x86 vDSO: use vdso-syms.lds

This patch changes the kernel's references to addresses in the vDSO image
to be based on the symbols defined by vdso-syms.lds instead of the old
vdso-syms.o symbols.  This is all wrapped up in a macro defined by the new
asm-x86/vdso.h header; that's the only place in the kernel source that has
to know the details of the scheme for getting vDSO symbol values.

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, 14 insertions, 0 deletions

diff --git a/include/asm-x86/vdso.h b/include/asm-x86/vdso.h
new file mode 100644
index 000000000000..9379ec06fd1f
--- /dev/null
+++ b/include/asm-x86/vdso.h
@@ -0,0 +1,14 @@
+#ifndef _ASM_X86_VDSO_H
+#define _ASM_X86_VDSO_H 1
+
+extern const char VDSO64_PRELINK[];
+
+/*
+ * Given a pointer to the vDSO image, find the pointer to VDSO64_name
+ * as that symbol is defined in the vDSO sources or linker script.
+ */
+#define VDSO64_SYMBOL(base, name) ({            \
+        extern const char VDSO64_##name[];      \
+        (void *) (VDSO64_##name - VDSO64_PRELINK + (unsigned long) (base)); })
+
+#endif  /* asm-x86/vdso.h */