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SubjectRe: [PATCH] powerpc/4xx: Fix setup_kuep() on SMP
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Le 29/06/2021 à 13:58, Michael Ellerman a écrit :
> Christophe Leroy <christophe.leroy@csgroup.eu> writes:
>> 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>
>> ---
>> 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
>
> Building ppc44x_defconfig gives me:
>
> /linux/arch/powerpc/mm/nohash/44x.c: In function 'setup_kuep':
> /linux/arch/powerpc/mm/nohash/44x.c:246:35: error: 'boot_cpuid' undeclared (first use in this function); did you mean 'boot_cpu_init'?
> 246 | if (smp_processor_id() != boot_cpuid)
> | ^~~~~~~~~~
> | boot_cpu_init
> /linux/arch/powerpc/mm/nohash/44x.c:246:35: note: each undeclared identifier is reported only once for each function it appears in


Seems like we need <asm/smp.h> when we don't have CONFIG_SMP.

I tested it with akebono_defconfig, looks like it has CONFIG_SMP.

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