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Commit 8f860591 authored by Zhang, Yanmin's avatar Zhang, Yanmin Committed by Linus Torvalds
Browse files

[PATCH] Enable mprotect on huge pages 



2.6.16-rc3 uses hugetlb on-demand paging, but it doesn_t support hugetlb
mprotect.

From: David Gibson <david@gibson.dropbear.id.au>

  Remove a test from the mprotect() path which checks that the mprotect()ed
  range on a hugepage VMA is hugepage aligned (yes, really, the sense of
  is_aligned_hugepage_range() is the opposite of what you'd guess :-/).

  In fact, we don't need this test.  If the given addresses match the
  beginning/end of a hugepage VMA they must already be suitably aligned.  If
  they don't, then mprotect_fixup() will attempt to split the VMA.  The very
  first test in split_vma() will check for a badly aligned address on a
  hugepage VMA and return -EINVAL if necessary.

From: "Chen, Kenneth W" <kenneth.w.chen@intel.com>

  On i386 and x86-64, pte flag _PAGE_PSE collides with _PAGE_PROTNONE.  The
  identify of hugetlb pte is lost when changing page protection via mprotect.
  A page fault occurs later will trigger a bug check in huge_pte_alloc().

  The fix is to always make new pte a hugetlb pte and also to clean up
  legacy code where _PAGE_PRESENT is forced on in the pre-faulting day.

Signed-off-by: default avatarZhang Yanmin <yanmin.zhang@intel.com>
Cc: David Gibson <david@gibson.dropbear.id.au>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: William Lee Irwin III <wli@holomorphy.com>
Signed-off-by: default avatarKen Chen <kenneth.w.chen@intel.com>
Signed-off-by: default avatarNishanth Aravamudan <nacc@us.ibm.com>
Cc: Andi Kleen <ak@muc.de>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent aed75ff3

include/asm-i386/pgtable.h

+2 −3
Original line number Diff line number Diff line
@@ -219,13 +219,12 @@ extern unsigned long pg0[]; 
 * The following only work if pte_present() is true.

 * Undefined behaviour if not..

 */

#define __LARGE_PTE (_PAGE_PSE | _PAGE_PRESENT)

static inline int pte_user(pte_t pte)		{ return (pte).pte_low & _PAGE_USER; }

static inline int pte_read(pte_t pte)		{ return (pte).pte_low & _PAGE_USER; }

static inline int pte_dirty(pte_t pte)		{ return (pte).pte_low & _PAGE_DIRTY; }

static inline int pte_young(pte_t pte)		{ return (pte).pte_low & _PAGE_ACCESSED; }

static inline int pte_write(pte_t pte)		{ return (pte).pte_low & _PAGE_RW; }

static inline int pte_huge(pte_t pte)		{ return ((pte).pte_low & __LARGE_PTE) == __LARGE_PTE; }

static inline int pte_huge(pte_t pte)		{ return (pte).pte_low & _PAGE_PSE; }



/*

 * The following only works if pte_present() is not true.
@@ -242,7 +241,7 @@ static inline pte_t pte_mkexec(pte_t pte) { (pte).pte_low |= _PAGE_USER; return 
static inline pte_t pte_mkdirty(pte_t pte)	{ (pte).pte_low |= _PAGE_DIRTY; return pte; }

static inline pte_t pte_mkyoung(pte_t pte)	{ (pte).pte_low |= _PAGE_ACCESSED; return pte; }

static inline pte_t pte_mkwrite(pte_t pte)	{ (pte).pte_low |= _PAGE_RW; return pte; }

static inline pte_t pte_mkhuge(pte_t pte)	{ (pte).pte_low |= __LARGE_PTE; return pte; }

static inline pte_t pte_mkhuge(pte_t pte)	{ (pte).pte_low |= _PAGE_PSE; return pte; }



#ifdef CONFIG_X86_PAE

# include <asm/pgtable-3level.h>

include/asm-ia64/pgtable.h

+1 −1
Original line number Diff line number Diff line
@@ -314,7 +314,7 @@ ia64_phys_addr_valid (unsigned long addr) 
#define pte_mkyoung(pte)	(__pte(pte_val(pte) | _PAGE_A))

#define pte_mkclean(pte)	(__pte(pte_val(pte) & ~_PAGE_D))

#define pte_mkdirty(pte)	(__pte(pte_val(pte) | _PAGE_D))

#define pte_mkhuge(pte)		(__pte(pte_val(pte) | _PAGE_P))

#define pte_mkhuge(pte)		(__pte(pte_val(pte)))



