[RFC PATCH v2 00/11] HugeTLB and THP support for ARM64.

[RFC PATCH v2 00/11] HugeTLB and THP support for ARM64.

[Steve Capper]

This series brings huge pages and transparent huge pages to ARM64.
The functionality is very similar to x86, and a lot of code that can
be used by both ARM64 and x86 is brought into mm to avoid the need
for code duplication.

One notable difference from x86 is that ARM64 supports normal pages
that are 64KB. When 64KB pages are enabled, huge page and
transparent huge pages are 512MB only, otherwise the sizes match
x86.

This series applies to 3.9, and requires one additional patch
ARM64: mm: Correct show_pte behaviour
http://lists.infradead.org/pipermail/linux-arm-kernel/2013-April/164157.html

I've tested this under the ARMv8 models (Fast and Foundation) and
the x86 code has been tested in a KVM guest. libhugetlbfs was used
for testing under both architectures.

The most significant changes since the first RFC are:

   * PROT_NONE support added for HugeTLB and THP.
   * pmd_modify implementation fixed.
   * Superfluous huge dcache flushing code removed.
   * Simplified (and corrected) MAX_ORDER raise for THP && 64KB
     pages.
   * The MAX_ORDER check in huge_mm.h has been corrected.

I would be particularly interested in any feedback regarding the
first 4 patches in the series (the promotion of some huge page
code from x86 to mm), as this would also allow me to simplify
my patches for huge page support in ARM.

--

Steve Capper (11):
  mm: hugetlb: Copy huge_pmd_share from x86 to mm.
  x86: mm: Remove x86 version of huge_pmd_share.
  mm: hugetlb: Copy general hugetlb code from x86 to mm.
  x86: mm: Remove general hugetlb code from x86.
  mm: thp: Correct the HPAGE_PMD_ORDER check.
  ARM64: mm: Restore memblock limit when map_mem finished.
  ARM64: mm: Make PAGE_NONE pages read only and no-execute.
  ARM64: mm: Swap PTE_FILE and PTE_PROT_NONE bits.
  ARM64: mm: HugeTLB support.
  ARM64: mm: Raise MAX_ORDER for 64KB pages and THP.
  ARM64: mm: THP support.

 arch/arm64/Kconfig                     |  17 +++
 arch/arm64/include/asm/hugetlb.h       | 121 ++++++++++++++++++
 arch/arm64/include/asm/pgtable-hwdef.h |  12 ++
 arch/arm64/include/asm/pgtable.h       |  80 ++++++++++--
 arch/arm64/include/asm/tlb.h           |   6 +
 arch/arm64/include/asm/tlbflush.h      |   2 +
 arch/arm64/mm/Makefile                 |   1 +
 arch/arm64/mm/fault.c                  |  19 +--
 arch/arm64/mm/hugetlbpage.c            |  70 +++++++++++
 arch/arm64/mm/mmu.c                    |  19 ++-
 arch/x86/Kconfig                       |   6 +
 arch/x86/mm/hugetlbpage.c              | 187 ----------------------------
 include/linux/huge_mm.h                |   2 +-
 include/linux/hugetlb.h                |   4 +
 mm/hugetlb.c                           | 219 +++++++++++++++++++++++++++++++--
 15 files changed, 539 insertions(+), 226 deletions(-)
 create mode 100644 arch/arm64/include/asm/hugetlb.h
 create mode 100644 arch/arm64/mm/hugetlbpage.c

-- 
1.8.1.4

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

[RFC PATCH v2 01/11] mm: hugetlb: Copy huge_pmd_share from x86 to mm.

[Steve Capper]

Under x86, multiple puds can be made to reference the same bank of
huge pmds provided that they represent a full PUD_SIZE of shared
huge memory that is aligned to a PUD_SIZE boundary.

The code to share pmds does not require any architecture specific
knowledge other than the fact that pmds can be indexed, thus can
be beneficial to some other architectures.

This patch copies the huge pmd sharing (and unsharing) logic from
x86/ to mm/ and introduces a new config option to activate it:
CONFIG_ARCH_WANTS_HUGE_PMD_SHARE

Signed-off-by: Steve Capper <steve.capper@linaro.org>
---
 include/linux/hugetlb.h |   4 ++
 mm/hugetlb.c            | 122 ++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 126 insertions(+)

diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index 16e4e9a..795c32d 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -68,6 +68,10 @@ void hugetlb_unreserve_pages(struct inode *inode, long offset, long freed);
 int dequeue_hwpoisoned_huge_page(struct page *page);
 void copy_huge_page(struct page *dst, struct page *src);
 
+#ifdef CONFIG_ARCH_WANT_HUGE_PMD_SHARE
+pte_t *huge_pmd_share(struct mm_struct *mm, unsigned long addr, pud_t *pud);
+#endif
+
 extern unsigned long hugepages_treat_as_movable;
 extern const unsigned long hugetlb_zero, hugetlb_infinity;
 extern int sysctl_hugetlb_shm_group;
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index ca9a7c6..41179b0 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -3142,6 +3142,128 @@ void hugetlb_unreserve_pages(struct inode *inode, long offset, long freed)
 	hugetlb_acct_memory(h, -(chg - freed));
 }
 
+#ifdef CONFIG_ARCH_WANT_HUGE_PMD_SHARE
+static unsigned long page_table_shareable(struct vm_area_struct *svma,
+				struct vm_area_struct *vma,
+				unsigned long addr, pgoff_t idx)
+{
+	unsigned long saddr = ((idx - svma->vm_pgoff) << PAGE_SHIFT) +
+				svma->vm_start;
+	unsigned long sbase = saddr & PUD_MASK;
+	unsigned long s_end = sbase + PUD_SIZE;
+
+	/* Allow segments to share if only one is marked locked */
+	unsigned long vm_flags = vma->vm_flags & ~VM_LOCKED;
+	unsigned long svm_flags = svma->vm_flags & ~VM_LOCKED;
+
+	/*
+	 * match the virtual addresses, permission and the alignment of the
+	 * page table page.
+	 */
+	if (pmd_index(addr) != pmd_index(saddr) ||
+	    vm_flags != svm_flags ||
+	    sbase < svma->vm_start || svma->vm_end < s_end)
+		return 0;
+
+	return saddr;
+}
+
+static int vma_shareable(struct vm_area_struct *vma, unsigned long addr)
+{
+	unsigned long base = addr & PUD_MASK;
+	unsigned long end = base + PUD_SIZE;
+
+	/*
+	 * check on proper vm_flags and page table alignment
+	 */
+	if (vma->vm_flags & VM_MAYSHARE &&
+	    vma->vm_start <= base && end <= vma->vm_end)
+		return 1;
+	return 0;
+}
+
+/*
+ * Search for a shareable pmd page for hugetlb. In any case calls pmd_alloc()
+ * and returns the corresponding pte. While this is not necessary for the
+ * !shared pmd case because we can allocate the pmd later as well, it makes the
+ * code much cleaner. pmd allocation is essential for the shared case because
+ * pud has to be populated inside the same i_mmap_mutex section - otherwise
+ * racing tasks could either miss the sharing (see huge_pte_offset) or select a
+ * bad pmd for sharing.
+ */
+pte_t *huge_pmd_share(struct mm_struct *mm, unsigned long addr, pud_t *pud)
+{
+	struct vm_area_struct *vma = find_vma(mm, addr);
+	struct address_space *mapping = vma->vm_file->f_mapping;
+	pgoff_t idx = ((addr - vma->vm_start) >> PAGE_SHIFT) +
+			vma->vm_pgoff;
+	struct vm_area_struct *svma;
+	unsigned long saddr;
+	pte_t *spte = NULL;
+	pte_t *pte;
+
+	if (!vma_shareable(vma, addr))
+		return (pte_t *)pmd_alloc(mm, pud, addr);
+
+	mutex_lock(&mapping->i_mmap_mutex);
+	vma_interval_tree_foreach(svma, &mapping->i_mmap, idx, idx) {
+		if (svma == vma)
+			continue;
+
+		saddr = page_table_shareable(svma, vma, addr, idx);
+		if (saddr) {
+			spte = huge_pte_offset(svma->vm_mm, saddr);
+			if (spte) {
+				get_page(virt_to_page(spte));
+				break;
+			}
+		}
+	}
+
+	if (!spte)
+		goto out;
+
+	spin_lock(&mm->page_table_lock);
+	if (pud_none(*pud))
+		pud_populate(mm, pud,
+				(pmd_t *)((unsigned long)spte & PAGE_MASK));
+	else
+		put_page(virt_to_page(spte));
+	spin_unlock(&mm->page_table_lock);
+out:
+	pte = (pte_t *)pmd_alloc(mm, pud, addr);
+	mutex_unlock(&mapping->i_mmap_mutex);
+	return pte;
+}
+
+/*
+ * unmap huge page backed by shared pte.
+ *
+ * Hugetlb pte page is ref counted at the time of mapping.  If pte is shared
+ * indicated by page_count > 1, unmap is achieved by clearing pud and
+ * decrementing the ref count. If count == 1, the pte page is not shared.
+ *
+ * called with vma->vm_mm->page_table_lock held.
+ *
+ * returns: 1 successfully unmapped a shared pte page
+ *	    0 the underlying pte page is not shared, or it is the last user
+ */
+int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep)
+{
+	pgd_t *pgd = pgd_offset(mm, *addr);
+	pud_t *pud = pud_offset(pgd, *addr);
+
+	BUG_ON(page_count(virt_to_page(ptep)) == 0);
+	if (page_count(virt_to_page(ptep)) == 1)
+		return 0;
+
+	pud_clear(pud);
+	put_page(virt_to_page(ptep));
+	*addr = ALIGN(*addr, HPAGE_SIZE * PTRS_PER_PTE) - HPAGE_SIZE;
+	return 1;
+}
+#endif /* CONFIG_ARCH_WANT_HUGE_PMD_SHARE */
+
 #ifdef CONFIG_MEMORY_FAILURE
 
 /* Should be called in hugetlb_lock */
-- 
1.8.1.4

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

[RFC PATCH v2 02/11] x86: mm: Remove x86 version of huge_pmd_share.

