Commit-ID: e3d03598e8ae7d195af5d3d049596dec336f569f Gitweb: https://git.kernel.org/tip/e3d03598e8ae7d195af5d3d049596dec336f569f Author: H.J. Lu <hjl.to...@gmail.com> AuthorDate: Mon, 19 Mar 2018 13:57:46 -0700 Committer: Ingo Molnar <mi...@kernel.org> CommitDate: Tue, 20 Mar 2018 08:03:03 +0100
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.to...@gmail.com> Cc: Andy Shevchenko <andy.shevche...@gmail.com> Cc: Eric Biederman <ebied...@xmission.com> Cc: H. Peter Anvin <h...@zytor.com> Cc: Juergen Gross <jgr...@suse.com> Cc: Kees Cook <keesc...@chromium.org> Cc: Kirill A. Shutemov <kirill.shute...@linux.intel.com> Cc: Linus Torvalds <torva...@linux-foundation.org> Cc: Peter Zijlstra <pet...@infradead.org> Cc: Thomas Gleixner <t...@linutronix.de> Link: http://lkml.kernel.org/r/came9rop4_%3d_8twdptyap2dhonoceatosnijloppzhonptl8...@mail.gmail.com Signed-off-by: Ingo Molnar <mi...@kernel.org> --- arch/x86/Makefile | 9 +++++++++ 1 file changed, 9 insertions(+) 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
