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authorNathan Chancellor <natechancellor@gmail.com>2020-09-28 15:48:54 -0700
committerKees Cook <keescook@chromium.org>2020-10-27 11:32:21 -0700
commitc39866f268f89868df17724cd2262d121552d8c9 (patch)
tree6b56330af63903e599965d5b0352181ea980456d /arch
parent3e6631485fae70f474d5bd85cfaf0f113f61ccce (diff)
downloadlinux-stericsson-c39866f268f89868df17724cd2262d121552d8c9.tar.gz
arm/build: Always handle .ARM.exidx and .ARM.extab sections
After turning on warnings for orphan section placement, enabling CONFIG_UNWINDER_FRAME_POINTER instead of CONFIG_UNWINDER_ARM causes thousands of warnings when clang + ld.lld are used: $ scripts/config --file arch/arm/configs/multi_v7_defconfig \ -d CONFIG_UNWINDER_ARM \ -e CONFIG_UNWINDER_FRAME_POINTER $ make -skj"$(nproc)" ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- LLVM=1 defconfig zImage ld.lld: warning: init/built-in.a(main.o):(.ARM.extab) is being placed in '.ARM.extab' ld.lld: warning: init/built-in.a(main.o):(.ARM.extab.init.text) is being placed in '.ARM.extab.init.text' ld.lld: warning: init/built-in.a(main.o):(.ARM.extab.ref.text) is being placed in '.ARM.extab.ref.text' ld.lld: warning: init/built-in.a(do_mounts.o):(.ARM.extab.init.text) is being placed in '.ARM.extab.init.text' ld.lld: warning: init/built-in.a(do_mounts.o):(.ARM.extab) is being placed in '.ARM.extab' ld.lld: warning: init/built-in.a(do_mounts_rd.o):(.ARM.extab.init.text) is being placed in '.ARM.extab.init.text' ld.lld: warning: init/built-in.a(do_mounts_rd.o):(.ARM.extab) is being placed in '.ARM.extab' ld.lld: warning: init/built-in.a(do_mounts_initrd.o):(.ARM.extab.init.text) is being placed in '.ARM.extab.init.text' ld.lld: warning: init/built-in.a(initramfs.o):(.ARM.extab.init.text) is being placed in '.ARM.extab.init.text' ld.lld: warning: init/built-in.a(initramfs.o):(.ARM.extab) is being placed in '.ARM.extab' ld.lld: warning: init/built-in.a(calibrate.o):(.ARM.extab.init.text) is being placed in '.ARM.extab.init.text' ld.lld: warning: init/built-in.a(calibrate.o):(.ARM.extab) is being placed in '.ARM.extab' These sections are handled by the ARM_UNWIND_SECTIONS define, which is only added to the list of sections when CONFIG_ARM_UNWIND is set. CONFIG_ARM_UNWIND is a hidden symbol that is only selected when CONFIG_UNWINDER_ARM is set so CONFIG_UNWINDER_FRAME_POINTER never handles these sections. According to the help text of CONFIG_UNWINDER_ARM, these sections should be discarded so that the kernel image size is not affected. Fixes: 5a17850e251a ("arm/build: Warn on orphan section placement") Link: https://github.com/ClangBuiltLinux/linux/issues/1152 Reported-by: kernel test robot <lkp@intel.com> Signed-off-by: Nathan Chancellor <natechancellor@gmail.com> Review-by: Nick Desaulniers <ndesaulniers@google.com> Tested-by: Nick Desaulniers <ndesaulniers@google.com> [kees: Made the discard slightly more specific] Signed-off-by: Kees Cook <keescook@chromium.org> Link: https://lore.kernel.org/r/20200928224854.3224862-1-natechancellor@gmail.com
Diffstat (limited to 'arch')
-rw-r--r--arch/arm/kernel/vmlinux.lds.S4
1 files changed, 4 insertions, 0 deletions
diff --git a/arch/arm/kernel/vmlinux.lds.S b/arch/arm/kernel/vmlinux.lds.S
index 5f4922e858d0..f7f4620d59c3 100644
--- a/arch/arm/kernel/vmlinux.lds.S
+++ b/arch/arm/kernel/vmlinux.lds.S
@@ -41,6 +41,10 @@ SECTIONS
#ifndef CONFIG_SMP_ON_UP
*(.alt.smp.init)
#endif
+#ifndef CONFIG_ARM_UNWIND
+ *(.ARM.exidx) *(.ARM.exidx.*)
+ *(.ARM.extab) *(.ARM.extab.*)
+#endif
}
. = PAGE_OFFSET + TEXT_OFFSET;