From 5b93049337301d6fbd3cf55db99b34e6b0dbd3a3 Mon Sep 17 00:00:00 2001
From: Roland McGrath <roland@redhat.com>
Date: Wed, 30 Jan 2008 13:30:40 +0100
Subject: [PATCH] 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>
---
arch/x86/vdso/Makefile | 14 ++++++++++++++
arch/x86/vdso/vdso.lds.S | 10 ++++++++++
2 files changed, 24 insertions(+)
diff --git a/arch/x86/vdso/Makefile b/arch/x86/vdso/Makefile
index e7bff0fbac23..d8200adae9fa 100644
--- a/arch/x86/vdso/Makefile
+++ b/arch/x86/vdso/Makefile
@@ -55,6 +55,20 @@ SYSCFLAGS_vdso-syms.o = -r -d
$(obj)/vdso-syms.o: $(src)/vdso.lds $(vobjs) FORCE
$(call if_changed,syscall)
+targets += vdso-syms.lds
+obj-y += vdso-syms.lds
+
+#
+# Match symbols in the DSO that look like VDSO*; produce a file of constants.
+#
+sed-vdsosym := -e 's/^00*/0/' \
+ -e 's/^\([0-9a-fA-F]*\) . \(VDSO[a-zA-Z0-9_]*\)$$/\2 = 0x\1;/p'
+quiet_cmd_vdsosym = VDSOSYM $@
+ cmd_vdsosym = $(NM) $< | sed -n $(sed-vdsosym) | LC_ALL=C sort > $@
+
+$(obj)/%-syms.lds: $(obj)/%.so.dbg FORCE
+ $(call if_changed,vdsosym)
+
quiet_cmd_vdso_install = INSTALL $@
cmd_vdso_install = cp $(obj)/$@.dbg $(MODLIB)/vdso/$@
vdso.so:
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;