[Steve Capper]

The huge_pmd_share code has been copied over to mm/hugetlb.c to
make it accessible to other architectures.

Remove the x86 copy of the huge_pmd_share code and enable the
ARCH_WANT_HUGE_PMD_SHARE config flag. That way we reference the
general one.

Signed-off-by: Steve Capper <steve.capper@linaro.org>
---
 arch/x86/Kconfig          |   3 ++
 arch/x86/mm/hugetlbpage.c | 120 ----------------------------------------------
 2 files changed, 3 insertions(+), 120 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 70c0f3d..60e3c402 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -212,6 +212,9 @@ config ARCH_HIBERNATION_POSSIBLE
 config ARCH_SUSPEND_POSSIBLE
 	def_bool y
 
+config ARCH_WANT_HUGE_PMD_SHARE
+	def_bool y
+
 config ZONE_DMA32
 	bool
 	default X86_64
diff --git a/arch/x86/mm/hugetlbpage.c b/arch/x86/mm/hugetlbpage.c
index ae1aa71..7e522a3 100644
--- a/arch/x86/mm/hugetlbpage.c
+++ b/arch/x86/mm/hugetlbpage.c
@@ -16,126 +16,6 @@
 #include <asm/tlbflush.h>
 #include <asm/pgalloc.h>
 
-static unsigned long page_table_shareable(struct vm_area_struct *svma,
-				struct vm_area_struct *vma,
-				unsigned long addr, pgoff_t idx)
-{
-	unsigned long saddr = ((idx - svma->vm_pgoff) << PAGE_SHIFT) +
-				svma->vm_start;
-	unsigned long sbase = saddr & PUD_MASK;
-	unsigned long s_end = sbase + PUD_SIZE;
-
-	/* Allow segments to share if only one is marked locked */
-	unsigned long vm_flags = vma->vm_flags & ~VM_LOCKED;
-	unsigned long svm_flags = svma->vm_flags & ~VM_LOCKED;
-
-	/*
-	 * match the virtual addresses, permission and the alignment of the
-	 * page table page.
-	 */
-	if (pmd_index(addr) != pmd_index(saddr) ||
-	    vm_flags != svm_flags ||
-	    sbase < svma->vm_start || svma->vm_end < s_end)
-		return 0;
-
-	return saddr;
-}
-
-static int vma_shareable(struct vm_area_struct *vma, unsigned long addr)
-{
-	unsigned long base = addr & PUD_MASK;
-	unsigned long end = base + PUD_SIZE;
-
-	/*
-	 * check on proper vm_flags and page table alignment
-	 */
-	if (vma->vm_flags & VM_MAYSHARE &&
-	    vma->vm_start <= base && end <= vma->vm_end)
-		return 1;
-	return 0;
-}
-
-/*
- * Search for a shareable pmd page for hugetlb. In any case calls pmd_alloc()
- * and returns the corresponding pte. While this is not necessary for the
- * !shared pmd case because we can allocate the pmd later as well, it makes the
- * code much cleaner. pmd allocation is essential for the shared case because
- * pud has to be populated inside the same i_mmap_mutex section - otherwise
- * racing tasks could either miss the sharing (see huge_pte_offset) or select a
- * bad pmd for sharing.
- */
-static pte_t *
-huge_pmd_share(struct mm_struct *mm, unsigned long addr, pud_t *pud)
-{
-	struct vm_area_struct *vma = find_vma(mm, addr);
-	struct address_space *mapping = vma->vm_file->f_mapping;
-	pgoff_t idx = ((addr - vma->vm_start) >> PAGE_SHIFT) +
-			vma->vm_pgoff;
-	struct vm_area_struct *svma;
-	unsigned long saddr;
-	pte_t *spte = NULL;
-	pte_t *pte;
-
-	if (!vma_shareable(vma, addr))
-		return (pte_t *)pmd_alloc(mm, pud, addr);
-
-	mutex_lock(&mapping->i_mmap_mutex);
-	vma_interval_tree_foreach(svma, &mapping->i_mmap, idx, idx) {
-		if (svma == vma)
-			continue;
-
-		saddr = page_table_shareable(svma, vma, addr, idx);
-		if (saddr) {
-			spte = huge_pte_offset(svma->vm_mm, saddr);
-			if (spte) {
-				get_page(virt_to_page(spte));
-				break;
-			}
-		}
-	}
-
-	if (!spte)
-		goto out;
-
-	spin_lock(&mm->page_table_lock);
-	if (pud_none(*pud))
-		pud_populate(mm, pud, (pmd_t *)((unsigned long)spte & PAGE_MASK));
-	else
-		put_page(virt_to_page(spte));
-	spin_unlock(&mm->page_table_lock);
-out:
-	pte = (pte_t *)pmd_alloc(mm, pud, addr);
-	mutex_unlock(&mapping->i_mmap_mutex);
-	return pte;
-}
-
-/*
- * unmap huge page backed by shared pte.
- *
- * Hugetlb pte page is ref counted at the time of mapping.  If pte is shared
- * indicated by page_count > 1, unmap is achieved by clearing pud and
- * decrementing the ref count. If count == 1, the pte page is not shared.
- *
- * called with vma->vm_mm->page_table_lock held.
- *
- * returns: 1 successfully unmapped a shared pte page
- *	    0 the underlying pte page is not shared, or it is the last user
- */
-int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep)
-{
-	pgd_t *pgd = pgd_offset(mm, *addr);
-	pud_t *pud = pud_offset(pgd, *addr);
-
-	BUG_ON(page_count(virt_to_page(ptep)) == 0);
-	if (page_count(virt_to_page(ptep)) == 1)
-		return 0;
-
-	pud_clear(pud);
-	put_page(virt_to_page(ptep));
-	*addr = ALIGN(*addr, HPAGE_SIZE * PTRS_PER_PTE) - HPAGE_SIZE;
-	return 1;
-}
-
 pte_t *huge_pte_alloc(struct mm_struct *mm,
 			unsigned long addr, unsigned long sz)
 {
-- 
1.8.1.4

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

[RFC PATCH v2 03/11] mm: hugetlb: Copy general hugetlb code from x86 to mm.

[Steve Capper]

The huge_pte_alloc, huge_pte_offset and follow_huge_p[mu]d
functions in x86/mm/hugetlbpage.c do not rely on any architecture
specific knowledge other than the fact that pmds and puds can be
treated as huge ptes.

To allow other architectures to use this code (and reduce the need
for code duplication), this patch copies these functions into mm
and provides a config flag to activate them:
CONFIG_ARCH_WANT_GENERAL_HUGETLB

If CONFIG_ARCH_WANT_HUGE_PMD_SHARE is also active then the
huge_pmd_share code will be called by huge_pte_alloc (othewise we
call pmd_alloc and skip the sharing code).

Signed-off-by: Steve Capper <steve.capper@linaro.org>
---
 mm/hugetlb.c | 97 ++++++++++++++++++++++++++++++++++++++++++++++++++++++------
 1 file changed, 88 insertions(+), 9 deletions(-)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 41179b0..e1dc5ae 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -2915,15 +2915,6 @@ out_mutex:
 	return ret;
 }
 
-/* Can be overriden by architectures */
-__attribute__((weak)) struct page *
-follow_huge_pud(struct mm_struct *mm, unsigned long address,
-	       pud_t *pud, int write)
-{
-	BUG();
-	return NULL;
-}
-
 long follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,
 			 struct page **pages, struct vm_area_struct **vmas,
 			 unsigned long *position, unsigned long *nr_pages,
@@ -3262,8 +3253,96 @@ int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep)
 	*addr = ALIGN(*addr, HPAGE_SIZE * PTRS_PER_PTE) - HPAGE_SIZE;
 	return 1;
 }
+#define want_pmd_share()	(1)
+#else /* !CONFIG_ARCH_WANT_HUGE_PMD_SHARE */
+pte_t *huge_pmd_share(struct mm_struct *mm, unsigned long addr, pud_t *pud)
+{
+	return NULL;
+}
+#define want_pmd_share()	(0)
 #endif /* CONFIG_ARCH_WANT_HUGE_PMD_SHARE */
 
