mm: use vm_unmapped_area() on x86_64 architecture

Update the x86_64 arch_get_unmapped_area[_topdown] functions to make use
of vm_unmapped_area() instead of implementing a brute force search.

Signed-off-by: Michel Lespinasse <walken@google.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 30 insertions, 121 deletions

diff --git a/arch/x86/kernel/sys_x86_64.c b/arch/x86/kernel/sys_x86_64.c
index b4d3c3927dd8..f00d006d60fd 100644
--- a/arch/x86/kernel/sys_x86_64.c
+++ b/arch/x86/kernel/sys_x86_64.c
@@ -21,37 +21,23 @@
 
 /*
  * Align a virtual address to avoid aliasing in the I$ on AMD F15h.
- *
- * @flags denotes the allocation direction - bottomup or topdown -
- * or vDSO; see call sites below.
  */
-unsigned long align_addr(unsigned long addr, struct file *filp,
-                         enum align_flags flags)
+static unsigned long get_align_mask(void)
 {
-        unsigned long tmp_addr;
-
         /* handle 32- and 64-bit case with a single conditional */
         if (va_align.flags < 0 || !(va_align.flags & (2 - mmap_is_ia32())))
-                return addr;
+                return 0;
 
         if (!(current->flags & PF_RANDOMIZE))
-                return addr;
-
-        if (!((flags & ALIGN_VDSO) || filp))
-                return addr;
-
-        tmp_addr = addr;
-
-        /*
-         * We need an address which is <= than the original
-         * one only when in topdown direction.
-         */
-        if (!(flags & ALIGN_TOPDOWN))
-                tmp_addr += va_align.mask;
+                return 0;
 
-        tmp_addr &= ~va_align.mask;
+        return va_align.mask;
+}
 
-        return tmp_addr;
+unsigned long align_vdso_addr(unsigned long addr)
+{
+        unsigned long align_mask = get_align_mask();
+        return (addr + align_mask) & ~align_mask;
 }
 
 static int __init control_va_addr_alignment(char *str)
@@ -126,7 +112,7 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
 {
         struct mm_struct *mm = current->mm;
         struct vm_area_struct *vma;
-        unsigned long start_addr;
+        struct vm_unmapped_area_info info;
         unsigned long begin, end;
 
         if (flags & MAP_FIXED)
@@ -144,50 +130,16 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
                     (!vma || addr + len <= vma->vm_start))
                         return addr;
         }
-        if (((flags & MAP_32BIT) || test_thread_flag(TIF_ADDR32))
-            && len <= mm->cached_hole_size) {
-                mm->cached_hole_size = 0;
-                mm->free_area_cache = begin;
-        }
-        addr = mm->free_area_cache;
-        if (addr < begin)
-                addr = begin;
-        start_addr = addr;
-
-full_search:
-
-        addr = align_addr(addr, filp, 0);
-
-        for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
-                /* At this point:  (!vma || addr < vma->vm_end). */
-                if (end - len < addr) {
-                        /*
-                         * Start a new search - just in case we missed
-                         * some holes.
-                         */
-                        if (start_addr != begin) {
-                                start_addr = addr = begin;
-                                mm->cached_hole_size = 0;
-                                goto full_search;
-                        }
-                        return -ENOMEM;
-                }
-                if (!vma || addr + len <= vma->vm_start) {
-                        /*
-                         * Remember the place where we stopped the search:
-                         */
-                        mm->free_area_cache = addr + len;
-                        return addr;
-                }
-                if (addr + mm->cached_hole_size < vma->vm_start)
-                        mm->cached_hole_size = vma->vm_start - addr;
 
-                addr = vma->vm_end;
-                addr = align_addr(addr, filp, 0);
-        }
+        info.flags = 0;
+        info.length = len;
+        info.low_limit = begin;
+        info.high_limit = end;
+        info.align_mask = filp ? get_align_mask() : 0;
+        info.align_offset = 0;
+        return vm_unmapped_area(&info);
 }
 
-
 unsigned long
 arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
                           const unsigned long len, const unsigned long pgoff,
@@ -195,7 +147,8 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 {
         struct vm_area_struct *vma;
         struct mm_struct *mm = current->mm;
-        unsigned long addr = addr0, start_addr;
+        unsigned long addr = addr0;
+        struct vm_unmapped_area_info info;
 
         /* requested length too big for entire address space */
         if (len > TASK_SIZE)
@@ -217,51 +170,16 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
                         return addr;
         }
 
-        /* check if free_area_cache is useful for us */
-        if (len <= mm->cached_hole_size) {
-                mm->cached_hole_size = 0;
-                mm->free_area_cache = mm->mmap_base;
-        }
-
-try_again:
-        /* either no address requested or can't fit in requested address hole */
-        start_addr = addr = mm->free_area_cache;
-
-        if (addr < len)
-                goto fail;
-
-        addr -= len;
-        do {
-                addr = align_addr(addr, filp, ALIGN_TOPDOWN);
-
-                /*
-                 * Lookup failure means no vma is above this address,
-                 * else if new region fits below vma->vm_start,
-                 * return with success:
-                 */
-                vma = find_vma(mm, addr);
-                if (!vma || addr+len <= vma->vm_start)
-                        /* remember the address as a hint for next time */
-                        return mm->free_area_cache = addr;
-
-                /* remember the largest hole we saw so far */
-                if (addr + mm->cached_hole_size < vma->vm_start)
-                        mm->cached_hole_size = vma->vm_start - addr;
-
-                /* try just below the current vma->vm_start */
-                addr = vma->vm_start-len;
-        } while (len < vma->vm_start);
-
-fail:
-        /*
-         * if hint left us with no space for the requested
-         * mapping then try again:
-         */
-        if (start_addr != mm->mmap_base) {
-                mm->free_area_cache = mm->mmap_base;
-                mm->cached_hole_size = 0;
-                goto try_again;
-        }
+        info.flags = VM_UNMAPPED_AREA_TOPDOWN;
+        info.length = len;
+        info.low_limit = PAGE_SIZE;
+        info.high_limit = mm->mmap_base;
+        info.align_mask = filp ? get_align_mask() : 0;
+        info.align_offset = 0;
+        addr = vm_unmapped_area(&info);
+        if (!(addr & ~PAGE_MASK))
+                return addr;
+        VM_BUG_ON(addr != -ENOMEM);
 
 bottomup:
         /*
@@ -270,14 +188,5 @@ bottomup:
          * can happen with large stack limits and large mmap()
          * allocations.
          */
-        mm->cached_hole_size = ~0UL;
-        mm->free_area_cache = TASK_UNMAPPED_BASE;
-        addr = arch_get_unmapped_area(filp, addr0, len, pgoff, flags);
-        /*
-         * Restore the topdown base:
-         */
-        mm->free_area_cache = mm->mmap_base;
-        mm->cached_hole_size = ~0UL;
-
-        return addr;
+        return arch_get_unmapped_area(filp, addr0, len, pgoff, flags);
 }