linux-kernel - [PATCH] powerpc/4xx: Fix setup

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Date:   Mon, 28 Jun 2021 06:56:12 +0000 (UTC)
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>
Cc:     linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: [PATCH] powerpc/4xx: Fix setup_kuep() on SMP

On SMP, setup_kuep() is also called from start_secondary() since
commit 86f46f343272 ("powerpc/32s: Initialise KUAP and KUEP in C").

start_secondary() is not an __init function.

Remove the __init marker from setup_kuep() and bail out when
not caller on the first CPU as the work is already done.

Reported-by: kernel test robot <lkp@...el.com>
Fixes: 10248dcba120 ("powerpc/44x: Implement Kernel Userspace Exec Protection (KUEP)")
Fixes: 86f46f343272 ("powerpc/32s: Initialise KUAP and KUEP in C").
Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
---
 arch/powerpc/mm/nohash/44x.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/mm/nohash/44x.c b/arch/powerpc/mm/nohash/44x.c
index 7da6d1e9fc9b..20c18bd5b9a0 100644
--- a/arch/powerpc/mm/nohash/44x.c
+++ b/arch/powerpc/mm/nohash/44x.c
@@ -241,8 +241,11 @@ void __init mmu_init_secondary(int cpu)
 #endif /* CONFIG_SMP */
 
 #ifdef CONFIG_PPC_KUEP
-void __init setup_kuep(bool disabled)
+void setup_kuep(bool disabled)
 {
+	if (smp_processor_id() != boot_cpuid)
+		return;
+
 	if (disabled)
 		patch_instruction_site(&patch__tlb_44x_kuep, ppc_inst(PPC_RAW_NOP()));
 	else
-- 
2.25.0