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SubjectRe: [PATCH 6/6] x86/vdso: Move out the CPU number store
Date
>> diff --git a/arch/x86/kernel/setup_percpu.c b/arch/x86/kernel/setup_percpu.c
>> index ea554f8..e716e94 100644
>> --- a/arch/x86/kernel/setup_percpu.c
>> +++ b/arch/x86/kernel/setup_percpu.c
>> @@ -155,12 +155,21 @@ static void __init pcpup_populate_pte(unsigned long addr)
>>
>> static inline void setup_percpu_segment(int cpu)
>> {
>> -#ifdef CONFIG_X86_32
>> - struct desc_struct d = GDT_ENTRY_INIT(0x8092, per_cpu_offset(cpu),
>> - 0xFFFFF);
>> +#ifdef CONFIG_NUMA
>> + unsigned long node = early_cpu_to_node(cpu);
>> +#else
>> + unsigned long node = 0;
>> +#endif
>> + struct desc_struct d = GDT_ENTRY_INIT(0x0, per_cpu_offset(cpu),
>> + make_lsl_tscp(cpu, node));
>> +
>> + d.type = 5; /* R0 data, expand down, accessed */
>> + d.dpl = 3; /* Visible to user code */
>> + d.s = 1; /* Not a system segment */
>> + d.p = 1; /* Present */
>> + d.d = 1; /* 32-bit */
>>
>> write_gdt_entry(get_cpu_gdt_rw(cpu), GDT_ENTRY_PERCPU, &d, DESCTYPE_S);
>> -#endif
>> }

> This won't work on X86-32 because it actually uses the segment limit with fs: access. So there
> is a reason why the lsl based method is X86-64 only.

The limit will be consumed in X86-64 only, while the unification with i386 was suggested for a
different reason.

Thanks,
Chang

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