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Merge tag 'modules-6.15-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/modules/linux

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Pull modules updates from Petr Pavlu:

 - Use RCU instead of RCU-sched

   The mix of rcu_read_lock(), rcu_read_lock_sched() and
   preempt_disable() in the module code and its users has
   been replaced with just rcu_read_lock()

 - The rest of changes are smaller fixes and updates

* tag 'modules-6.15-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/modules/linux: (32 commits)
  MAINTAINERS: Update the MODULE SUPPORT section
  module: Remove unnecessary size argument when calling strscpy()
  module: Replace deprecated strncpy() with strscpy()
  params: Annotate struct module_param_attrs with __counted_by()
  bug: Use RCU instead RCU-sched to protect module_bug_list.
  static_call: Use RCU in all users of __module_text_address().
  kprobes: Use RCU in all users of __module_text_address().
  bpf: Use RCU in all users of __module_text_address().
  jump_label: Use RCU in all users of __module_text_address().
  jump_label: Use RCU in all users of __module_address().
  x86: Use RCU in all users of __module_address().
  cfi: Use RCU while invoking __module_address().
  powerpc/ftrace: Use RCU in all users of __module_text_address().
  LoongArch: ftrace: Use RCU in all users of __module_text_address().
  LoongArch/orc: Use RCU in all users of __module_address().
  arm64: module: Use RCU in all users of __module_text_address().
  ARM: module: Use RCU in all users of __module_text_address().
  module: Use RCU in all users of __module_text_address().
  module: Use RCU in all users of __module_address().
  module: Use RCU in search_module_extables().
  ...
This commit is contained in:
Linus Torvalds
2025-03-30 15:44:36 -07:00
parent 7405c0f01a 897c0b4e27
commit 01d5b167dc
27 changed files with 160 additions and 250 deletions
Download Patch File Download Diff File Expand all files Collapse all files

11
kernel/module/internal.h
View File

@@ -124,17 +124,6 @@ char *module_next_tag_pair(char *string, unsigned long *secsize);
#define for_each_modinfo_entry(entry, info, name) \
for (entry = get_modinfo(info, name); entry; entry = get_next_modinfo(info, name, entry))
static inline void module_assert_mutex_or_preempt(void)
{
#ifdef CONFIG_LOCKDEP
if (unlikely(!debug_locks))
return;
WARN_ON_ONCE(!rcu_read_lock_sched_held() &&
!lockdep_is_held(&module_mutex));
#endif
}
static inline unsigned long kernel_symbol_value(const struct kernel_symbol *sym)
{
#ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS

