| Date | Mon, 20 Nov 2017 21:22:53 +0100 (CET) | From | Thomas Gleixner <> | Subject | Re: [PATCH 12/30] x86, kaiser: map GDT into user page tables |
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On Fri, 10 Nov 2017, Dave Hansen wrote: > __set_fixmap(get_cpu_gdt_ro_index(cpu), get_cpu_gdt_paddr(cpu), prot); > + > + /* CPU 0's mapping is done in kaiser_init() */ > + if (cpu) { > + int ret; > + > + ret = kaiser_add_mapping((unsigned long) get_cpu_gdt_ro(cpu), > + PAGE_SIZE, __PAGE_KERNEL_RO); > + /* > + * We do not have a good way to fail CPU bringup. > + * Just WARN about it and hope we boot far enough > + * to get a good log out. > + */
The GDT fixmap can be set up before the CPU is started. There is no reason to do that in cpu_init().
> + > + /* > + * We could theoretically do this in setup_fixmap_gdt(). > + * But, we would need to rewrite the above page table > + * allocation code to use the bootmem allocator. The > + * buddy allocator is not available at the time that we > + * call setup_fixmap_gdt() for CPU 0. > + */ > + kaiser_add_user_map_early(get_cpu_gdt_ro(0), PAGE_SIZE, > + __PAGE_KERNEL_RO | _PAGE_GLOBAL);
This one is needs to stay.
Thanks,
tglx
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