4.4-stable review patch. If anyone has any objections, please let me know.
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From: H.J. Lu hjl.tools@gmail.com
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@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_8twdpTyAP2DhONOCeaTOsniJLoppzhoNptL8x... Signed-off-by: Ingo Molnar mingo@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- arch/x86/Makefile | 9 +++++++++ 1 file changed, 9 insertions(+)
--- a/arch/x86/Makefile +++ b/arch/x86/Makefile @@ -179,6 +179,15 @@ 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