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![Dmitry Safonov](/assets/img/avatar_default.png)
1. With CONFIG_JUMP_LABEL=n static_key_slow_inc() doesn't have any protection against key->enabled refcounter overflow. 2. With CONFIG_JUMP_LABEL=y static_key_slow_inc_cpuslocked() still may turn the refcounter negative as (v + 1) may overflow. key->enabled is indeed a ref-counter as it's documented in multiple places: top comment in jump_label.h, Documentation/staging/static-keys.rst, etc. As -1 is reserved for static key that's in process of being enabled, functions would break with negative key->enabled refcount: - for CONFIG_JUMP_LABEL=n negative return of static_key_count() breaks static_key_false(), static_key_true() - the ref counter may become 0 from negative side by too many static_key_slow_inc() calls and lead to use-after-free issues. These flaws result in that some users have to introduce an additional mutex and prevent the reference counter from overflowing themselves, see bpf_enable_runtime_stats() checking the counter against INT_MAX / 2. Prevent the reference counter overflow by checking if (v + 1) > 0. Change functions API to return whether the increment was successful. Signed-off-by: Dmitry Safonov <dima@arista.com> Acked-by: Jakub Kicinski <kuba@kernel.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
867 lines
21 KiB
C
867 lines
21 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* jump label support
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*
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* Copyright (C) 2009 Jason Baron <jbaron@redhat.com>
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* Copyright (C) 2011 Peter Zijlstra
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*
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*/
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#include <linux/memory.h>
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#include <linux/uaccess.h>
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#include <linux/module.h>
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#include <linux/list.h>
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#include <linux/slab.h>
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#include <linux/sort.h>
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#include <linux/err.h>
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#include <linux/static_key.h>
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#include <linux/jump_label_ratelimit.h>
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#include <linux/bug.h>
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#include <linux/cpu.h>
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#include <asm/sections.h>
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/* mutex to protect coming/going of the jump_label table */
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static DEFINE_MUTEX(jump_label_mutex);
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void jump_label_lock(void)
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{
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mutex_lock(&jump_label_mutex);
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}
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void jump_label_unlock(void)
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{
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mutex_unlock(&jump_label_mutex);
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}
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static int jump_label_cmp(const void *a, const void *b)
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{
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const struct jump_entry *jea = a;
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const struct jump_entry *jeb = b;
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/*
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* Entrires are sorted by key.
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*/
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if (jump_entry_key(jea) < jump_entry_key(jeb))
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return -1;
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if (jump_entry_key(jea) > jump_entry_key(jeb))
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return 1;
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/*
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* In the batching mode, entries should also be sorted by the code
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* inside the already sorted list of entries, enabling a bsearch in
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* the vector.
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*/
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if (jump_entry_code(jea) < jump_entry_code(jeb))
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return -1;
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if (jump_entry_code(jea) > jump_entry_code(jeb))
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return 1;
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return 0;
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}
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static void jump_label_swap(void *a, void *b, int size)
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{
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long delta = (unsigned long)a - (unsigned long)b;
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struct jump_entry *jea = a;
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struct jump_entry *jeb = b;
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struct jump_entry tmp = *jea;
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jea->code = jeb->code - delta;
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jea->target = jeb->target - delta;
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jea->key = jeb->key - delta;
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jeb->code = tmp.code + delta;
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jeb->target = tmp.target + delta;
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jeb->key = tmp.key + delta;
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}
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static void
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jump_label_sort_entries(struct jump_entry *start, struct jump_entry *stop)
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{
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unsigned long size;
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void *swapfn = NULL;
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if (IS_ENABLED(CONFIG_HAVE_ARCH_JUMP_LABEL_RELATIVE))
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swapfn = jump_label_swap;
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size = (((unsigned long)stop - (unsigned long)start)
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/ sizeof(struct jump_entry));
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sort(start, size, sizeof(struct jump_entry), jump_label_cmp, swapfn);
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}
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static void jump_label_update(struct static_key *key);
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/*
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* There are similar definitions for the !CONFIG_JUMP_LABEL case in jump_label.h.
