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From: Nathan Chancellor <>
To: Kees Cook <>, Ingo Molnar <>
Cc: Russell King <>,,,,
	Nathan Chancellor <>,
	kernel test robot <>
Subject: [PATCH] arm/build: Always handle .ARM.exidx and .ARM.extab sections
Date: Mon, 28 Sep 2020 15:48:54 -0700	[thread overview]
Message-ID: <> (raw)

After turning on warnings for orphan section placement, enabling
thousands of warnings when clang + ld.lld are used:

$ scripts/config --file arch/arm/configs/multi_v7_defconfig \
                 -d CONFIG_UNWINDER_ARM \
$ 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
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")
Reported-by: kernel test robot <>
Signed-off-by: Nathan Chancellor <>
 arch/arm/kernel/ | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/arm/kernel/ b/arch/arm/kernel/
index 5f4922e858d0..a2c0d96b0580 100644
--- a/arch/arm/kernel/
+++ b/arch/arm/kernel/
@@ -40,6 +40,10 @@ SECTIONS
+		*(.ARM.exidx*)
+		*(.ARM.extab*)

base-commit: 6e0bf0e0e55000742a53c5f3b58f8669e0091a11

             reply	other threads:[~2020-09-28 23:28 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-28 22:48 Nathan Chancellor [this message]
2020-10-12 21:10 ` Nick Desaulniers
2020-10-12 21:22   ` Fāng-ruì Sòng
2020-10-12 21:26     ` Kees Cook
2020-10-13  3:26       ` Nathan Chancellor
2020-10-13 22:56         ` Nick Desaulniers

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