x86 vDSO: generate vdso-syms.lds

This patch adds a new way of extracting symbols from the built vDSO image.
This is much simpler and less fragile than using ld -R; it removes the
need to control the DSO layout quite so exactly.  I was clearly unduly
distracted by clever ld uses when I did the original vDSO implementation.

Signed-off-by: Roland McGrath <roland@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 10 insertions, 0 deletions

diff --git a/arch/x86/vdso/vdso.lds.S b/arch/x86/vdso/vdso.lds.S
index 667d3245d972..d40d0e906190 100644
--- a/arch/x86/vdso/vdso.lds.S
+++ b/arch/x86/vdso/vdso.lds.S
@@ -8,6 +8,16 @@
 
 #define VDSO_PRELINK 0xffffffffff700000
 
+/*
+ * Symbols we define here called VDSO* get their values into vdso-syms.lds
+ * and become visible to the kernel itself.
+ */
+VDSO64_PRELINK = VDSO_PRELINK;
+
+#define VEXTERN(x)      VDSO64_ ## x = vdso_ ## x;
+#include "vextern.h"
+#undef  VEXTERN
+
 SECTIONS
 {
   . = VDSO_PRELINK + SIZEOF_HEADERS;