[mirror_ubuntu-hirsute-kernel.git] / kernel / static_call.c

// SPDX-License-Identifier: GPL-2.0
#include <linux/init.h>
#include <linux/static_call.h>
#include <linux/bug.h>
#include <linux/smp.h>
#include <linux/sort.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/cpu.h>
#include <linux/processor.h>
#include <asm/sections.h>

extern struct static_call_site __start_static_call_sites[],
			       __stop_static_call_sites[];
extern struct static_call_tramp_key __start_static_call_tramp_key[],
				    __stop_static_call_tramp_key[];

static bool static_call_initialized;

/* mutex to protect key modules/sites */
static DEFINE_MUTEX(static_call_mutex);

static void static_call_lock(void)
{
	mutex_lock(&static_call_mutex);
}

static void static_call_unlock(void)
{
	mutex_unlock(&static_call_mutex);
}

static inline void *static_call_addr(struct static_call_site *site)
{
	return (void *)((long)site->addr + (long)&site->addr);
}


static inline struct static_call_key *static_call_key(const struct static_call_site *site)
{
	return (struct static_call_key *)
		(((long)site->key + (long)&site->key) & ~STATIC_CALL_SITE_FLAGS);
}

/* These assume the key is word-aligned. */
static inline bool static_call_is_init(struct static_call_site *site)
{
	return ((long)site->key + (long)&site->key) & STATIC_CALL_SITE_INIT;
}

static inline bool static_call_is_tail(struct static_call_site *site)
{
	return ((long)site->key + (long)&site->key) & STATIC_CALL_SITE_TAIL;
}

static inline void static_call_set_init(struct static_call_site *site)
{
	site->key = ((long)static_call_key(site) | STATIC_CALL_SITE_INIT) -
		    (long)&site->key;
}

static int static_call_site_cmp(const void *_a, const void *_b)
{
	const struct static_call_site *a = _a;
	const struct static_call_site *b = _b;
	const struct static_call_key *key_a = static_call_key(a);
	const struct static_call_key *key_b = static_call_key(b);

	if (key_a < key_b)
		return -1;

	if (key_a > key_b)
		return 1;

	return 0;
}

static void static_call_site_swap(void *_a, void *_b, int size)
{
	long delta = (unsigned long)_a - (unsigned long)_b;
	struct static_call_site *a = _a;
	struct static_call_site *b = _b;
	struct static_call_site tmp = *a;

	a->addr = b->addr  - delta;
	a->key  = b->key   - delta;

	b->addr = tmp.addr + delta;
	b->key  = tmp.key  + delta;
}

static inline void static_call_sort_entries(struct static_call_site *start,
					    struct static_call_site *stop)
{
	sort(start, stop - start, sizeof(struct static_call_site),
	     static_call_site_cmp, static_call_site_swap);
}

static inline bool static_call_key_has_mods(struct static_call_key *key)
{
	return !(key->type & 1);
}

static inline struct static_call_mod *static_call_key_next(struct static_call_key *key)
{
	if (!static_call_key_has_mods(key))
		return NULL;

	return key->mods;
}

static inline struct static_call_site *static_call_key_sites(struct static_call_key *key)
{
	if (static_call_key_has_mods(key))
		return NULL;

	return (struct static_call_site *)(key->type & ~1);
}

void __static_call_update(struct static_call_key *key, void *tramp, void *func)
{
	struct static_call_site *site, *stop;
	struct static_call_mod *site_mod, first;

	cpus_read_lock();
	static_call_lock();

	if (key->func == func)
		goto done;

	key->func = func;

	arch_static_call_transform(NULL, tramp, func, false);

	/*
	 * If uninitialized, we'll not update the callsites, but they still
	 * point to the trampoline and we just patched that.
	 */
	if (WARN_ON_ONCE(!static_call_initialized))
		goto done;

	first = (struct static_call_mod){
		.next = static_call_key_next(key),
		.mod = NULL,
		.sites = static_call_key_sites(key),
	};

	for (site_mod = &first; site_mod; site_mod = site_mod->next) {
		struct module *mod = site_mod->mod;

		if (!site_mod->sites) {
			/*
			 * This can happen if the static call key is defined in
			 * a module which doesn't use it.
			 *
			 * It also happens in the has_mods case, where the
			 * 'first' entry has no sites associated with it.
			 */
			continue;
		}

		stop = __stop_static_call_sites;

