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From: Kees Cook <keescook@chromium.org>
To: Borislav Petkov <bp@suse.de>
Cc: Kees Cook <keescook@chromium.org>,
	"H.J. Lu" <hjl.tools@gmail.com>,
	Russell King <linux@armlinux.org.uk>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Peter Collingbourne <pcc@google.com>,
	James Morse <james.morse@arm.com>, Arnd Bergmann <arnd@arndb.de>,
	Masahiro Yamada <masahiroy@kernel.org>,
	x86@kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-arch@vger.kernel.org, linux-kbuild@vger.kernel.org,
	clang-built-linux@googlegroups.com, linux-kernel@vger.kernel.org
Subject: [PATCH 4/9] x86/boot: Warn on orphan section placement
Date: Thu, 27 Feb 2020 16:22:39 -0800
Message-ID: <20200228002244.15240-5-keescook@chromium.org> (raw)
In-Reply-To: <20200228002244.15240-1-keescook@chromium.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 <keescook@chromium.org>
---
 arch/x86/boot/compressed/Makefile      |  3 ++-
 arch/x86/boot/compressed/vmlinux.lds.S | 13 +++++++++++++
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile
index c33111341325..e0ea6b0924e8 100644
--- a/arch/x86/boot/compressed/Makefile
+++ b/arch/x86/boot/compressed/Makefile
@@ -46,6 +46,7 @@ GCOV_PROFILE := n
 UBSAN_SANITIZE :=n
 
 KBUILD_LDFLAGS := -m elf_$(UTS_MACHINE)
+KBUILD_LDFLAGS += --no-ld-generated-unwind-info
 # Compressed kernel should be built as PIE since it may be loaded at any
 # address by the bootloader.
 ifeq ($(CONFIG_X86_32),y)
@@ -57,7 +58,7 @@ 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 508cfa6828c5..b5406a8cebe0 100644
--- a/arch/x86/boot/compressed/vmlinux.lds.S
+++ b/arch/x86/boot/compressed/vmlinux.lds.S
@@ -73,4 +73,17 @@ SECTIONS
 #endif
 	. = 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)
+	}
 }
-- 
2.20.1


  parent reply index

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-28  0:22 [PATCH 0/9] Enable orphan section warning Kees Cook
2020-02-28  0:22 ` [PATCH 1/9] scripts/link-vmlinux.sh: Delay orphan handling warnings until final link Kees Cook
2020-03-20  2:47   ` Nicholas Piggin
2020-03-20 18:24     ` Kees Cook
2020-03-22  9:16       ` Nicholas Piggin
2020-03-22 16:00         ` Kees Cook
2020-02-28  0:22 ` [PATCH 2/9] vmlinux.lds.h: Add .gnu.version* to DISCARDS Kees Cook
2020-02-28  0:22 ` [PATCH 3/9] x86/build: Warn on orphan section placement Kees Cook
2020-02-28  0:22 ` Kees Cook [this message]
2020-02-28  0:22 ` [PATCH 5/9] Add RUNTIME_DISCARD_EXIT to generic DISCARDS Kees Cook
2020-02-28  0:22 ` [PATCH 6/9] arm64/build: Use common DISCARDS in linker script Kees Cook
2020-03-17 21:52   ` Will Deacon
2020-02-28  0:22 ` [PATCH 7/9] arm64/build: Warn on orphan section placement Kees Cook
2020-03-17 21:56   ` Will Deacon
2020-03-17 23:01     ` Kees Cook
2020-03-17 23:10       ` Nick Desaulniers
2020-02-28  0:22 ` [PATCH 8/9] arm/build: " Kees Cook
2020-02-28  0:22 ` [PATCH 9/9] arm/boot: " Kees Cook
2020-02-28  6:51 ` [PATCH 0/9] Enable orphan section warning Sedat Dilek
2020-03-03  4:32   ` Kees Cook
2020-04-02 16:20 ` Sedat Dilek
2020-04-02 17:26   ` Kees Cook
2020-04-05 11:15     ` Sedat Dilek

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