> > > section(36) .comment, size 44, link 0, flags 30, type=1 > > > section(37) .debug_aranges, size 45684, link 0, flags 800, type=1 > > > - fixing wrong alignment sh_addralign 16, expected 8 > > > section(38) .debug_info, size 129104957, link 0, flags 800, type=1 > > > - fixing wrong alignment sh_addralign 1, expected 8 > > > section(39) .debug_abbrev, size 1152583, link 0, flags 800, type=1 > > > - fixing wrong alignment sh_addralign 1, expected 8 > > > section(40) .debug_line, size 7374522, link 0, flags 800, type=1 > > > - fixing wrong alignment sh_addralign 1, expected 8 > > > section(41) .debug_frame, size 702463, link 0, flags 800, type=1 > > > section(42) .debug_str, size 1017571, link 0, flags 830, type=1 > > > - fixing wrong alignment sh_addralign 1, expected 8 > > > section(43) .debug_loc, size 3019453, link 0, flags 800, type=1 > > > - fixing wrong alignment sh_addralign 1, expected 8 > > > section(44) .debug_ranges, size 1744583, link 0, flags 800, type=1 > > > - fixing wrong alignment sh_addralign 16, expected 8 > > > section(45) .symtab, size 2955888, link 46, flags 0, type=2 > > > section(46) .strtab, size 2613072, link 0, flags 0, type=3 I think this is resolve_btfids's bug. GNU ld and LLD are innocent. These .debug_* sections work fine if their sh_addralign is 1. When the section flag SHF_COMPRESSED is set, the meaningful alignment is Elf64_Chdr::ch_addralign, after the header is uncompressed. On Wed, Aug 19, 2020 at 2:30 PM Yonghong Song <yhs@xxxxxx> wrote: > > > > On 8/19/20 11:16 AM, Nick Desaulniers wrote: > > On Wed, Aug 19, 2020 at 10:36 AM Jiri Olsa <jolsa@xxxxxxxxxx> wrote: > >> > >> On Wed, Aug 19, 2020 at 08:31:51AM -0700, Yonghong Song wrote: > >>> > >>> > >>> On 8/19/20 2:23 AM, Jiri Olsa wrote: > >>>> The data of compressed section should be aligned to 4 > >>>> (for 32bit) or 8 (for 64 bit) bytes. > >>>> > >>>> The binutils ld sets sh_addralign to 1, which makes libelf > >>>> fail with misaligned section error during the update as > >>>> reported by Jesper: > >>>> > >>>> FAILED elf_update(WRITE): invalid section alignment > >>>> > >>>> While waiting for ld fix, we can fix compressed sections > >>>> sh_addralign value manually. > > > > Is there a bug filed against GNU ld? Link? > > > >>>> > >>>> Adding warning in -vv mode when the fix is triggered: > >>>> > >>>> $ ./tools/bpf/resolve_btfids/resolve_btfids -vv vmlinux > >>>> ... > >>>> section(36) .comment, size 44, link 0, flags 30, type=1 > >>>> section(37) .debug_aranges, size 45684, link 0, flags 800, type=1 > >>>> - fixing wrong alignment sh_addralign 16, expected 8 > >>>> section(38) .debug_info, size 129104957, link 0, flags 800, type=1 > >>>> - fixing wrong alignment sh_addralign 1, expected 8 > >>>> section(39) .debug_abbrev, size 1152583, link 0, flags 800, type=1 > >>>> - fixing wrong alignment sh_addralign 1, expected 8 > >>>> section(40) .debug_line, size 7374522, link 0, flags 800, type=1 > >>>> - fixing wrong alignment sh_addralign 1, expected 8 > >>>> section(41) .debug_frame, size 702463, link 0, flags 800, type=1 > >>>> section(42) .debug_str, size 1017571, link 0, flags 830, type=1 > >>>> - fixing wrong alignment sh_addralign 1, expected 8 > >>>> section(43) .debug_loc, size 3019453, link 0, flags 800, type=1 > >>>> - fixing wrong alignment sh_addralign 1, expected 8 > >>>> section(44) .debug_ranges, size 1744583, link 0, flags 800, type=1 > >>>> - fixing wrong alignment sh_addralign 16, expected 8 > >>>> section(45) .symtab, size 2955888, link 46, flags 0, type=2 > >>>> section(46) .strtab, size 2613072, link 0, flags 0, type=3 > >>>> ... > >>>> update ok for vmlinux > >>>> > >>>> Another workaround is to disable compressed debug info data > >>>> CONFIG_DEBUG_INFO_COMPRESSED kernel option. > >>> > >>> So CONFIG_DEBUG_INFO_COMPRESSED is required to reproduce the bug, right? > >> > >> correct > >> > >>> > >>> I turned on CONFIG_DEBUG_INFO_COMPRESSED in my config and got a bunch of > >>> build failures. > >>> > >>> ld: drivers/crypto/virtio/virtio_crypto_algs.o: unable to initialize > >>> decompress status for section .debug_info > >>> ld: drivers/crypto/virtio/virtio_crypto_algs.o: unable to initialize > >>> decompress status for section .debug_info > >>> ld: drivers/crypto/virtio/virtio_crypto_algs.o: unable to initialize > >>> decompress status for section .debug_info > >>> ld: drivers/crypto/virtio/virtio_crypto_algs.o: unable to initialize > >>> decompress status for section .debug_info > >>> drivers/crypto/virtio/virtio_crypto_algs.o: file not recognized: File format > >>> not recognized > >>> > >>> ld: net/llc/llc_core.o: unable to initialize decompress status for section > >>> .debug_info > >>> ld: net/llc/llc_core.o: unable to initialize decompress status for section > >>> .debug_info > >>> ld: net/llc/llc_core.o: unable to initialize decompress status for section > >>> .debug_info > >>> ld: net/llc/llc_core.o: unable to initialize decompress status for section > >>> .debug_info > >>> net/llc/llc_core.o: file not recognized: File format not recognized > >>> > >>> ... > >>> > >>> The 'ld' in my system: > >>> > >>> $ ld -V > >>> GNU ld version 2.30-74.el8 > >>> Supported emulations: > >>> elf_x86_64 > >>> elf32_x86_64 > >>> elf_i386 > >>> elf_iamcu > >>> i386linux > >>> elf_l1om > >>> elf_k1om > >>> i386pep > >>> i386pe > > > > According to Documentation/process/changes.rst, the minimum supported > > version of GNU binutils for the kernels is 2.23. Can you upgrade to > > that and confirm that you still observe the issue? I don't want to > > spend time chasing bugs in old, unsupported versions of GNU binutils, > > especially as Jiri notes, 2.26 is required for > > CONFIG_DEBUG_INFO_COMPRESSED. We can always strengthen the Kconfig > > check for it. Otherwise, I'm not familiar with the observed error > > message. > > I built a "ld" with latest binutils-gdb repo and I can reproduced > the issue. Indeed applying the patch here fixed the issue. So > I think there is no need to investigate since upstream exhibits > the exact issue described here. > > > > >>> $ > >>> > >>> Do you know what is the issue here? > >> > >> mine's: GNU ld version 2.32-31.fc31 > >> > >> there's version info in commit: > >> 10e68b02c861 Makefile: support compressed debug info > >> > >> Compress the debug information using zlib. Requires GCC 5.0+ or Clang > >> 5.0+, binutils 2.26+, and zlib. > >> > >> cc-ing Nick Desaulniers, author of that patch.. any idea about the error above? > >> > >> thanks, > >> jirka > >> > > > > -- 宋方睿
