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Subject: Re: [PATCH 12/30] x86, kaiser: map GDT into user page tables
To: Andy Lutomirski <luto@kernel.org>
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From: Dave Hansen <dave.hansen@linux.intel.com>
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Date: Tue, 21 Nov 2017 16:37:07 -0800
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On 11/21/2017 04:17 PM, Andy Lutomirski wrote:
> On Tue, Nov 21, 2017 at 3:42 PM, Dave Hansen
> unsigned long start = (unsigned long)get_cpu_entry_area(cpu);
> for (unsigned long addr = start; addr < start + sizeof(struct
> cpu_entry_area); addr += PAGE_SIZE) {
>   pte_t pte = *pte_offset_k(addr);  /* or however you do this */
>   kaiser_add_mapping(pte_pfn(pte), pte_prot(pte));
> }
> 
> modulo the huge pile of typos in there that surely exist.

That would work.  I just need to find a suitable pte_offset_k() in the
kernel and make sure it works for these purposes.  We probably have one.

> But I still prefer my approach of just sharing the cpu_entry_area pmd
> entries between the user and kernel tables.

That would be spiffy.