#ifdef CONFIG_MODULES
		if (mod) {
			stop = mod->static_call_sites +
			       mod->num_static_call_sites;
		}
#endif

		for (site = site_mod->sites;
		     site < stop && static_call_key(site) == key; site++) {
			void *site_addr = static_call_addr(site);

			if (static_call_is_init(site)) {
				/*
				 * Don't write to call sites which were in
				 * initmem and have since been freed.
				 */
				if (!mod && system_state >= SYSTEM_RUNNING)
					continue;
				if (mod && !within_module_init((unsigned long)site_addr, mod))
					continue;
			}

			if (!kernel_text_address((unsigned long)site_addr)) {
				/*
				 * This skips patching built-in __exit, which
				 * is part of init_section_contains() but is
				 * not part of kernel_text_address().
				 *
				 * Skipping built-in __exit is fine since it
				 * will never be executed.
				 */
				WARN_ONCE(!static_call_is_init(site),
					  "can't patch static call site at %pS",
					  site_addr);
				continue;
			}

			arch_static_call_transform(site_addr, NULL, func,
				static_call_is_tail(site));
		}
	}

done:
	static_call_unlock();
	cpus_read_unlock();
}
EXPORT_SYMBOL_GPL(__static_call_update);

static int __static_call_init(struct module *mod,
			      struct static_call_site *start,
			      struct static_call_site *stop)
{
	struct static_call_site *site;
	struct static_call_key *key, *prev_key = NULL;
	struct static_call_mod *site_mod;

	if (start == stop)
		return 0;

	static_call_sort_entries(start, stop);

	for (site = start; site < stop; site++) {
		void *site_addr = static_call_addr(site);

		if ((mod && within_module_init((unsigned long)site_addr, mod)) ||
		    (!mod && init_section_contains(site_addr, 1)))
			static_call_set_init(site);

		key = static_call_key(site);
		if (key != prev_key) {
			prev_key = key;

			/*
			 * For vmlinux (!mod) avoid the allocation by storing
			 * the sites pointer in the key itself. Also see
			 * __static_call_update()'s @first.
			 *
			 * This allows architectures (eg. x86) to call
			 * static_call_init() before memory allocation works.
			 */
			if (!mod) {
				key->sites = site;
				key->type |= 1;
				goto do_transform;
			}

			site_mod = kzalloc(sizeof(*site_mod), GFP_KERNEL);
			if (!site_mod)
				return -ENOMEM;

			/*
			 * When the key has a direct sites pointer, extract
			 * that into an explicit struct static_call_mod, so we
			 * can have a list of modules.
			 */
			if (static_call_key_sites(key)) {
				site_mod->mod = NULL;
				site_mod->next = NULL;
				site_mod->sites = static_call_key_sites(key);

				key->mods = site_mod;

				site_mod = kzalloc(sizeof(*site_mod), GFP_KERNEL);
				if (!site_mod)
					return -ENOMEM;
			}

			site_mod->mod = mod;
			site_mod->sites = site;
			site_mod->next = static_call_key_next(key);
			key->mods = site_mod;
		}

do_transform:
		arch_static_call_transform(site_addr, NULL, key->func,
				static_call_is_tail(site));
	}

	return 0;
}

static int addr_conflict(struct static_call_site *site, void *start, void *end)
{
	unsigned long addr = (unsigned long)static_call_addr(site);

	if (addr <= (unsigned long)end &&
	    addr + CALL_INSN_SIZE > (unsigned long)start)
		return 1;

	return 0;
}

static int __static_call_text_reserved(struct static_call_site *iter_start,
				       struct static_call_site *iter_stop,
				       void *start, void *end)
{
	struct static_call_site *iter = iter_start;

