On Wed, Aug 19, 2020 at 08:23:10PM -0700, Yonghong Song wrote: > > > On 8/19/20 7:27 PM, Fāng-ruì Sòng wrote: > > > > > 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 > > Jiri, > > Since Fangrui mentioned this is not a ld/lld bug, then changing > alighment from 1 to 4 might have some adverse effect for the binary, > I guess. not sure about that.. Mark? ;-) > > Do you think we could skip these .debug_* sections somehow in elf parsing in > resolve_btfids? resolve_btfids does not need to read > these sections. This way, no need to change their alignment either. I'm don't think libelf interface allows for that, will check jirka
