[PATCH 7/9] arm64/build: Warn on orphan section placement
From: Kees Cook <hidden>
Date: 2020-02-28 00:23:16
Also in:
linux-arch, linux-kbuild, lkml
Subsystem:
arm64 port (aarch64 architecture), the rest · Maintainers:
Catalin Marinas, Will Deacon, Linus Torvalds
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. Explicitly include debug sections when they're present. Add .eh_frame* to discard as it seems that these are still generated even though -fno-asynchronous-unwind-tables is being specified. Add .plt and .data.rel.ro to discards as they are not actually used. Add .got.plt to the image as it does appear to be mapped near .data. Finally enable orphan section warnings. Signed-off-by: Kees Cook <redacted> --- arch/arm64/Makefile | 4 ++++ arch/arm64/kernel/vmlinux.lds.S | 5 ++++- 2 files changed, 8 insertions(+), 1 deletion(-)
diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile
index dca1a97751ab..c682a65b3ab8 100644
--- a/arch/arm64/Makefile
+++ b/arch/arm64/Makefile@@ -30,6 +30,10 @@ LDFLAGS_vmlinux += --fix-cortex-a53-843419 endif endif +# We never want expected sections to be placed heuristically by the +# linker. All sections should be explicitly named in the linker script. +LDFLAGS_vmlinux += --orphan-handling=warn + ifeq ($(CONFIG_ARM64_USE_LSE_ATOMICS), y) ifneq ($(CONFIG_ARM64_LSE_ATOMICS), y) $(warning LSE atomics not supported by binutils)
diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S
index c61d9ab3211c..6141d5b72f8f 100644
--- a/arch/arm64/kernel/vmlinux.lds.S
+++ b/arch/arm64/kernel/vmlinux.lds.S@@ -98,7 +98,8 @@ SECTIONS /DISCARD/ : { *(.interp .dynamic) *(.dynsym .dynstr .hash .gnu.hash) - *(.eh_frame) + *(.plt) *(.data.rel.ro) + *(.eh_frame) *(.init.eh_frame) } . = KIMAGE_VADDR + TEXT_OFFSET;
@@ -212,6 +213,7 @@ SECTIONS _data = .; _sdata = .; RW_DATA(L1_CACHE_BYTES, PAGE_SIZE, THREAD_ALIGN) + .got.plt : ALIGN(8) { *(.got.plt) } /* * Data written with the MMU off but read with the MMU on requires
@@ -246,6 +248,7 @@ SECTIONS _end = .; STABS_DEBUG + DWARF_DEBUG HEAD_SYMBOLS }
--
2.20.1
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel