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author | Nathan Chancellor <natechancellor@gmail.com> | 2020-09-28 15:48:54 -0700 |
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committer | Kees Cook <keescook@chromium.org> | 2020-10-27 11:32:21 -0700 |
commit | c39866f268f89868df17724cd2262d121552d8c9 (patch) | |
tree | 6b56330af63903e599965d5b0352181ea980456d /arch/arm | |
parent | 3e6631485fae70f474d5bd85cfaf0f113f61ccce (diff) | |
download | linux-stable-c39866f268f89868df17724cd2262d121552d8c9.tar.gz linux-stable-c39866f268f89868df17724cd2262d121552d8c9.tar.bz2 linux-stable-c39866f268f89868df17724cd2262d121552d8c9.zip |
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/arm')
-rw-r--r-- | arch/arm/kernel/vmlinux.lds.S | 4 |
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; |