[PATCH mm-unstable v2 14/16] mm: xtensa: Introduce arch_mmap_hint()

[Kalesh Singh <kaleshsingh@google.com>]

Introduce xtensa arch_mmap_hint() and define HAVE_ARCH_MMAP_HINT.

If a sufficiently sized hole doesn't exist at the hint address,
fallback to searching the entire valid VA space instead of only
the VA space above the hint address.

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/xtensa/kernel/syscall.c | 31 +++++++++++++++++++++----------
 1 file changed, 21 insertions(+), 10 deletions(-)

diff --git a/arch/xtensa/kernel/syscall.c b/arch/xtensa/kernel/syscall.c
index dc54f854c2f5..6bbe10c2a633 100644
--- a/arch/xtensa/kernel/syscall.c
+++ b/arch/xtensa/kernel/syscall.c
@@ -54,12 +54,12 @@ asmlinkage long xtensa_fadvise64_64(int fd, int advice,
 }
 
 #ifdef CONFIG_MMU
-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 vm_area_struct *vmm;
-	struct vma_iterator vmi;
+	if (len > TASK_SIZE)
+		return -ENOMEM;
 
 	if (flags & MAP_FIXED) {
 		/* We do not accept a shared mapping if it would violate
@@ -71,16 +71,27 @@ unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr,
 		return addr;
 	}
 
-	if (len > TASK_SIZE)
-		return -ENOMEM;
-	if (!addr)
-		addr = TASK_UNMAPPED_BASE;
-
 	if (flags & MAP_SHARED)
 		addr = COLOUR_ALIGN(addr, pgoff);
 	else
 		addr = PAGE_ALIGN(addr);
 
+	return generic_mmap_hint(filp, addr, len, pgoff, flags);
+}
+
+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_area_struct *vmm;
+	struct vma_iterator vmi;
+
+	addr = arch_mmap_hint(filp, addr, len, pgoff, flags);
+	if (addr)
+		return addr;
+
+	addr = TASK_UNMAPPED_BASE;
+
 	vma_iter_init(&vmi, current->mm, addr);
 	for_each_vma(vmi, vmm) {
 		/* At this point:  (addr < vmm->vm_end). */
-- 
2.47.0.338.g60cca15819-goog