From 7f115ff4fc20698452ff4a1cbb9c790be10b0066 Mon Sep 17 00:00:00 2001 From: Nathan Chancellor Date: Tue, 20 Feb 2024 13:44:48 -0700 Subject: [PATCH] s390/boot: workaround current 'llvm-objdump -t -j ...' behavior When building with OBJDUMP=llvm-objdump, there are a series of warnings from the section comparisons that arch/s390/boot/Makefile performs between vmlinux and arch/s390/boot/vmlinux: llvm-objdump: warning: section '.boot.preserved.data' mentioned in a -j/--section option, but not found in any input file llvm-objdump: warning: section '.boot.data' mentioned in a -j/--section option, but not found in any input file llvm-objdump: warning: section '.boot.preserved.data' mentioned in a -j/--section option, but not found in any input file llvm-objdump: warning: section '.boot.data' mentioned in a -j/--section option, but not found in any input file The warning is a little misleading, as these sections do exist in the input files. It is really pointing out that llvm-objdump does not match GNU objdump's behavior of respecting '-j' / '--section' in combination with '-t' / '--syms': $ s390x-linux-gnu-objdump -t -j .boot.data vmlinux.full vmlinux.full: file format elf64-s390 SYMBOL TABLE: 0000000001951000 l O .boot.data 0000000000003000 sclp_info_sccb 00000000019550e0 l O .boot.data 0000000000000001 sclp_info_sccb_valid 00000000019550e2 g O .boot.data 0000000000001000 early_command_line ... $ llvm-objdump -t -j .boot.data vmlinux.full vmlinux.full: file format elf64-s390 SYMBOL TABLE: 0000000000100040 l O .text 0000000000000010 dw_psw 0000000000000000 l df *ABS* 0000000000000000 main.c 00000000001001b0 l F .text 00000000000000c6 trace_event_raw_event_initcall_level 0000000000100280 l F .text 0000000000000100 perf_trace_initcall_level ... It may be possible to change llvm-objdump's behavior to match GNU objdump's behavior but the difficulty of that task has not yet been explored. The combination of '$(OBJDUMP) -t -j' is not common in the kernel tree on a whole, so workaround this tool difference by grepping for the sections in the full symbol table output in a similar manner to the sed invocation. This results in no visible change for GNU objdump users while fixing the warnings for OBJDUMP=llvm-objdump, further enabling use of LLVM=1 for ARCH=s390 with versions of LLVM that have support for s390 in ld.lld and llvm-objcopy. Reported-by: Heiko Carstens Closes: https://lore.kernel.org/20240219113248.16287-C-hca@linux.ibm.com/ Link: https://github.com/ClangBuiltLinux/linux/issues/859 Signed-off-by: Nathan Chancellor Link: https://lore.kernel.org/r/20240220-s390-work-around-llvm-objdump-t-j-v1-1-47bb0366a831@kernel.org Signed-off-by: Heiko Carstens --- arch/s390/boot/Makefile | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/s390/boot/Makefile b/arch/s390/boot/Makefile index aecafabc2054..294f08a8811a 100644 --- a/arch/s390/boot/Makefile +++ b/arch/s390/boot/Makefile @@ -60,9 +60,9 @@ clean-files += vmlinux.map quiet_cmd_section_cmp = SECTCMP $* define cmd_section_cmp - s1=`$(OBJDUMP) -t -j "$*" "$<" | sort | \ + s1=`$(OBJDUMP) -t "$<" | grep "\s$*\s\+" | sort | \ sed -n "/0000000000000000/! s/.*\s$*\s\+//p" | sha256sum`; \ - s2=`$(OBJDUMP) -t -j "$*" "$(word 2,$^)" | sort | \ + s2=`$(OBJDUMP) -t "$(word 2,$^)" | grep "\s$*\s\+" | sort | \ sed -n "/0000000000000000/! s/.*\s$*\s\+//p" | sha256sum`; \ if [ "$$s1" != "$$s2" ]; then \ echo "error: section $* differs between $< and $(word 2,$^)" >&2; \ -- 2.20.1