Messages in this thread | | | From | "Bae, Chang Seok" <> | Subject | Re: [PATCH 6/6] x86/vdso: Move out the CPU number store | Date | Tue, 5 Jun 2018 04:44:16 +0000 |
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>> 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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