[PATCH 3/6] x86/arch_prctl/vdso: add ARCH_MAP_VDSO_*

[Dmitry Safonov <dsafonov@virtuozzo.com>]

Add API to change vdso blob type with arch_prctl.
As this is useful yet only by needs of CRIU, expose
this interface under CONFIG_CHECKPOINT_RESTORE.

Cc: Andy Lutomirski <luto@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Dmitry Safonov <dsafonov@virtuozzo.com>
---
 arch/x86/include/uapi/asm/prctl.h |  6 ++++++
 arch/x86/kernel/process_64.c      | 10 ++++++++++
 2 files changed, 16 insertions(+)

diff --git a/arch/x86/include/uapi/asm/prctl.h b/arch/x86/include/uapi/asm/prctl.h
index 3ac5032fae09..ae135de547f5 100644
--- a/arch/x86/include/uapi/asm/prctl.h
+++ b/arch/x86/include/uapi/asm/prctl.h
@@ -6,4 +6,10 @@
 #define ARCH_GET_FS 0x1003
 #define ARCH_GET_GS 0x1004
 
+#ifdef CONFIG_CHECKPOINT_RESTORE
+# define ARCH_MAP_VDSO_X32	0x2001
+# define ARCH_MAP_VDSO_32	0x2002
+# define ARCH_MAP_VDSO_64	0x2003
+#endif
+
 #endif /* _ASM_X86_PRCTL_H */
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index 6e789ca1f841..64459c88b3d9 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -49,6 +49,7 @@
 #include <asm/debugreg.h>
 #include <asm/switch_to.h>
 #include <asm/xen/hypervisor.h>
+#include <asm/vdso.h>
 
 asmlinkage extern void ret_from_fork(void);
 
@@ -577,6 +578,15 @@ long do_arch_prctl(struct task_struct *task, int code, unsigned long addr)
 		break;
 	}
 
+#ifdef CONFIG_CHECKPOINT_RESTORE
+	case ARCH_MAP_VDSO_X32:
+		return do_map_vdso(VDSO_X32, addr, false);
+	case ARCH_MAP_VDSO_32:
+		return do_map_vdso(VDSO_32, addr, false);
+	case ARCH_MAP_VDSO_64:
+		return do_map_vdso(VDSO_64, addr, false);
+#endif
+
 	default:
 		ret = -EINVAL;
 		break;
-- 
2.8.2