+#ifdef CONFIG_ARCH_WANT_GENERAL_HUGETLB
+pte_t *huge_pte_alloc(struct mm_struct *mm,
+			unsigned long addr, unsigned long sz)
+{
+	pgd_t *pgd;
+	pud_t *pud;
+	pte_t *pte = NULL;
+
+	pgd = pgd_offset(mm, addr);
+	pud = pud_alloc(mm, pgd, addr);
+	if (pud) {
+		if (sz == PUD_SIZE) {
+			pte = (pte_t *)pud;
+		} else {
+			BUG_ON(sz != PMD_SIZE);
+			if (want_pmd_share() && pud_none(*pud))
+				pte = huge_pmd_share(mm, addr, pud);
+			else
+				pte = (pte_t *)pmd_alloc(mm, pud, addr);
+		}
+	}
+	BUG_ON(pte && !pte_none(*pte) && !pte_huge(*pte));
+
+	return pte;
+}
+
+pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr)
+{
+	pgd_t *pgd;
+	pud_t *pud;
+	pmd_t *pmd = NULL;
+
+	pgd = pgd_offset(mm, addr);
+	if (pgd_present(*pgd)) {
+		pud = pud_offset(pgd, addr);
+		if (pud_present(*pud)) {
+			if (pud_large(*pud))
+				return (pte_t *)pud;
+			pmd = pmd_offset(pud, addr);
+		}
+	}
+	return (pte_t *) pmd;
+}
+
+struct page *
+follow_huge_pmd(struct mm_struct *mm, unsigned long address,
+		pmd_t *pmd, int write)
+{
+	struct page *page;
+
+	page = pte_page(*(pte_t *)pmd);
+	if (page)
+		page += ((address & ~PMD_MASK) >> PAGE_SHIFT);
+	return page;
+}
+
+struct page *
+follow_huge_pud(struct mm_struct *mm, unsigned long address,
+		pud_t *pud, int write)
+{
+	struct page *page;
+
+	page = pte_page(*(pte_t *)pud);
+	if (page)
+		page += ((address & ~PUD_MASK) >> PAGE_SHIFT);
+	return page;
+}
+
+#else /* !CONFIG_ARCH_WANT_GENERAL_HUGETLB */
+
+/* Can be overriden by architectures */
+__attribute__((weak)) struct page *
+follow_huge_pud(struct mm_struct *mm, unsigned long address,
+	       pud_t *pud, int write)
+{
+	BUG();
+	return NULL;
+}
+
+#endif /* CONFIG_ARCH_WANT_GENERAL_HUGETLB */
+
 #ifdef CONFIG_MEMORY_FAILURE
 
 /* Should be called in hugetlb_lock */
-- 
1.8.1.4

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

[RFC PATCH v2 04/11] x86: mm: Remove general hugetlb code from x86.

[Steve Capper]

huge_pte_alloc, huge_pte_offset and follow_huge_p[mu]d have
already been copied over to mm.

This patch removes the x86 copies of these functions and activates
the general ones by enabling:
CONFIG_ARCH_WANT_GENERAL_HUGETLB

Signed-off-by: Steve Capper <steve.capper@linaro.org>
---
 arch/x86/Kconfig          |  3 +++
 arch/x86/mm/hugetlbpage.c | 67 -----------------------------------------------
 2 files changed, 3 insertions(+), 67 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 60e3c402..db1ff87 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -215,6 +215,9 @@ config ARCH_SUSPEND_POSSIBLE
 config ARCH_WANT_HUGE_PMD_SHARE
 	def_bool y
 
+config ARCH_WANT_GENERAL_HUGETLB
+	def_bool y
+
 config ZONE_DMA32
 	bool
 	default X86_64
diff --git a/arch/x86/mm/hugetlbpage.c b/arch/x86/mm/hugetlbpage.c
index 7e522a3..7e73e8c 100644
--- a/arch/x86/mm/hugetlbpage.c
+++ b/arch/x86/mm/hugetlbpage.c
@@ -16,49 +16,6 @@
 #include <asm/tlbflush.h>
 #include <asm/pgalloc.h>
 
-pte_t *huge_pte_alloc(struct mm_struct *mm,
-			unsigned long addr, unsigned long sz)
-{
-	pgd_t *pgd;
-	pud_t *pud;
-	pte_t *pte = NULL;
-
-	pgd = pgd_offset(mm, addr);
-	pud = pud_alloc(mm, pgd, addr);
-	if (pud) {
-		if (sz == PUD_SIZE) {
-			pte = (pte_t *)pud;
-		} else {
-			BUG_ON(sz != PMD_SIZE);
-			if (pud_none(*pud))
-				pte = huge_pmd_share(mm, addr, pud);
-			else
-				pte = (pte_t *)pmd_alloc(mm, pud, addr);
-		}
-	}
-	BUG_ON(pte && !pte_none(*pte) && !pte_huge(*pte));
-
-	return pte;
-}
-
-pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr)
-{
-	pgd_t *pgd;
-	pud_t *pud;
-	pmd_t *pmd = NULL;
-
-	pgd = pgd_offset(mm, addr);
-	if (pgd_present(*pgd)) {
-		pud = pud_offset(pgd, addr);
-		if (pud_present(*pud)) {
-			if (pud_large(*pud))
-				return (pte_t *)pud;
-			pmd = pmd_offset(pud, addr);
-		}
-	}
-	return (pte_t *) pmd;
-}
-
 #if 0	/* This is just for testing */
 struct page *
 follow_huge_addr(struct mm_struct *mm, unsigned long address, int write)
@@ -120,30 +77,6 @@ int pud_huge(pud_t pud)
 	return !!(pud_val(pud) & _PAGE_PSE);
 }
 
-struct page *
-follow_huge_pmd(struct mm_struct *mm, unsigned long address,
-		pmd_t *pmd, int write)
-{
-	struct page *page;
-
-	page = pte_page(*(pte_t *)pmd);
-	if (page)
-		page += ((address & ~PMD_MASK) >> PAGE_SHIFT);
-	return page;
-}
-
-struct page *
-follow_huge_pud(struct mm_struct *mm, unsigned long address,
-		pud_t *pud, int write)
-{
-	struct page *page;
-
-	page = pte_page(*(pte_t *)pud);
-	if (page)
-		page += ((address & ~PUD_MASK) >> PAGE_SHIFT);
-	return page;
-}
-
 #endif
 
 /* x86_64 also uses this file */
-- 
1.8.1.4

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

[RFC PATCH v2 05/11] mm: thp: Correct the HPAGE_PMD_ORDER check.

[Steve Capper]

All Transparent Huge Pages are allocated by the buddy allocator.

A compile time check is in place that fails when the order of a
transparent huge page is too large to be allocated by the buddy
allocator. Unfortunately that compile time check passes when:
HPAGE_PMD_ORDER == MAX_ORDER
( which is incorrect as the buddy allocator can only allocate
memory of order strictly less than MAX_ORDER. )

This patch updates the compile time check to fail in the above
case.

Signed-off-by: Steve Capper <steve.capper@linaro.org>
---
 include/linux/huge_mm.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index ee1c244..3d71e5c 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -119,7 +119,7 @@ extern void __split_huge_page_pmd(struct vm_area_struct *vma,
 	} while (0)
 extern void split_huge_page_pmd_mm(struct mm_struct *mm, unsigned long address,
 		pmd_t *pmd);
-#if HPAGE_PMD_ORDER > MAX_ORDER
+#if HPAGE_PMD_ORDER >= MAX_ORDER
 #error "hugepages can't be allocated by the buddy allocator"
 #endif
 extern int hugepage_madvise(struct vm_area_struct *vma,
-- 
1.8.1.4

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

Re: [RFC PATCH v2 05/11] mm: thp: Correct the HPAGE_PMD_ORDER check.

[Kirill A. Shutemov]

On Wed, May 08, 2013 at 10:52:37AM +0100, Steve Capper wrote:
> All Transparent Huge Pages are allocated by the buddy allocator.
> 
> A compile time check is in place that fails when the order of a
> transparent huge page is too large to be allocated by the buddy
> allocator. Unfortunately that compile time check passes when:
> HPAGE_PMD_ORDER == MAX_ORDER
> ( which is incorrect as the buddy allocator can only allocate
> memory of order strictly less than MAX_ORDER. )

It looks confusing to me. Shouldn't we fix what MAX_ORDER means instead?

-- 
 Kirill A. Shutemov

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

Re: [RFC PATCH v2 05/11] mm: thp: Correct the HPAGE_PMD_ORDER check.

[Steve Capper]

On Wed, May 08, 2013 at 03:44:17PM +0300, Kirill A. Shutemov wrote:
> On Wed, May 08, 2013 at 10:52:37AM +0100, Steve Capper wrote:
> > All Transparent Huge Pages are allocated by the buddy allocator.
> > 
> > A compile time check is in place that fails when the order of a
> > transparent huge page is too large to be allocated by the buddy
> > allocator. Unfortunately that compile time check passes when:
> > HPAGE_PMD_ORDER == MAX_ORDER
> > ( which is incorrect as the buddy allocator can only allocate
> > memory of order strictly less than MAX_ORDER. )
> 
> It looks confusing to me. Shouldn't we fix what MAX_ORDER means instead?
> 

It confused me as I originally had 13 as the order and couldn't
allocate any 512MB THPs :-).

