[PATCH -mm 3/6] Fix the x86-64 page colouring code to take pgoff into account and use that code as the basis for a generic page colouring code.

[Rik van Riel <riel@redhat.com>]

From: Rik van Riel <riel@surriel.com>

Teach the generic arch_get_unmapped_area(_topdown) code to call the
page colouring code.

Signed-off-by: Rik van Riel <riel@redhat.com>
---
 arch/mips/include/asm/page.h      |    2 -
 arch/mips/include/asm/pgtable.h   |    1 +
 arch/x86/include/asm/elf.h        |    3 -
 arch/x86/include/asm/pgtable_64.h |    1 +
 arch/x86/kernel/sys_x86_64.c      |   35 +++++++++-----
 arch/x86/vdso/vma.c               |    2 +-
 include/linux/sched.h             |    8 +++-
 mm/mmap.c                         |   91 ++++++++++++++++++++++++++++++++-----
 8 files changed, 111 insertions(+), 32 deletions(-)

diff --git a/arch/mips/include/asm/page.h b/arch/mips/include/asm/page.h
index da9bd7d..459cc25 100644
--- a/arch/mips/include/asm/page.h
+++ b/arch/mips/include/asm/page.h
@@ -63,8 +63,6 @@ extern void build_copy_page(void);
 extern void clear_page(void * page);
 extern void copy_page(void * to, void * from);
 
-extern unsigned long shm_align_mask;
-
 static inline unsigned long pages_do_alias(unsigned long addr1,
 	unsigned long addr2)
 {
diff --git a/arch/mips/include/asm/pgtable.h b/arch/mips/include/asm/pgtable.h
index b2202a6..f133a4c 100644
--- a/arch/mips/include/asm/pgtable.h
+++ b/arch/mips/include/asm/pgtable.h
@@ -415,6 +415,7 @@ int phys_mem_access_prot_allowed(struct file *file, unsigned long pfn,
  */
 #define HAVE_ARCH_UNMAPPED_AREA
 #define HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
+#define HAVE_ARCH_ALIGN_ADDR
 
 /*
  * No page table caches to initialise
diff --git a/arch/x86/include/asm/elf.h b/arch/x86/include/asm/elf.h
index 5939f44..dc2d0bf 100644
--- a/arch/x86/include/asm/elf.h
+++ b/arch/x86/include/asm/elf.h
@@ -358,8 +358,6 @@ static inline int mmap_is_ia32(void)
 enum align_flags {
 	ALIGN_VA_32	= BIT(0),
 	ALIGN_VA_64	= BIT(1),
-	ALIGN_VDSO	= BIT(2),
-	ALIGN_TOPDOWN	= BIT(3),
 };
 
 struct va_alignment {
@@ -368,5 +366,4 @@ struct va_alignment {
 } ____cacheline_aligned;
 
 extern struct va_alignment va_align;
-extern unsigned long align_addr(unsigned long, struct file *, enum align_flags);
 #endif /* _ASM_X86_ELF_H */
diff --git a/arch/x86/include/asm/pgtable_64.h b/arch/x86/include/asm/pgtable_64.h
index 8af36f6..8408ccd 100644
--- a/arch/x86/include/asm/pgtable_64.h
+++ b/arch/x86/include/asm/pgtable_64.h
@@ -170,6 +170,7 @@ extern void cleanup_highmap(void);
 #define HAVE_ARCH_UNMAPPED_AREA
 #define HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
 #define HAVE_ARCH_GET_ADDRESS_RANGE
+#define HAVE_ARCH_ALIGN_ADDR
 
 #define pgtable_cache_init()   do { } while (0)
 #define check_pgt_cache()      do { } while (0)
diff --git a/arch/x86/kernel/sys_x86_64.c b/arch/x86/kernel/sys_x86_64.c
index 2595a5e..ac0afb8 100644
--- a/arch/x86/kernel/sys_x86_64.c
+++ b/arch/x86/kernel/sys_x86_64.c
@@ -25,31 +25,40 @@
  * @flags denotes the allocation direction - bottomup or topdown -
  * or vDSO; see call sites below.
  */
-unsigned long align_addr(unsigned long addr, struct file *filp,
-			 enum align_flags flags)
+unsigned long arch_align_addr(unsigned long addr, struct file *filp,
+			unsigned long pgoff, unsigned long flags,
+			enum mmap_allocation_direction direction)
 {
-	unsigned long tmp_addr;
+	unsigned long tmp_addr = PAGE_ALIGN(addr);
 
 	/* handle 32- and 64-bit case with a single conditional */
 	if (va_align.flags < 0 || !(va_align.flags & (2 - mmap_is_ia32())))
-		return addr;
+		return tmp_addr;
 
-	if (!(current->flags & PF_RANDOMIZE))
-		return addr;
+	/* Always allow MAP_FIXED. Colouring is a performance thing only. */
+	if (flags & MAP_FIXED)
+		return tmp_addr;
 
-	if (!((flags & ALIGN_VDSO) || filp))
-		return addr;
+	if (!(current->flags & PF_RANDOMIZE))
+		return tmp_addr;
 