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* The use of 'atomic_read()' requires atomic.h and its problematic for some
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* kernel headers such as kernel.h and others. Since static_key_count() is not
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* used in the branch statements as it is for the !CONFIG_JUMP_LABEL case its ok
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* to have it be a function here. Similarly, for 'static_key_enable()' and
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* 'static_key_disable()', which require bug.h. This should allow jump_label.h
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* to be included from most/all places for CONFIG_JUMP_LABEL.
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*/
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int static_key_count(struct static_key *key)
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{
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/*
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* -1 means the first static_key_slow_inc() is in progress.
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* static_key_enabled() must return true, so return 1 here.
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*/
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int n = atomic_read(&key->enabled);
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return n >= 0 ? n : 1;
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}
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EXPORT_SYMBOL_GPL(static_key_count);
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/*
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* static_key_fast_inc_not_disabled - adds a user for a static key
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* @key: static key that must be already enabled
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*
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* The caller must make sure that the static key can't get disabled while
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* in this function. It doesn't patch jump labels, only adds a user to
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* an already enabled static key.
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*
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* Returns true if the increment was done. Unlike refcount_t the ref counter
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* is not saturated, but will fail to increment on overflow.
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*/
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bool static_key_fast_inc_not_disabled(struct static_key *key)
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{
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int v;
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STATIC_KEY_CHECK_USE(key);
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/*
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* Negative key->enabled has a special meaning: it sends
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* static_key_slow_inc() down the slow path, and it is non-zero
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* so it counts as "enabled" in jump_label_update(). Note that
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* atomic_inc_unless_negative() checks >= 0, so roll our own.
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*/
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v = atomic_read(&key->enabled);
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do {
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if (v <= 0 || (v + 1) < 0)
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return false;
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} while (!likely(atomic_try_cmpxchg(&key->enabled, &v, v + 1)));
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return true;
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}
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EXPORT_SYMBOL_GPL(static_key_fast_inc_not_disabled);
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bool static_key_slow_inc_cpuslocked(struct static_key *key)
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{
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lockdep_assert_cpus_held();
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/*
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* Careful if we get concurrent static_key_slow_inc() calls;
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* later calls must wait for the first one to _finish_ the
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* jump_label_update() process. At the same time, however,
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* the jump_label_update() call below wants to see
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* static_key_enabled(&key) for jumps to be updated properly.
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*/
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if (static_key_fast_inc_not_disabled(key))
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return true;
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jump_label_lock();
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if (atomic_read(&key->enabled) == 0) {
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atomic_set(&key->enabled, -1);
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jump_label_update(key);
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/*
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* Ensure that if the above cmpxchg loop observes our positive
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* value, it must also observe all the text changes.
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*/
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atomic_set_release(&key->enabled, 1);
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} else {
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if (WARN_ON_ONCE(!static_key_fast_inc_not_disabled(key))) {
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jump_label_unlock();
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return false;
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}
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}
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jump_label_unlock();
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return true;
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}
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bool static_key_slow_inc(struct static_key *key)
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{
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bool ret;
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cpus_read_lock();
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ret = static_key_slow_inc_cpuslocked(key);
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cpus_read_unlock();
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return ret;
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}
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EXPORT_SYMBOL_GPL(static_key_slow_inc);
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void static_key_enable_cpuslocked(struct static_key *key)
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{
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STATIC_KEY_CHECK_USE(key);
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lockdep_assert_cpus_held();
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if (atomic_read(&key->enabled) > 0) {
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WARN_ON_ONCE(atomic_read(&key->enabled) != 1);
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return;
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}
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jump_label_lock();
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if (atomic_read(&key->enabled) == 0) {
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atomic_set(&key->enabled, -1);
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jump_label_update(key);
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/*
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* See static_key_slow_inc().
