1 files changed, 36 insertions, 16 deletions
diff --git a/arch/i386/kernel/vsyscall-note.S b/arch/i386/kernel/vsyscall-note.S
index d4b5be4f3d5f..07c0daf78237 100644
--- a/arch/i386/kernel/vsyscall-note.S
+++ b/arch/i386/kernel/vsyscall-note.S
@@ -3,23 +3,43 @@
  * Here we can supply some information useful to userland.
  */
 
-#include <linux/uts.h>
 #include <linux/version.h>
+#include <linux/elfnote.h>
 
-#define ASM_ELF_NOTE_BEGIN(name, flags, vendor, type)			      \
-	.section name, flags;						      \
-	.balign 4;							      \
-	.long 1f - 0f;		/* name length */			      \
-	.long 3f - 2f;		/* data length */			      \
-	.long type;		/* note type */				      \
-0:	.asciz vendor;		/* vendor name */			      \
-1:	.balign 4;							      \
-2:
+/* Ideally this would use UTS_NAME, but using a quoted string here
+   doesn't work. Remember to change this when changing the
+   kernel's name. */
+ELFNOTE_START(Linux, 0, "a")
+	.long LINUX_VERSION_CODE
+ELFNOTE_END
 
-#define ASM_ELF_NOTE_END						      \
-3:	.balign 4;		/* pad out section */			      \
-	.previous
+#ifdef CONFIG_XEN
+/*
+ * Add a special note telling glibc's dynamic linker a fake hardware
+ * flavor that it will use to choose the search path for libraries in the
+ * same way it uses real hardware capabilities like "mmx".
+ * We supply "nosegneg" as the fake capability, to indicate that we
+ * do not like negative offsets in instructions using segment overrides,
+ * since we implement those inefficiently.  This makes it possible to
+ * install libraries optimized to avoid those access patterns in someplace
+ * like /lib/i686/tls/nosegneg.  Note that an /etc/ld.so.conf.d/file
+ * corresponding to the bits here is needed to make ldconfig work right.
+ * It should contain:
+ *	hwcap 1 nosegneg
+ * to match the mapping of bit to name that we give here.
+ *
+ * At runtime, the fake hardware feature will be considered to be present
+ * if its bit is set in the mask word.  So, we start with the mask 0, and
+ * at boot time we set VDSO_NOTE_NONEGSEG_BIT if running under Xen.
+ */
 
-	ASM_ELF_NOTE_BEGIN(".note.kernel-version", "a", UTS_SYSNAME, 0)
-	.long LINUX_VERSION_CODE
-	ASM_ELF_NOTE_END
+#include "../xen/vdso.h"	/* Defines VDSO_NOTE_NONEGSEG_BIT.  */
+
+	.globl VDSO_NOTE_MASK
+ELFNOTE_START(GNU, 2, "a")
+	.long 1			/* ncaps */
+VDSO_NOTE_MASK:
+	.long 0			/* mask */
+	.byte VDSO_NOTE_NONEGSEG_BIT; .asciz "nosegneg"	/* bit, name */
+ELFNOTE_END
+#endif