-	tmp_addr = addr;
+	if (!(filp || direction == ALLOC_VDSO))
+		return tmp_addr;
 
 	/*
 	 * We need an address which is <= than the original
 	 * one only when in topdown direction.
 	 */
-	if (!(flags & ALIGN_TOPDOWN))
+	if (direction == ALLOC_UP)
 		tmp_addr += va_align.mask;
 
 	tmp_addr &= ~va_align.mask;
+	tmp_addr += ((pgoff << PAGE_SHIFT) & va_align.mask);
+
+	if (direction == ALLOC_DOWN && tmp_addr > addr) {
+		tmp_addr -= va_align.mask;
+		tmp_addr &= ~va_align.mask;
+	}
 
 	return tmp_addr;
 }
@@ -159,7 +168,7 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
 
 full_search:
 
-	addr = align_addr(addr, filp, 0);
+	addr = arch_align_addr(addr, filp, pgoff, flags, ALLOC_UP);
 
 	for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
 		/* At this point:  (!vma || addr < vma->vm_end). */
@@ -186,7 +195,7 @@ full_search:
 			mm->cached_hole_size = vma->vm_start - addr;
 
 		addr = vma->vm_end;
-		addr = align_addr(addr, filp, 0);
+		addr = arch_align_addr(addr, filp, pgoff, flags, ALLOC_UP);
 	}
 }
 
@@ -235,7 +244,7 @@ try_again:
 
 	addr -= len;
 	do {
-		addr = align_addr(addr, filp, ALIGN_TOPDOWN);
+		addr = arch_align_addr(addr, filp, pgoff, flags, ALLOC_DOWN);
 
 		/*
 		 * Lookup failure means no vma is above this address,
diff --git a/arch/x86/vdso/vma.c b/arch/x86/vdso/vma.c
index 00aaf04..83e0355 100644
--- a/arch/x86/vdso/vma.c
+++ b/arch/x86/vdso/vma.c
@@ -141,7 +141,7 @@ static unsigned long vdso_addr(unsigned long start, unsigned len)
 	 * unaligned here as a result of stack start randomization.
 	 */
 	addr = PAGE_ALIGN(addr);
-	addr = align_addr(addr, NULL, ALIGN_VDSO);
+	addr = arch_align_addr(addr, NULL, 0, 0, ALLOC_VDSO);
 
 	return addr;
 }
diff --git a/include/linux/sched.h b/include/linux/sched.h
index fc76318..18f9326 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -390,12 +390,18 @@ extern int sysctl_max_map_count;
 #ifdef CONFIG_MMU
 enum mmap_allocation_direction {
 	ALLOC_UP,
-	ALLOC_DOWN
+	ALLOC_DOWN,
+	ALLOC_VDSO,
 };
 extern void arch_pick_mmap_layout(struct mm_struct *mm);
 extern void
 arch_get_address_range(unsigned long flags, unsigned long *begin,
 		unsigned long *end, enum mmap_allocation_direction direction);
+extern unsigned long shm_align_mask;
+extern unsigned long
+arch_align_addr(unsigned long addr, struct file *filp,
+		unsigned long pgoff, unsigned long flags,
+		enum mmap_allocation_direction direction);
 extern unsigned long
 arch_get_unmapped_area(struct file *, unsigned long, unsigned long,
 		       unsigned long, unsigned long);
diff --git a/mm/mmap.c b/mm/mmap.c
index 92cf0bf..0314cb1 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1465,6 +1465,51 @@ unacct_error:
 	return error;
 }
 
+#ifndef HAVE_ARCH_ALIGN_ADDR
+/* Each architecture is responsible for setting this to the required value. */
+unsigned long shm_align_mask = PAGE_SIZE - 1;
+EXPORT_SYMBOL(shm_align_mask);
+
+unsigned long arch_align_addr(unsigned long addr, struct file *filp,
+			unsigned long pgoff, unsigned long flags,
+			enum mmap_allocation_direction direction)
+{
+	unsigned long tmp_addr = PAGE_ALIGN(addr);
+
+	if (shm_align_mask <= PAGE_SIZE)
+		return tmp_addr;
+
+	/* Allow MAP_FIXED without MAP_SHARED at any address. */
+	if ((flags & (MAP_FIXED|MAP_SHARED)) == MAP_FIXED)
+		return tmp_addr;
+
+	/* Enforce page colouring for any file or MAP_SHARED mapping. */
+	if (!(filp || (flags & MAP_SHARED)))
+		return tmp_addr;
+
+	/*
+	 * We need an address which is <= than the original
+	 * one only when in topdown direction.
+	 */
+	if (direction == ALLOC_UP)
+		tmp_addr += shm_align_mask;
+
+	tmp_addr &= ~shm_align_mask;
+	tmp_addr += ((pgoff << PAGE_SHIFT) & shm_align_mask);
+
+	/*
+	 * When aligning down, make sure we did not accidentally go up.
+	 * The caller will check for underflow.
+	 */
+	if (direction == ALLOC_DOWN && tmp_addr > addr) {
+		tmp_addr -= shm_align_mask;
+		tmp_addr &= ~shm_align_mask;
+	}
+
+	return tmp_addr;
+}
+#endif
+
 #ifndef HAVE_ARCH_GET_ADDRESS_RANGE
 void arch_get_address_range(unsigned long flags, unsigned long *begin,
 		unsigned long *end, enum mmap_allocation_direction direction)
@@ -1513,18 +1558,22 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
 	struct mm_struct *mm = current->mm;
 	struct vm_area_struct *vma = NULL;
 	struct rb_node *rb_node;
-	unsigned long lower_limit, upper_limit;
+	unsigned long lower_limit, upper_limit, tmp_addr;
 