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*/
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atomic_set_release(&key->enabled, 1);
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}
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jump_label_unlock();
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}
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EXPORT_SYMBOL_GPL(static_key_enable_cpuslocked);
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void static_key_enable(struct static_key *key)
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{
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cpus_read_lock();
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static_key_enable_cpuslocked(key);
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cpus_read_unlock();
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}
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EXPORT_SYMBOL_GPL(static_key_enable);
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void static_key_disable_cpuslocked(struct static_key *key)
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{
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STATIC_KEY_CHECK_USE(key);
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lockdep_assert_cpus_held();
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if (atomic_read(&key->enabled) != 1) {
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WARN_ON_ONCE(atomic_read(&key->enabled) != 0);
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return;
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}
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jump_label_lock();
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if (atomic_cmpxchg(&key->enabled, 1, 0))
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jump_label_update(key);
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jump_label_unlock();
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}
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EXPORT_SYMBOL_GPL(static_key_disable_cpuslocked);
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void static_key_disable(struct static_key *key)
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{
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cpus_read_lock();
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static_key_disable_cpuslocked(key);
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cpus_read_unlock();
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}
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EXPORT_SYMBOL_GPL(static_key_disable);
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static bool static_key_slow_try_dec(struct static_key *key)
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{
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int val;
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val = atomic_fetch_add_unless(&key->enabled, -1, 1);
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if (val == 1)
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return false;
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/*
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* The negative count check is valid even when a negative
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* key->enabled is in use by static_key_slow_inc(); a
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* __static_key_slow_dec() before the first static_key_slow_inc()
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* returns is unbalanced, because all other static_key_slow_inc()
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* instances block while the update is in progress.
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*/
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WARN(val < 0, "jump label: negative count!\n");
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return true;
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}
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static void __static_key_slow_dec_cpuslocked(struct static_key *key)
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{
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lockdep_assert_cpus_held();
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if (static_key_slow_try_dec(key))
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return;
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jump_label_lock();
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if (atomic_dec_and_test(&key->enabled))
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jump_label_update(key);
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jump_label_unlock();
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}
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static void __static_key_slow_dec(struct static_key *key)
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{
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cpus_read_lock();
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__static_key_slow_dec_cpuslocked(key);
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cpus_read_unlock();
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}
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void jump_label_update_timeout(struct work_struct *work)
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{
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struct static_key_deferred *key =
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container_of(work, struct static_key_deferred, work.work);
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__static_key_slow_dec(&key->key);
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}
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EXPORT_SYMBOL_GPL(jump_label_update_timeout);
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void static_key_slow_dec(struct static_key *key)
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{
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STATIC_KEY_CHECK_USE(key);
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__static_key_slow_dec(key);
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}
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EXPORT_SYMBOL_GPL(static_key_slow_dec);
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void static_key_slow_dec_cpuslocked(struct static_key *key)
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{
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STATIC_KEY_CHECK_USE(key);
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__static_key_slow_dec_cpuslocked(key);
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}
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void __static_key_slow_dec_deferred(struct static_key *key,
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struct delayed_work *work,
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unsigned long timeout)
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{
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STATIC_KEY_CHECK_USE(key);
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if (static_key_slow_try_dec(key))
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return;
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schedule_delayed_work(work, timeout);
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}
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EXPORT_SYMBOL_GPL(__static_key_slow_dec_deferred);
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void __static_key_deferred_flush(void *key, struct delayed_work *work)
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{
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STATIC_KEY_CHECK_USE(key);
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flush_delayed_work(work);
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}
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EXPORT_SYMBOL_GPL(__static_key_deferred_flush);
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void jump_label_rate_limit(struct static_key_deferred *key,
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unsigned long rl)
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{
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STATIC_KEY_CHECK_USE(key);
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key->timeout = rl;
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INIT_DELAYED_WORK(&key->work, jump_label_update_timeout);
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}
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EXPORT_SYMBOL_GPL(jump_label_rate_limit);
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static int addr_conflict(struct jump_entry *entry, void *start, void *end)
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{
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if (jump_entry_code(entry) <= (unsigned long)end &&
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jump_entry_code(entry) + jump_entry_size(entry) > (unsigned long)start)
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return 1;
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return 0;
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}
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static int __jump_label_text_reserved(struct jump_entry *iter_start,
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struct jump_entry *iter_stop, void *start, void *end, bool init)
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{
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struct jump_entry *iter;
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iter = iter_start;
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while (iter < iter_stop) {
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if (init || !jump_entry_is_init(iter)) {
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if (addr_conflict(iter, start, end))
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return 1;
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}
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iter++;
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}
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return 0;
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}
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#ifndef arch_jump_label_transform_static
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static void arch_jump_label_transform_static(struct jump_entry *entry,
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enum jump_label_type type)
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{
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/* nothing to do on most architectures */
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}
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#endif
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static inline struct jump_entry *static_key_entries(struct static_key *key)
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{
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WARN_ON_ONCE(key->type & JUMP_TYPE_LINKED);
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return (struct jump_entry *)(key->type & ~JUMP_TYPE_MASK);
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}
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static inline bool static_key_type(struct static_key *key)
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{
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return key->type & JUMP_TYPE_TRUE;
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}
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static inline bool static_key_linked(struct static_key *key)
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{
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return key->type & JUMP_TYPE_LINKED;
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}
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static inline void static_key_clear_linked(struct static_key *key)
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{
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key->type &= ~JUMP_TYPE_LINKED;
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}
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static inline void static_key_set_linked(struct static_key *key)
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{
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key->type |= JUMP_TYPE_LINKED;
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}
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/***
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* A 'struct static_key' uses a union such that it either points directly
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* to a table of 'struct jump_entry' or to a linked list of modules which in
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* turn point to 'struct jump_entry' tables.