73
kernel/module/kallsyms.c
View File

@@ -177,19 +177,15 @@ void add_kallsyms(struct module *mod, const struct load_info *info)
unsigned long strtab_size;
void *data_base = mod->mem[MOD_DATA].base;
void *init_data_base = mod->mem[MOD_INIT_DATA].base;
struct mod_kallsyms *kallsyms;
/* Set up to point into init section. */
mod->kallsyms = (void __rcu *)init_data_base +
info->mod_kallsyms_init_off;
kallsyms = init_data_base + info->mod_kallsyms_init_off;
rcu_read_lock();
/* The following is safe since this pointer cannot change */
rcu_dereference(mod->kallsyms)->symtab = (void *)symsec->sh_addr;
rcu_dereference(mod->kallsyms)->num_symtab = symsec->sh_size / sizeof(Elf_Sym);
kallsyms->symtab = (void *)symsec->sh_addr;
kallsyms->num_symtab = symsec->sh_size / sizeof(Elf_Sym);
/* Make sure we get permanent strtab: don't use info->strtab. */
rcu_dereference(mod->kallsyms)->strtab =
(void *)info->sechdrs[info->index.str].sh_addr;
rcu_dereference(mod->kallsyms)->typetab = init_data_base + info->init_typeoffs;
kallsyms->strtab = (void *)info->sechdrs[info->index.str].sh_addr;
kallsyms->typetab = init_data_base + info->init_typeoffs;
/*
* Now populate the cut down core kallsyms for after init
@@ -199,20 +195,19 @@ void add_kallsyms(struct module *mod, const struct load_info *info)
mod->core_kallsyms.strtab = s = data_base + info->stroffs;
mod->core_kallsyms.typetab = data_base + info->core_typeoffs;
strtab_size = info->core_typeoffs - info->stroffs;
src = rcu_dereference(mod->kallsyms)->symtab;
for (ndst = i = 0; i < rcu_dereference(mod->kallsyms)->num_symtab; i++) {
rcu_dereference(mod->kallsyms)->typetab[i] = elf_type(src + i, info);
src = kallsyms->symtab;
for (ndst = i = 0; i < kallsyms->num_symtab; i++) {
kallsyms->typetab[i] = elf_type(src + i, info);
if (i == 0 || is_livepatch_module(mod) ||
is_core_symbol(src + i, info->sechdrs, info->hdr->e_shnum,
info->index.pcpu)) {
ssize_t ret;
mod->core_kallsyms.typetab[ndst] =
rcu_dereference(mod->kallsyms)->typetab[i];
kallsyms->typetab[i];
dst[ndst] = src[i];
dst[ndst++].st_name = s - mod->core_kallsyms.strtab;
ret = strscpy(s,
&rcu_dereference(mod->kallsyms)->strtab[src[i].st_name],
ret = strscpy(s, &kallsyms->strtab[src[i].st_name],
strtab_size);
if (ret < 0)
break;
@@ -220,7 +215,9 @@ void add_kallsyms(struct module *mod, const struct load_info *info)
strtab_size -= ret + 1;
}
}
rcu_read_unlock();
/* Set up to point into init section. */
rcu_assign_pointer(mod->kallsyms, kallsyms);
mod->core_kallsyms.num_symtab = ndst;
}
@@ -260,7 +257,7 @@ static const char *find_kallsyms_symbol(struct module *mod,
{
unsigned int i, best = 0;
unsigned long nextval, bestval;
struct mod_kallsyms *kallsyms = rcu_dereference_sched(mod->kallsyms);
struct mod_kallsyms *kallsyms = rcu_dereference(mod->kallsyms);
struct module_memory *mod_mem;
/* At worse, next value is at end of module */
@@ -319,7 +316,7 @@ void * __weak dereference_module_function_descriptor(struct module *mod,
/*
* For kallsyms to ask for address resolution. NULL means not found. Careful
* not to lock to avoid deadlock on oopses, simply disable preemption.
* not to lock to avoid deadlock on oopses, RCU is enough.
*/
int module_address_lookup(unsigned long addr,
unsigned long *size,
@@ -332,7 +329,7 @@ int module_address_lookup(unsigned long addr,
int ret = 0;
struct module *mod;
preempt_disable();
guard(rcu)();
mod = __module_address(addr);
if (mod) {
if (modname)
@@ -350,8 +347,6 @@ int module_address_lookup(unsigned long addr,
if (sym)
ret = strscpy(namebuf, sym, KSYM_NAME_LEN);
}
preempt_enable();
return ret;
}
@@ -359,7 +354,7 @@ int lookup_module_symbol_name(unsigned long addr, char *symname)
{
struct module *mod;
preempt_disable();
guard(rcu)();
list_for_each_entry_rcu(mod, &modules, list) {
if (mod->state == MODULE_STATE_UNFORMED)
continue;
@@ -371,12 +366,10 @@ int lookup_module_symbol_name(unsigned long addr, char *symname)
goto out;
strscpy(symname, sym, KSYM_NAME_LEN);
preempt_enable();
return 0;
}
}
out:
preempt_enable();
return -ERANGE;
}
@@ -385,13 +378,13 @@ int module_get_kallsym(unsigned int symnum, unsigned long *value, char *type,
{
struct module *mod;
preempt_disable();
guard(rcu)();
list_for_each_entry_rcu(mod, &modules, list) {
struct mod_kallsyms *kallsyms;
if (mod->state == MODULE_STATE_UNFORMED)
continue;
kallsyms = rcu_dereference_sched(mod->kallsyms);
kallsyms = rcu_dereference(mod->kallsyms);
if (symnum < kallsyms->num_symtab) {
const Elf_Sym *sym = &kallsyms->symtab[symnum];
@@ -400,12 +393,10 @@ int module_get_kallsym(unsigned int symnum, unsigned long *value, char *type,
strscpy(name, kallsyms_symbol_name(kallsyms, symnum), KSYM_NAME_LEN);
strscpy(module_name, mod->name, MODULE_NAME_LEN);
*exported = is_exported(name, *value, mod);
preempt_enable();
return 0;
}
symnum -= kallsyms->num_symtab;
}
preempt_enable();
return -ERANGE;
}
@@ -413,7 +404,7 @@ int module_get_kallsym(unsigned int symnum, unsigned long *value, char *type,
static unsigned long __find_kallsyms_symbol_value(struct module *mod, const char *name)
{
unsigned int i;
struct mod_kallsyms *kallsyms = rcu_dereference_sched(mod->kallsyms);
struct mod_kallsyms *kallsyms = rcu_dereference(mod->kallsyms);
for (i = 0; i < kallsyms->num_symtab; i++) {
const Elf_Sym *sym = &kallsyms->symtab[i];
@@ -453,23 +444,15 @@ static unsigned long __module_kallsyms_lookup_name(const char *name)
/* Look for this name: can be of form module:name. */
unsigned long module_kallsyms_lookup_name(const char *name)
{
unsigned long ret;
/* Don't lock: we're in enough trouble already. */
preempt_disable();
ret = __module_kallsyms_lookup_name(name);
preempt_enable();
return ret;
guard(rcu)();
return __module_kallsyms_lookup_name(name);
}
unsigned long find_kallsyms_symbol_value(struct module *mod, const char *name)
{
unsigned long ret;
preempt_disable();
ret = __find_kallsyms_symbol_value(mod, name);
preempt_enable();
return ret;
guard(rcu)();
return __find_kallsyms_symbol_value(mod, name);
}
int module_kallsyms_on_each_symbol(const char *modname,
@@ -490,10 +473,8 @@ int module_kallsyms_on_each_symbol(const char *modname,
if (modname && strcmp(modname, mod->name))
continue;
/* Use rcu_dereference_sched() to remain compliant with the sparse tool */
preempt_disable();
kallsyms = rcu_dereference_sched(mod->kallsyms);
preempt_enable();
kallsyms = rcu_dereference_check(mod->kallsyms,
lockdep_is_held(&module_mutex));
for (i = 0; i < kallsyms->num_symtab; i++) {
const Elf_Sym *sym = &kallsyms->symtab[i];

