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

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__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>
This commit is contained in:
Sebastian Andrzej Siewior 2025-01-08 10:04:43 +01:00 committed by Petr Pavlu
parent 2abf84f688
commit 6593a2c990
3 changed files with 4 additions and 13 deletions
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3
include/linux/kallsyms.h
View File

@ -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;
}

5
kernel/module/kallsyms.c
View File

@ -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;
}

9
kernel/module/main.c
View File

@ -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;
}
/**