MAX_ORDER appears to be used quite a lot so I think it would be
safer to change the use case here rather than its meaning.

Cheers,
-- 
Steve

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

[RFC PATCH v2 06/11] ARM64: mm: Restore memblock limit when map_mem finished.

[Steve Capper]

In paging_init the memblock limit is set to restrict any addresses
returned by early_alloc to fit within the initial direct kernel
mapping in swapper_pg_dir. This allows map_mem to allocate puds,
pmds and ptes from the initial direct kernel mapping.

The limit stays low after paging_init() though, meaning any
bootmem allocations will be from a restricted subset of memory.
Gigabyte huge pages, for instance, are normally allocated from
bootmem as their order (18) is too large for the default buddy
allocator (MAX_ORDER = 11).

This patch restores the memblock limit when map_mem has finished,
allowing gigabyte huge pages (and other objects) to be allocated
from all of bootmem.

Signed-off-by: Steve Capper <steve.capper@linaro.org>
---
 arch/arm64/mm/mmu.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 70b8cd4..d23188c 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -297,6 +297,16 @@ static void __init map_mem(void)
 {
 	struct memblock_region *reg;
 
+	/*
+	 * Temporarily limit the memblock range. We need to do this as
+	 * create_mapping requires puds, pmds and ptes to be allocated from
+	 * memory addressable from the initial direct kernel mapping.
+	 *
+	 * The initial direct kernel mapping, located at swapper_pg_dir,
+	 * gives us PGDIR_SIZE memory starting from PHYS_OFFSET (aligned).
+	 */
+	memblock_set_current_limit((PHYS_OFFSET & PGDIR_MASK) + PGDIR_SIZE);
+
 	/* map all the memory banks */
 	for_each_memblock(memory, reg) {
 		phys_addr_t start = reg->base;
@@ -307,6 +317,9 @@ static void __init map_mem(void)
 
 		create_mapping(start, __phys_to_virt(start), end - start);
 	}
+
+	/* Limit no longer required. */
+	memblock_set_current_limit(MEMBLOCK_ALLOC_ANYWHERE);
 }
 
 /*
@@ -317,12 +330,6 @@ void __init paging_init(void)
 {
 	void *zero_page;
 
-	/*
-	 * Maximum PGDIR_SIZE addressable via the initial direct kernel
-	 * mapping in swapper_pg_dir.
-	 */
-	memblock_set_current_limit((PHYS_OFFSET & PGDIR_MASK) + PGDIR_SIZE);
-
 	init_mem_pgprot();
 	map_mem();
 
-- 
1.8.1.4

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

Re: [RFC PATCH v2 06/11] ARM64: mm: Restore memblock limit when map_mem finished.

[Catalin Marinas]

On Wed, May 08, 2013 at 10:52:38AM +0100, Steve Capper wrote:
> In paging_init the memblock limit is set to restrict any addresses
> returned by early_alloc to fit within the initial direct kernel
> mapping in swapper_pg_dir. This allows map_mem to allocate puds,
> pmds and ptes from the initial direct kernel mapping.
> 
> The limit stays low after paging_init() though, meaning any
> bootmem allocations will be from a restricted subset of memory.
> Gigabyte huge pages, for instance, are normally allocated from
> bootmem as their order (18) is too large for the default buddy
> allocator (MAX_ORDER = 11).
> 
> This patch restores the memblock limit when map_mem has finished,
> allowing gigabyte huge pages (and other objects) to be allocated
> from all of bootmem.
> 
> Signed-off-by: Steve Capper <steve.capper@linaro.org>

Acked-by: Catalin Marinas <catalin.marinas@arm.com>

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

[RFC PATCH v2 07/11] ARM64: mm: Make PAGE_NONE pages read only and no-execute.

[Steve Capper]

If we consider the following code sequence:

	my_pte = pte_modify(entry, myprot);
	x = pte_write(my_pte);
	y = pte_exec(my_pte);

If myprot comes from a PROT_NONE page, then x and y will both be
true which is undesireable behaviour.

This patch sets the no-execute and read-only bits for PAGE_NONE
such that the code above will return false for both x and y.

Signed-off-by: Steve Capper <steve.capper@linaro.org>
---
 arch/arm64/include/asm/pgtable.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index e333a24..b1a1b59 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -66,7 +66,7 @@ extern pgprot_t pgprot_default;
 
 #define _MOD_PROT(p, b)		__pgprot_modify(p, 0, b)
 
-#define PAGE_NONE		__pgprot_modify(pgprot_default, PTE_TYPE_MASK, PTE_PROT_NONE)
+#define PAGE_NONE		__pgprot_modify(pgprot_default, PTE_TYPE_MASK, PTE_PROT_NONE | PTE_RDONLY | PTE_UXN)
 #define PAGE_SHARED		_MOD_PROT(pgprot_default, PTE_USER | PTE_NG | PTE_PXN | PTE_UXN)
 #define PAGE_SHARED_EXEC	_MOD_PROT(pgprot_default, PTE_USER | PTE_NG | PTE_PXN)
 #define PAGE_COPY		_MOD_PROT(pgprot_default, PTE_USER | PTE_NG | PTE_PXN | PTE_UXN | PTE_RDONLY)
@@ -76,7 +76,7 @@ extern pgprot_t pgprot_default;
 #define PAGE_KERNEL		_MOD_PROT(pgprot_default, PTE_PXN | PTE_UXN | PTE_DIRTY)
 #define PAGE_KERNEL_EXEC	_MOD_PROT(pgprot_default, PTE_UXN | PTE_DIRTY)
 
-#define __PAGE_NONE		__pgprot(((_PAGE_DEFAULT) & ~PTE_TYPE_MASK) | PTE_PROT_NONE)
+#define __PAGE_NONE		__pgprot(((_PAGE_DEFAULT) & ~PTE_TYPE_MASK) | PTE_PROT_NONE | PTE_RDONLY | PTE_UXN)
 #define __PAGE_SHARED		__pgprot(_PAGE_DEFAULT | PTE_USER | PTE_NG | PTE_PXN | PTE_UXN)
 #define __PAGE_SHARED_EXEC	__pgprot(_PAGE_DEFAULT | PTE_USER | PTE_NG | PTE_PXN)
 #define __PAGE_COPY		__pgprot(_PAGE_DEFAULT | PTE_USER | PTE_NG | PTE_PXN | PTE_UXN | PTE_RDONLY)
-- 
1.8.1.4

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

Re: [RFC PATCH v2 07/11] ARM64: mm: Make PAGE_NONE pages read only and no-execute.

[Will Deacon]

On Wed, May 08, 2013 at 10:52:39AM +0100, Steve Capper wrote:
> If we consider the following code sequence:
> 
> 	my_pte = pte_modify(entry, myprot);
> 	x = pte_write(my_pte);
> 	y = pte_exec(my_pte);
> 
> If myprot comes from a PROT_NONE page, then x and y will both be
> true which is undesireable behaviour.
> 
> This patch sets the no-execute and read-only bits for PAGE_NONE
> such that the code above will return false for both x and y.
> 
> Signed-off-by: Steve Capper <steve.capper@linaro.org>
> ---
>  arch/arm64/include/asm/pgtable.h | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
> index e333a24..b1a1b59 100644
> --- a/arch/arm64/include/asm/pgtable.h
> +++ b/arch/arm64/include/asm/pgtable.h
> @@ -66,7 +66,7 @@ extern pgprot_t pgprot_default;
>  
>  #define _MOD_PROT(p, b)		__pgprot_modify(p, 0, b)
>  
> -#define PAGE_NONE		__pgprot_modify(pgprot_default, PTE_TYPE_MASK, PTE_PROT_NONE)
> +#define PAGE_NONE		__pgprot_modify(pgprot_default, PTE_TYPE_MASK, PTE_PROT_NONE | PTE_RDONLY | PTE_UXN)
>  #define PAGE_SHARED		_MOD_PROT(pgprot_default, PTE_USER | PTE_NG | PTE_PXN | PTE_UXN)
>  #define PAGE_SHARED_EXEC	_MOD_PROT(pgprot_default, PTE_USER | PTE_NG | PTE_PXN)
>  #define PAGE_COPY		_MOD_PROT(pgprot_default, PTE_USER | PTE_NG | PTE_PXN | PTE_UXN | PTE_RDONLY)
> @@ -76,7 +76,7 @@ extern pgprot_t pgprot_default;
>  #define PAGE_KERNEL		_MOD_PROT(pgprot_default, PTE_PXN | PTE_UXN | PTE_DIRTY)
>  #define PAGE_KERNEL_EXEC	_MOD_PROT(pgprot_default, PTE_UXN | PTE_DIRTY)
>  
> -#define __PAGE_NONE		__pgprot(((_PAGE_DEFAULT) & ~PTE_TYPE_MASK) | PTE_PROT_NONE)
> +#define __PAGE_NONE		__pgprot(((_PAGE_DEFAULT) & ~PTE_TYPE_MASK) | PTE_PROT_NONE | PTE_RDONLY | PTE_UXN)
>  #define __PAGE_SHARED		__pgprot(_PAGE_DEFAULT | PTE_USER | PTE_NG | PTE_PXN | PTE_UXN)
>  #define __PAGE_SHARED_EXEC	__pgprot(_PAGE_DEFAULT | PTE_USER | PTE_NG | PTE_PXN)
>  #define __PAGE_COPY		__pgprot(_PAGE_DEFAULT | PTE_USER | PTE_NG | PTE_PXN | PTE_UXN | PTE_RDONLY)

Whilst it's not strictly needed for pte_exec to work, I think you should
include PTE_PXN in the PAGE_NONE definitions as well.