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*
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* The two lower bits of the pointer are used to keep track of which pointer
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* type is in use and to store the initial branch direction, we use an access
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* function which preserves these bits.
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*/
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static void static_key_set_entries(struct static_key *key,
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struct jump_entry *entries)
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{
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unsigned long type;
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WARN_ON_ONCE((unsigned long)entries & JUMP_TYPE_MASK);
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type = key->type & JUMP_TYPE_MASK;
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key->entries = entries;
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key->type |= type;
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}
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static enum jump_label_type jump_label_type(struct jump_entry *entry)
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{
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struct static_key *key = jump_entry_key(entry);
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bool enabled = static_key_enabled(key);
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bool branch = jump_entry_is_branch(entry);
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/* See the comment in linux/jump_label.h */
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return enabled ^ branch;
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}
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static bool jump_label_can_update(struct jump_entry *entry, bool init)
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{
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/*
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* Cannot update code that was in an init text area.
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*/
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if (!init && jump_entry_is_init(entry))
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return false;
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if (!kernel_text_address(jump_entry_code(entry))) {
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/*
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* This skips patching built-in __exit, which
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* is part of init_section_contains() but is
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* not part of kernel_text_address().
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*
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* Skipping built-in __exit is fine since it
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* will never be executed.
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*/
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WARN_ONCE(!jump_entry_is_init(entry),
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"can't patch jump_label at %pS",
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(void *)jump_entry_code(entry));
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return false;
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}
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return true;
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}
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#ifndef HAVE_JUMP_LABEL_BATCH
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static void __jump_label_update(struct static_key *key,
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struct jump_entry *entry,
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struct jump_entry *stop,
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bool init)
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{
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for (; (entry < stop) && (jump_entry_key(entry) == key); entry++) {
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if (jump_label_can_update(entry, init))
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arch_jump_label_transform(entry, jump_label_type(entry));
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}
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}
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#else
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static void __jump_label_update(struct static_key *key,
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struct jump_entry *entry,
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struct jump_entry *stop,
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bool init)
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{
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for (; (entry < stop) && (jump_entry_key(entry) == key); entry++) {
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if (!jump_label_can_update(entry, init))
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continue;
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if (!arch_jump_label_transform_queue(entry, jump_label_type(entry))) {
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/*
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* Queue is full: Apply the current queue and try again.
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*/
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arch_jump_label_transform_apply();
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BUG_ON(!arch_jump_label_transform_queue(entry, jump_label_type(entry)));
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}
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}
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arch_jump_label_transform_apply();
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}
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#endif
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void __init jump_label_init(void)
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{
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struct jump_entry *iter_start = __start___jump_table;
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struct jump_entry *iter_stop = __stop___jump_table;
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struct static_key *key = NULL;
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struct jump_entry *iter;
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/*
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* Since we are initializing the static_key.enabled field with
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* with the 'raw' int values (to avoid pulling in atomic.h) in
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* jump_label.h, let's make sure that is safe. There are only two
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* cases to check since we initialize to 0 or 1.