	while (iter < iter_stop) {
		if (addr_conflict(iter, start, end))
			return 1;
		iter++;
	}

	return 0;
}

#ifdef CONFIG_MODULES

static int __static_call_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 = __static_call_text_reserved(mod->static_call_sites,
			mod->static_call_sites + mod->num_static_call_sites,
			start, end);

	module_put(mod);

	return ret;
}

static unsigned long tramp_key_lookup(unsigned long addr)
{
	struct static_call_tramp_key *start = __start_static_call_tramp_key;
	struct static_call_tramp_key *stop = __stop_static_call_tramp_key;
	struct static_call_tramp_key *tramp_key;

	for (tramp_key = start; tramp_key != stop; tramp_key++) {
		unsigned long tramp;

		tramp = (long)tramp_key->tramp + (long)&tramp_key->tramp;
		if (tramp == addr)
			return (long)tramp_key->key + (long)&tramp_key->key;
	}

	return 0;
}

static int static_call_add_module(struct module *mod)
{
	struct static_call_site *start = mod->static_call_sites;
	struct static_call_site *stop = start + mod->num_static_call_sites;
	struct static_call_site *site;

	for (site = start; site != stop; site++) {
		unsigned long s_key = (long)site->key + (long)&site->key;
		unsigned long addr = s_key & ~STATIC_CALL_SITE_FLAGS;
		unsigned long key;

		/*
		 * Is the key is exported, 'addr' points to the key, which
		 * means modules are allowed to call static_call_update() on
		 * it.
		 *
		 * Otherwise, the key isn't exported, and 'addr' points to the
		 * trampoline so we need to lookup the key.
		 *
		 * We go through this dance to prevent crazy modules from
		 * abusing sensitive static calls.
		 */
		if (!kernel_text_address(addr))
			continue;

		key = tramp_key_lookup(addr);
		if (!key) {
			pr_warn("Failed to fixup __raw_static_call() usage at: %ps\n",
				static_call_addr(site));
			return -EINVAL;
		}

		key |= s_key & STATIC_CALL_SITE_FLAGS;
		site->key = key - (long)&site->key;
	}

	return __static_call_init(mod, start, stop);
}

static void static_call_del_module(struct module *mod)
{
	struct static_call_site *start = mod->static_call_sites;
	struct static_call_site *stop = mod->static_call_sites +
					mod->num_static_call_sites;
	struct static_call_key *key, *prev_key = NULL;
	struct static_call_mod *site_mod, **prev;
	struct static_call_site *site;

	for (site = start; site < stop; site++) {
		key = static_call_key(site);
		if (key == prev_key)
			continue;

		prev_key = key;

		for (prev = &key->mods, site_mod = key->mods;
		     site_mod && site_mod->mod != mod;
		     prev = &site_mod->next, site_mod = site_mod->next)
			;

		if (!site_mod)
			continue;

		*prev = site_mod->next;
		kfree(site_mod);
	}
}

static int static_call_module_notify(struct notifier_block *nb,
				     unsigned long val, void *data)
{
	struct module *mod = data;
	int ret = 0;

	cpus_read_lock();
	static_call_lock();

	switch (val) {
	case MODULE_STATE_COMING:
		ret = static_call_add_module(mod);
		if (ret) {
			WARN(1, "Failed to allocate memory for static calls");
			static_call_del_module(mod);
		}
		break;
	case MODULE_STATE_GOING:
		static_call_del_module(mod);
		break;
	}

	static_call_unlock();
	cpus_read_unlock();

	return notifier_from_errno(ret);
}

static struct notifier_block static_call_module_nb = {
	.notifier_call = static_call_module_notify,
};

#else

static inline int __static_call_mod_text_reserved(void *start, void *end)
{
	return 0;
}

