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Commit db3eb96f authored by Andrea Arcangeli's avatar Andrea Arcangeli Committed by Linus Torvalds
Browse files

thp: add pmd mangling functions to x86 



Add needed pmd mangling functions with symmetry with their pte
counterparts.  pmdp_splitting_flush() is the only new addition on the pmd_
methods and it's needed to serialize the VM against split_huge_page.  It
simply atomically sets the splitting bit in a similar way
pmdp_clear_flush_young atomically clears the accessed bit.
pmdp_splitting_flush() also has to flush the tlb to make it effective
against gup_fast, but it wouldn't really require to flush the tlb too.
Just the tlb flush is the simplest operation we can invoke to serialize
pmdp_splitting_flush() against gup_fast.

Signed-off-by: default avatarAndrea Arcangeli <aarcange@redhat.com>
Acked-by: default avatarRik van Riel <riel@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent e2cda322

arch/x86/include/asm/pgtable.h

+1 −1
Original line number Diff line number Diff line
@@ -353,7 +353,7 @@ static inline unsigned long pmd_page_vaddr(pmd_t pmd) 
 * Currently stuck as a macro due to indirect forward reference to

 * linux/mmzone.h's __section_mem_map_addr() definition:

 */

#define pmd_page(pmd)	pfn_to_page(pmd_val(pmd) >> PAGE_SHIFT)

#define pmd_page(pmd)	pfn_to_page((pmd_val(pmd) & PTE_PFN_MASK) >> PAGE_SHIFT)



/*

 * the pmd page can be thought of an array like this: pmd_t[PTRS_PER_PMD]

arch/x86/include/asm/pgtable_64.h

+112 −7
Original line number Diff line number Diff line
@@ -59,6 +59,16 @@ static inline void native_set_pte_atomic(pte_t *ptep, pte_t pte) 
	native_set_pte(ptep, pte);

}



static inline void native_set_pmd(pmd_t *pmdp, pmd_t pmd)

{

	*pmdp = pmd;

}



static inline void native_pmd_clear(pmd_t *pmd)

{

	native_set_pmd(pmd, native_make_pmd(0));

}



static inline pte_t native_ptep_get_and_clear(pte_t *xp)

{

#ifdef CONFIG_SMP
@@ -72,14 +82,17 @@ static inline pte_t native_ptep_get_and_clear(pte_t *xp) 
#endif

}



static inline void native_set_pmd(pmd_t *pmdp, pmd_t pmd)

{

	*pmdp = pmd;

}



static inline void native_pmd_clear(pmd_t *pmd)

static inline pmd_t native_pmdp_get_and_clear(pmd_t *xp)

{

	native_set_pmd(pmd, native_make_pmd(0));

#ifdef CONFIG_SMP

	return native_make_pmd(xchg(&xp->pmd, 0));

#else

	/* native_local_pmdp_get_and_clear,

	   but duplicated because of cyclic dependency */

	pmd_t ret = *xp;

	native_pmd_clear(xp);

	return ret;

#endif

}



static inline void native_set_pud(pud_t *pudp, pud_t pud)
@@ -181,6 +194,98 @@ static inline int pmd_trans_huge(pmd_t pmd) 
}

#endif /* CONFIG_TRANSPARENT_HUGEPAGE */



#define mk_pmd(page, pgprot)   pfn_pmd(page_to_pfn(page), (pgprot))



#define  __HAVE_ARCH_PMDP_SET_ACCESS_FLAGS

extern int pmdp_set_access_flags(struct vm_area_struct *vma,

				 unsigned long address, pmd_t *pmdp,

				 pmd_t entry, int dirty);



#define __HAVE_ARCH_PMDP_TEST_AND_CLEAR_YOUNG

extern int pmdp_test_and_clear_young(struct vm_area_struct *vma,

				     unsigned long addr, pmd_t *pmdp);



#define __HAVE_ARCH_PMDP_CLEAR_YOUNG_FLUSH

extern int pmdp_clear_flush_young(struct vm_area_struct *vma,

				  unsigned long address, pmd_t *pmdp);





#define __HAVE_ARCH_PMDP_SPLITTING_FLUSH

extern void pmdp_splitting_flush(struct vm_area_struct *vma,

				 unsigned long addr, pmd_t *pmdp);



#define __HAVE_ARCH_PMD_WRITE

static inline int pmd_write(pmd_t pmd)

{

	return pmd_flags(pmd) & _PAGE_RW;

}



#define __HAVE_ARCH_PMDP_GET_AND_CLEAR

static inline pmd_t pmdp_get_and_clear(struct mm_struct *mm, unsigned long addr,

				       pmd_t *pmdp)

{

	pmd_t pmd = native_pmdp_get_and_clear(pmdp);

	pmd_update(mm, addr, pmdp);

	return pmd;

