powerpc/mm/radix: Pick the address layout for radix config

Hash needs special get_unmapped_area() handling because of limitations
around base page size, so we have to set HAVE_ARCH_UNMAPPED_AREA.

With radix we don't have such restrictions, so we could use the generic
code. But because we've set HAVE_ARCH_UNMAPPED_AREA (for hash), we have
to re-implement the same logic as the generic code.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

diff --git a/arch/powerpc/mm/mmap.c b/arch/powerpc/mm/mmap.c
index 30611f832923e4e9c607a908d9a1eeb9fb11410d..2f1e44362198d3f16d85fdd4656d37e618b51824 100644 (file)
--- a/arch/powerpc/mm/mmap.c
+++ b/arch/powerpc/mm/mmap.c
@@ -27,6 +27,8 @@
 #include <linux/random.h>
 #include <linux/sched.h>
 #include <linux/elf-randomize.h>
+#include <linux/security.h>
+#include <linux/mman.h>
 
 /*
  * Top of mmap area (just below the process stack).
@@ -79,6 +81,111 @@ static inline unsigned long mmap_base(unsigned long rnd)
        return PAGE_ALIGN(TASK_SIZE - gap - rnd);
 }
 
+#ifdef CONFIG_PPC_RADIX_MMU
+/*
+ * Same function as generic code used only for radix, because we don't need to overload
+ * the generic one. But we will have to duplicate, because hash select
+ * HAVE_ARCH_UNMAPPED_AREA
+ */
+static unsigned long
+radix__arch_get_unmapped_area(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;
+       struct vm_unmapped_area_info info;
+
+       if (len > TASK_SIZE - mmap_min_addr)
+               return -ENOMEM;
+
+       if (flags & MAP_FIXED)
+               return addr;
+
+       if (addr) {
+               addr = PAGE_ALIGN(addr);
+               vma = find_vma(mm, addr);
+               if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
+                   (!vma || addr + len <= vma->vm_start))
+                       return addr;
+       }
+
+       info.flags = 0;
+       info.length = len;
+       info.low_limit = mm->mmap_base;
+       info.high_limit = TASK_SIZE;
+       info.align_mask = 0;
+       return vm_unmapped_area(&info);
+}
+
+static unsigned long
+radix__arch_get_unmapped_area_topdown(struct file *filp,
+                                    const unsigned long addr0,
+                                    const unsigned long len,
+                                    const unsigned long pgoff,
+                                    const unsigned long flags)
+{
+       struct vm_area_struct *vma;
+       struct mm_struct *mm = current->mm;
+       unsigned long addr = addr0;
+       struct vm_unmapped_area_info info;
+
+       /* requested length too big for entire address space */
+       if (len > TASK_SIZE - mmap_min_addr)
+               return -ENOMEM;
+
+       if (flags & MAP_FIXED)
+               return addr;
+
+       /* requesting a specific address */
+       if (addr) {
+               addr = PAGE_ALIGN(addr);
+               vma = find_vma(mm, addr);
+               if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
+                               (!vma || addr + len <= vma->vm_start))
+                       return addr;
+       }
+
+       info.flags = VM_UNMAPPED_AREA_TOPDOWN;
+       info.length = len;
+       info.low_limit = max(PAGE_SIZE, mmap_min_addr);
+       info.high_limit = mm->mmap_base;
+       info.align_mask = 0;
+       addr = vm_unmapped_area(&info);
+
+       /*
+        * 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.
+        */
+       if (addr & ~PAGE_MASK) {
+               VM_BUG_ON(addr != -ENOMEM);
+               info.flags = 0;
+               info.low_limit = TASK_UNMAPPED_BASE;
+               info.high_limit = TASK_SIZE;
+               addr = vm_unmapped_area(&info);
+       }
+
+       return addr;
+}
+
+static void radix__arch_pick_mmap_layout(struct mm_struct *mm,
+                                       unsigned long random_factor)
+{
+       if (mmap_is_legacy()) {
+               mm->mmap_base = TASK_UNMAPPED_BASE;
+               mm->get_unmapped_area = radix__arch_get_unmapped_area;
+       } else {
+               mm->mmap_base = mmap_base(random_factor);
+               mm->get_unmapped_area = radix__arch_get_unmapped_area_topdown;
+       }
+}
+#else
+/* dummy */
+extern void radix__arch_pick_mmap_layout(struct mm_struct *mm,
+                                       unsigned long random_factor);
+#endif
 /*
  * This function, called very early during the creation of a new
  * process VM image, sets up which VM layout function to use:
@@ -90,6 +197,8 @@ void arch_pick_mmap_layout(struct mm_struct *mm)
        if (current->flags & PF_RANDOMIZE)
                random_factor = arch_mmap_rnd();
 
+       if (radix_enabled())
+               return radix__arch_pick_mmap_layout(mm, random_factor);
        /*
         * Fall back to the standard layout if the personality
         * bit is set, or if the expected stack growth is unlimited: