module: Use RCU in all users of __module_address().

__module_address() can be invoked within a RCU section, there is no
requirement to have preemption disabled.

Replace the preempt_disable() section around __module_address() with
RCU.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20250108090457.512198-15-bigeasy@linutronix.de
Signed-off-by: Petr Pavlu <petr.pavlu@suse.com>

diff --git a/include/linux/kallsyms.h b/include/linux/kallsyms.h
index 1c6a6c1704d8d059ac759d4a8652a86acaa605fe..d5dd54c53ace618fa37a167ec69da1dba2f0763c 100644 (file)
--- a/include/linux/kallsyms.h
+++ b/include/linux/kallsyms.h
@@ -55,12 +55,11 @@ static inline void *dereference_symbol_descriptor(void *ptr)
        if (is_ksym_addr((unsigned long)ptr))
                return ptr;
 
-       preempt_disable();
+       guard(rcu)();
        mod = __module_address((unsigned long)ptr);
 
        if (mod)
                ptr = dereference_module_function_descriptor(mod, ptr);
-       preempt_enable();
 #endif
        return ptr;
 }

diff --git a/kernel/module/kallsyms.c b/kernel/module/kallsyms.c
index 0e8ec6486d95c8362d847d550d09ec6922d408f3..00a60796327c0611049acfeb33ed8d1308dca0ae 100644 (file)
--- a/kernel/module/kallsyms.c
+++ b/kernel/module/kallsyms.c
@@ -316,7 +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,
@@ -330,7 +330,6 @@ int module_address_lookup(unsigned long addr,
        struct module *mod;
 
        guard(rcu)();
-       preempt_disable();
        mod = __module_address(addr);
        if (mod) {
                if (modname)
@@ -348,8 +347,6 @@ int module_address_lookup(unsigned long addr,
                if (sym)
                        ret = strscpy(namebuf, sym, KSYM_NAME_LEN);
        }
-       preempt_enable();
-
        return ret;
 }
 

diff --git a/kernel/module/main.c b/kernel/module/main.c
index aebb17e1bfb976e6a6d889b844b7b883e90da313..8a8b499730d865e8ac5e684207dd5cb882ac4018 100644 (file)
--- a/kernel/module/main.c
+++ b/kernel/module/main.c
@@ -3731,13 +3731,8 @@ const struct exception_table_entry *search_module_extables(unsigned long addr)
  */
 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;
 }
 
 /**