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*/
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BUILD_BUG_ON((int)ATOMIC_INIT(0) != 0);
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BUILD_BUG_ON((int)ATOMIC_INIT(1) != 1);
|
|
|
|
if (static_key_initialized)
|
|
return;
|
|
|
|
cpus_read_lock();
|
|
jump_label_lock();
|
|
jump_label_sort_entries(iter_start, iter_stop);
|
|
|
|
for (iter = iter_start; iter < iter_stop; iter++) {
|
|
struct static_key *iterk;
|
|
bool in_init;
|
|
|
|
/* rewrite NOPs */
|
|
if (jump_label_type(iter) == JUMP_LABEL_NOP)
|
|
arch_jump_label_transform_static(iter, JUMP_LABEL_NOP);
|
|
|
|
in_init = init_section_contains((void *)jump_entry_code(iter), 1);
|
|
jump_entry_set_init(iter, in_init);
|
|
|
|
iterk = jump_entry_key(iter);
|
|
if (iterk == key)
|
|
continue;
|
|
|
|
key = iterk;
|
|
static_key_set_entries(key, iter);
|
|
}
|
|
static_key_initialized = true;
|
|
jump_label_unlock();
|
|
cpus_read_unlock();
|
|
}
|
|
|
|
#ifdef CONFIG_MODULES
|
|
|
|
enum jump_label_type jump_label_init_type(struct jump_entry *entry)
|
|
{
|
|
struct static_key *key = jump_entry_key(entry);
|
|
bool type = static_key_type(key);
|
|
bool branch = jump_entry_is_branch(entry);
|
|
|
|
/* See the comment in linux/jump_label.h */
|
|
return type ^ branch;
|
|
}
|
|
|
|
struct static_key_mod {
|
|
struct static_key_mod *next;
|
|
struct jump_entry *entries;
|
|
struct module *mod;
|
|
};
|
|
|
|
static inline struct static_key_mod *static_key_mod(struct static_key *key)
|
|
{
|
|
WARN_ON_ONCE(!static_key_linked(key));
|
|
return (struct static_key_mod *)(key->type & ~JUMP_TYPE_MASK);
|
|
}
|
|
|
|
/***
|
|
* key->type and key->next are the same via union.
|
|
* This sets key->next and preserves the type bits.
|
|
*
|
|
* See additional comments above static_key_set_entries().
|
|
*/
|
|
static void static_key_set_mod(struct static_key *key,
|
|
struct static_key_mod *mod)
|
|
{
|
|
unsigned long type;
|
|
|
|
WARN_ON_ONCE((unsigned long)mod & JUMP_TYPE_MASK);
|
|
type = key->type & JUMP_TYPE_MASK;
|
|
key->next = mod;
|
|
key->type |= type;
|
|
}
|
|
|
|
static int __jump_label_mod_text_reserved(void *start, void *end)
|
|
{
|
|
struct module *mod;
|
|
int ret;
|
|
|
|
preempt_disable();
|
|
mod = __module_text_address((unsigned long)start);
|
|
WARN_ON_ONCE(__module_text_address((unsigned long)end) != mod);
|
|
if (!try_module_get(mod))
|
|
mod = NULL;
|
|
preempt_enable();
|
|
|
|
if (!mod)
|
|
return 0;
|
|
|
|
ret = __jump_label_text_reserved(mod->jump_entries,
|
|
mod->jump_entries + mod->num_jump_entries,
|
|
start, end, mod->state == MODULE_STATE_COMING);
|
|
|
|
module_put(mod);
|
|
|
|
return ret;
|
|
}
|
|
|
|
static void __jump_label_mod_update(struct static_key *key)
|
|
{
|
|
struct static_key_mod *mod;
|
|
|
|
for (mod = static_key_mod(key); mod; mod = mod->next) {
|
|
struct jump_entry *stop;
|
|
struct module *m;
|
|
|
|
/*
|
|
* NULL if the static_key is defined in a module
|
|
* that does not use it
|
|
*/
|
|
if (!mod->entries)
|
|
continue;
|
|
|
|
m = mod->mod;
|
|
if (!m)
|
|
stop = __stop___jump_table;
|
|
else
|
|
stop = m->jump_entries + m->num_jump_entries;
|
|
__jump_label_update(key, mod->entries, stop,
|
|
m && m->state == MODULE_STATE_COMING);
|
|
}
|
|
}
|
|
|
|
static int jump_label_add_module(struct module *mod)
|
|
{
|
|
struct jump_entry *iter_start = mod->jump_entries;
|
|
struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
|
|
struct jump_entry *iter;
|
|
struct static_key *key = NULL;
|
|
struct static_key_mod *jlm, *jlm2;
|
|
|
|
/* if the module doesn't have jump label entries, just return */
|
|
if (iter_start == iter_stop)
|
|
return 0;
|
|
|
|
jump_label_sort_entries(iter_start, iter_stop);
|
|
|
|
for (iter = iter_start; iter < iter_stop; iter++) {
|
|
