__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.

Cc: H. Peter Anvin <h...@zytor.com>
Cc: Borislav Petkov <b...@alien8.de>
Cc: Dave Hansen <dave.han...@linux.intel.com>
Cc: Ingo Molnar <mi...@redhat.com>
Cc: Josh Poimboeuf <jpoim...@kernel.org>
Cc: Peter Zijlstra <pet...@infradead.org>
Cc: Thomas Gleixner <t...@linutronix.de>
Cc: x...@kernel.org
Acked-by: Peter Zijlstra (Intel) <pet...@infradead.org>
Signed-off-by: Sebastian Andrzej Siewior <bige...@linutronix.de>
---
 arch/x86/kernel/callthunks.c | 3 +--
 arch/x86/kernel/unwind_orc.c | 4 +---
 2 files changed, 2 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kernel/callthunks.c b/arch/x86/kernel/callthunks.c
index f17d166078823..276b5368ff6b0 100644
--- a/arch/x86/kernel/callthunks.c
+++ b/arch/x86/kernel/callthunks.c
@@ -98,11 +98,10 @@ static inline bool within_module_coretext(void *addr)
 #ifdef CONFIG_MODULES
        struct module *mod;
 
-       preempt_disable();
+       guard(rcu)();
        mod = __module_address((unsigned long)addr);
        if (mod && within_module_core((unsigned long)addr, mod))
                ret = true;
-       preempt_enable();
 #endif
        return ret;
 }
diff --git a/arch/x86/kernel/unwind_orc.c b/arch/x86/kernel/unwind_orc.c
index d4705a348a804..977ee75e047c8 100644
--- a/arch/x86/kernel/unwind_orc.c
+++ b/arch/x86/kernel/unwind_orc.c
@@ -476,7 +476,7 @@ bool unwind_next_frame(struct unwind_state *state)
                return false;
 
        /* Don't let modules unload while we're reading their ORC data. */
-       preempt_disable();
+       guard(rcu)();
 
        /* End-of-stack check for user tasks: */
        if (state->regs && user_mode(state->regs))
@@ -669,14 +669,12 @@ bool unwind_next_frame(struct unwind_state *state)
                goto err;
        }
 
-       preempt_enable();
        return true;
 
 err:
        state->error = true;
 
 the_end:
-       preempt_enable();
        state->stack_info.type = STACK_TYPE_UNKNOWN;
        return false;
 }
-- 
2.47.1


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