#endif /* CONFIG_MODULES */

int static_call_text_reserved(void *start, void *end)
{
	int ret = __static_call_text_reserved(__start_static_call_sites,
			__stop_static_call_sites, start, end);

	if (ret)
		return ret;

	return __static_call_mod_text_reserved(start, end);
}

int __init static_call_init(void)
{
	int ret;

	if (static_call_initialized)
		return 0;

	cpus_read_lock();
	static_call_lock();
	ret = __static_call_init(NULL, __start_static_call_sites,
				 __stop_static_call_sites);
	static_call_unlock();
	cpus_read_unlock();

	if (ret) {
		pr_err("Failed to allocate memory for static_call!\n");
		BUG();
	}

	static_call_initialized = true;

#ifdef CONFIG_MODULES
	register_module_notifier(&static_call_module_nb);
#endif
	return 0;
}
early_initcall(static_call_init);

#ifdef CONFIG_STATIC_CALL_SELFTEST

static int func_a(int x)
{
	return x+1;
}

static int func_b(int x)
{
	return x+2;
}

DEFINE_STATIC_CALL(sc_selftest, func_a);

static struct static_call_data {
      int (*func)(int);
      int val;
      int expect;
} static_call_data [] __initdata = {
      { NULL,   2, 3 },
      { func_b, 2, 4 },
      { func_a, 2, 3 }
};

static int __init test_static_call_init(void)
{
      int i;

      for (i = 0; i < ARRAY_SIZE(static_call_data); i++ ) {
	      struct static_call_data *scd = &static_call_data[i];

              if (scd->func)
                      static_call_update(sc_selftest, scd->func);

              WARN_ON(static_call(sc_selftest)(scd->val) != scd->expect);
      }

      return 0;
}
early_initcall(test_static_call_init);

