+ xen-paravirt-add-nosegneg-capability-to-the-vsyscall-page-notes.patch added to -mm tree

+ xen-paravirt-add-nosegneg-capability-to-the-vsyscall-page-notes.patch added to -mm tree

[akpm]

The patch titled
     Xen-paravirt: add nosegneg capability to the vsyscall page notes
has been added to the -mm tree.  Its filename is
     xen-paravirt-add-nosegneg-capability-to-the-vsyscall-page-notes.patch

*** Remember to use Documentation/SubmitChecklist when testing your code ***

See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this

------------------------------------------------------
Subject: Xen-paravirt: add nosegneg capability to the vsyscall page notes
From: Jeremy Fitzhardinge <jeremy@goop.org>

Add the "nosegneg" fake capabilty to the vsyscall page notes.  This is used by
the runtime linker to select a glibc version which then disables
negative-offset accesses to the thread-local segment via %gs.  These accesses
require emulation in Xen (because segments are truncated to protect the
hypervisor address space) and avoiding them provides a measurable performance
boost.

Signed-off-by: Ian Pratt <ian.pratt@xensource.com>
Signed-off-by: Christian Limpach <Christian.Limpach@cl.cam.ac.uk>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
Cc: Zachary Amsden <zach@vmware.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 arch/i386/kernel/vsyscall-note.S |   28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff -puN arch/i386/kernel/vsyscall-note.S~xen-paravirt-add-nosegneg-capability-to-the-vsyscall-page-notes arch/i386/kernel/vsyscall-note.S
--- a/arch/i386/kernel/vsyscall-note.S~xen-paravirt-add-nosegneg-capability-to-the-vsyscall-page-notes
+++ a/arch/i386/kernel/vsyscall-note.S
@@ -23,3 +23,31 @@
 	ASM_ELF_NOTE_BEGIN(".note.kernel-version", "a", UTS_SYSNAME, 0)
 	.long LINUX_VERSION_CODE
 	ASM_ELF_NOTE_END
+
+#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 0 nosegneg
+ * to match the mapping of bit to name that we give here.
+ */
+#define NOTE_KERNELCAP_BEGIN(ncaps, mask) \
+	ASM_ELF_NOTE_BEGIN(".note.kernelcap", "a", "GNU", 2) \
+	.long ncaps, mask
+#define NOTE_KERNELCAP(bit, name) \
+	.byte bit; .asciz name
+#define NOTE_KERNELCAP_END ASM_ELF_NOTE_END
+
+NOTE_KERNELCAP_BEGIN(1, 1)
+NOTE_KERNELCAP(1, "nosegneg")
+NOTE_KERNELCAP_END
+#endif
+
_

Patches currently in -mm which might be from jeremy@goop.org are

i386-probe_roms-cleanup.patch
no-need-to-use-traditional-for-processing-asm-in-i386-kernel.patch
xen-paravirt-fix-typo-in-sync_constant_test_bits-name.patch
xen-paravirt-ignore-vgacon-if-hardware-not-present.patch
xen-paravirt-add-pagetable-accessors-to-pack-and-unpack-pagetable-entries.patch
xen-paravirt-paravirt_ops-hooks-to-set-up-initial-pagetable.patch
xen-paravirt-paravirt_ops-allocate-a-fixmap-slot.patch
xen-paravirt-remove-ctor-for-pgd-cache.patch
xen-paravirt-allow-paravirt-backend-to-choose-kernel-pmd-sharing.patch
xen-paravirt-allow-paravirt-backend-to-select-pgd-allocation-alignment.patch
xen-paravirt-add-hooks-to-intercept-mm-creation-and-destruction.patch
xen-paravirt-add-apply_to_page_range-which-applies-a-function-to-a-pte-range.patch
xen-paravirt-allocate-and-free-vmalloc-areas.patch
xen-paravirt-add-nosegneg-capability-to-the-vsyscall-page-notes.patch
xen-paravirt-add-xen-config-options-and-disable-unsupported-config-options.patch
xen-paravirt-add-xen-interface-header-files.patch
xen-paravirt-core-xen-implementation.patch
xen-paravirt-add-the-xen-virtual-console-driver.patch
xen-paravirt-add-xen-grant-table-support.patch
xen-paravirt-add-the-xenbus-sysfs-and-virtual-device-hotplug-driver.patch
xen-paravirt-add-xen-virtual-block-device-driver.patch
xen-paravirt-add-the-xen-virtual-network-device-driver.patch
uninline-jiffiesh-functions.patch