Will

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

Re: [RFC PATCH v2 07/11] ARM64: mm: Make PAGE_NONE pages read only and no-execute.

[Steve Capper]

On Wed, May 08, 2013 at 05:43:41PM +0100, Will Deacon wrote:
> On Wed, May 08, 2013 at 10:52:39AM +0100, Steve Capper wrote:
 
> Whilst it's not strictly needed for pte_exec to work, I think you should
> include PTE_PXN in the PAGE_NONE definitions as well.

Agreed, it does look a little weird without it.

Cheers,
-- 
Steve

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

[RFC PATCH v2 08/11] ARM64: mm: Swap PTE_FILE and PTE_PROT_NONE bits.

[Steve Capper]

Under ARM64, PTEs can be broadly categorised as follows:
   - Present and valid: Bit #0 is set. The PTE is valid and memory
     access to the region may fault.

   - Present and invalid: Bit #0 is clear and bit #1 is set.
     Represents present memory with PROT_NONE protection. The PTE
     is an invalid entry, and the user fault handler will raise a
     SIGSEGV.

   - Not present (file): Bits #0 and #1 are clear, bit #2 is set.
     Memory represented has been paged out. The PTE is an invalid
     entry, and the fault handler will try and re-populate the
     memory where necessary.

Huge PTEs are block descriptors that have bit #1 clear. If we wish
to represent PROT_NONE huge PTEs we then run into a problem as
there is no way to distinguish between regular and huge PTEs if we
set bit #1.

As huge PTEs are always present, the meaning of bits #1 and #2 can
be swapped for invalid PTEs. This patch swaps the PTE_FILE and
PTE_PROT_NONE constants, allowing us to represent PROT_NONE huge
PTEs.

Signed-off-by: Steve Capper <steve.capper@linaro.org>
---
 arch/arm64/include/asm/pgtable.h | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index b1a1b59..e245260 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -25,8 +25,8 @@
  * Software defined PTE bits definition.
  */
 #define PTE_VALID		(_AT(pteval_t, 1) << 0)
-#define PTE_PROT_NONE		(_AT(pteval_t, 1) << 1)	/* only when !PTE_VALID */
-#define PTE_FILE		(_AT(pteval_t, 1) << 2)	/* only when !pte_present() */
+#define PTE_FILE		(_AT(pteval_t, 1) << 1)	/* only when !pte_present() */
+#define PTE_PROT_NONE		(_AT(pteval_t, 1) << 2)	/* only when !PTE_VALID */
 #define PTE_DIRTY		(_AT(pteval_t, 1) << 55)
 #define PTE_SPECIAL		(_AT(pteval_t, 1) << 56)
 
@@ -306,8 +306,8 @@ extern pgd_t idmap_pg_dir[PTRS_PER_PGD];
 
 /*
  * Encode and decode a file entry:
- *	bits 0-1:	present (must be zero)
- *	bit  2:		PTE_FILE
+ *	bits 0 & 2:	present (must be zero)
+ *	bit  1:		PTE_FILE
  *	bits 3-63:	file offset / PAGE_SIZE
  */
 #define pte_file(pte)		(pte_val(pte) & PTE_FILE)
-- 
1.8.1.4

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

Re: [RFC PATCH v2 08/11] ARM64: mm: Swap PTE_FILE and PTE_PROT_NONE bits.

[Christopher Covington]

Hi Steve,

On 05/08/2013 05:52 AM, Steve Capper wrote:
> Under ARM64, PTEs can be broadly categorised as follows:
>    - Present and valid: Bit #0 is set. The PTE is valid and memory
>      access to the region may fault.
> 
>    - Present and invalid: Bit #0 is clear and bit #1 is set.
>      Represents present memory with PROT_NONE protection. The PTE
>      is an invalid entry, and the user fault handler will raise a
>      SIGSEGV.
> 
>    - Not present (file): Bits #0 and #1 are clear, bit #2 is set.
>      Memory represented has been paged out. The PTE is an invalid
>      entry, and the fault handler will try and re-populate the
>      memory where necessary.
> 
> Huge PTEs are block descriptors that have bit #1 clear. If we wish
> to represent PROT_NONE huge PTEs we then run into a problem as
> there is no way to distinguish between regular and huge PTEs if we
> set bit #1.
> 
> As huge PTEs are always present, the meaning of bits #1 and #2 can
> be swapped for invalid PTEs. This patch swaps the PTE_FILE and
> PTE_PROT_NONE constants, allowing us to represent PROT_NONE huge
> PTEs.

[...]

> diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h

[...]

> @@ -306,8 +306,8 @@ extern pgd_t idmap_pg_dir[PTRS_PER_PGD];
>  
>  /*
>   * Encode and decode a file entry:
> - *	bits 0-1:	present (must be zero)
> - *	bit  2:		PTE_FILE
> + *	bits 0 & 2:	present (must be zero)

Consider using punctuation like "bits 0, 2" here to disambiguate from the
binary and operation.

[...]

Christopher

-- 
Employee of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
hosted by the Linux Foundation.

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

Re: [RFC PATCH v2 08/11] ARM64: mm: Swap PTE_FILE and PTE_PROT_NONE bits.

[Steve Capper]

On Wed, May 08, 2013 at 12:17:35PM -0400, Christopher Covington wrote:
> Hi Steve,
> 
> On 05/08/2013 05:52 AM, Steve Capper wrote:
 
 [...]
> 
> > diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
> 
 [...]
> 
> > @@ -306,8 +306,8 @@ extern pgd_t idmap_pg_dir[PTRS_PER_PGD];
> >  
> >  /*
> >   * Encode and decode a file entry:
> > - *	bits 0-1:	present (must be zero)
> > - *	bit  2:		PTE_FILE
> > + *	bits 0 & 2:	present (must be zero)
> 
> Consider using punctuation like "bits 0, 2" here to disambiguate from the
> binary and operation.
> 

Hi Christopher,
Thanks, I now have:
       bits 0, 2:      present (must both be zero)

Cheers,
-- 
Steve

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

Re: [RFC PATCH v2 08/11] ARM64: mm: Swap PTE_FILE and PTE_PROT_NONE bits.

[Will Deacon]

On Wed, May 08, 2013 at 10:52:40AM +0100, Steve Capper wrote:
> Under ARM64, PTEs can be broadly categorised as follows:
>    - Present and valid: Bit #0 is set. The PTE is valid and memory
>      access to the region may fault.
> 
>    - Present and invalid: Bit #0 is clear and bit #1 is set.
>      Represents present memory with PROT_NONE protection. The PTE
>      is an invalid entry, and the user fault handler will raise a
>      SIGSEGV.
> 
>    - Not present (file): Bits #0 and #1 are clear, bit #2 is set.
>      Memory represented has been paged out. The PTE is an invalid
>      entry, and the fault handler will try and re-populate the
>      memory where necessary.
> 
> Huge PTEs are block descriptors that have bit #1 clear. If we wish
> to represent PROT_NONE huge PTEs we then run into a problem as
> there is no way to distinguish between regular and huge PTEs if we
> set bit #1.
> 
> As huge PTEs are always present, the meaning of bits #1 and #2 can
> be swapped for invalid PTEs. This patch swaps the PTE_FILE and
> PTE_PROT_NONE constants, allowing us to represent PROT_NONE huge
> PTEs.
> 
> Signed-off-by: Steve Capper <steve.capper@linaro.org>
> ---
>  arch/arm64/include/asm/pgtable.h | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
> index b1a1b59..e245260 100644
> --- a/arch/arm64/include/asm/pgtable.h
> +++ b/arch/arm64/include/asm/pgtable.h
> @@ -25,8 +25,8 @@
>   * Software defined PTE bits definition.
>   */
>  #define PTE_VALID		(_AT(pteval_t, 1) << 0)
> -#define PTE_PROT_NONE		(_AT(pteval_t, 1) << 1)	/* only when !PTE_VALID */
> -#define PTE_FILE		(_AT(pteval_t, 1) << 2)	/* only when !pte_present() */
> +#define PTE_FILE		(_AT(pteval_t, 1) << 1)	/* only when !pte_present() */
> +#define PTE_PROT_NONE		(_AT(pteval_t, 1) << 2)	/* only when !PTE_VALID */
>  #define PTE_DIRTY		(_AT(pteval_t, 1) << 55)
>  #define PTE_SPECIAL		(_AT(pteval_t, 1) << 56)
>  
> @@ -306,8 +306,8 @@ extern pgd_t idmap_pg_dir[PTRS_PER_PGD];
>  
>  /*
>   * Encode and decode a file entry:
> - *	bits 0-1:	present (must be zero)
> - *	bit  2:		PTE_FILE
> + *	bits 0 & 2:	present (must be zero)
> + *	bit  1:		PTE_FILE
>   *	bits 3-63:	file offset / PAGE_SIZE
>   */
>  #define pte_file(pte)		(pte_val(pte) & PTE_FILE)

Can you update the comment describing swp entries too please? I *think* the
__SWP_* defines can remain untouched, but the comment is now wrong.