}



#define __HAVE_ARCH_PMDP_SET_WRPROTECT

static inline void pmdp_set_wrprotect(struct mm_struct *mm,

				      unsigned long addr, pmd_t *pmdp)

{

	clear_bit(_PAGE_BIT_RW, (unsigned long *)&pmdp->pmd);

	pmd_update(mm, addr, pmdp);

}



static inline int pmd_young(pmd_t pmd)

{

	return pmd_flags(pmd) & _PAGE_ACCESSED;

}



static inline pmd_t pmd_set_flags(pmd_t pmd, pmdval_t set)

{

	pmdval_t v = native_pmd_val(pmd);



	return native_make_pmd(v | set);

}



static inline pmd_t pmd_clear_flags(pmd_t pmd, pmdval_t clear)

{

	pmdval_t v = native_pmd_val(pmd);



	return native_make_pmd(v & ~clear);

}



static inline pmd_t pmd_mkold(pmd_t pmd)

{

	return pmd_clear_flags(pmd, _PAGE_ACCESSED);

}



static inline pmd_t pmd_wrprotect(pmd_t pmd)

{

	return pmd_clear_flags(pmd, _PAGE_RW);

}



static inline pmd_t pmd_mkdirty(pmd_t pmd)

{

	return pmd_set_flags(pmd, _PAGE_DIRTY);

}



static inline pmd_t pmd_mkhuge(pmd_t pmd)

{

	return pmd_set_flags(pmd, _PAGE_PSE);

}



static inline pmd_t pmd_mkyoung(pmd_t pmd)

{

	return pmd_set_flags(pmd, _PAGE_ACCESSED);

}



static inline pmd_t pmd_mkwrite(pmd_t pmd)

{

	return pmd_set_flags(pmd, _PAGE_RW);

}



#endif /* !__ASSEMBLY__ */



#endif /* _ASM_X86_PGTABLE_64_H */

arch/x86/mm/pgtable.c

+66 −0
Original line number Diff line number Diff line
@@ -320,6 +320,25 @@ int ptep_set_access_flags(struct vm_area_struct *vma, 
	return changed;

}



#ifdef CONFIG_TRANSPARENT_HUGEPAGE

int pmdp_set_access_flags(struct vm_area_struct *vma,

			  unsigned long address, pmd_t *pmdp,

			  pmd_t entry, int dirty)

{

	int changed = !pmd_same(*pmdp, entry);



	VM_BUG_ON(address & ~HPAGE_PMD_MASK);



	if (changed && dirty) {

		*pmdp = entry;

		pmd_update_defer(vma->vm_mm, address, pmdp);

		flush_tlb_range(vma, address, address + HPAGE_PMD_SIZE);

	}



	return changed;

}

#endif



int ptep_test_and_clear_young(struct vm_area_struct *vma,

			      unsigned long addr, pte_t *ptep)

{
@@ -335,6 +354,23 @@ int ptep_test_and_clear_young(struct vm_area_struct *vma, 
	return ret;

}



#ifdef CONFIG_TRANSPARENT_HUGEPAGE

int pmdp_test_and_clear_young(struct vm_area_struct *vma,

			      unsigned long addr, pmd_t *pmdp)

{

	int ret = 0;



	if (pmd_young(*pmdp))

		ret = test_and_clear_bit(_PAGE_BIT_ACCESSED,

					 (unsigned long *) &pmdp->pmd);



	if (ret)

		pmd_update(vma->vm_mm, addr, pmdp);



	return ret;

}

#endif



int ptep_clear_flush_young(struct vm_area_struct *vma,

			   unsigned long address, pte_t *ptep)

{
@@ -347,6 +383,36 @@ int ptep_clear_flush_young(struct vm_area_struct *vma, 
	return young;

}



#ifdef CONFIG_TRANSPARENT_HUGEPAGE

int pmdp_clear_flush_young(struct vm_area_struct *vma,

			   unsigned long address, pmd_t *pmdp)

{

	int young;



	VM_BUG_ON(address & ~HPAGE_PMD_MASK);



	young = pmdp_test_and_clear_young(vma, address, pmdp);

	if (young)

		flush_tlb_range(vma, address, address + HPAGE_PMD_SIZE);



	return young;

}



void pmdp_splitting_flush(struct vm_area_struct *vma,

			  unsigned long address, pmd_t *pmdp)

{

	int set;

	VM_BUG_ON(address & ~HPAGE_PMD_MASK);

	set = !test_and_set_bit(_PAGE_BIT_SPLITTING,

				(unsigned long *)&pmdp->pmd);

	if (set) {

		pmd_update(vma->vm_mm, address, pmdp);

		/* need tlb flush only to serialize against gup-fast */

		flush_tlb_range(vma, address, address + HPAGE_PMD_SIZE);

	}

}

#endif



/**

 * reserve_top_address - reserves a hole in the top of kernel address space

 * @reserve - size of hole to reserve