539 строки
12 KiB
C
539 строки
12 KiB
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)) {
|
|
WARN_ONCE(1, "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 addr = (unsigned long)static_call_key(site);
|
|
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;
|
|
}
|
|
|
|
site->key = (key - (long)&site->key) |
|
|
(site->key & STATIC_CALL_SITE_FLAGS);
|
|
}
|
|
|
|
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);
|
|
|
|
long __static_call_return0(void)
|
|
{
|
|
return 0;
|
|
}
|
|
|
|
#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 */
|