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x86/mm/pkeys: Add arch-specific VMA protection bits

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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>
This commit is contained in:
Dave Hansen 2016-02-12 13:02:10 -08:00 committed by Ingo Molnar
parent 63c17fb8e5
commit 8f62c88322
4 changed files with 44 additions and 2 deletions
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11
arch/x86/include/asm/mmu_context.h
View File

@ -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 */

12
arch/x86/include/asm/pgtable_types.h
View File

@ -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;

16
arch/x86/include/uapi/asm/mman.h
View File

@ -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 */

7
include/linux/mm.h
View File

@ -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)