From c5c27b82d2e19add5372a6b2eaa00119e896d9ff Mon Sep 17 00:00:00 2001 From: "H.J. Lu" Date: Fri, 16 Feb 2018 14:07:38 -0800 Subject: [PATCH] x86-64: Force 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 --- arch/x86/Makefile | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/arch/x86/Makefile b/arch/x86/Makefile index 68f4963501ae..dc2419883c97 100644 --- a/arch/x86/Makefile +++ b/arch/x86/Makefile @@ -229,6 +229,12 @@ KBUILD_AFLAGS += $(cfi) $(cfi-sigframe) $(cfi-sections) $(asinstr) $(avx_instr) KBUILD_CFLAGS += $(cfi) $(cfi-sigframe) $(cfi-sections) $(asinstr) $(avx_instr) $(avx2_instr) $(avx512_instr) $(sha1_ni_instr) $(sha256_ni_instr) LDFLAGS := -m elf_$(UTS_MACHINE) +ifdef CONFIG_X86_64 +# 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. +LDFLAGS += $(call ld-option, -z max-page-size=0x200000) +endif # Speed up the build KBUILD_CFLAGS += -pipe -- 2.14.3