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authorH.J. Lu <hjl.tools@gmail.com>2018-03-19 13:57:46 -0700
committerIngo Molnar <mingo@kernel.org>2018-03-20 08:03:03 +0100
commite3d03598e8ae7d195af5d3d049596dec336f569f (patch)
tree82c24ad16425d121eba392163c61a31e4c87f3c7 /arch
parent4b0b37d4cc54b21a6ecad7271cbc850555869c62 (diff)
downloadlinux-e3d03598e8ae7d195af5d3d049596dec336f569f.tar.bz2
x86/build/64: Force the linker to use 2MB page size
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@gmail.com> Cc: Andy Shevchenko <andy.shevchenko@gmail.com> Cc: Eric Biederman <ebiederm@xmission.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Juergen Gross <jgross@suse.com> Cc: Kees Cook <keescook@chromium.org> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/CAMe9rOp4_%3D_8twdpTyAP2DhONOCeaTOsniJLoppzhoNptL8xzA@mail.gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/Makefile9
1 files changed, 9 insertions, 0 deletions
diff --git a/arch/x86/Makefile b/arch/x86/Makefile
index 498c1b812300..1c4d012550ec 100644
--- a/arch/x86/Makefile
+++ b/arch/x86/Makefile
@@ -223,6 +223,15 @@ KBUILD_CFLAGS += $(cfi) $(cfi-sigframe) $(cfi-sections) $(asinstr) $(avx_instr)
LDFLAGS := -m elf_$(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