linux/tools/bpf
Jiri Olsa 51f6463aac tools/resolve_btfids: Fix sections with wrong alignment
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.

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.

Fixes: fbbb68de80 ("bpf: Add resolve_btfids tool to resolve BTF IDs in ELF object")
Reported-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Acked-by: Yonghong Song <yhs@fb.com>
Cc: Mark Wielaard <mjw@redhat.com>
Cc: Nick Clifton <nickc@redhat.com>
Link: https://lore.kernel.org/bpf/20200819092342.259004-1-jolsa@kernel.org
2020-08-20 14:17:20 -07:00
..
bpftool bpftool: Handle EAGAIN error code properly in pids collection 2020-08-18 17:36:23 -07:00
resolve_btfids tools/resolve_btfids: Fix sections with wrong alignment 2020-08-20 14:17:20 -07:00
runqslower bpf, runqslower: include proper uapi/bpf.h 2020-05-09 18:01:33 -07:00
.gitignore .gitignore: add SPDX License Identifier 2020-03-25 11:50:48 +01:00
bpf_asm.c docs: networking: convert filter.txt to ReST 2020-04-28 14:39:46 -07:00
bpf_dbg.c docs: networking: convert filter.txt to ReST 2020-04-28 14:39:46 -07:00
bpf_exp.l bpf: fix cbpf parser bug for octal numbers 2018-06-03 07:46:55 -07:00
bpf_exp.y tools, bpf_asm: Warn when jumps are out of range 2019-11-07 16:01:34 +01:00
bpf_jit_disasm.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 232 2019-06-19 17:09:06 +02:00
Makefile Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next 2020-08-05 20:13:21 -07:00
Makefile.helpers treewide: Add SPDX license identifier - Makefile/Kconfig 2019-05-21 10:50:46 +02:00