Re: [PATCH v2] arch: fix broken BuildID for arm64 and riscv
From: Nathan Chancellor <nathan@kernel.org>
Date: 2023-01-02 04:16:35
Also in:
linux-arm-kernel, linux-kbuild, linux-riscv, lkml, llvm
Hi Masahiro, On Tue, Dec 27, 2022 at 03:45:37AM +0900, Masahiro Yamada wrote:
quoted hunk ↗ jump to hunk
Dennis Gilmore reports that the BuildID is missing in the arm64 vmlinux since commit 994b7ac1697b ("arm64: remove special treatment for the link order of head.o"). The issue is that the type of .notes section, which contains the BuildID, changed from NOTES to PROGBITS. Ard Biesheuvel figured out that whichever object gets linked first gets to decide the type of a section. The PROGBITS type is the result of the compiler emitting .note.GNU-stack as PROGBITS rather than NOTE. While Ard provided a fix for arm64, I want to fix this globally because the same issue is happening on riscv since commit 2348e6bf4421 ("riscv: remove special treatment for the link order of head.o"). This problem will happen in general for other architectures if they start to drop unneeded entries from scripts/head-object-list.txt. Discard .note.GNU-stack in include/asm-generic/vmlinux.lds.h. Link: https://lore.kernel.org/lkml/CAABkxwuQoz1CTbyb57n0ZX65eSYiTonFCU8-LCQc=74D=xE=rA@mail.gmail.com/ (local) Fixes: 994b7ac1697b ("arm64: remove special treatment for the link order of head.o") Fixes: 2348e6bf4421 ("riscv: remove special treatment for the link order of head.o") Reported-by: Dennis Gilmore <redacted> Suggested-by: Ard Biesheuvel <ardb@kernel.org> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> --- Changes in v2: - discard .note.GNU-stack before .notes because many architectures call DISCARDS at the end of their linker scripts include/asm-generic/vmlinux.lds.h | 5 +++++ 1 file changed, 5 insertions(+)diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h index a94219e9916f..659bf3b31c91 100644 --- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h@@ -891,7 +891,12 @@ #define PRINTK_INDEX #endif +/* + * Discard .note.GNU-stack, which is emitted as PROGBITS by the compiler. + * Otherwise, the type of .notes section would become PROGBITS instead of NOTES. + */ #define NOTES \ + /DISCARD/ : { *(.note.GNU-stack) } \ .notes : AT(ADDR(.notes) - LOAD_OFFSET) { \ BOUNDED_SECTION_BY(.note.*, _notes) \ } NOTES_HEADERS \-- 2.34.1
I just bisected this change as the cause of a few link failures that we now see in CI with Debian's binutils (2.35.2): https://storage.tuxsuite.com/public/clangbuiltlinux/continuous-integration2/builds/2Jjl88DXc3YRi2RtvXAzlS8NQ4p/build.log This does not appear to be related to clang/LLVM because I can easily reproduce it with Debian's s390x GCC and binutils building defconfig: $ s390x-linux-gnu-gcc --version | head -1 s390x-linux-gnu-gcc (Debian 10.2.1-6) 10.2.1 20210110 $ s390x-linux-gnu-ld --version | head -1 GNU ld (GNU Binutils for Debian) 2.35.2 $ make -skj"$(nproc)" ARCH=s390 CROSS_COMPILE=s390x-linux-gnu- O=build mrproper defconfig all ... `.exit.text' referenced in section `.s390_return_reg' of fs/jbd2/journal.o: defined in discarded section `.exit.text' of fs/jbd2/journal.o `.exit.text' referenced in section `__jump_table' of fs/fuse/inode.o: defined in discarded section `.exit.text' of fs/fuse/inode.o `.exit.text' referenced in section `__jump_table' of fs/fuse/inode.o: defined in discarded section `.exit.text' of fs/fuse/inode.o `.exit.text' referenced in section `.s390_indirect_call' of fs/btrfs/super.o: defined in discarded section `.exit.text' of fs/btrfs/super.o `.exit.text' referenced in section `.s390_return_mem' of fs/btrfs/super.o: defined in discarded section `.exit.text' of fs/btrfs/super.o `.exit.text' referenced in section `.s390_return_mem' of fs/btrfs/volumes.o: defined in discarded section `.exit.text' of fs/btrfs/volumes.o `.exit.text' referenced in section `.s390_return_mem' of fs/btrfs/volumes.o: defined in discarded section `.exit.text' of fs/btrfs/volumes.o `.exit.text' referenced in section `__bug_table' of crypto/algboss.o: defined in discarded section `.exit.text' of crypto/algboss.o `.exit.text' referenced in section `.s390_return_mem' of crypto/algboss.o: defined in discarded section `.exit.text' of crypto/algboss.o `.exit.text' referenced in section `.s390_return_reg' of crypto/xor.o: defined in discarded section `.exit.text' of crypto/xor.o `.exit.text' referenced in section `.s390_return_reg' of lib/atomic64_test.o: defined in discarded section `.exit.text' of lib/atomic64_test.o `.exit.text' referenced in section `.s390_return_mem' of drivers/char/tpm/tpm-dev-common.o: defined in discarded section `.exit.text' of drivers/char/tpm/tpm-dev-common.o `.exit.text' referenced in section `.s390_return_mem' of drivers/char/tpm/tpm-dev-common.o: defined in discarded section `.exit.text' of drivers/char/tpm/tpm-dev-common.o `.exit.text' referenced in section `.s390_return_mem' of drivers/scsi/sd.o: defined in discarded section `.exit.text' of drivers/scsi/sd.o `.exit.text' referenced in section `.altinstructions' of drivers/md/md.o: defined in discarded section `.exit.text' of drivers/md/md.o `.exit.text' referenced in section `.altinstructions' of drivers/md/md.o: defined in discarded section `.exit.text' of drivers/md/md.o `.exit.text' referenced in section `.s390_indirect_call' of drivers/md/dm.o: defined in discarded section `.exit.text' of drivers/md/dm.o `.exit.text' referenced in section `.s390_return_reg' of net/802/psnap.o: defined in discarded section `.exit.text' of net/802/psnap.o `.exit.text' referenced in section `.altinstructions' of net/iucv/iucv.o: defined in discarded section `.exit.text' of net/iucv/iucv.o `.exit.text' referenced in section `__bug_table' of drivers/s390/cio/qdio_thinint.o: defined in discarded section `.exit.text' of drivers/s390/cio/qdio_thinint.o `.exit.text' referenced in section `.s390_return_mem' of drivers/s390/block/dasd_diag.o: defined in discarded section `.exit.text' of drivers/s390/block/dasd_diag.o `.exit.text' referenced in section `.s390_return_mem' of drivers/s390/char/tty3270.o: defined in discarded section `.exit.text' of drivers/s390/char/tty3270.o `.exit.text' referenced in section `__bug_table' of drivers/s390/net/qeth_l3_main.o: defined in discarded section `.exit.text' of drivers/s390/net/qeth_l3_main.o `.exit.text' referenced in section `__bug_table' of drivers/s390/net/qeth_l3_main.o: defined in discarded section `.exit.text' of drivers/s390/net/qeth_l3_main.o s390x-linux-gnu-ld: BFD (GNU Binutils for Debian) 2.35.2 assertion fail ../../bfd/elf64-s390.c:3349 ... I ended up bisecting binutils for the fix, as I could not reproduce it with 2.36+. My bisect landed on commit 21401fc7bf6 ("Duplicate output sections in scripts"): https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=21401fc7bf67dbf73f4a3eda4bcfc58fa4211584 Unfortunately, I cannot immediately grok why this commit cause the above issue nor why the binutils commit resolves it so I figured I would immediately report it for public investigation's sake and quicker resolution. Cheers, Nathan