s390/mm: simplify arch_get_unmapped_area[_topdown]

With TASK_SIZE now reflecting the maximum size of the address space for
a process the code for arch_get_unmapped_area[_topdown] can be simplified.
Just let the logic pick a suitable address and deal with the page table
upgrade after the address has been selected.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

diff --git a/arch/s390/mm/mmap.c b/arch/s390/mm/mmap.c
index eed233ce59dd9cece190d0d88cab9a103fdd033a..b017daed6887847c8eb025e146ae22b37dedfb2c 100644 (file)
--- a/arch/s390/mm/mmap.c
+++ b/arch/s390/mm/mmap.c
@@ -89,32 +89,43 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
        struct mm_struct *mm = current->mm;
        struct vm_area_struct *vma;
        struct vm_unmapped_area_info info;
+       int rc;
 
-       if (len > mm->context.asce_limit - mmap_min_addr)
+       if (len > TASK_SIZE - mmap_min_addr)
                return -ENOMEM;
 
        if (flags & MAP_FIXED)
-               return addr;
+               goto check_asce_limit;
 
        if (addr) {
                addr = PAGE_ALIGN(addr);
                vma = find_vma(mm, addr);
-               if (mm->context.asce_limit - len >= addr &&
-                   addr >= mmap_min_addr &&
+               if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
                    (!vma || addr + len <= vma->vm_start))
-                       return addr;
+                       goto check_asce_limit;
        }
 
        info.flags = 0;
        info.length = len;
        info.low_limit = mm->mmap_base;
-       info.high_limit = mm->context.asce_limit;
+       info.high_limit = TASK_SIZE;
        if (filp || (flags & MAP_SHARED))
                info.align_mask = MMAP_ALIGN_MASK << PAGE_SHIFT;
        else
                info.align_mask = 0;
        info.align_offset = pgoff << PAGE_SHIFT;
-       return vm_unmapped_area(&info);
+       addr = vm_unmapped_area(&info);
+       if (addr & ~PAGE_MASK)
+               return addr;
+
+check_asce_limit:
+       if (addr + len > current->mm->context.asce_limit) {
+               rc = crst_table_upgrade(mm);
+               if (rc)
+                       return (unsigned long) rc;
+       }
+
+       return addr;
 }
 
 unsigned long
@@ -126,22 +137,22 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
        struct mm_struct *mm = current->mm;
        unsigned long addr = addr0;
        struct vm_unmapped_area_info info;
+       int rc;
 
        /* requested length too big for entire address space */
-       if (len > mm->context.asce_limit - mmap_min_addr)
+       if (len > TASK_SIZE - mmap_min_addr)
                return -ENOMEM;
 
        if (flags & MAP_FIXED)
-               return addr;
+               goto check_asce_limit;
 
        /* requesting a specific address */
        if (addr) {
                addr = PAGE_ALIGN(addr);
                vma = find_vma(mm, addr);
-               if (mm->context.asce_limit - len >= addr &&
-                   addr >= mmap_min_addr &&
+               if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
                                (!vma || addr + len <= vma->vm_start))
-                       return addr;
+                       goto check_asce_limit;
        }
 
        info.flags = VM_UNMAPPED_AREA_TOPDOWN;
@@ -165,58 +176,22 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
                VM_BUG_ON(addr != -ENOMEM);
                info.flags = 0;
                info.low_limit = TASK_UNMAPPED_BASE;
-               info.high_limit = mm->context.asce_limit;
+               info.high_limit = TASK_SIZE;
                addr = vm_unmapped_area(&info);
+               if (addr & ~PAGE_MASK)
+                       return addr;
        }
 
-       return addr;
-}
-
-static unsigned long
-s390_get_unmapped_area(struct file *filp, unsigned long addr,
-               unsigned long len, unsigned long pgoff, unsigned long flags)
-{
-       struct mm_struct *mm = current->mm;
-       unsigned long area;
-       int rc;
-
-       area = arch_get_unmapped_area(filp, addr, len, pgoff, flags);
-       if (!(area & ~PAGE_MASK))
-               return area;
-       if (area == -ENOMEM && !is_compat_task() &&
-           current->mm->context.asce_limit < TASK_SIZE_MAX) {
-               /* Upgrade the page table to 4 levels and retry. */
+check_asce_limit:
+       if (addr + len > current->mm->context.asce_limit) {
                rc = crst_table_upgrade(mm);
                if (rc)
                        return (unsigned long) rc;
-               area = arch_get_unmapped_area(filp, addr, len, pgoff, flags);
        }
-       return area;
-}
-
-static unsigned long
-s390_get_unmapped_area_topdown(struct file *filp, const unsigned long addr,
-                         const unsigned long len, const unsigned long pgoff,
-                         const unsigned long flags)
-{
-       struct mm_struct *mm = current->mm;
-       unsigned long area;
-       int rc;
 
-       area = arch_get_unmapped_area_topdown(filp, addr, len, pgoff, flags);
-       if (!(area & ~PAGE_MASK))
-               return area;
-       if (area == -ENOMEM && !is_compat_task() &&
-           current->mm->context.asce_limit < TASK_SIZE_MAX) {
-               /* Upgrade the page table to 4 levels and retry. */
-               rc = crst_table_upgrade(mm);
-               if (rc)
-                       return (unsigned long) rc;
-               area = arch_get_unmapped_area_topdown(filp, addr, len,
-                                                     pgoff, flags);
-       }
-       return area;
+       return addr;
 }
+
 /*
  * This function, called very early during the creation of a new
  * process VM image, sets up which VM layout function to use:
@@ -234,9 +209,9 @@ void arch_pick_mmap_layout(struct mm_struct *mm)
         */
        if (mmap_is_legacy()) {
                mm->mmap_base = mmap_base_legacy(random_factor);
-               mm->get_unmapped_area = s390_get_unmapped_area;
+               mm->get_unmapped_area = arch_get_unmapped_area;
        } else {
                mm->mmap_base = mmap_base(random_factor);
-               mm->get_unmapped_area = s390_get_unmapped_area_topdown;
+               mm->get_unmapped_area = arch_get_unmapped_area_topdown;
        }
 }