Messages in this thread | | | Date | Mon, 20 Nov 2017 23:01:19 +0100 (CET) | From | Thomas Gleixner <> | Subject | Re: [PATCH 04/16] x86/fixmap: Generalize the GDT fixmap mechanism |
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On Mon, 20 Nov 2017, Andy Lutomirski wrote:
Just a few nits.
> /* Provide the fixmap address of the remapped GDT */ > static inline struct desc_struct *get_cpu_gdt_ro(int cpu) > { > - unsigned int idx = get_cpu_gdt_ro_index(cpu); > - return (struct desc_struct *)__fix_to_virt(idx); > + return (struct desc_struct *)&get_cpu_entry_area(cpu)->gdt; > } > > /* Provide the current read-only GDT */ > diff --git a/arch/x86/include/asm/fixmap.h b/arch/x86/include/asm/fixmap.h > index b0c505fe9a95..5ff8e251772a 100644 > --- a/arch/x86/include/asm/fixmap.h > +++ b/arch/x86/include/asm/fixmap.h > @@ -44,6 +44,17 @@ extern unsigned long __FIXADDR_TOP; > PAGE_SIZE) > #endif > > +/* > + * cpu_entry_area is a percpu region in the fixmap that contains things > + * need by the CPU and early entry/exit code. Real types aren't used here
s/need/needed/
> + * to avoid circular header dependencies.
:(
> + */ > +struct cpu_entry_area > +{ > + char gdt[PAGE_SIZE]; > +}; > + > +#define CPU_ENTRY_AREA_PAGES (sizeof(struct cpu_entry_area) / PAGE_SIZE)
> +static inline unsigned int __get_cpu_entry_area_page_index(int cpu, int page) > +{ > + BUILD_BUG_ON(sizeof(struct cpu_entry_area) % PAGE_SIZE != 0); > + > + return FIX_CPU_ENTRY_AREA_BOTTOM - cpu*CPU_ENTRY_AREA_PAGES - page; > +} > + > +#define __get_cpu_entry_area_offset_index(cpu, offset) ({ \ > + BUILD_BUG_ON(offset % PAGE_SIZE != 0); \ > + __get_cpu_entry_area_page_index(cpu, offset / PAGE_SIZE); \ > + }) > + > +#define get_cpu_entry_area_index(cpu, field) \ > + __get_cpu_entry_area_offset_index((cpu), offsetof(struct cpu_entry_area, field))
Any reason why those need to be macros?
> +static inline struct cpu_entry_area *get_cpu_entry_area(int cpu) > +{ > + return (struct cpu_entry_area *) > + __fix_to_virt(__get_cpu_entry_area_page_index(cpu, 0)); > +} > +
Thanks,
tglx
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