[PATCH mm-unstable v2 11/16] mm: sh: Introduce arch_mmap_hint()

[Kalesh Singh]

Introduce sh 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 at 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/sh/include/asm/pgtable.h |  1 +
 arch/sh/mm/mmap.c             | 83 ++++++++++++++---------------------
 2 files changed, 33 insertions(+), 51 deletions(-)

diff --git a/arch/sh/include/asm/pgtable.h b/arch/sh/include/asm/pgtable.h
index 729f5c6225fb..072dbe038808 100644
--- a/arch/sh/include/asm/pgtable.h
+++ b/arch/sh/include/asm/pgtable.h
@@ -149,5 +149,6 @@ static inline bool pte_access_permitted(pte_t pte, bool write)
 /* arch/sh/mm/mmap.c */
 #define HAVE_ARCH_UNMAPPED_AREA
 #define HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
+#define HAVE_ARCH_MMAP_HINT
 
 #endif /* __ASM_SH_PGTABLE_H */
diff --git a/arch/sh/mm/mmap.c b/arch/sh/mm/mmap.c
index c442734d9b0c..ebda962e8c4e 100644
--- a/arch/sh/mm/mmap.c
+++ b/arch/sh/mm/mmap.c
@@ -51,14 +51,14 @@ static inline unsigned long COLOUR_ALIGN(unsigned long addr,
 	return base + off;
 }
 
-unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr,
-	unsigned long len, unsigned long pgoff, unsigned long flags,
-	vm_flags_t vm_flags)
+unsigned long arch_mmap_hint(struct file *filp, unsigned long addr,
+			     unsigned long len, unsigned long pgoff,
+			     unsigned long flags)
 {
-	struct mm_struct *mm = current->mm;
-	struct vm_area_struct *vma;
-	int do_colour_align;
-	struct vm_unmapped_area_info info = {};
+	bool do_colour_align;
+
+	if (unlikely(len > TASK_SIZE))
+		return -ENOMEM;
 
 	if (flags & MAP_FIXED) {
 		/* We do not accept a shared mapping if it would violate
@@ -70,24 +70,29 @@ unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr,
 		return addr;
 	}
 
-	if (unlikely(len > TASK_SIZE))
-		return -ENOMEM;
+	do_colour_align = filp || (flags & MAP_SHARED);
 
-	do_colour_align = 0;
-	if (filp || (flags & MAP_SHARED))
-		do_colour_align = 1;
+	if (do_colour_align)
+		addr = COLOUR_ALIGN(addr, pgoff);
+	else
+		addr = PAGE_ALIGN(addr);
 
-	if (addr) {
-		if (do_colour_align)
-			addr = COLOUR_ALIGN(addr, pgoff);
-		else
-			addr = PAGE_ALIGN(addr);
+	return generic_mmap_hint(filp, addr, len, pgoff, flags);
+}
 
-		vma = find_vma(mm, addr);
-		if (TASK_SIZE - len >= addr &&
-		    (!vma || addr + len <= vm_start_gap(vma)))
-			return addr;
-	}
+
+unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr,
+	unsigned long len, unsigned long pgoff, unsigned long flags,
+	vm_flags_t vm_flags)
+{
+	struct vm_unmapped_area_info info = {};
+	bool do_colour_align;
+
+	addr = arch_mmap_hint(filp, addr, len, pgoff, flags);
+	if (addr)
+		return addr;
+
+	do_colour_align = filp || (flags & MAP_SHARED);
 
 	info.length = len;
 	info.low_limit = TASK_UNMAPPED_BASE;
@@ -102,41 +107,17 @@ 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_colour_align;
 	struct vm_unmapped_area_info info = {};
+	bool do_colour_align;
 
-	if (flags & MAP_FIXED) {
-		/* We do not accept a shared mapping if it would violate
-		 * cache aliasing constraints.
-		 */
-		if ((flags & MAP_SHARED) &&
-		    ((addr - (pgoff << PAGE_SHIFT)) & shm_align_mask))
-			return -EINVAL;
+	/* requesting a specific address */
+	addr = arch_mmap_hint(filp, addr, len, pgoff, flags);
+	if (addr)
 		return addr;
-	}
 
-	if (unlikely(len > TASK_SIZE))
-		return -ENOMEM;
-
-	do_colour_align = 0;
-	if (filp || (flags & MAP_SHARED))
-		do_colour_align = 1;
-
-	/* requesting a specific address */
-	if (addr) {
-		if (do_colour_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_colour_align = filp || (flags & MAP_SHARED);
 
 	info.flags = VM_UNMAPPED_AREA_TOPDOWN;
 	info.length = len;
-- 
2.47.0.338.g60cca15819-goog