Will

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

Re: [RFC PATCH v2 08/11] ARM64: mm: Swap PTE_FILE and PTE_PROT_NONE bits.

[Steve Capper]

On Wed, May 08, 2013 at 05:40:19PM +0100, Will Deacon wrote:
> On Wed, May 08, 2013 at 10:52:40AM +0100, Steve Capper wrote:

 [...] 

> Can you update the comment describing swp entries too please? I *think* the
> __SWP_* defines can remain untouched, but the comment is now wrong.
> 
> Will

Ta Will, I've now changed the other comment.
The __SWP_* entries look ok to me. I'm going to run some swap tests though
to see if anything crops up.

Cheers,
-- 
Steve

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

Re: [RFC PATCH v2 08/11] ARM64: mm: Swap PTE_FILE and PTE_PROT_NONE bits.

[Catalin Marinas]

On Wed, May 08, 2013 at 10:52:40AM +0100, Steve Capper wrote:
> Under ARM64, PTEs can be broadly categorised as follows:
>    - Present and valid: Bit #0 is set. The PTE is valid and memory
>      access to the region may fault.
> 
>    - Present and invalid: Bit #0 is clear and bit #1 is set.
>      Represents present memory with PROT_NONE protection. The PTE
>      is an invalid entry, and the user fault handler will raise a
>      SIGSEGV.
> 
>    - Not present (file): Bits #0 and #1 are clear, bit #2 is set.
>      Memory represented has been paged out. The PTE is an invalid
>      entry, and the fault handler will try and re-populate the
>      memory where necessary.
> 
> Huge PTEs are block descriptors that have bit #1 clear. If we wish
> to represent PROT_NONE huge PTEs we then run into a problem as
> there is no way to distinguish between regular and huge PTEs if we
> set bit #1.
> 
> As huge PTEs are always present, the meaning of bits #1 and #2 can
> be swapped for invalid PTEs. This patch swaps the PTE_FILE and
> PTE_PROT_NONE constants, allowing us to represent PROT_NONE huge
> PTEs.

I guess we'll never get a huge_(pte|pmd)_file() (but we can shift the
file bits up anyway).

> Signed-off-by: Steve Capper <steve.capper@linaro.org>

Apart from the comments you already got:

Acked-by: Catalin Marinas <catalin.marinas@arm.com>

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

[RFC PATCH v2 09/11] ARM64: mm: HugeTLB support.

[Steve Capper]

Add huge page support to ARM64, different huge page sizes are
supported depending on the size of normal pages:

PAGE_SIZE is 4KB:
   2MB - (pmds) these can be allocated at any time.
1024MB - (puds) usually allocated on bootup with the command line
         with something like: hugepagesz=1G hugepages=6

PAGE_SIZE is 64KB:
 512MB - (pmds) usually allocated on bootup via command line.

Signed-off-by: Steve Capper <steve.capper@linaro.org>
---
 arch/arm64/Kconfig                     |   9 +++
 arch/arm64/include/asm/hugetlb.h       | 121 +++++++++++++++++++++++++++++++++
 arch/arm64/include/asm/pgtable-hwdef.h |   8 +++
 arch/arm64/include/asm/pgtable.h       |  13 +++-
 arch/arm64/mm/Makefile                 |   1 +
 arch/arm64/mm/fault.c                  |  19 ++----
 arch/arm64/mm/hugetlbpage.c            |  70 +++++++++++++++++++
 7 files changed, 224 insertions(+), 17 deletions(-)
 create mode 100644 arch/arm64/include/asm/hugetlb.h
 create mode 100644 arch/arm64/mm/hugetlbpage.c

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 43b0e9f..053533b 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -185,6 +185,15 @@ config HW_PERF_EVENTS
 	  Enable hardware performance counter support for perf events. If
 	  disabled, perf events will use software events only.
 
+config SYS_SUPPORTS_HUGETLBFS
+	def_bool y
+
+config ARCH_WANT_GENERAL_HUGETLB
+	def_bool y
+
+config ARCH_WANT_HUGE_PMD_SHARE
+	def_bool y if !ARM64_64K_PAGES
+
 source "mm/Kconfig"
 
 endmenu
diff --git a/arch/arm64/include/asm/hugetlb.h b/arch/arm64/include/asm/hugetlb.h
new file mode 100644
index 0000000..fb08fbb
--- /dev/null
+++ b/arch/arm64/include/asm/hugetlb.h
@@ -0,0 +1,121 @@
+/*
+ * arch/arm64/include/asm/hugetlb.h
+ *
+ * Copyright (C) 2013 Linaro Ltd.
+ *
+ * Based on arch/x86/include/asm/hugetlb.h
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+#ifndef __ASM_HUGETLB_H
+#define __ASM_HUGETLB_H
+
+#include <asm/page.h>
+
+static inline pte_t huge_ptep_get(pte_t *ptep)
+{
+	return *ptep;
+}
+
+static inline void set_huge_pte_at(struct mm_struct *mm, unsigned long addr,
+				   pte_t *ptep, pte_t pte)
+{
+	set_pte_at(mm, addr, ptep, pte);
+}
+
+static inline void huge_ptep_clear_flush(struct vm_area_struct *vma,
+					 unsigned long addr, pte_t *ptep)
+{
+	ptep_clear_flush(vma, addr, ptep);
+}
+
+static inline void huge_ptep_set_wrprotect(struct mm_struct *mm,
+					   unsigned long addr, pte_t *ptep)
+{
+	ptep_set_wrprotect(mm, addr, ptep);
+}
+
+static inline pte_t huge_ptep_get_and_clear(struct mm_struct *mm,
+					    unsigned long addr, pte_t *ptep)
+{
+	return ptep_get_and_clear(mm, addr, ptep);
+}
+
+static inline int huge_ptep_set_access_flags(struct vm_area_struct *vma,
+					     unsigned long addr, pte_t *ptep,
+					     pte_t pte, int dirty)
+{
+	return ptep_set_access_flags(vma, addr, ptep, pte, dirty);
+}
+
+static inline void hugetlb_free_pgd_range(struct mmu_gather *tlb,
+					  unsigned long addr, unsigned long end,
+					  unsigned long floor,
+					  unsigned long ceiling)
+{
+	free_pgd_range(tlb, addr, end, floor, ceiling);
+}
+
+static inline int is_hugepage_only_range(struct mm_struct *mm,
+					 unsigned long addr, unsigned long len)
+{
+	return 0;
+}
+
+static inline int prepare_hugepage_range(struct file *file,
+					 unsigned long addr, unsigned long len)
+{
+	struct hstate *h = hstate_file(file);
+	if (len & ~huge_page_mask(h))
+		return -EINVAL;
+	if (addr & ~huge_page_mask(h))
+		return -EINVAL;
+	return 0;
+}
+
+static inline void hugetlb_prefault_arch_hook(struct mm_struct *mm)
+{
+}
+
+static inline int huge_pte_none(pte_t pte)
+{
+	return pte_none(pte);
+}
+
+static inline pte_t huge_pte_wrprotect(pte_t pte)
+{
+	return pte_wrprotect(pte);
+}
+
+static inline int arch_prepare_hugepage(struct page *page)
+{
+	return 0;
+}
+
+static inline void arch_release_hugepage(struct page *page)
+{
+}
+
+static inline void arch_clear_hugepage_flags(struct page *page)
+{
+	clear_bit(PG_dcache_clean, &page->flags);
+}
+
+static inline int pud_large(pud_t pud)
+{
+	return !(pud_val(pud) & PUD_TABLE_BIT);
+}
+
+#endif /* __ASM_HUGETLB_H */
diff --git a/arch/arm64/include/asm/pgtable-hwdef.h b/arch/arm64/include/asm/pgtable-hwdef.h
index 75fd13d..e6e0a0d 100644
--- a/arch/arm64/include/asm/pgtable-hwdef.h
+++ b/arch/arm64/include/asm/pgtable-hwdef.h
@@ -25,12 +25,19 @@
 /*
  * Hardware page table definitions.
  *
+ * Level 1 descriptor (PUD).
+ */
+
+#define PUD_TABLE_BIT		(_AT(pgdval_t, 1) << 1)
+
+/*
  * Level 2 descriptor (PMD).
  */
 #define PMD_TYPE_MASK		(_AT(pmdval_t, 3) << 0)
 #define PMD_TYPE_FAULT		(_AT(pmdval_t, 0) << 0)
 #define PMD_TYPE_TABLE		(_AT(pmdval_t, 3) << 0)
 #define PMD_TYPE_SECT		(_AT(pmdval_t, 1) << 0)
+#define PMD_TABLE_BIT		(_AT(pmdval_t, 1) << 1)
 
