[PATCH mm-unstable v2 03/16] mm: arm: Introduce arch_mmap_hint()

[Kalesh Singh <kaleshsingh@google.com>]

Introduce arm arch_mmap_hint() and define HAVE_ARCH_MMAP_HINT.
This is a preparatory patch, no functional change is introduced.

Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
---

Changes in v2:
  - MAP_FIXED case is also handled in arch_mmap_hint() since this is just a
    special case of the hint addr being "enforced", per Yang Shi.
  - Consolidate error handling in arch_mmap_hint().

 arch/arm/include/asm/pgtable.h |   1 +
 arch/arm/mm/mmap.c             | 107 ++++++++++++++-------------------
 2 files changed, 46 insertions(+), 62 deletions(-)

diff --git a/arch/arm/include/asm/pgtable.h b/arch/arm/include/asm/pgtable.h
index be91e376df79..1433b3ff4caa 100644
--- a/arch/arm/include/asm/pgtable.h
+++ b/arch/arm/include/asm/pgtable.h
@@ -330,6 +330,7 @@ static inline pte_t pte_swp_clear_exclusive(pte_t pte)
  */
 #define HAVE_ARCH_UNMAPPED_AREA
 #define HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
+#define HAVE_ARCH_MMAP_HINT
 
 #endif /* !__ASSEMBLY__ */
 
diff --git a/arch/arm/mm/mmap.c b/arch/arm/mm/mmap.c
index 3dbb383c26d5..15e7e4348af7 100644
--- a/arch/arm/mm/mmap.c
+++ b/arch/arm/mm/mmap.c
@@ -17,6 +17,41 @@
 	((((addr)+SHMLBA-1)&~(SHMLBA-1)) +	\
 	 (((pgoff)<<PAGE_SHIFT) & (SHMLBA-1)))
 
+unsigned long arch_mmap_hint(struct file *filp, unsigned long addr,
+			     unsigned long len, unsigned long pgoff,
+			     unsigned long flags)
+{
+	bool aliasing = cache_is_vipt_aliasing();
+	bool do_align;
+
+	/* requested length too big for entire address space */
+	if (len > TASK_SIZE)
+		return -ENOMEM;
+
+	/*
+	 * We enforce the MAP_FIXED case.
+	 */
+	if (flags & MAP_FIXED) {
+		if (aliasing && flags & MAP_SHARED &&
+		    (addr - (pgoff << PAGE_SHIFT)) & (SHMLBA - 1))
+			return -EINVAL;
+		return addr;
+	}
+
+	/*
+	 * We only need to do colour alignment if either the I or D
+	 * caches alias.
+	 */
+	do_align = aliasing && (filp || (flags & MAP_SHARED));
+
+	if (do_align)
+		addr = COLOUR_ALIGN(addr, pgoff);
+	else
+		addr = PAGE_ALIGN(addr);
+
+	return generic_mmap_hint(filp, addr, len, pgoff, flags);
+}
+
 /*
  * We need to ensure that shared mappings are correctly aligned to
  * avoid aliasing issues with VIPT caches.  We need to ensure that
@@ -32,42 +67,15 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
 		unsigned long flags, vm_flags_t vm_flags)
 {
 	struct mm_struct *mm = current->mm;
-	struct vm_area_struct *vma;
-	int do_align = 0;
-	int aliasing = cache_is_vipt_aliasing();
 	struct vm_unmapped_area_info info = {};
+	bool aliasing = cache_is_vipt_aliasing();
+	bool do_align;
 
-	/*
-	 * We only need to do colour alignment if either the I or D
-	 * caches alias.
-	 */
-	if (aliasing)
-		do_align = filp || (flags & MAP_SHARED);
-
-	/*
-	 * We enforce the MAP_FIXED case.
-	 */
-	if (flags & MAP_FIXED) {
-		if (aliasing && flags & MAP_SHARED &&
-		    (addr - (pgoff << PAGE_SHIFT)) & (SHMLBA - 1))
-			return -EINVAL;
+	addr = arch_mmap_hint(filp, addr, len, pgoff, flags);
+	if (addr)
 		return addr;
-	}
-
-	if (len > TASK_SIZE)
-		return -ENOMEM;
 
-	if (addr) {
-		if (do_align)
-			addr = COLOUR_ALIGN(addr, pgoff);
-		else
-			addr = PAGE_ALIGN(addr);
-
-		vma = find_vma(mm, addr);
-		if (TASK_SIZE - len >= addr &&
-		    (!vma || addr + len <= vm_start_gap(vma)))
-			return addr;
-	}
+	do_align = aliasing && (filp || (flags & MAP_SHARED));
 
 	info.length = len;
 	info.low_limit = mm->mmap_base;
@@ -82,42 +90,17 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 		        const unsigned long len, const unsigned long pgoff,
 		        const unsigned long flags, vm_flags_t vm_flags)
 {
-	struct vm_area_struct *vma;
 	struct mm_struct *mm = current->mm;
 	unsigned long addr = addr0;
-	int do_align = 0;
-	int aliasing = cache_is_vipt_aliasing();
 	struct vm_unmapped_area_info info = {};
+	bool aliasing = cache_is_vipt_aliasing();
+	bool do_align;
 
-	/*
-	 * We only need to do colour alignment if either the I or D
-	 * caches alias.
-	 */
-	if (aliasing)
-		do_align = filp || (flags & MAP_SHARED);
-
-	/* requested length too big for entire address space */
-	if (len > TASK_SIZE)
-		return -ENOMEM;
-
-	if (flags & MAP_FIXED) {
-		if (aliasing && flags & MAP_SHARED &&
-		    (addr - (pgoff << PAGE_SHIFT)) & (SHMLBA - 1))
-			return -EINVAL;
+	addr = arch_mmap_hint(filp, addr, len, pgoff, flags);
+	if (addr)
 		return addr;
-	}
 
-	/* requesting a specific address */
-	if (addr) {
-		if (do_align)
-			addr = COLOUR_ALIGN(addr, pgoff);
-		else
-			addr = PAGE_ALIGN(addr);
-		vma = find_vma(mm, addr);
-		if (TASK_SIZE - len >= addr &&
-				(!vma || addr + len <= vm_start_gap(vma)))
-			return addr;
-	}
+	do_align = aliasing && (filp || (flags & MAP_SHARED));
 
 	info.flags = VM_UNMAPPED_AREA_TOPDOWN;
 	info.length = len;
-- 
2.47.0.338.g60cca15819-goog