x86/vdso: Replace calculate_addr in map_vdso() with addr

That will allow to specify address where to map vDSO blob.
For the randomized vDSO mappings introduce map_vdso_randomized()
which will simplify calls to map_vdso.

Signed-off-by: Dmitry Safonov <dsafonov@virtuozzo.com>
Acked-by: Andy Lutomirski <luto@kernel.org>
Cc: 0x7f454c46@gmail.com
Cc: oleg@redhat.com
Cc: linux-mm@kvack.org
Cc: gorcunov@openvz.org
Cc: xemul@virtuozzo.com
Link: http://lkml.kernel.org/r/20160905133308.28234-3-dsafonov@virtuozzo.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

diff --git a/arch/x86/entry/vdso/vma.c b/arch/x86/entry/vdso/vma.c
index 3bab6ba3ffc50f6e465b58f3870aeb9be67a8ec1..5bcb25a9e573158d0d8b83f06420c9896e4e1a14 100644 (file)
--- a/arch/x86/entry/vdso/vma.c
+++ b/arch/x86/entry/vdso/vma.c
@@ -176,11 +176,16 @@ static int vvar_fault(const struct vm_special_mapping *sm,
        return VM_FAULT_SIGBUS;
 }
 
-static int map_vdso(const struct vdso_image *image, bool calculate_addr)
+/*
+ * Add vdso and vvar mappings to current process.
+ * @image          - blob to map
+ * @addr           - request a specific address (zero to map at free addr)
+ */
+static int map_vdso(const struct vdso_image *image, unsigned long addr)
 {
        struct mm_struct *mm = current->mm;
        struct vm_area_struct *vma;
-       unsigned long addr, text_start;
+       unsigned long text_start;
        int ret = 0;
 
        static const struct vm_special_mapping vdso_mapping = {
@@ -193,13 +198,6 @@ static int map_vdso(const struct vdso_image *image, bool calculate_addr)
                .fault = vvar_fault,
        };
 
-       if (calculate_addr) {
-               addr = vdso_addr(current->mm->start_stack,
-                                image->size - image->sym_vvar_start);
-       } else {
-               addr = 0;
-       }
-
        if (down_write_killable(&mm->mmap_sem))
                return -EINTR;
 
@@ -251,13 +249,20 @@ up_fail:
        return ret;
 }
 
+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);
+       return map_vdso(image, addr);
+}
+
 #if defined(CONFIG_X86_32) || defined(CONFIG_IA32_EMULATION)
 static int load_vdso32(void)
 {
        if (vdso32_enabled != 1)  /* Other values all mean "disabled" */
                return 0;
 
-       return map_vdso(&vdso_image_32, false);
+       return map_vdso(&vdso_image_32, 0);
 }
 #endif
 
@@ -267,7 +272,7 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
        if (!vdso64_enabled)
                return 0;
 
-       return map_vdso(&vdso_image_64, true);
+       return map_vdso_randomized(&vdso_image_64);
 }
 
 #ifdef CONFIG_COMPAT
@@ -278,8 +283,7 @@ int compat_arch_setup_additional_pages(struct linux_binprm *bprm,
        if (test_thread_flag(TIF_X32)) {
                if (!vdso64_enabled)
                        return 0;
-
-               return map_vdso(&vdso_image_x32, true);
+               return map_vdso_randomized(&vdso_image_x32);
        }
 #endif
 #ifdef CONFIG_IA32_EMULATION