#endif /* CONFIG_STATIC_CALL_SELFTEST */
Commit	Line	Data
9183c3f9 JP	1	// SPDX-License-Identifier: GPL-2.0
	2	#include <linux/init.h>
	3	#include <linux/static_call.h>
	4	#include <linux/bug.h>
	5	#include <linux/smp.h>
	6	#include <linux/sort.h>
	7	#include <linux/slab.h>
	8	#include <linux/module.h>
	9	#include <linux/cpu.h>
	10	#include <linux/processor.h>
	11	#include <asm/sections.h>
	12
	13	extern struct static_call_site __start_static_call_sites[],
	14	__stop_static_call_sites[];
6e2f698e JP	15	extern struct static_call_tramp_key __start_static_call_tramp_key[],
6e2f698e JP	16	__stop_static_call_tramp_key[];
9183c3f9 JP	17
	18	static bool static_call_initialized;
	19
9183c3f9 JP	20	/* mutex to protect key modules/sites */
	21	static DEFINE_MUTEX(static_call_mutex);
	22
	23	static void static_call_lock(void)
	24	{
	25	mutex_lock(&static_call_mutex);
	26	}
	27
	28	static void static_call_unlock(void)
	29	{
	30	mutex_unlock(&static_call_mutex);
	31	}
	32
	33	static inline void static_call_addr(struct static_call_site site)
	34	{
	35	return (void *)((long)site->addr + (long)&site->addr);
	36	}
	37
	38
	39	static inline struct static_call_key static_call_key(const struct static_call_site site)
	40	{
	41	return (struct static_call_key *)
5b06fd3b	42	(((long)site->key + (long)&site->key) & ~STATIC_CALL_SITE_FLAGS);
9183c3f9 JP	43	}
	44
	45	/* These assume the key is word-aligned. */
	46	static inline bool static_call_is_init(struct static_call_site *site)
	47	{
5b06fd3b PZ	48	return ((long)site->key + (long)&site->key) & STATIC_CALL_SITE_INIT;
	49	}
	50
	51	static inline bool static_call_is_tail(struct static_call_site *site)
	52	{
	53	return ((long)site->key + (long)&site->key) & STATIC_CALL_SITE_TAIL;
9183c3f9 JP	54	}
	55
	56	static inline void static_call_set_init(struct static_call_site *site)
	57	{
5b06fd3b	58	site->key = ((long)static_call_key(site) \| STATIC_CALL_SITE_INIT) -
9183c3f9 JP	59	(long)&site->key;
	60	}
	61
	62	static int static_call_site_cmp(const void _a, const void _b)
	63	{
	64	const struct static_call_site *a = _a;
	65	const struct static_call_site *b = _b;
	66	const struct static_call_key *key_a = static_call_key(a);
	67	const struct static_call_key *key_b = static_call_key(b);
	68
	69	if (key_a < key_b)
	70	return -1;
	71
	72	if (key_a > key_b)
	73	return 1;
	74
	75	return 0;
	76	}
	77
	78	static void static_call_site_swap(void _a, void _b, int size)
	79	{
	80	long delta = (unsigned long)_a - (unsigned long)_b;
	81	struct static_call_site *a = _a;
	82	struct static_call_site *b = _b;
	83	struct static_call_site tmp = *a;
	84
	85	a->addr = b->addr - delta;
	86	a->key = b->key - delta;
	87
	88	b->addr = tmp.addr + delta;
	89	b->key = tmp.key + delta;
	90	}
	91
	92	static inline void static_call_sort_entries(struct static_call_site *start,
	93	struct static_call_site *stop)
	94	{
	95	sort(start, stop - start, sizeof(struct static_call_site),
	96	static_call_site_cmp, static_call_site_swap);
	97	}
	98
a945c834 PZ	99	static inline bool static_call_key_has_mods(struct static_call_key *key)
	100	{
	101	return !(key->type & 1);
	102	}
	103
	104	static inline struct static_call_mod static_call_key_next(struct static_call_key key)
	105	{
	106	if (!static_call_key_has_mods(key))
	107	return NULL;
	108
	109	return key->mods;
	110	}
	111
	112	static inline struct static_call_site static_call_key_sites(struct static_call_key key)
	113	{
	114	if (static_call_key_has_mods(key))
	115	return NULL;
	116
	117	return (struct static_call_site *)(key->type & ~1);
	118	}
	119
9183c3f9 JP	120	void __static_call_update(struct static_call_key key, void tramp, void *func)
	121	{
	122	struct static_call_site site, stop;
a945c834	123	struct static_call_mod *site_mod, first;
9183c3f9 JP	124
