[PATCH v2] powerpc/4xx: Fix setup_kuep() on SMP

[PATCH v2] powerpc/4xx: Fix setup_kuep() on SMP

[Christophe Leroy]

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@intel.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@csgroup.eu>
---
v2: Add missing asm/smp.h to avoid build failure without CONFIG_SMP
---
 arch/powerpc/mm/nohash/44x.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/mm/nohash/44x.c b/arch/powerpc/mm/nohash/44x.c
index 7da6d1e9fc9b..e079f26b267e 100644
--- a/arch/powerpc/mm/nohash/44x.c
+++ b/arch/powerpc/mm/nohash/44x.c
@@ -25,6 +25,7 @@
 #include <asm/page.h>
 #include <asm/cacheflush.h>
 #include <asm/code-patching.h>
+#include <asm/smp.h>
 
 #include <mm/mmu_decl.h>
 
@@ -241,8 +242,11 @@ 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

Re: [PATCH v2] powerpc/4xx: Fix setup_kuep() on SMP

[Michael Ellerman]

On Tue, 29 Jun 2021 12:24:21 +0000 (UTC), Christophe Leroy wrote:
> 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.

Applied to powerpc/next.

[1/1] powerpc/4xx: Fix setup_kuep() on SMP
      https://git.kernel.org/powerpc/c/fc4999864bca323f1b844fefe1b402632443c076

cheers