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Commit 8f62c883 authored by Dave Hansen's avatar Dave Hansen Committed by Ingo Molnar
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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: default avatarDave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: default avatarThomas 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: default avatarIngo Molnar <mingo@kernel.org>
parent 63c17fb8

arch/x86/include/asm/mmu_context.h

+11 −0
Original line number Diff line number Diff line
@@ -275,4 +275,15 @@ static inline void arch_unmap(struct mm_struct *mm, struct vm_area_struct *vma, 
		mpx_notify_unmap(mm, vma, start, end);

}



static inline int vma_pkey(struct vm_area_struct *vma)

{

	u16 pkey = 0;

#ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS

	unsigned long vma_pkey_mask = VM_PKEY_BIT0 | VM_PKEY_BIT1 |

				      VM_PKEY_BIT2 | VM_PKEY_BIT3;

	pkey = (vma->vm_flags & vma_pkey_mask) >> VM_PKEY_SHIFT;

#endif

	return pkey;

}



#endif /* _ASM_X86_MMU_CONTEXT_H */

arch/x86/include/asm/pgtable_types.h

+10 −2
Original line number Diff line number Diff line
@@ -115,7 +115,12 @@ 
#define _KERNPG_TABLE	(_PAGE_PRESENT | _PAGE_RW | _PAGE_ACCESSED |	\

			 _PAGE_DIRTY)



/* Set of bits not changed in pte_modify */

/*

 * Set of bits not changed in pte_modify.  The pte's

 * protection key is treated like _PAGE_RW, for

 * instance, and is *not* included in this mask since

 * pte_modify() does modify it.

 */

#define _PAGE_CHG_MASK	(PTE_PFN_MASK | _PAGE_PCD | _PAGE_PWT |		\

			 _PAGE_SPECIAL | _PAGE_ACCESSED | _PAGE_DIRTY |	\

			 _PAGE_SOFT_DIRTY)
@@ -231,7 +236,10 @@ enum page_cache_mode { 
/* Extracts the PFN from a (pte|pmd|pud|pgd)val_t of a 4KB page */

#define PTE_PFN_MASK		((pteval_t)PHYSICAL_PAGE_MASK)



/* Extracts the flags from a (pte|pmd|pud|pgd)val_t of a 4KB page */

/*

 *  Extracts the flags from a (pte|pmd|pud|pgd)val_t

 *  This includes the protection key value.

 */

#define PTE_FLAGS_MASK		(~PTE_PFN_MASK)



typedef struct pgprot { pgprotval_t pgprot; } pgprot_t;

arch/x86/include/uapi/asm/mman.h

+16 −0
Original line number Diff line number Diff line
@@ -6,6 +6,22 @@ 
#define MAP_HUGE_2MB    (21 << MAP_HUGE_SHIFT)

#define MAP_HUGE_1GB    (30 << MAP_HUGE_SHIFT)



#ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS

/*

 * Take the 4 protection key bits out of the vma->vm_flags

 * value and turn them in to the bits that we can put in

 * to a pte.

 *

 * Only override these if Protection Keys are available

 * (which is only on 64-bit).

 */

#define arch_vm_get_page_prot(vm_flags)	__pgprot(	\

		((vm_flags) & VM_PKEY_BIT0 ? _PAGE_PKEY_BIT0 : 0) |	\

		((vm_flags) & VM_PKEY_BIT1 ? _PAGE_PKEY_BIT1 : 0) |	\

		((vm_flags) & VM_PKEY_BIT2 ? _PAGE_PKEY_BIT2 : 0) |	\

		((vm_flags) & VM_PKEY_BIT3 ? _PAGE_PKEY_BIT3 : 0))

#endif



#include <asm-generic/mman.h>



#endif /* _ASM_X86_MMAN_H */

include/linux/mm.h

+7 −0
Original line number Diff line number Diff line
@@ -183,6 +183,13 @@ extern unsigned int kobjsize(const void *objp); 


#if defined(CONFIG_X86)

# define VM_PAT		VM_ARCH_1	/* PAT reserves whole VMA at once (x86) */

#if defined (CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS)

# define VM_PKEY_SHIFT	VM_HIGH_ARCH_BIT_0

# define VM_PKEY_BIT0	VM_HIGH_ARCH_0	/* A protection key is a 4-bit value */

# define VM_PKEY_BIT1	VM_HIGH_ARCH_1

# define VM_PKEY_BIT2	VM_HIGH_ARCH_2

# define VM_PKEY_BIT3	VM_HIGH_ARCH_3

#endif

#elif defined(CONFIG_PPC)

# define VM_SAO		VM_ARCH_1	/* Strong Access Ordering (powerpc) */

#elif defined(CONFIG_PARISC)