The patch titled
From: Jeremy Fitzhardinge <jeremy@xxxxxxxx>
has been removed from the -mm tree. Its filename was
xen-paravirt_ops-add-nosegneg-capability-to-the-vsyscall-page-notes.patch
This patch was dropped because an updated version will be merged
------------------------------------------------------
Subject: From: Jeremy Fitzhardinge <jeremy@xxxxxxxx>
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@xxxxxxxxxxxxx>
Signed-off-by: Christian Limpach <Christian.Limpach@xxxxxxxxxxxx>
Signed-off-by: Chris Wright <chrisw@xxxxxxxxxxxx>
Acked-by: Zachary Amsden <zach@xxxxxxxxxx>
---
===================================================================
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/i386/kernel/vsyscall-note.S | 28 ++++++++++++++++++++++++++++
1 file changed, 28 insertions(+)
diff -puN arch/i386/kernel/vsyscall-note.S~xen-paravirt_ops-add-nosegneg-capability-to-the-vsyscall-page-notes arch/i386/kernel/vsyscall-note.S
--- a/arch/i386/kernel/vsyscall-note.S~xen-paravirt_ops-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@xxxxxxxx are
make-hvc_consolec-compile-on-non-powerpc-remove-no_irq.patch
xen-paravirt_ops-no-need-to-use-traditional-for-processing-asm-in-arch-i386.patch
xen-paravirt_ops-clean-up-elf-note-generation.patch
xen-paravirt_ops-fix-typo-in-sync_constant_test_bits-name.patch
xen-paravirt_ops-ignore-vgacon-if-hardware-not-present.patch
xen-paravirt_ops-add-pagetable-accessors-to-pack-and-unpack-pagetable-entries.patch
xen-paravirt_ops-paravirt_ops-hooks-to-set-up-initial-pagetable.patch
xen-paravirt_ops-paravirt_ops-allocate-a-fixmap-slot.patch
xen-paravirt_ops-allow-paravirt-backend-to-choose-kernel-pmd-sharing.patch
xen-paravirt_ops-remove-have_arch_mm_lifetime-define-no-op-architecture-implementations.patch
xen-paravirt_ops-allocate-and-free-vmalloc-areas.patch
xen-paravirt_ops-add-nosegneg-capability-to-the-vsyscall-page-notes.patch
xen-paravirt_ops-add-xen-config-options.patch
xen-paravirt_ops-add-xen-interface-header-files.patch
xen-paravirt_ops-core-xen-implementation.patch
xen-paravirt_ops-some-generic-early-printk-boot-console-fixups.patch
xen-paravirt_ops-use-the-hvc-console-infrastructure-for-xen-console.patch
xen-paravirt_ops-add-xen-grant-table-support.patch
xen-paravirt_ops-add-the-xenbus-sysfs-and-virtual-device-hotplug-driver.patch
xen-paravirt_ops-add-xen-virtual-block-device-driver.patch
xen-paravirt_ops-add-the-xen-virtual-network-device-driver.patch
fixes-and-cleanups-for-earlyprintk-aka-boot-console.patch
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