 /*
  * Section
@@ -53,6 +60,7 @@
 #define PTE_TYPE_MASK		(_AT(pteval_t, 3) << 0)
 #define PTE_TYPE_FAULT		(_AT(pteval_t, 0) << 0)
 #define PTE_TYPE_PAGE		(_AT(pteval_t, 3) << 0)
+#define PTE_TABLE_BIT		(_AT(pteval_t, 1) << 1)
 #define PTE_USER		(_AT(pteval_t, 1) << 6)		/* AP[1] */
 #define PTE_RDONLY		(_AT(pteval_t, 1) << 7)		/* AP[2] */
 #define PTE_SHARED		(_AT(pteval_t, 3) << 8)		/* SH[1:0], inner shareable */
diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index e245260..6bcbcfd 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -173,8 +173,17 @@ static inline void set_pte_at(struct mm_struct *mm, unsigned long addr,
 /*
  * Huge pte definitions.
  */
-#define pte_huge(pte)		((pte_val(pte) & PTE_TYPE_MASK) == PTE_TYPE_HUGEPAGE)
-#define pte_mkhuge(pte)		(__pte((pte_val(pte) & ~PTE_TYPE_MASK) | PTE_TYPE_HUGEPAGE))
+#define pte_huge(pte)		(!(pte_val(pte) & PTE_TABLE_BIT))
+#define pte_mkhuge(pte)		(__pte(pte_val(pte) & ~PTE_TABLE_BIT))
+
+/*
+ * Hugetlb definitions.
+ */
+#define HUGE_MAX_HSTATE		2
+#define HPAGE_SHIFT		PMD_SHIFT
+#define HPAGE_SIZE		(_AC(1, UL) << HPAGE_SHIFT)
+#define HPAGE_MASK		(~(HPAGE_SIZE - 1))
+#define HUGETLB_PAGE_ORDER	(HPAGE_SHIFT - PAGE_SHIFT)
 
 #define __HAVE_ARCH_PTE_SPECIAL
 
diff --git a/arch/arm64/mm/Makefile b/arch/arm64/mm/Makefile
index 3140a2a..b51d364 100644
--- a/arch/arm64/mm/Makefile
+++ b/arch/arm64/mm/Makefile
@@ -2,3 +2,4 @@ obj-y				:= dma-mapping.o extable.o fault.o init.o \
 				   cache.o copypage.o flush.o \
 				   ioremap.o mmap.o pgd.o mmu.o \
 				   context.o tlb.o proc.o
+obj-$(CONFIG_HUGETLB_PAGE)	+= hugetlbpage.o
diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index 5263817..36e3080 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -363,17 +363,6 @@ static int __kprobes do_translation_fault(unsigned long addr,
 }
 
 /*
- * Some section permission faults need to be handled gracefully.  They can
- * happen due to a __{get,put}_user during an oops.
- */
-static int do_sect_fault(unsigned long addr, unsigned int esr,
-			 struct pt_regs *regs)
-{
-	do_bad_area(addr, esr, regs);
-	return 0;
-}
-
-/*
  * This abort handler always returns "fault".
  */
 static int do_bad(unsigned long addr, unsigned int esr, struct pt_regs *regs)
@@ -396,12 +385,12 @@ static struct fault_info {
 	{ do_translation_fault,	SIGSEGV, SEGV_MAPERR,	"level 2 translation fault"	},
 	{ do_page_fault,	SIGSEGV, SEGV_MAPERR,	"level 3 translation fault"	},
 	{ do_bad,		SIGBUS,  0,		"reserved access flag fault"	},
-	{ do_bad,		SIGSEGV, SEGV_ACCERR,	"level 1 access flag fault"	},
-	{ do_bad,		SIGSEGV, SEGV_ACCERR,	"level 2 access flag fault"	},
+	{ do_page_fault,	SIGSEGV, SEGV_ACCERR,	"level 1 access flag fault"	},
+	{ do_page_fault,	SIGSEGV, SEGV_ACCERR,	"level 2 access flag fault"	},
 	{ do_page_fault,	SIGSEGV, SEGV_ACCERR,	"level 3 access flag fault"	},
 	{ do_bad,		SIGBUS,  0,		"reserved permission fault"	},
-	{ do_bad,		SIGSEGV, SEGV_ACCERR,	"level 1 permission fault"	},
-	{ do_sect_fault,	SIGSEGV, SEGV_ACCERR,	"level 2 permission fault"	},
+	{ do_page_fault,	SIGSEGV, SEGV_ACCERR,	"level 1 permission fault"	},
+	{ do_page_fault,	SIGSEGV, SEGV_ACCERR,	"level 2 permission fault"	},
 	{ do_page_fault,	SIGSEGV, SEGV_ACCERR,	"level 3 permission fault"	},
 	{ do_bad,		SIGBUS,  0,		"synchronous external abort"	},
 	{ do_bad,		SIGBUS,  0,		"asynchronous external abort"	},
diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c
new file mode 100644
index 0000000..2fc8258
--- /dev/null
+++ b/arch/arm64/mm/hugetlbpage.c
@@ -0,0 +1,70 @@
+/*
+ * arch/arm64/mm/hugetlbpage.c
+ *
+ * Copyright (C) 2013 Linaro Ltd.
+ *
+ * Based on arch/x86/mm/hugetlbpage.c.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+#include <linux/init.h>
+#include <linux/fs.h>
+#include <linux/mm.h>
+#include <linux/hugetlb.h>
+#include <linux/pagemap.h>
+#include <linux/err.h>
+#include <linux/sysctl.h>
+#include <asm/mman.h>
+#include <asm/tlb.h>
+#include <asm/tlbflush.h>
+#include <asm/pgalloc.h>
+
+#ifndef CONFIG_ARCH_WANT_HUGE_PMD_SHARE
+int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep)
+{
+	return 0;
+}
+#endif
+
+struct page *follow_huge_addr(struct mm_struct *mm, unsigned long address,
+			      int write)
+{
+	return ERR_PTR(-EINVAL);
+}
+
+int pmd_huge(pmd_t pmd)
+{
+	return !(pmd_val(pmd) & PMD_TABLE_BIT);
+}
+
+int pud_huge(pud_t pud)
+{
+	return !(pud_val(pud) & PUD_TABLE_BIT);
+}
+
+static __init int setup_hugepagesz(char *opt)
+{
+	unsigned long ps = memparse(opt, &opt);
+	if (ps == PMD_SIZE) {
+		hugetlb_add_hstate(PMD_SHIFT - PAGE_SHIFT);
+	} else if (ps == PUD_SIZE) {
+		hugetlb_add_hstate(PUD_SHIFT - PAGE_SHIFT);
+	} else {
+		pr_err("hugepagesz: Unsupported page size %lu M\n", ps >> 20);
+		return 0;
+	}
+	return 1;
+}
+__setup("hugepagesz=", setup_hugepagesz);
-- 
1.8.1.4

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

Re: [RFC PATCH v2 09/11] ARM64: mm: HugeTLB support.

[Catalin Marinas]

On Wed, May 08, 2013 at 10:52:41AM +0100, Steve Capper wrote:
> --- /dev/null
> +++ b/arch/arm64/include/asm/hugetlb.h
...
> +static inline int pud_large(pud_t pud)
> +{
> +	return !(pud_val(pud) & PUD_TABLE_BIT);
> +}

I already commented on this - do we really need pud_large() which is
the same as pud_huge()? It's only defined on x86 and can be safely
replaced with pud_huge().

> --- /dev/null
> +++ b/arch/arm64/mm/hugetlbpage.c
> @@ -0,0 +1,70 @@
...
> +int pmd_huge(pmd_t pmd)
> +{
> +	return !(pmd_val(pmd) & PMD_TABLE_BIT);
> +}
> +
> +int pud_huge(pud_t pud)
> +{
> +	return !(pud_val(pud) & PUD_TABLE_BIT);
> +}

You could even go further and make pud/pmd_huge static inline functions
for slightly better efficiency (needs changing in the linux/hugetlb.h
header).

-- 
Catalin

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

Re: [RFC PATCH v2 09/11] ARM64: mm: HugeTLB support.

[Steve Capper]

On Thu, May 16, 2013 at 03:32:36PM +0100, Catalin Marinas wrote:
> On Wed, May 08, 2013 at 10:52:41AM +0100, Steve Capper wrote:
> > --- /dev/null
> > +++ b/arch/arm64/include/asm/hugetlb.h
> ...
> > +static inline int pud_large(pud_t pud)
> > +{
> > +	return !(pud_val(pud) & PUD_TABLE_BIT);
> > +}
> 
> I already commented on this - do we really need pud_large() which is
> the same as pud_huge()? It's only defined on x86 and can be safely
> replaced with pud_huge().
> 

Thanks, yes, sorry this one slipped through the cracks.
I'll update this to use pud_huge.

> > --- /dev/null
> > +++ b/arch/arm64/mm/hugetlbpage.c
> > @@ -0,0 +1,70 @@
> ...
> > +int pmd_huge(pmd_t pmd)
> > +{
> > +	return !(pmd_val(pmd) & PMD_TABLE_BIT);
> > +}
> > +
> > +int pud_huge(pud_t pud)
> > +{
> > +	return !(pud_val(pud) & PUD_TABLE_BIT);
> > +}
> 
> You could even go further and make pud/pmd_huge static inline functions
> for slightly better efficiency (needs changing in the linux/hugetlb.h
> header).

I'll have to have a think about this and a tinker :-). 