109
kernel/module/main.c
View File

@@ -67,7 +67,7 @@
/*
* Mutex protects:
* 1) List of modules (also safely readable with preempt_disable),
* 1) List of modules (also safely readable within RCU read section),
* 2) module_use links,
* 3) mod_tree.addr_min/mod_tree.addr_max.
* (delete and add uses RCU list operations).
@@ -331,7 +331,7 @@ static bool find_exported_symbol_in_section(const struct symsearch *syms,
/*
* Find an exported symbol and return it, along with, (optional) crc and
* (optional) module which owns it. Needs preempt disabled or module_mutex.
* (optional) module which owns it. Needs RCU or module_mutex.
*/
bool find_symbol(struct find_symbol_arg *fsa)
{
@@ -345,8 +345,6 @@ bool find_symbol(struct find_symbol_arg *fsa)
struct module *mod;
unsigned int i;
module_assert_mutex_or_preempt();
for (i = 0; i < ARRAY_SIZE(arr); i++)
if (find_exported_symbol_in_section(&arr[i], NULL, fsa))
return true;
@@ -374,16 +372,14 @@ bool find_symbol(struct find_symbol_arg *fsa)
}
/*
* Search for module by name: must hold module_mutex (or preempt disabled
* for read-only access).
* Search for module by name: must hold module_mutex (or RCU for read-only
* access).
*/
struct module *find_module_all(const char *name, size_t len,
bool even_unformed)
{
struct module *mod;
module_assert_mutex_or_preempt();
list_for_each_entry_rcu(mod, &modules, list,
lockdep_is_held(&module_mutex)) {
if (!even_unformed && mod->state == MODULE_STATE_UNFORMED)
@@ -454,8 +450,7 @@ bool __is_module_percpu_address(unsigned long addr, unsigned long *can_addr)
struct module *mod;
unsigned int cpu;
preempt_disable();
guard(rcu)();
list_for_each_entry_rcu(mod, &modules, list) {
if (mod->state == MODULE_STATE_UNFORMED)
continue;
@@ -472,13 +467,10 @@ bool __is_module_percpu_address(unsigned long addr, unsigned long *can_addr)
per_cpu_ptr(mod->percpu,
get_boot_cpu_id());
}
preempt_enable();
return true;
}
}
}
preempt_enable();
return false;
}
@@ -795,8 +787,8 @@ SYSCALL_DEFINE2(delete_module, const char __user *, name_user,
async_synchronize_full();
/* Store the name and taints of the last unloaded module for diagnostic purposes */
strscpy(last_unloaded_module.name, mod->name, sizeof(last_unloaded_module.name));
strscpy(last_unloaded_module.taints, module_flags(mod, buf, false), sizeof(last_unloaded_module.taints));
strscpy(last_unloaded_module.name, mod->name);
strscpy(last_unloaded_module.taints, module_flags(mod, buf, false));
free_module(mod);
/* someone could wait for the module in add_unformed_module() */
@@ -814,10 +806,9 @@ void __symbol_put(const char *symbol)
.gplok = true,
};
preempt_disable();
guard(rcu)();
BUG_ON(!find_symbol(&fsa));
module_put(fsa.owner);
preempt_enable();
}
EXPORT_SYMBOL(__symbol_put);
@@ -832,13 +823,12 @@ void symbol_put_addr(void *addr)
/*
* Even though we hold a reference on the module; we still need to
* disable preemption in order to safely traverse the data structure.
* RCU read section in order to safely traverse the data structure.
*/
preempt_disable();
guard(rcu)();
modaddr = __module_text_address(a);
BUG_ON(!modaddr);
module_put(modaddr);
preempt_enable();
}
EXPORT_SYMBOL_GPL(symbol_put_addr);
@@ -1189,7 +1179,7 @@ static const struct kernel_symbol *resolve_symbol(struct module *mod,
getname:
/* We must make copy under the lock if we failed to get ref. */
strncpy(ownername, module_name(fsa.owner), MODULE_NAME_LEN);
strscpy(ownername, module_name(fsa.owner), MODULE_NAME_LEN);
unlock:
mutex_unlock(&module_mutex);
return fsa.sym;
@@ -1341,7 +1331,7 @@ static void free_module(struct module *mod)
mod_tree_remove(mod);
/* Remove this module from bug list, this uses list_del_rcu */
module_bug_cleanup(mod);
/* Wait for RCU-sched synchronizing before releasing mod->list and buglist. */
/* Wait for RCU synchronizing before releasing mod->list and buglist. */
synchronize_rcu();
if (try_add_tainted_module(mod))
pr_err("%s: adding tainted module to the unloaded tainted modules list failed.\n",
