to transition all normal tasks */
    > + read_lock(&tasklist_lock);
    > + for_each_process_thread(g, t)
    > + if (!klp_transition_task(t))
    > + complete = false;
    > + read_unlock(&tasklist_lock);
    > +
    > + /* try to transition the idle "swapper" tasks */
    > + get_online_cpus();
    > + for_each_online_cpu(cpu)
    > + if (!klp_transition_task(idle_task(cpu)))
    > + complete = false;
    > + put_online_cpus();
    > +
    > + /* if not complete, try again later */
    > + if (!complete) {
    > + schedule_delayed_work(&klp_transition_work,
    > + round_jiffies_relative(HZ));
    > + return;
    > + }
    > +
    > + /* success! unpatch obsolete functions and do some cleanup */
    > +
    > + if (klp_universe_goal == KLP_UNIVERSE_OLD) {
    > + klp_unpatch_objects(klp_transition_patch);
    > +
    > + /* prevent ftrace handler from reading old func->transition */
    > + synchronize_rcu();
    > + }
    > +
    > + pr_notice("'%s': %s complete\n", klp_transition_patch->mod->name,
    > + klp_universe_goal == KLP_UNIVERSE_NEW ? "patching" :
    > + "unpatching");
    > +
    > + klp_complete_transition();
    > +}
    > +
    > +static void klp_transition_work_fn(struct work_struct *work)
    > +{
    > + mutex_lock(&klp_mutex);
    > +
    > + if (klp_transition_patch)
    > + klp_try_complete_transition();
    > +
    > + mutex_unlock(&klp_mutex);
    > +}
    > +
    > +/*
    > + * Start the transition to the specified universe so tasks can begin switching
    > + * to it.
    > + */
    > +void klp_start_transition(int universe)
    > +{
    > + if (WARN_ON(klp_universe_goal == universe))
    > + return;
    > +
    > + pr_notice("'%s': %s...\n", klp_transition_patch->mod->name,
    > + universe == KLP_UNIVERSE_NEW ? "patching" : "unpatching");
    > +
    > + klp_set_universe_goal(universe);
    > +}
    > +
    > +/*
    > + * Can be called in the middle of an existing transition to reverse the
    > + * direction of the universe goal. This can be done to effectively cancel an
    > + * existing enable or disable operation if there are any tasks which are stuck
    > + * in the original universe.
    > + */
    > +void klp_reverse_transition(void)
    > +{
    > + struct klp_patch *patch = klp_transition_patch;
    > +
    > + klp_start_transition(!klp_universe_goal);
    > + klp_try_complete_transition();
    > +
    > + patch->enabled = !patch->enabled;
    > +}
    > +
    > +/*
    > + * Reset the universe goal and all tasks to the starting universe, and set all
    > + * func->transition's to 1 to prepare for patching.
    > + */
    > +void klp_init_transition(struct klp_patch *patch, int universe)
    > +{
    > + struct task_struct *g, *t;
    > + unsigned int cpu;
    > + struct klp_object *obj;
    > + struct klp_func *func;
    > +
    > + klp_transition_patch = patch;
    > +
    > + /*
    > + * If the previous transition was in the opposite direction, we may
    > + * already be in the requested initial universe.
    > + */
    > + if (klp_universe_goal == universe)
    > + goto init_funcs;
    > +
    > + klp_set_universe_goal(universe);
    > +
    > + /* init all normal task universes */
    > + read_lock(&tasklist_lock);
    > + for_each_process_thread(g, t)
    > + klp_update_task_universe(t);
    > + read_unlock(&tasklist_lock);
    > +
    > + /* init all idle "swapper" task universes */
    > + get_online_cpus();
    > + for_each_online_cpu(cpu)
    > + klp_update_task_universe(idle_task(cpu));
    > + put_online_cpus();
    > +
    > +init_funcs:
    > + /* corresponding smp_rmb() is in klp_ftrace_handler() */
    > + smp_wmb();
    > +
    > + for (obj = patch->objs; obj->funcs; obj++)
    > + for (func = obj->funcs; func->old_name; func++)
    > + func->transition = 1;
    > +}
    > diff --git a/kernel/livepatch/transition.h b/kernel/livepatch/transition.h
    > new file mode 100644
    > index 0000000..ba9a55c
    > --- /dev/null
    > +++ b/kernel/livepatch/transition.h
    > @@ -0,0 +1,16 @@
    > +#include <linux/livepatch.h>
    > +
    > +enum {
    > + KLP_UNIVERSE_UNDEFINED = -1,
    > + KLP_UNIVERSE_OLD,
    > + KLP_UNIVERSE_NEW,
    > +};
    > +
    > +extern struct mutex klp_mutex;
    > +extern struct klp_patch *klp_transition_patch;
    > +
    > +extern void klp_init_transition(struct klp_patch *patch, int universe);
    > +extern void klp_start_transition(int universe);
    > +extern void klp_reverse_transition(void);
    > +extern void klp_try_complete_transition(void);
    > +extern void klp_complete_transition(void);
    > diff --git a/kernel/sched/core.c b/kernel/sched/core.c
    > index 78d91e6..7b877f4 100644
    > --- a/kernel/sched/core.c
    > +++ b/kernel/sched/core.c
    > @@ -74,6 +74,7 @@
    > #include <linux/binfmts.h>
    > #include <linux/context_tracking.h>
    > #include <linux/compiler.h>
    > +#include <linux/livepatch.h>
    >
    > #include <asm/switch_to.h>
    > #include <asm/tlb.h>
    > @@ -4601,6 +4602,7 @@ void init_idle(struct task_struct *idle, int cpu)
    > #if defined(CONFIG_SMP)
    > sprintf(idle->comm, "%s/%d", INIT_TASK_COMM, cpu);
    > #endif
    > + klp_update_task_universe(idle);
    > }
    >
    > int cpuset_cpumask_can_shrink(const struct cpumask *cur,
    >


    --
    Masami HIRAMATSU
    Software Platform Research Dept. Linux Technology Research Center
    Hitachi, Ltd., Yokohama Research Laboratory
    E-mail: masami.hiramatsu.pt@hitachi.com




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