From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kees Cook Subject: [PATCH v3 5/9] x86/boot: Warn on orphan section placement Date: Tue, 23 Jun 2020 18:49:36 -0700 Message-ID: <20200624014940.1204448-6-keescook@chromium.org> References: <20200624014940.1204448-1-keescook@chromium.org> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Return-path: Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46720 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388565AbgFXBty (ORCPT ); Tue, 23 Jun 2020 21:49:54 -0400 Received: from mail-pj1-x1044.google.com (mail-pj1-x1044.google.com [IPv6:2607:f8b0:4864:20::1044]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BEE7DC061573 for ; Tue, 23 Jun 2020 18:49:53 -0700 (PDT) Received: by mail-pj1-x1044.google.com with SMTP id i4so386721pjd.0 for ; Tue, 23 Jun 2020 18:49:53 -0700 (PDT) In-Reply-To: <20200624014940.1204448-1-keescook@chromium.org> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Will Deacon Cc: Kees Cook , Catalin Marinas , Mark Rutland , Ard Biesheuvel , Peter Collingbourne , James Morse , Borislav Petkov , Thomas Gleixner , Ingo Molnar , Russell King , Masahiro Yamada , Arvind Sankar , Nick Desaulniers , Nathan Chancellor , Arnd Bergmann , x86@kernel.org, clang-built-linux@googlegroups.com, linux-arch@vger.kernel.org, linux-efi@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org We don't want to depend on the linker's orphan section placement heuristics as these can vary between linkers, and may change between versions. All sections need to be explicitly named in the linker script. Add the common debugging sections. Discard the unused note, rel, plt, dyn, and hash sections that are not needed in the compressed vmlinux. Disable .eh_frame generation in the linker and enable orphan section warnings. Signed-off-by: Kees Cook --- arch/x86/boot/compressed/Makefile | 3 ++- arch/x86/boot/compressed/vmlinux.lds.S | 11 +++++++++++ 2 files changed, 13 insertions(+), 1 deletion(-) diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile index 7619742f91c9..646720a05f89 100644 --- a/arch/x86/boot/compressed/Makefile +++ b/arch/x86/boot/compressed/Makefile @@ -48,6 +48,7 @@ GCOV_PROFILE := n UBSAN_SANITIZE :=n KBUILD_LDFLAGS := -m elf_$(UTS_MACHINE) +KBUILD_LDFLAGS += $(call ld-option,--no-ld-generated-unwind-info) # Compressed kernel should be built as PIE since it may be loaded at any # address by the bootloader. ifeq ($(CONFIG_X86_32),y) @@ -59,7 +60,7 @@ else KBUILD_LDFLAGS += $(shell $(LD) --help 2>&1 | grep -q "\-z noreloc-overflow" \ && echo "-z noreloc-overflow -pie --no-dynamic-linker") endif -LDFLAGS_vmlinux := -T +LDFLAGS_vmlinux := --orphan-handling=warn -T hostprogs := mkpiggy HOST_EXTRACFLAGS += -I$(srctree)/tools/include diff --git a/arch/x86/boot/compressed/vmlinux.lds.S b/arch/x86/boot/compressed/vmlinux.lds.S index 8f1025d1f681..6fe3ecdfd685 100644 --- a/arch/x86/boot/compressed/vmlinux.lds.S +++ b/arch/x86/boot/compressed/vmlinux.lds.S @@ -75,5 +75,16 @@ SECTIONS . = ALIGN(PAGE_SIZE); /* keep ZO size page aligned */ _end = .; + STABS_DEBUG + DWARF_DEBUG + DISCARDS + /DISCARD/ : { + *(.note.*) + *(.rela.*) *(.rela_*) + *(.rel.*) *(.rel_*) + *(.plt) *(.plt.*) + *(.dyn*) + *(.hash) *(.gnu.hash) + } } -- 2.25.1