	125	cpus_read_lock();
	126	static_call_lock();
	127
	128	if (key->func == func)
	129	goto done;
	130
	131	key->func = func;
	132
5b06fd3b	133	arch_static_call_transform(NULL, tramp, func, false);
9183c3f9 JP	134
	135	/*
	136	* If uninitialized, we'll not update the callsites, but they still
	137	* point to the trampoline and we just patched that.
	138	*/
	139	if (WARN_ON_ONCE(!static_call_initialized))
	140	goto done;
	141
a945c834 PZ	142	first = (struct static_call_mod){
	143	.next = static_call_key_next(key),
	144	.mod = NULL,
	145	.sites = static_call_key_sites(key),
	146	};
	147
	148	for (site_mod = &first; site_mod; site_mod = site_mod->next) {
9183c3f9 JP	149	struct module *mod = site_mod->mod;
	150
	151	if (!site_mod->sites) {
	152	/*
	153	* This can happen if the static call key is defined in
	154	* a module which doesn't use it.
a945c834 PZ	155	*
	156	* It also happens in the has_mods case, where the
	157	* 'first' entry has no sites associated with it.
9183c3f9 JP	158	*/
	159	continue;
	160	}
	161
	162	stop = __stop_static_call_sites;
	163
	164	#ifdef CONFIG_MODULES
	165	if (mod) {
	166	stop = mod->static_call_sites +
	167	mod->num_static_call_sites;
	168	}
	169	#endif
	170
	171	for (site = site_mod->sites;
	172	site < stop && static_call_key(site) == key; site++) {
	173	void *site_addr = static_call_addr(site);
	174
	175	if (static_call_is_init(site)) {
	176	/*
	177	* Don't write to call sites which were in
	178	* initmem and have since been freed.
	179	*/
	180	if (!mod && system_state >= SYSTEM_RUNNING)
	181	continue;
	182	if (mod && !within_module_init((unsigned long)site_addr, mod))
	183	continue;
	184	}
	185
	186	if (!kernel_text_address((unsigned long)site_addr)) {
d4ea1929 PZ	187	/*
	188	* This skips patching built-in __exit, which
	189	* is part of init_section_contains() but is
	190	* not part of kernel_text_address().
	191	*
	192	* Skipping built-in __exit is fine since it
	193	* will never be executed.
	194	*/
	195	WARN_ONCE(!static_call_is_init(site),
	196	"can't patch static call site at %pS",
9183c3f9 JP	197	site_addr);
	198	continue;
	199	}
	200
5b06fd3b PZ	201	arch_static_call_transform(site_addr, NULL, func,
5b06fd3b PZ	202	static_call_is_tail(site));
9183c3f9 JP	203	}
	204	}
	205
	206	done:
	207	static_call_unlock();
	208	cpus_read_unlock();
	209	}
	210	EXPORT_SYMBOL_GPL(__static_call_update);
	211
	212	static int __static_call_init(struct module *mod,
	213	struct static_call_site *start,
	214	struct static_call_site *stop)
	215	{
	216	struct static_call_site *site;
	217	struct static_call_key key, prev_key = NULL;
	218	struct static_call_mod *site_mod;
	219
	220	if (start == stop)
	221	return 0;
	222
	223	static_call_sort_entries(start, stop);
	224
	225	for (site = start; site < stop; site++) {
	226	void *site_addr = static_call_addr(site);
	227
	228	if ((mod && within_module_init((unsigned long)site_addr, mod)) \|\|
	229	(!mod && init_section_contains(site_addr, 1)))
	230	static_call_set_init(site);
	231
	232	key = static_call_key(site);
	233	if (key != prev_key) {
	234	prev_key = key;
	235
a945c834 PZ	236	/*
	237	* For vmlinux (!mod) avoid the allocation by storing
	238	* the sites pointer in the key itself. Also see
	239	* __static_call_update()'s @first.
	240	*
	241	* This allows architectures (eg. x86) to call
	242	* static_call_init() before memory allocation works.
	243	*/
	244	if (!mod) {
	245	key->sites = site;
	246	key->type \|= 1;
	247	goto do_transform;
	248	}
	249
9183c3f9 JP	250	site_mod = kzalloc(sizeof(*site_mod), GFP_KERNEL);
	251	if (!site_mod)
	252	return -ENOMEM;
	253
a945c834 PZ	254	/*
	255	* When the key has a direct sites pointer, extract
	256	* that into an explicit struct static_call_mod, so we
	257	* can have a list of modules.
