x86/vdso: Only define map_vdso_randomized() if CONFIG_X86_64

... otherwise the compiler complains:

   arch/x86/entry/vdso/vma.c:252:12: warning: ‘map_vdso_randomized’ defined but not used [-Wunused-function]

But the #ifdeffery here is getting pretty ugly, so move around
vdso_addr() as well to cluster the dependencies a bit more.

It's still not particulary pretty though ...

Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Dmitry Safonov <dsafonov@virtuozzo.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: gorcunov@openvz.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-mm@kvack.org
Cc: oleg@redhat.com
Cc: xemul@virtuozzo.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/arch/x86/entry/vdso/vma.c b/arch/x86/entry/vdso/vma.c
index 4459e73e234d3816a92c6f69ac78cf43435a0802..23c881caabd1ce1d702ef86c0c5e2ba170283516 100644 (file)
--- a/arch/x86/entry/vdso/vma.c
+++ b/arch/x86/entry/vdso/vma.c
@@ -37,54 +37,6 @@ void __init init_vdso_image(const struct vdso_image *image)
 
 struct linux_binprm;
 
-/*
- * Put the vdso above the (randomized) stack with another randomized
- * offset.  This way there is no hole in the middle of address space.
- * To save memory make sure it is still in the same PTE as the stack
- * top.  This doesn't give that many random bits.
- *
- * Note that this algorithm is imperfect: the distribution of the vdso
- * start address within a PMD is biased toward the end.
- *
- * Only used for the 64-bit and x32 vdsos.
- */
-static unsigned long vdso_addr(unsigned long start, unsigned len)
-{
-#ifdef CONFIG_X86_32
-       return 0;
-#else
-       unsigned long addr, end;
-       unsigned offset;
-
-       /*
-        * Round up the start address.  It can start out unaligned as a result
-        * of stack start randomization.
-        */
-       start = PAGE_ALIGN(start);
-
-       /* Round the lowest possible end address up to a PMD boundary. */
-       end = (start + len + PMD_SIZE - 1) & PMD_MASK;
-       if (end >= TASK_SIZE_MAX)
-               end = TASK_SIZE_MAX;
-       end -= len;
-
-       if (end > start) {
-               offset = get_random_int() % (((end - start) >> PAGE_SHIFT) + 1);
-               addr = start + (offset << PAGE_SHIFT);
-       } else {
-               addr = start;
-       }
-
-       /*
-        * Forcibly align the final address in case we have a hardware
-        * issue that requires alignment for performance reasons.
-        */
-       addr = align_vdso_addr(addr);
-
-       return addr;
-#endif
-}
-
 static int vdso_fault(const struct vm_special_mapping *sm,
                      struct vm_area_struct *vma, struct vm_fault *vmf)
 {
@@ -249,12 +201,58 @@ up_fail:
        return ret;
 }
 
+#ifdef CONFIG_X86_64
+/*
+ * Put the vdso above the (randomized) stack with another randomized
+ * offset.  This way there is no hole in the middle of address space.
+ * To save memory make sure it is still in the same PTE as the stack
+ * top.  This doesn't give that many random bits.
+ *
+ * Note that this algorithm is imperfect: the distribution of the vdso
+ * start address within a PMD is biased toward the end.
+ *
+ * Only used for the 64-bit and x32 vdsos.
+ */
+static unsigned long vdso_addr(unsigned long start, unsigned len)
+{
+       unsigned long addr, end;
+       unsigned offset;
+
+       /*
+        * Round up the start address.  It can start out unaligned as a result
+        * of stack start randomization.
+        */
+       start = PAGE_ALIGN(start);
+
+       /* Round the lowest possible end address up to a PMD boundary. */
+       end = (start + len + PMD_SIZE - 1) & PMD_MASK;
+       if (end >= TASK_SIZE_MAX)
+               end = TASK_SIZE_MAX;
+       end -= len;
+
+       if (end > start) {
+               offset = get_random_int() % (((end - start) >> PAGE_SHIFT) + 1);
+               addr = start + (offset << PAGE_SHIFT);
+       } else {
+               addr = start;
+       }
+
+       /*
+        * Forcibly align the final address in case we have a hardware
+        * issue that requires alignment for performance reasons.
+        */
+       addr = align_vdso_addr(addr);
+
+       return addr;
+}
+
 static int map_vdso_randomized(const struct vdso_image *image)
 {
-       unsigned long addr = vdso_addr(current->mm->start_stack,
-                                image->size - image->sym_vvar_start);
+       unsigned long addr = vdso_addr(current->mm->start_stack, image->size-image->sym_vvar_start);
+
        return map_vdso(image, addr);
 }
+#endif
 
 int map_vdso_once(const struct vdso_image *image, unsigned long addr)
 {