Cheers,
-- 
Steve

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

[RFC PATCH v2 10/11] ARM64: mm: Raise MAX_ORDER for 64KB pages and THP.

[Steve Capper]

The buddy allocator has a default MAX_ORDER of 11, which is too
low to allocate enough memory for 512MB Transparent HugePages if
our base page size is 64KB.

This patch introduces MAX_ZONE_ORDER and sets it to 14 when 64KB
pages are used in conjuction with THP, otherwise the default value
of 11 is used.

Signed-off-by: Steve Capper <steve.capper@linaro.org>
---
 arch/arm64/Kconfig | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 053533b..a5f76cf 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -196,6 +196,11 @@ config ARCH_WANT_HUGE_PMD_SHARE
 
 source "mm/Kconfig"
 
+config FORCE_MAX_ZONEORDER
+	int
+	default "14" if (ARM64_64K_PAGES && TRANSPARENT_HUGEPAGE)
+	default "11"
+
 endmenu
 
 menu "Boot options"
-- 
1.8.1.4

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

Re: [RFC PATCH v2 10/11] ARM64: mm: Raise MAX_ORDER for 64KB pages and THP.

[Catalin Marinas]

On Wed, May 08, 2013 at 10:52:42AM +0100, Steve Capper wrote:
> The buddy allocator has a default MAX_ORDER of 11, which is too
> low to allocate enough memory for 512MB Transparent HugePages if
> our base page size is 64KB.
> 
> This patch introduces MAX_ZONE_ORDER and sets it to 14 when 64KB
> pages are used in conjuction with THP, otherwise the default value
> of 11 is used.
> 
> Signed-off-by: Steve Capper <steve.capper@linaro.org>

Acked-by: Catalin Marinas <catalin.marinas@arm.com>

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

[RFC PATCH v2 11/11] ARM64: mm: THP support.

[Steve Capper]

Bring Transparent HugePage support to ARM. The size of a
transparent huge page depends on the normal page size. A
transparent huge page is always represented as a pmd.

If PAGE_SIZE is 4KB, THPs are 2MB.
If PAGE_SIZE is 64KB, THPs are 512MB.

Signed-off-by: Steve Capper <steve.capper@linaro.org>
---
 arch/arm64/Kconfig                     |  3 ++
 arch/arm64/include/asm/pgtable-hwdef.h |  4 +++
 arch/arm64/include/asm/pgtable.h       | 55 ++++++++++++++++++++++++++++++++++
 arch/arm64/include/asm/tlb.h           |  6 ++++
 arch/arm64/include/asm/tlbflush.h      |  2 ++
 5 files changed, 70 insertions(+)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index a5f76cf..93a3b9e 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -194,6 +194,9 @@ config ARCH_WANT_GENERAL_HUGETLB
 config ARCH_WANT_HUGE_PMD_SHARE
 	def_bool y if !ARM64_64K_PAGES
 
+config HAVE_ARCH_TRANSPARENT_HUGEPAGE
+	def_bool y
+
 source "mm/Kconfig"
 
 config FORCE_MAX_ZONEORDER
diff --git a/arch/arm64/include/asm/pgtable-hwdef.h b/arch/arm64/include/asm/pgtable-hwdef.h
index e6e0a0d..63c9d0d 100644
--- a/arch/arm64/include/asm/pgtable-hwdef.h
+++ b/arch/arm64/include/asm/pgtable-hwdef.h
@@ -42,6 +42,10 @@
 /*
  * Section
  */
+#define PMD_SECT_VALID		(_AT(pmdval_t, 1) << 0)
+#define PMD_SECT_PROT_NONE	(_AT(pmdval_t, 1) << 2)
+#define PMD_SECT_USER		(_AT(pmdval_t, 1) << 6)		/* AP[1] */
+#define PMD_SECT_RDONLY		(_AT(pmdval_t, 1) << 7)		/* AP[2] */
 #define PMD_SECT_S		(_AT(pmdval_t, 3) << 8)
 #define PMD_SECT_AF		(_AT(pmdval_t, 1) << 10)
 #define PMD_SECT_NG		(_AT(pmdval_t, 1) << 11)
diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index 6bcbcfd..fd17e0b 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -188,6 +188,61 @@ static inline void set_pte_at(struct mm_struct *mm, unsigned long addr,
 #define __HAVE_ARCH_PTE_SPECIAL
 
 /*
+ * Software PMD bits for THP
+ */
+
+#define PMD_SECT_DIRTY		(_AT(pmdval_t, 1) << 55)
+#define PMD_SECT_SPLITTING	(_AT(pmdval_t, 1) << 57)
+
+/*
+ * THP definitions.
+ */
+#define pmd_young(pmd)		(pmd_val(pmd) & PMD_SECT_AF)
+
+#define __HAVE_ARCH_PMD_WRITE
+#define pmd_write(pmd)		(!(pmd_val(pmd) & PMD_SECT_RDONLY))
+
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+#define pmd_trans_huge(pmd)	(pmd_val(pmd) && !(pmd_val(pmd) & PMD_TABLE_BIT))
+#define pmd_trans_splitting(pmd) (pmd_val(pmd) & PMD_SECT_SPLITTING)
+#endif
+
+#define PMD_BIT_FUNC(fn,op) \
+static inline pmd_t pmd_##fn(pmd_t pmd) { pmd_val(pmd) op; return pmd; }
+
+PMD_BIT_FUNC(wrprotect,	|= PMD_SECT_RDONLY);
+PMD_BIT_FUNC(mkold,	&= ~PMD_SECT_AF);
+PMD_BIT_FUNC(mksplitting, |= PMD_SECT_SPLITTING);
+PMD_BIT_FUNC(mkwrite,   &= ~PMD_SECT_RDONLY);
+PMD_BIT_FUNC(mkdirty,   |= PMD_SECT_DIRTY);
+PMD_BIT_FUNC(mkyoung,   |= PMD_SECT_AF);
+PMD_BIT_FUNC(mknotpresent, &= ~PMD_TYPE_MASK);
+
+#define pmd_mkhuge(pmd)		(__pmd(pmd_val(pmd) & ~PMD_TABLE_BIT))
+
+#define pmd_pfn(pmd)		(((pmd_val(pmd) & PMD_MASK) & PHYS_MASK) >> PAGE_SHIFT)
+#define pfn_pmd(pfn,prot)	(__pmd(((phys_addr_t)(pfn) << PAGE_SHIFT) | pgprot_val(prot)))
+#define mk_pmd(page,prot)	pfn_pmd(page_to_pfn(page),prot)
+
+#define pmd_page(pmd)           pfn_to_page(__phys_to_pfn(pmd_val(pmd) & PHYS_MASK))
+
+static inline pmd_t pmd_modify(pmd_t pmd, pgprot_t newprot)
+{
+	const pmdval_t mask = PMD_SECT_USER | PMD_SECT_PXN | PMD_SECT_UXN |
+			      PMD_SECT_RDONLY | PMD_SECT_PROT_NONE |
+			      PMD_SECT_VALID;
+	pmd_val(pmd) = (pmd_val(pmd) & ~mask) | (pgprot_val(newprot) & mask);
+	return pmd;
+}
+
+#define set_pmd_at(mm, addr, pmdp, pmd)	set_pmd(pmdp, pmd)
+
+static inline int has_transparent_hugepage(void)
+{
+	return 1;
+}
+
+/*
  * Mark the prot value as uncacheable and unbufferable.
  */
 #define pgprot_noncached(prot) \
diff --git a/arch/arm64/include/asm/tlb.h b/arch/arm64/include/asm/tlb.h
index 654f096..46b3beb 100644
--- a/arch/arm64/include/asm/tlb.h
+++ b/arch/arm64/include/asm/tlb.h
@@ -187,4 +187,10 @@ static inline void __pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmdp,
 
 #define tlb_migrate_finish(mm)		do { } while (0)
 
+static inline void
+tlb_remove_pmd_tlb_entry(struct mmu_gather *tlb, pmd_t *pmdp, unsigned long addr)
+{
+	tlb_add_flush(tlb, addr);
+}
+
 #endif
diff --git a/arch/arm64/include/asm/tlbflush.h b/arch/arm64/include/asm/tlbflush.h
index 122d632..8b48203 100644
--- a/arch/arm64/include/asm/tlbflush.h
+++ b/arch/arm64/include/asm/tlbflush.h
@@ -117,6 +117,8 @@ static inline void update_mmu_cache(struct vm_area_struct *vma,
 	dsb();
 }
 
+#define update_mmu_cache_pmd(vma, address, pmd) do { } while (0)
+
 #endif
 
 #endif
-- 
1.8.1.4

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

Re: [RFC PATCH v2 11/11] ARM64: mm: THP support.

[Catalin Marinas]

On Wed, May 08, 2013 at 10:52:43AM +0100, Steve Capper wrote:
> Bring Transparent HugePage support to ARM. The size of a
> transparent huge page depends on the normal page size. A
> transparent huge page is always represented as a pmd.
> 
> If PAGE_SIZE is 4KB, THPs are 2MB.
> If PAGE_SIZE is 64KB, THPs are 512MB.
> 
> Signed-off-by: Steve Capper <steve.capper@linaro.org>

Acked-by: Catalin Marinas <catalin.marinas@arm.com>

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>