	258	*/
	259	if (static_call_key_sites(key)) {
	260	site_mod->mod = NULL;
	261	site_mod->next = NULL;
	262	site_mod->sites = static_call_key_sites(key);
	263
	264	key->mods = site_mod;
	265
	266	site_mod = kzalloc(sizeof(*site_mod), GFP_KERNEL);
	267	if (!site_mod)
	268	return -ENOMEM;
	269	}
	270
9183c3f9 JP	271	site_mod->mod = mod;
9183c3f9 JP	272	site_mod->sites = site;
a945c834	273	site_mod->next = static_call_key_next(key);
9183c3f9 JP	274	key->mods = site_mod;
	275	}
	276
a945c834	277	do_transform:
5b06fd3b PZ	278	arch_static_call_transform(site_addr, NULL, key->func,
5b06fd3b PZ	279	static_call_is_tail(site));
9183c3f9 JP	280	}
	281
	282	return 0;
	283	}
	284
6333e8f7 PZ	285	static int addr_conflict(struct static_call_site site, void start, void *end)
	286	{
	287	unsigned long addr = (unsigned long)static_call_addr(site);
	288
	289	if (addr <= (unsigned long)end &&
	290	addr + CALL_INSN_SIZE > (unsigned long)start)
	291	return 1;
	292
	293	return 0;
	294	}
	295
	296	static int __static_call_text_reserved(struct static_call_site *iter_start,
	297	struct static_call_site *iter_stop,
	298	void start, void end)
	299	{
	300	struct static_call_site *iter = iter_start;
	301
	302	while (iter < iter_stop) {
	303	if (addr_conflict(iter, start, end))
	304	return 1;
	305	iter++;
	306	}
	307
	308	return 0;
	309	}
	310
9183c3f9 JP	311	#ifdef CONFIG_MODULES
9183c3f9 JP	312
6333e8f7 PZ	313	static int __static_call_mod_text_reserved(void start, void end)
	314	{
	315	struct module *mod;
	316	int ret;
	317
	318	preempt_disable();
	319	mod = __module_text_address((unsigned long)start);
	320	WARN_ON_ONCE(__module_text_address((unsigned long)end) != mod);
	321	if (!try_module_get(mod))
	322	mod = NULL;
	323	preempt_enable();
	324
	325	if (!mod)
	326	return 0;
	327
	328	ret = __static_call_text_reserved(mod->static_call_sites,
	329	mod->static_call_sites + mod->num_static_call_sites,
	330	start, end);
	331
	332	module_put(mod);
	333
	334	return ret;
	335	}
	336
6e2f698e JP	337	static unsigned long tramp_key_lookup(unsigned long addr)
	338	{
	339	struct static_call_tramp_key *start = __start_static_call_tramp_key;
	340	struct static_call_tramp_key *stop = __stop_static_call_tramp_key;
	341	struct static_call_tramp_key *tramp_key;
	342
	343	for (tramp_key = start; tramp_key != stop; tramp_key++) {
	344	unsigned long tramp;
	345
	346	tramp = (long)tramp_key->tramp + (long)&tramp_key->tramp;
	347	if (tramp == addr)
	348	return (long)tramp_key->key + (long)&tramp_key->key;
	349	}
	350
	351	return 0;
	352	}
	353
9183c3f9 JP	354	static int static_call_add_module(struct module *mod)
9183c3f9 JP	355	{
6e2f698e JP	356	struct static_call_site *start = mod->static_call_sites;
	357	struct static_call_site *stop = start + mod->num_static_call_sites;
	358	struct static_call_site *site;
	359
	360	for (site = start; site != stop; site++) {
373c7c37 PZ	361	unsigned long s_key = (long)site->key + (long)&site->key;
373c7c37 PZ	362	unsigned long addr = s_key & ~STATIC_CALL_SITE_FLAGS;
6e2f698e JP	363	unsigned long key;
	364
	365	/*
	366	* Is the key is exported, 'addr' points to the key, which
	367	* means modules are allowed to call static_call_update() on
	368	* it.
	369	*
	370	* Otherwise, the key isn't exported, and 'addr' points to the
	371	* trampoline so we need to lookup the key.
	372	*
	373	* We go through this dance to prevent crazy modules from
	374	* abusing sensitive static calls.
	375	*/
	376	if (!kernel_text_address(addr))
	377	continue;
	378
	379	key = tramp_key_lookup(addr);
	380	if (!key) {
	381	pr_warn("Failed to fixup __raw_static_call() usage at: %ps\n",
	382	static_call_addr(site));
	383	return -EINVAL;
	384	}
	385
373c7c37 PZ	386	key \|= s_key & STATIC_CALL_SITE_FLAGS;
373c7c37 PZ	387	site->key = key - (long)&site->key;
