1 files changed, 101 insertions, 25 deletions

diff --git a/arch/mips/mm/mmap.c b/arch/mips/mm/mmap.c
index ae3c20a9556..f1baadd56e8 100644
--- a/arch/mips/mm/mmap.c
+++ b/arch/mips/mm/mmap.c
@@ -6,32 +6,66 @@
  * Copyright (C) 2011 Wind River Systems,
  *   written by Ralf Baechle <ralf@linux-mips.org>
  */
+#include <linux/compiler.h>
 #include <linux/errno.h>
 #include <linux/mm.h>
 #include <linux/mman.h>
 #include <linux/module.h>
+#include <linux/personality.h>
 #include <linux/random.h>
 #include <linux/sched.h>
 
 unsigned long shm_align_mask = PAGE_SIZE - 1;	/* Sane caches */
-
 EXPORT_SYMBOL(shm_align_mask);
 
-#define COLOUR_ALIGN(addr,pgoff)				\
+/* gap between mmap and stack */
+#define MIN_GAP (128*1024*1024UL)
+#define MAX_GAP ((TASK_SIZE)/6*5)
+
+static int mmap_is_legacy(void)
+{
+	if (current->personality & ADDR_COMPAT_LAYOUT)
+		return 1;
+
+	if (rlimit(RLIMIT_STACK) == RLIM_INFINITY)
+		return 1;
+
+	return sysctl_legacy_va_layout;
+}
+
+static unsigned long mmap_base(unsigned long rnd)
+{
+	unsigned long gap = rlimit(RLIMIT_STACK);
+
+	if (gap < MIN_GAP)
+		gap = MIN_GAP;
+	else if (gap > MAX_GAP)
+		gap = MAX_GAP;
+
+	return PAGE_ALIGN(TASK_SIZE - gap - rnd);
+}
+
+#define COLOUR_ALIGN(addr, pgoff)				\
 	((((addr) + shm_align_mask) & ~shm_align_mask) +	\
 	 (((pgoff) << PAGE_SHIFT) & shm_align_mask))
 
-unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr,
-	unsigned long len, unsigned long pgoff, unsigned long flags)
+enum mmap_allocation_direction {UP, DOWN};
+
+static unsigned long arch_get_unmapped_area_common(struct file *filp,
+	unsigned long addr0, unsigned long len, unsigned long pgoff,
+	unsigned long flags, enum mmap_allocation_direction dir)
 {
-	struct vm_area_struct * vmm;
+	struct mm_struct *mm = current->mm;
+	struct vm_area_struct *vma;
+	unsigned long addr = addr0;
 	int do_color_align;
+	struct vm_unmapped_area_info info;
 
-	if (len > TASK_SIZE)
+	if (unlikely(len > TASK_SIZE))
 		return -ENOMEM;
 
 	if (flags & MAP_FIXED) {
-		/* Even MAP_FIXED mappings must reside within TASK_SIZE.  */
+		/* Even MAP_FIXED mappings must reside within TASK_SIZE */
 		if (TASK_SIZE - len < addr)
 			return -EINVAL;
 
@@ -48,32 +82,64 @@ unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr,
 	do_color_align = 0;
 	if (filp || (flags & MAP_SHARED))
 		do_color_align = 1;
+
+	/* requesting a specific address */
 	if (addr) {
 		if (do_color_align)
 			addr = COLOUR_ALIGN(addr, pgoff);
 		else
 			addr = PAGE_ALIGN(addr);
-		vmm = find_vma(current->mm, addr);
+
+		vma = find_vma(mm, addr);
 		if (TASK_SIZE - len >= addr &&
-		    (!vmm || addr + len <= vmm->vm_start))
+		    (!vma || addr + len <= vma->vm_start))
 			return addr;
 	}
-	addr = current->mm->mmap_base;
-	if (do_color_align)
-		addr = COLOUR_ALIGN(addr, pgoff);
-	else
-		addr = PAGE_ALIGN(addr);
 
-	for (vmm = find_vma(current->mm, addr); ; vmm = vmm->vm_next) {
-		/* At this point:  (!vmm || addr < vmm->vm_end). */
-		if (TASK_SIZE - len < addr)
-			return -ENOMEM;
-		if (!vmm || addr + len <= vmm->vm_start)
+	info.length = len;
+	info.align_mask = do_color_align ? (PAGE_MASK & shm_align_mask) : 0;
+	info.align_offset = pgoff << PAGE_SHIFT;
+
+	if (dir == DOWN) {
+		info.flags = VM_UNMAPPED_AREA_TOPDOWN;
+		info.low_limit = PAGE_SIZE;
+		info.high_limit = mm->mmap_base;
+		addr = vm_unmapped_area(&info);
+
+		if (!(addr & ~PAGE_MASK))
 			return addr;
-		addr = vmm->vm_end;
-		if (do_color_align)
-			addr = COLOUR_ALIGN(addr, pgoff);
+
+		/*
+		 * A failed mmap() very likely causes application failure,
+		 * so fall back to the bottom-up function here. This scenario
+		 * can happen with large stack limits and large mmap()
+		 * allocations.
+		 */
 	}
+
+	info.flags = 0;
+	info.low_limit = mm->mmap_base;
+	info.high_limit = TASK_SIZE;
+	return vm_unmapped_area(&info);
+}
+
+unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr0,
+	unsigned long len, unsigned long pgoff, unsigned long flags)
+{
+	return arch_get_unmapped_area_common(filp,
+			addr0, len, pgoff, flags, UP);
+}
+
+/*
+ * There is no need to export this but sched.h declares the function as
+ * extern so making it static here results in an error.
+ */
+unsigned long arch_get_unmapped_area_topdown(struct file *filp,
+	unsigned long addr0, unsigned long len, unsigned long pgoff,
+	unsigned long flags)
+{
+	return arch_get_unmapped_area_common(filp,
+			addr0, len, pgoff, flags, DOWN);
 }
 
 void arch_pick_mmap_layout(struct mm_struct *mm)
@@ -89,9 +155,13 @@ void arch_pick_mmap_layout(struct mm_struct *mm)
 			random_factor &= 0xffffffful;
 	}
 
-	mm->mmap_base = TASK_UNMAPPED_BASE + random_factor;
-	mm->get_unmapped_area = arch_get_unmapped_area;
-	mm->unmap_area = arch_unmap_area;
+	if (mmap_is_legacy()) {
+		mm->mmap_base = TASK_UNMAPPED_BASE + random_factor;
+		mm->get_unmapped_area = arch_get_unmapped_area;
+	} else {
+		mm->mmap_base = mmap_base(random_factor);
+		mm->get_unmapped_area = arch_get_unmapped_area_topdown;
+	}
 }
 
 static inline unsigned long brk_rnd(void)
@@ -120,3 +190,9 @@ unsigned long arch_randomize_brk(struct mm_struct *mm)
 
 	return ret;
 }
+
+int __virt_addr_valid(const volatile void *kaddr)
+{
+	return pfn_valid(PFN_DOWN(virt_to_phys(kaddr)));
+}
+EXPORT_SYMBOL_GPL(__virt_addr_valid);