@@ -1364,21 +1354,18 @@ void *__symbol_get(const char *symbol)
.warn = true,
};
preempt_disable();
if (!find_symbol(&fsa))
goto fail;
if (fsa.license != GPL_ONLY) {
pr_warn("failing symbol_get of non-GPLONLY symbol %s.\n",
symbol);
goto fail;
scoped_guard(rcu) {
if (!find_symbol(&fsa))
return NULL;
if (fsa.license != GPL_ONLY) {
pr_warn("failing symbol_get of non-GPLONLY symbol %s.\n",
symbol);
return NULL;
}
if (strong_try_module_get(fsa.owner))
return NULL;
}
if (strong_try_module_get(fsa.owner))
goto fail;
preempt_enable();
return (void *)kernel_symbol_value(fsa.sym);
fail:
preempt_enable();
return NULL;
}
EXPORT_SYMBOL_GPL(__symbol_get);
@@ -3013,7 +3000,7 @@ static noinline int do_init_module(struct module *mod)
#endif
/*
* We want to free module_init, but be aware that kallsyms may be
* walking this with preempt disabled. In all the failure paths, we
* walking this within an RCU read section. In all the failure paths, we
* call synchronize_rcu(), but we don't want to slow down the success
* path. execmem_free() cannot be called in an interrupt, so do the
* work and call synchronize_rcu() in a work queue.
@@ -3680,28 +3667,23 @@ out:
/* Given an address, look for it in the module exception tables. */
const struct exception_table_entry *search_module_extables(unsigned long addr)
{
const struct exception_table_entry *e = NULL;
struct module *mod;
preempt_disable();
guard(rcu)();
mod = __module_address(addr);
if (!mod)
goto out;
return NULL;
if (!mod->num_exentries)
goto out;
e = search_extable(mod->extable,
mod->num_exentries,
addr);
out:
preempt_enable();
return NULL;
/*
* Now, if we found one, we are running inside it now, hence
* we cannot unload the module, hence no refcnt needed.
* The address passed here belongs to a module that is currently
* invoked (we are running inside it). Therefore its module::refcnt
* needs already be >0 to ensure that it is not removed at this stage.
* All other user need to invoke this function within a RCU read
* section.
*/
return e;
return search_extable(mod->extable, mod->num_exentries, addr);
}
/**
@@ -3713,20 +3695,15 @@ out:
*/
bool is_module_address(unsigned long addr)
{
bool ret;
preempt_disable();
ret = __module_address(addr) != NULL;
preempt_enable();
return ret;
guard(rcu)();
return __module_address(addr) != NULL;
}
/**
* __module_address() - get the module which contains an address.
* @addr: the address.
*
* Must be called with preempt disabled or module mutex held so that
* Must be called within RCU read section or module mutex held so that
* module doesn't get freed during this.
*/
struct module *__module_address(unsigned long addr)
@@ -3744,8 +3721,6 @@ struct module *__module_address(unsigned long addr)
return NULL;
lookup:
module_assert_mutex_or_preempt();
mod = mod_find(addr, &mod_tree);
if (mod) {
BUG_ON(!within_module(addr, mod));
@@ -3765,20 +3740,15 @@ lookup:
*/
bool is_module_text_address(unsigned long addr)
{
bool ret;
preempt_disable();
ret = __module_text_address(addr) != NULL;
preempt_enable();
return ret;
guard(rcu)();
return __module_text_address(addr) != NULL;
}
/**
* __module_text_address() - get the module whose code contains an address.
* @addr: the address.
*
* Must be called with preempt disabled or module mutex held so that
* Must be called within RCU read section or module mutex held so that
* module doesn't get freed during this.
*/
struct module *__module_text_address(unsigned long addr)
@@ -3801,7 +3771,7 @@ void print_modules(void)
printk(KERN_DEFAULT "Modules linked in:");
/* Most callers should already have preempt disabled, but make sure */
preempt_disable();
guard(rcu)();
list_for_each_entry_rcu(mod, &modules, list) {
if (mod->state == MODULE_STATE_UNFORMED)
continue;
@@ -3809,7 +3779,6 @@ void print_modules(void)
}
print_unloaded_tainted_modules();
preempt_enable();
if (last_unloaded_module.name[0])
pr_cont(" [last unloaded: %s%s]", last_unloaded_module.name,
last_unloaded_module.taints);

