From c5e8fa7f725ac44ce7b66fe6322d50cd3a7b8a70 Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Thu, 4 Apr 2019 14:40:27 -0700 Subject: x86/build: Keep local relocations with ld.lld [ Upstream commit 7c21383f3429dd70da39c0c7f1efa12377a47ab6 ] The LLVM linker (ld.lld) defaults to removing local relocations, which causes KASLR boot failures. ld.bfd and ld.gold already handle this correctly. This adds the explicit instruction "--discard-none" during the link phase. There is no change in output for ld.bfd and ld.gold, but ld.lld now produces an image with all the needed relocations. Signed-off-by: Kees Cook Signed-off-by: Borislav Petkov Cc: "H. Peter Anvin" Cc: Ingo Molnar Cc: Nick Desaulniers Cc: Thomas Gleixner Cc: clang-built-linux@googlegroups.com Cc: x86-ml Link: https://lkml.kernel.org/r/20190404214027.GA7324@beast Link: https://github.com/ClangBuiltLinux/linux/issues/404 Signed-off-by: Sasha Levin --- arch/x86/Makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch/x86/Makefile') diff --git a/arch/x86/Makefile b/arch/x86/Makefile index b5226a009973..2996a1d0a410 100644 --- a/arch/x86/Makefile +++ b/arch/x86/Makefile @@ -47,7 +47,7 @@ export REALMODE_CFLAGS export BITS ifdef CONFIG_X86_NEED_RELOCS - LDFLAGS_vmlinux := --emit-relocs + LDFLAGS_vmlinux := --emit-relocs --discard-none endif # -- cgit v1.2.3 From d076efab417bbab5c5ac683b4b14b0451da6c2ec Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Wed, 28 Aug 2019 10:56:48 +0200 Subject: x86/build: Add -Wnoaddress-of-packed-member to REALMODE_CFLAGS, to silence GCC9 build warning MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit commit 42e0e95474fc6076b5cd68cab8fa0340a1797a72 upstream. One of the very few warnings I have in the current build comes from arch/x86/boot/edd.c, where I get the following with a gcc9 build: arch/x86/boot/edd.c: In function ‘query_edd’: arch/x86/boot/edd.c:148:11: warning: taking address of packed member of ‘struct boot_params’ may result in an unaligned pointer value [-Waddress-of-packed-member] 148 | mbrptr = boot_params.edd_mbr_sig_buffer; | ^~~~~~~~~~~ This warning triggers because we throw away all the CFLAGS and then make a new set for REALMODE_CFLAGS, so the -Wno-address-of-packed-member we added in the following commit is not present: 6f303d60534c ("gcc-9: silence 'address-of-packed-member' warning") The simplest solution for now is to adjust the warning for this version of CFLAGS as well, but it would definitely make sense to examine whether REALMODE_CFLAGS could be derived from CFLAGS, so that it picks up changes in the compiler flags environment automatically. Signed-off-by: Linus Torvalds Acked-by: Borislav Petkov Cc: Peter Zijlstra Cc: Thomas Gleixner Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman --- arch/x86/Makefile | 1 + 1 file changed, 1 insertion(+) (limited to 'arch/x86/Makefile') diff --git a/arch/x86/Makefile b/arch/x86/Makefile index 2996a1d0a410..940ed27a6212 100644 --- a/arch/x86/Makefile +++ b/arch/x86/Makefile @@ -38,6 +38,7 @@ REALMODE_CFLAGS := $(M16_CFLAGS) -g -Os -D__KERNEL__ \ REALMODE_CFLAGS += $(call __cc-option, $(CC), $(REALMODE_CFLAGS), -ffreestanding) REALMODE_CFLAGS += $(call __cc-option, $(CC), $(REALMODE_CFLAGS), -fno-stack-protector) +REALMODE_CFLAGS += $(call __cc-option, $(CC), $(REALMODE_CFLAGS), -Wno-address-of-packed-member) REALMODE_CFLAGS += $(call __cc-option, $(CC), $(REALMODE_CFLAGS), $(cc_stack_align4)) export REALMODE_CFLAGS -- cgit v1.2.3