x86/mm/pkeys: Add arch-specific VMA protection bits
authorDave Hansen <dave.hansen@linux.intel.com>
Fri, 12 Feb 2016 21:02:10 +0000 (13:02 -0800)
committerIngo Molnar <mingo@kernel.org>
Thu, 18 Feb 2016 08:31:51 +0000 (09:31 +0100)
commit8f62c883222c9e3c06d60b5e55e307a3d1f18257
tree7b9a6263f7232ebc49bfeae15668b198d1a0b032
parent63c17fb8e5a46a16e10e82005748837fd11a2024
x86/mm/pkeys: Add arch-specific VMA protection bits

Lots of things seem to do:

        vma->vm_page_prot = vm_get_page_prot(flags);

and the ptes get created right from things we pull out
of ->vm_page_prot.  So it is very convenient if we can
store the protection key in flags and vm_page_prot, just
like the existing permission bits (_PAGE_RW/PRESENT).  It
greatly reduces the amount of plumbing and arch-specific
hacking we have to do in generic code.

This also takes the new PROT_PKEY{0,1,2,3} flags and
turns *those* in to VM_ flags for vma->vm_flags.

The protection key values are stored in 4 places:
1. "prot" argument to system calls
2. vma->vm_flags, filled from the mmap "prot"
3. vma->vm_page prot, filled from vma->vm_flags
4. the PTE itself.

The pseudocode for these for steps are as follows:

mmap(PROT_PKEY*)
vma->vm_flags    = ... | arch_calc_vm_prot_bits(mmap_prot);
vma->vm_page_prot = ... | arch_vm_get_page_prot(vma->vm_flags);
pte = pfn | vma->vm_page_prot

Note that this provides a new definitions for x86:

arch_vm_get_page_prot()

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave@sr71.net>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/20160212210210.FE483A42@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
arch/x86/include/asm/mmu_context.h
arch/x86/include/asm/pgtable_types.h
arch/x86/include/uapi/asm/mman.h
include/linux/mm.h