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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id h3sm19838700pje.28.2020.06.28.23.27.28 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 28 Jun 2020 23:27:28 -0700 (PDT) From: Kees Cook 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 Subject: [PATCH v4 17/17] x86/boot: Warn on orphan section placement Date: Sun, 28 Jun 2020 23:18:40 -0700 Message-Id: <20200629061840.4065483-18-keescook@chromium.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200629061840.4065483-1-keescook@chromium.org> References: <20200629061840.4065483-1-keescook@chromium.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: 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 | 10 ++++++++++ 2 files changed, 12 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 d88612e3091f..9afb8737896f 100644 --- a/arch/x86/boot/compressed/vmlinux.lds.S +++ b/arch/x86/boot/compressed/vmlinux.lds.S @@ -75,7 +75,17 @@ SECTIONS . = ALIGN(PAGE_SIZE); /* keep ZO size page aligned */ _end = .; + STABS_DEBUG + DWARF_DEBUG ELF_DETAILS DISCARDS + /DISCARD/ : { + *(.note.*) + *(.rela.*) *(.rela_*) + *(.rel.*) *(.rel_*) + *(.plt) *(.plt.*) + *(.dyn*) + *(.hash) *(.gnu.hash) + } } -- 2.25.1