vdso: Move parking into a separate routine

Since we might have a several vDSO zones lets hide
handling in arch-specific routines.
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

arch/x86/include/asm/vdso.h

@@ -146,7 +146,7 @@ extern struct vdso_symtable vdso_sym_rt;
 extern u64 vdso_pfn;
 
 extern int vdso_init(void);
-extern int vdso_remap(char *who, unsigned long from, unsigned long to, size_t size);
+extern int vdso_do_park(struct vdso_symtable *sym_rt, unsigned long park_at, unsigned long park_size);
 extern int vdso_fill_symtable(char *mem, size_t size, struct vdso_symtable *t);
 extern int vdso_proxify(char *who, struct vdso_symtable *sym_rt,
 			VmaEntry *vdso_vma, VmaEntry *vvar_vma,

arch/x86/vdso-pie.c

@@ -19,6 +19,7 @@
 #include "vdso.h"
 #include "vma.h"
 #include "log.h"
+#include "bug.h"
 
 #ifdef LOG_PREFIX
 # undef LOG_PREFIX
@@ -246,7 +247,7 @@ err_oob:
 	return -EFAULT;
 }
 
-int vdso_remap(char *who, unsigned long from, unsigned long to, size_t size)
+static int vdso_remap(char *who, unsigned long from, unsigned long to, size_t size)
 {
 	unsigned long addr;
 
@@ -262,6 +263,33 @@ int vdso_remap(char *who, unsigned long from, unsigned long to, size_t size)
 	return 0;
 }
 
+/* Park runtime vDSO in some safe place where it can be accessible from restorer */
+int vdso_do_park(struct vdso_symtable *sym_rt, unsigned long park_at, unsigned long park_size)
+{
+	int ret;
+
+	BUG_ON((vdso_vma_size(sym_rt) + vvar_vma_size(sym_rt)) < park_size);
+
+	if (sym_rt->vvar_start != VDSO_BAD_ADDR) {
+		if (sym_rt->vma_start < sym_rt->vvar_start) {
+			ret  = vdso_remap("rt-vdso", sym_rt->vma_start,
+					  park_at, vdso_vma_size(sym_rt));
+			park_at += vdso_vma_size(sym_rt);
+			ret |= vdso_remap("rt-vvar", sym_rt->vvar_start,
+					  park_at, vvar_vma_size(sym_rt));
+		} else {
+			ret  = vdso_remap("rt-vvar", sym_rt->vvar_start,
+					  park_at, vvar_vma_size(sym_rt));
+			park_at += vvar_vma_size(sym_rt);
+			ret |= vdso_remap("rt-vdso", sym_rt->vma_start,
+					  park_at, vdso_vma_size(sym_rt));
+		}
+	} else
+		ret = vdso_remap("rt-vdso", sym_rt->vma_start,
+				 park_at, vdso_vma_size(sym_rt));
+	return ret;
+}
+
 int vdso_proxify(char *who, struct vdso_symtable *sym_rt,
 		 VmaEntry *vdso_vma, VmaEntry *vvar_vma,
 		 unsigned long vdso_rt_parked_at)

include/vdso.h

@@ -15,6 +15,7 @@
 #define vdso_init()						(0)
 #define parasite_fixup_vdso(ctl, pid, vma_area_list)		(0)
 #define vdso_vma_size(t)					(0)
+#define vdso_do_park(sym_rt, park_at, park_size)		(0)
 #define vdso_remap(who, from, to, size)				(0)
 #define vdso_proxify(who, sym_rt, vdso_vma, \
 		     vvar_vma, vdso_rt_parked_at)		(0)

pie/restorer.c

@@ -701,16 +701,8 @@ long __export_restore_task(struct task_restore_args *args)
 	pr_info("Switched to the restorer %d\n", my_pid);
 
 #ifdef CONFIG_VDSO
-	if (vdso_remap("rt-vdso", args->vdso_sym_rt.vma_start,
-		       args->vdso_rt_parked_at,
-		       vdso_vma_size(&args->vdso_sym_rt)))
+	if (vdso_do_park(&args->vdso_sym_rt, args->vdso_rt_parked_at, vdso_rt_size))
 		goto core_restore_end;
-	if (args->vdso_sym_rt.vvar_start != VVAR_BAD_ADDR) {
-		if (vdso_remap("rt-vvar", args->vdso_sym_rt.vvar_start,
-			       args->vdso_rt_parked_at + vdso_vma_size(&args->vdso_sym_rt),
-			       vvar_vma_size(&args->vdso_sym_rt)))
-			goto core_restore_end;
-	}
 #endif
 
 	if (unmap_old_vmas((void *)args->premmapped_addr, args->premmapped_len,