[PATCH mm-unstable 02/17] mm: x86: Introduce arch_mmap_hint()

[Kalesh Singh]

Introduce x86 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>
---
 arch/x86/include/asm/pgtable_64.h |  1 +
 arch/x86/kernel/sys_x86_64.c      | 49 ++++++++++++++++++-------------
 include/linux/sched/mm.h          |  4 +++
 3 files changed, 33 insertions(+), 21 deletions(-)

diff --git a/arch/x86/include/asm/pgtable_64.h b/arch/x86/include/asm/pgtable_64.h
index d1426b64c1b9..4472fd0040c3 100644
--- a/arch/x86/include/asm/pgtable_64.h
+++ b/arch/x86/include/asm/pgtable_64.h
@@ -245,6 +245,7 @@ extern void cleanup_highmap(void);
 
 #define HAVE_ARCH_UNMAPPED_AREA
 #define HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
+#define HAVE_ARCH_MMAP_HINT
 
 #define PAGE_AGP    PAGE_KERNEL_NOCACHE
 #define HAVE_PAGE_AGP 1
diff --git a/arch/x86/kernel/sys_x86_64.c b/arch/x86/kernel/sys_x86_64.c
index 776ae6fa7f2d..95a39ef915b7 100644
--- a/arch/x86/kernel/sys_x86_64.c
+++ b/arch/x86/kernel/sys_x86_64.c
@@ -123,12 +123,32 @@ static inline unsigned long stack_guard_placement(vm_flags_t vm_flags)
 	return 0;
 }
 
+unsigned long arch_mmap_hint(struct file *filp, unsigned long addr,
+			     unsigned long len, unsigned long pgoff,
+			     unsigned long flags)
+{
+	unsigned long begin, end;
+
+	if (!addr)
+		return 0;
+
+	find_start_end(addr, flags, &begin, &end);
+
+	addr = PAGE_ALIGN(addr);
+
+	if (!mmap_address_hint_valid(addr, len))
+		return 0;
+
+	if (len > end)
+		return 0;
+
+	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 mm_struct *mm = current->mm;
-	struct vm_area_struct *vma;
 	struct vm_unmapped_area_info info = {};
 	unsigned long begin, end;
 
@@ -140,13 +160,9 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr, unsigned long len,
 	if (len > end)
 		return -ENOMEM;
 
-	if (addr) {
-		addr = PAGE_ALIGN(addr);
-		vma = find_vma(mm, addr);
-		if (end - len >= addr &&
-		    (!vma || addr + len <= vm_start_gap(vma)))
-			return addr;
-	}
+	addr = arch_mmap_hint(filp, addr, len, pgoff, flags);
+	if (addr)
+		return addr;
 
 	info.length = len;
 	info.low_limit = begin;
@@ -168,8 +184,6 @@ arch_get_unmapped_area_topdown(struct file *filp, unsigned long addr0,
 			  unsigned long len, unsigned long pgoff,
 			  unsigned long flags, vm_flags_t vm_flags)
 {
-	struct vm_area_struct *vma;
-	struct mm_struct *mm = current->mm;
 	unsigned long addr = addr0;
 	struct vm_unmapped_area_info info = {};
 
@@ -186,16 +200,9 @@ arch_get_unmapped_area_topdown(struct file *filp, unsigned long addr0,
 		goto bottomup;
 
 	/* requesting a specific address */
-	if (addr) {
-		addr &= PAGE_MASK;
-		if (!mmap_address_hint_valid(addr, len))
-			goto get_unmapped_area;
-
-		vma = find_vma(mm, addr);
-		if (!vma || addr + len <= vm_start_gap(vma))
-			return addr;
-	}
-get_unmapped_area:
+	addr = arch_mmap_hint(filp, addr, len, pgoff, flags);
+	if (addr)
+		return addr;
 
 	info.flags = VM_UNMAPPED_AREA_TOPDOWN;
 	info.length = len;
diff --git a/include/linux/sched/mm.h b/include/linux/sched/mm.h
index edeec19d1708..f12d094649f7 100644
--- a/include/linux/sched/mm.h
+++ b/include/linux/sched/mm.h
@@ -205,6 +205,10 @@ unsigned long generic_mmap_hint(struct file *filp, unsigned long addr,
 				unsigned long len, unsigned long pgoff,
 				unsigned long flags);
 
+unsigned long arch_mmap_hint(struct file *filp, unsigned long addr,
+			     unsigned long len, unsigned long pgoff,
+			     unsigned long flags);
+
 unsigned long
 generic_get_unmapped_area(struct file *filp, unsigned long addr,
 			  unsigned long len, unsigned long pgoff,
-- 
2.47.0.338.g60cca15819-goog