Commit 6593a2c9 authored by Sebastian Andrzej Siewior's avatar Sebastian Andrzej Siewior Committed by Petr Pavlu
Browse files

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: default avatarSebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20250108090457.512198-15-bigeasy@linutronix.de


Signed-off-by: default avatarPetr Pavlu <petr.pavlu@suse.com>
parent 2abf84f6

include/linux/kallsyms.h

+1 −2
Original line number Diff line number Diff line
@@ -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;

}

kernel/module/kallsyms.c

+1 −4
Original line number Diff line number Diff line
@@ -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;

}

kernel/module/main.c

+2 −7
Original line number Diff line number Diff line
@@ -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;

}



/**