struct static_key *iterk;
|
|
bool in_init;
|
|
|
|
in_init = within_module_init(jump_entry_code(iter), mod);
|
|
jump_entry_set_init(iter, in_init);
|
|
|
|
iterk = jump_entry_key(iter);
|
|
if (iterk == key)
|
|
continue;
|
|
|
|
key = iterk;
|
|
if (within_module((unsigned long)key, mod)) {
|
|
static_key_set_entries(key, iter);
|
|
continue;
|
|
}
|
|
jlm = kzalloc(sizeof(struct static_key_mod), GFP_KERNEL);
|
|
if (!jlm)
|
|
return -ENOMEM;
|
|
if (!static_key_linked(key)) {
|
|
jlm2 = kzalloc(sizeof(struct static_key_mod),
|
|
GFP_KERNEL);
|
|
if (!jlm2) {
|
|
kfree(jlm);
|
|
return -ENOMEM;
|
|
}
|
|
preempt_disable();
|
|
jlm2->mod = __module_address((unsigned long)key);
|
|
preempt_enable();
|
|
jlm2->entries = static_key_entries(key);
|
|
jlm2->next = NULL;
|
|
static_key_set_mod(key, jlm2);
|
|
static_key_set_linked(key);
|
|
}
|
|
jlm->mod = mod;
|
|
jlm->entries = iter;
|
|
jlm->next = static_key_mod(key);
|
|
static_key_set_mod(key, jlm);
|
|
static_key_set_linked(key);
|
|
|
|
/* Only update if we've changed from our initial state */
|
|
if (jump_label_type(iter) != jump_label_init_type(iter))
|
|
__jump_label_update(key, iter, iter_stop, true);
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void jump_label_del_module(struct module *mod)
|
|
{
|
|
struct jump_entry *iter_start = mod->jump_entries;
|
|
struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
|
|
struct jump_entry *iter;
|
|
struct static_key *key = NULL;
|
|
struct static_key_mod *jlm, **prev;
|
|
|
|
for (iter = iter_start; iter < iter_stop; iter++) {
|
|
if (jump_entry_key(iter) == key)
|
|
continue;
|
|
|
|
key = jump_entry_key(iter);
|
|
|
|
if (within_module((unsigned long)key, mod))
|
|
continue;
|
|
|
|
/* No memory during module load */
|
|
if (WARN_ON(!static_key_linked(key)))
|
|
continue;
|
|
|
|
prev = &key->next;
|
|
jlm = static_key_mod(key);
|
|
|
|
while (jlm && jlm->mod != mod) {
|
|
prev = &jlm->next;
|
|
jlm = jlm->next;
|
|
}
|
|
|
|
/* No memory during module load */
|
|
if (WARN_ON(!jlm))
|
|
continue;
|
|
|
|
if (prev == &key->next)
|
|
static_key_set_mod(key, jlm->next);
|
|
else
|
|
*prev = jlm->next;
|
|
|
|
kfree(jlm);
|
|
|
|
jlm = static_key_mod(key);
|
|
/* if only one etry is left, fold it back into the static_key */
|
|
if (jlm->next == NULL) {
|
|
static_key_set_entries(key, jlm->entries);
|
|
static_key_clear_linked(key);
|
|
kfree(jlm);
|
|
}
|
|
}
|
|
}
|
|
|
|
static int
|
|
jump_label_module_notify(struct notifier_block *self, unsigned long val,
|
|
void *data)
|
|
{
|
|
struct module *mod = data;
|
|
int ret = 0;
|
|
|
|
cpus_read_lock();
|
|
jump_label_lock();
|
|
|
|
switch (val) {
|
|
case MODULE_STATE_COMING:
|
|
ret = jump_label_add_module(mod);
|
|
if (ret) {
|
|
WARN(1, "Failed to allocate memory: jump_label may not work properly.\n");
|
|
jump_label_del_module(mod);
|
|
}
|
|
break;
|
|
case MODULE_STATE_GOING:
|
|
jump_label_del_module(mod);
|
|
break;
|
|
}
|
|
|
|
jump_label_unlock();
|
|
cpus_read_unlock();
|
|
|
|
return notifier_from_errno(ret);
|
|
}
|
|
|
|
static struct notifier_block jump_label_module_nb = {
|
|
.notifier_call = jump_label_module_notify,
|
|
.priority = 1, /* higher than tracepoints */
|
|
};
|
|
|
|
static __init int jump_label_init_module(void)
|
|
{
|
|
return register_module_notifier(&jump_label_module_nb);
|
|
}
|
|
early_initcall(jump_label_init_module);
|
|
|
|
#endif /* CONFIG_MODULES */
|
|
|
|
/***
|
|
* jump_label_text_reserved - check if addr range is reserved
|
|
* @start: start text addr
|
|
* @end: end text addr
|
|
*
|
|
* checks if the text addr located between @start and @end
|
|
* overlaps with any of the jump label patch addresses. Code
|
|
* that wants to modify kernel text should first verify that
|
|
* it does not overlap with any of the jump label addresses.