2
kernel/module/tracking.c
View File

@@ -21,8 +21,6 @@ int try_add_tainted_module(struct module *mod)
{
struct mod_unload_taint *mod_taint;
module_assert_mutex_or_preempt();
if (!mod->taints)
goto out;

8
kernel/module/tree_lookup.c
View File

@@ -12,11 +12,11 @@
/*
* Use a latched RB-tree for __module_address(); this allows us to use
* RCU-sched lookups of the address from any context.
* RCU lookups of the address from any context.
*
* This is conditional on PERF_EVENTS || TRACING because those can really hit
* __module_address() hard by doing a lot of stack unwinding; potentially from
* NMI context.
* This is conditional on PERF_EVENTS || TRACING || CFI_CLANG because those can
* really hit __module_address() hard by doing a lot of stack unwinding;
* potentially from NMI context.
*/
static __always_inline unsigned long __mod_tree_val(struct latch_tree_node *n)

14
kernel/module/version.c
View File

@@ -79,17 +79,17 @@ int check_modstruct_version(const struct load_info *info,
.name = "module_layout",
.gplok = true,
};
bool have_symbol;
/*
* Since this should be found in kernel (which can't be removed), no
* locking is necessary -- use preempt_disable() to placate lockdep.
* locking is necessary. Regardless use a RCU read section to keep
* lockdep happy.
*/
preempt_disable();
if (!find_symbol(&fsa)) {
preempt_enable();
BUG();
}
preempt_enable();
scoped_guard(rcu)
have_symbol = find_symbol(&fsa);
BUG_ON(!have_symbol);
return check_version(info, "module_layout", mod, fsa.crc);
}