This is a note to let you know that I've just added the patch titled
x86/build/64: Force the linker to use 2MB page size
to the 4.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
x86-build-64-force-the-linker-to-use-2mb-page-size.patch
and it can be found in the queue-4.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From e3d03598e8ae7d195af5d3d049596dec336f569f Mon Sep 17 00:00:00 2001
From: "H.J. Lu" <hjl.tools@xxxxxxxxx>
Date: Mon, 19 Mar 2018 13:57:46 -0700
Subject: x86/build/64: Force the linker to use 2MB page size
From: H.J. Lu <hjl.tools@xxxxxxxxx>
commit e3d03598e8ae7d195af5d3d049596dec336f569f upstream.
Binutils 2.31 will enable -z separate-code by default for x86 to avoid
mixing code pages with data to improve cache performance as well as
security. To reduce x86-64 executable and shared object sizes, the
maximum page size is reduced from 2MB to 4KB. But x86-64 kernel must
be aligned to 2MB. Pass -z max-page-size=0x200000 to linker to force
2MB page size regardless of the default page size used by linker.
Tested with Linux kernel 4.15.6 on x86-64.
Signed-off-by: H.J. Lu <hjl.tools@xxxxxxxxx>
Cc: Andy Shevchenko <andy.shevchenko@xxxxxxxxx>
Cc: Eric Biederman <ebiederm@xxxxxxxxxxxx>
Cc: H. Peter Anvin <hpa@xxxxxxxxx>
Cc: Juergen Gross <jgross@xxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/CAMe9rOp4_%3D_8twdpTyAP2DhONOCeaTOsniJLoppzhoNptL8xzA@xxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/Makefile | 9 +++++++++
1 file changed, 9 insertions(+)
--- a/arch/x86/Makefile
+++ b/arch/x86/Makefile
@@ -223,6 +223,15 @@ KBUILD_CFLAGS += $(cfi) $(cfi-sigframe)
LDFLAGS := -m elf_$(UTS_MACHINE)
+#
+# The 64-bit kernel must be aligned to 2MB. Pass -z max-page-size=0x200000 to
+# the linker to force 2MB page size regardless of the default page size used
+# by the linker.
+#
+ifdef CONFIG_X86_64
+LDFLAGS += $(call ld-option, -z max-page-size=0x200000)
+endif
+
# Speed up the build
KBUILD_CFLAGS += -pipe
# Workaround for a gcc prelease that unfortunately was shipped in a suse release
Patches currently in stable-queue which might be from hjl.tools@xxxxxxxxx are
queue-4.15/x86-boot-64-verify-alignment-of-the-load-segment.patch
queue-4.15/x86-build-64-force-the-linker-to-use-2mb-page-size.patch