powerpc: Align vDSO base address

The ABI specifies a 64K alignment, we need to map the vDSO accordingly

Signed-off-by: Andreas Schwab <schwab@linux-m68k.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 10 insertions, 1 deletions

diff --git a/arch/powerpc/kernel/vdso.c b/arch/powerpc/kernel/vdso.c
index 94e2df3cae07..137dc22afa42 100644
--- a/arch/powerpc/kernel/vdso.c
+++ b/arch/powerpc/kernel/vdso.c
@@ -50,6 +50,9 @@
 /* Max supported size for symbol names */
 #define MAX_SYMNAME     64
 
+/* The alignment of the vDSO */
+#define VDSO_ALIGNMENT  (1 << 16)
+
 extern char vdso32_start, vdso32_end;
 static void *vdso32_kbase = &vdso32_start;
 static unsigned int vdso32_pages;
@@ -231,15 +234,21 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
          * pick a base address for the vDSO in process space. We try to put it
          * at vdso_base which is the "natural" base for it, but we might fail
          * and end up putting it elsewhere.
+         * Add enough to the size so that the result can be aligned.
          */
         down_write(&mm->mmap_sem);
         vdso_base = get_unmapped_area(NULL, vdso_base,
-                                      vdso_pages << PAGE_SHIFT, 0, 0);
+                                      (vdso_pages << PAGE_SHIFT) +
+                                      ((VDSO_ALIGNMENT - 1) & PAGE_MASK),
+                                      0, 0);
         if (IS_ERR_VALUE(vdso_base)) {
                 rc = vdso_base;
                 goto fail_mmapsem;
         }
 
+        /* Add required alignment. */
+        vdso_base = ALIGN(vdso_base, VDSO_ALIGNMENT);
+
         /*
          * Put vDSO base into mm struct. We need to do this before calling
          * install_special_mapping or the perf counter mmap tracking code