/*

 * Macro to a page protection value as "uncacheable".  Note that "protection" is really a

include/asm-x86_64/pgtable.h

+2 −2
Original line number Diff line number Diff line
@@ -273,7 +273,7 @@ static inline int pte_dirty(pte_t pte) { return pte_val(pte) & _PAGE_DIRTY; } 
static inline int pte_young(pte_t pte)		{ return pte_val(pte) & _PAGE_ACCESSED; }

static inline int pte_write(pte_t pte)		{ return pte_val(pte) & _PAGE_RW; }

static inline int pte_file(pte_t pte)		{ return pte_val(pte) & _PAGE_FILE; }

static inline int pte_huge(pte_t pte)		{ return (pte_val(pte) & __LARGE_PTE) == __LARGE_PTE; }

static inline int pte_huge(pte_t pte)		{ return pte_val(pte) & _PAGE_PSE; }



static inline pte_t pte_rdprotect(pte_t pte)	{ set_pte(&pte, __pte(pte_val(pte) & ~_PAGE_USER)); return pte; }

static inline pte_t pte_exprotect(pte_t pte)	{ set_pte(&pte, __pte(pte_val(pte) & ~_PAGE_USER)); return pte; }
@@ -285,7 +285,7 @@ static inline pte_t pte_mkexec(pte_t pte) { set_pte(&pte, __pte(pte_val(pte) | _ 
static inline pte_t pte_mkdirty(pte_t pte)	{ set_pte(&pte, __pte(pte_val(pte) | _PAGE_DIRTY)); return pte; }

static inline pte_t pte_mkyoung(pte_t pte)	{ set_pte(&pte, __pte(pte_val(pte) | _PAGE_ACCESSED)); return pte; }

static inline pte_t pte_mkwrite(pte_t pte)	{ set_pte(&pte, __pte(pte_val(pte) | _PAGE_RW)); return pte; }

static inline pte_t pte_mkhuge(pte_t pte)	{ set_pte(&pte, __pte(pte_val(pte) | __LARGE_PTE)); return pte; }

static inline pte_t pte_mkhuge(pte_t pte)	{ set_pte(&pte, __pte(pte_val(pte) | _PAGE_PSE)); return pte; }



struct vm_area_struct;

include/linux/hugetlb.h

+4 −0
Original line number Diff line number Diff line
@@ -41,6 +41,8 @@ struct page *follow_huge_pmd(struct mm_struct *mm, unsigned long address, 
				pmd_t *pmd, int write);

int is_aligned_hugepage_range(unsigned long addr, unsigned long len);

int pmd_huge(pmd_t pmd);

void hugetlb_change_protection(struct vm_area_struct *vma,

		unsigned long address, unsigned long end, pgprot_t newprot);



#ifndef ARCH_HAS_HUGEPAGE_ONLY_RANGE

#define is_hugepage_only_range(mm, addr, len)	0
@@ -101,6 +103,8 @@ static inline unsigned long hugetlb_total_pages(void) 
#define free_huge_page(p)			({ (void)(p); BUG(); })

#define hugetlb_fault(mm, vma, addr, write)	({ BUG(); 0; })



#define hugetlb_change_protection(vma, address, end, newprot)



#ifndef HPAGE_MASK

#define HPAGE_MASK	PAGE_MASK		/* Keep the compiler happy */

#define HPAGE_SIZE	PAGE_SIZE

mm/hugetlb.c

+29 −0
Original line number Diff line number Diff line
@@ -565,3 +565,32 @@ int follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma, 


	return i;

}



void hugetlb_change_protection(struct vm_area_struct *vma,

		unsigned long address, unsigned long end, pgprot_t newprot)

{

	struct mm_struct *mm = vma->vm_mm;

	unsigned long start = address;

	pte_t *ptep;

	pte_t pte;



	BUG_ON(address >= end);

	flush_cache_range(vma, address, end);



	spin_lock(&mm->page_table_lock);

	for (; address < end; address += HPAGE_SIZE) {

		ptep = huge_pte_offset(mm, address);

		if (!ptep)

			continue;

		if (!pte_none(*ptep)) {

			pte = huge_ptep_get_and_clear(mm, address, ptep);

			pte = pte_mkhuge(pte_modify(pte, newprot));

			set_huge_pte_at(mm, address, ptep, pte);

			lazy_mmu_prot_update(pte);

		}

	}

	spin_unlock(&mm->page_table_lock);



	flush_tlb_range(vma, start, end);

}