|
|
* Caller must hold jump_label_mutex.
|
|
*
|
|
* returns 1 if there is an overlap, 0 otherwise
|
|
*/
|
|
int jump_label_text_reserved(void *start, void *end)
|
|
{
|
|
bool init = system_state < SYSTEM_RUNNING;
|
|
int ret = __jump_label_text_reserved(__start___jump_table,
|
|
__stop___jump_table, start, end, init);
|
|
|
|
if (ret)
|
|
return ret;
|
|
|
|
#ifdef CONFIG_MODULES
|
|
ret = __jump_label_mod_text_reserved(start, end);
|
|
#endif
|
|
return ret;
|
|
}
|
|
|
|
static void jump_label_update(struct static_key *key)
|
|
{
|
|
struct jump_entry *stop = __stop___jump_table;
|
|
bool init = system_state < SYSTEM_RUNNING;
|
|
struct jump_entry *entry;
|
|
#ifdef CONFIG_MODULES
|
|
struct module *mod;
|
|
|
|
if (static_key_linked(key)) {
|
|
__jump_label_mod_update(key);
|
|
return;
|
|
}
|
|
|
|
preempt_disable();
|
|
mod = __module_address((unsigned long)key);
|
|
if (mod) {
|
|
stop = mod->jump_entries + mod->num_jump_entries;
|
|
init = mod->state == MODULE_STATE_COMING;
|
|
}
|
|
preempt_enable();
|
|
#endif
|
|
entry = static_key_entries(key);
|
|
/* if there are no users, entry can be NULL */
|
|
if (entry)
|
|
__jump_label_update(key, entry, stop, init);
|
|
}
|
|
|
|
#ifdef CONFIG_STATIC_KEYS_SELFTEST
|
|
static DEFINE_STATIC_KEY_TRUE(sk_true);
|
|
static DEFINE_STATIC_KEY_FALSE(sk_false);
|
|
|
|
static __init int jump_label_test(void)
|
|
{
|
|
int i;
|
|
|
|
for (i = 0; i < 2; i++) {
|
|
WARN_ON(static_key_enabled(&sk_true.key) != true);
|
|
WARN_ON(static_key_enabled(&sk_false.key) != false);
|
|
|
|
WARN_ON(!static_branch_likely(&sk_true));
|
|
WARN_ON(!static_branch_unlikely(&sk_true));
|
|
WARN_ON(static_branch_likely(&sk_false));
|
|
WARN_ON(static_branch_unlikely(&sk_false));
|
|
|
|
static_branch_disable(&sk_true);
|
|
static_branch_enable(&sk_false);
|
|
|
|
WARN_ON(static_key_enabled(&sk_true.key) == true);
|
|
WARN_ON(static_key_enabled(&sk_false.key) == false);
|
|
|
|
WARN_ON(static_branch_likely(&sk_true));
|
|
WARN_ON(static_branch_unlikely(&sk_true));
|
|
WARN_ON(!static_branch_likely(&sk_false));
|
|
WARN_ON(!static_branch_unlikely(&sk_false));
|
|
|
|
static_branch_enable(&sk_true);
|
|
static_branch_disable(&sk_false);
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
early_initcall(jump_label_test);
|
|
#endif /* STATIC_KEYS_SELFTEST */
|