6e2f698e JP	388	}
	389
	390	return __static_call_init(mod, start, stop);
9183c3f9 JP	391	}
	392
	393	static void static_call_del_module(struct module *mod)
	394	{
	395	struct static_call_site *start = mod->static_call_sites;
	396	struct static_call_site *stop = mod->static_call_sites +
	397	mod->num_static_call_sites;
	398	struct static_call_key key, prev_key = NULL;
	399	struct static_call_mod site_mod, *prev;
	400	struct static_call_site *site;
	401
	402	for (site = start; site < stop; site++) {
	403	key = static_call_key(site);
	404	if (key == prev_key)
	405	continue;
	406
	407	prev_key = key;
	408
	409	for (prev = &key->mods, site_mod = key->mods;
	410	site_mod && site_mod->mod != mod;
	411	prev = &site_mod->next, site_mod = site_mod->next)
	412	;
	413
	414	if (!site_mod)
	415	continue;
	416
	417	*prev = site_mod->next;
	418	kfree(site_mod);
	419	}
	420	}
	421
	422	static int static_call_module_notify(struct notifier_block *nb,
	423	unsigned long val, void *data)
	424	{
	425	struct module *mod = data;
	426	int ret = 0;
	427
	428	cpus_read_lock();
	429	static_call_lock();
	430
	431	switch (val) {
	432	case MODULE_STATE_COMING:
	433	ret = static_call_add_module(mod);
	434	if (ret) {
	435	WARN(1, "Failed to allocate memory for static calls");
	436	static_call_del_module(mod);
	437	}
	438	break;
	439	case MODULE_STATE_GOING:
	440	static_call_del_module(mod);
	441	break;
	442	}
	443
	444	static_call_unlock();
	445	cpus_read_unlock();
	446
	447	return notifier_from_errno(ret);
	448	}
	449
	450	static struct notifier_block static_call_module_nb = {
	451	.notifier_call = static_call_module_notify,
	452	};
	453
6333e8f7 PZ	454	#else
	455
	456	static inline int __static_call_mod_text_reserved(void start, void end)
	457	{
	458	return 0;
	459	}
	460
9183c3f9 JP	461	#endif /* CONFIG_MODULES */
9183c3f9 JP	462
6333e8f7 PZ	463	int static_call_text_reserved(void start, void end)
	464	{
	465	int ret = __static_call_text_reserved(__start_static_call_sites,
	466	__stop_static_call_sites, start, end);
	467
	468	if (ret)
	469	return ret;
	470
	471	return __static_call_mod_text_reserved(start, end);
	472	}
	473
69e0ad37	474	int __init static_call_init(void)
9183c3f9 JP	475	{
	476	int ret;
	477
	478	if (static_call_initialized)
69e0ad37	479	return 0;
9183c3f9 JP	480
	481	cpus_read_lock();
	482	static_call_lock();
	483	ret = __static_call_init(NULL, __start_static_call_sites,
	484	__stop_static_call_sites);
	485	static_call_unlock();
	486	cpus_read_unlock();
	487
	488	if (ret) {
	489	pr_err("Failed to allocate memory for static_call!\n");
	490	BUG();
	491	}
	492
	493	static_call_initialized = true;
	494
	495	#ifdef CONFIG_MODULES
	496	register_module_notifier(&static_call_module_nb);
	497	#endif
69e0ad37	498	return 0;
9183c3f9 JP	499	}
9183c3f9 JP	500	early_initcall(static_call_init);
f03c4129 PZ	501
	502	#ifdef CONFIG_STATIC_CALL_SELFTEST
	503
	504	static int func_a(int x)
	505	{
	506	return x+1;
	507	}
	508
	509	static int func_b(int x)
	510	{
	511	return x+2;
	512	}
	513
	514	DEFINE_STATIC_CALL(sc_selftest, func_a);
	515
	516	static struct static_call_data {
	517	int (*func)(int);
	518	int val;
	519	int expect;
	520	} static_call_data [] __initdata = {
	521	{ NULL, 2, 3 },
	522	{ func_b, 2, 4 },
	523	{ func_a, 2, 3 }
	524	};
	525
	526	static int __init test_static_call_init(void)
	527	{
	528	int i;
	529
	530	for (i = 0; i < ARRAY_SIZE(static_call_data); i++ ) {
	531	struct static_call_data *scd = &static_call_data[i];
	532
	533	if (scd->func)
	534	static_call_update(sc_selftest, scd->func);
	535
	536	WARN_ON(static_call(sc_selftest)(scd->val) != scd->expect);
	537	}
	538
	539	return 0;
	540	}
	541	early_initcall(test_static_call_init);
	542
	543	#endif /* CONFIG_STATIC_CALL_SELFTEST */