 	arch_get_address_range(flags, &lower_limit, &upper_limit, ALLOC_UP);
 
 	if (len > TASK_SIZE)
 		return -ENOMEM;
 
-	if (flags & MAP_FIXED)
+	if (flags & MAP_FIXED) {
+		tmp_addr = arch_align_addr(addr, filp, pgoff, flags, ALLOC_UP);
+		if (tmp_addr != PAGE_ALIGN(addr))
+			return -EINVAL;
 		return addr;
+	}
 
 	if (addr) {
-		addr = PAGE_ALIGN(addr);
+		addr = arch_align_addr(addr, filp, pgoff, flags, ALLOC_UP);
 		vma = find_vma(mm, addr);
 		if (TASK_SIZE - len >= addr &&
 		    (!vma || addr + len <= vma->vm_start))
@@ -1533,7 +1582,7 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
 
 	/* Find the left-most free area of sufficient size. */
 	for (addr = 0, rb_node = mm->mm_rb.rb_node; rb_node; ) {
-		unsigned long vma_start;
+		unsigned long vma_start, tmp_addr;
 		int found_here = 0;
 
 		vma = rb_to_vma(rb_node);
@@ -1541,13 +1590,17 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
 		if (vma->vm_start > len) {
 			if (!vma->vm_prev) {
 				/* This is the left-most VMA. */
-				if (vma->vm_start - len >= lower_limit) {
-					addr = lower_limit;
+				tmp_addr = arch_align_addr(lower_limit, filp,
+						pgoff, flags, ALLOC_UP);
+				if (vma->vm_start - len >= tmp_addr) {
+					addr = tmp_addr;
 					goto found_addr;
 				}
 			} else {
 				/* Is this hole large enough? Remember it. */
 				vma_start = max(vma->vm_prev->vm_end, lower_limit);
+				vma_start = arch_align_addr(vma_start, filp,
+						pgoff, flags, ALLOC_UP);
 				if (vma->vm_start - len >= vma_start) {
 					addr = vma_start;
 					found_here = 1;
@@ -1599,6 +1652,8 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
 	if (addr < lower_limit)
 		addr = lower_limit;
 
+	addr = arch_align_addr(addr, filp, pgoff, flags, ALLOC_UP);
+
  found_addr:
 	if (TASK_SIZE - len < addr)
 		return -ENOMEM;
@@ -1656,12 +1711,17 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 	if (len > TASK_SIZE)
 		return -ENOMEM;
 
-	if (flags & MAP_FIXED)
+	if (flags & MAP_FIXED) {
+		unsigned long tmp_addr;
+		tmp_addr = arch_align_addr(addr, filp, pgoff, flags, ALLOC_DOWN);
+		if (tmp_addr != PAGE_ALIGN(addr))
+			return -EINVAL;
 		return addr;
+	}
 
 	/* requesting a specific address */
 	if (addr) {
-		addr = PAGE_ALIGN(addr);
+		addr = arch_align_addr(addr, filp, pgoff, flags, ALLOC_DOWN);
 		vma = find_vma(mm, addr);
 		if (TASK_SIZE - len >= addr &&
 				(!vma || addr + len <= vma->vm_start))
@@ -1678,7 +1738,9 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 	 */
 	if (upper_limit - len > mm->highest_vma) {
 		addr = upper_limit - len;
-		goto found_addr;
+		addr = arch_align_addr(addr, filp, pgoff, flags, ALLOC_DOWN);
+		if (addr > mm->highest_vma);
+			goto found_addr;
 	}
 
 	/* Find the right-most free area of sufficient size. */
@@ -1691,9 +1753,14 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 		/* Is this hole large enough? Remember it. */
 		vma_start = min(vma->vm_start, upper_limit);
 		if (vma_start > len) {
-			if (!vma->vm_prev ||
-			    (vma_start - len >= vma->vm_prev->vm_end)) {
-				addr = vma_start - len;
+			unsigned long tmp_addr = vma_start - len;
+			tmp_addr = arch_align_addr(tmp_addr, filp,
+						   pgoff, flags, ALLOC_DOWN);
+			/* No underflow? Does it still fit the hole? */
+			if (tmp_addr && tmp_addr <= vma_start - len &&
+					(!vma->vm_prev ||
+					 tmp_addr >= vma->vm_prev->vm_end)) {
+				addr = tmp_addr;
 				found_here = 1;
 			}
 		}
-- 
1.7.7.6

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