linux.git/tools/bpf/resolve_btfids, branch v5.9

tools/bpf: build: Make sure resolve_btfids cleans up after itself

2020-09-01T16:04:15+00:00

The new resolve_btfids tool did not clean up the feature detection folder
on 'make clean', and also was not called properly from the clean rule in
tools/make/ folder on its 'make clean'. This lead to stale objects being
left around, which could cause feature detection to fail on subsequent
builds.

Fixes: fbbb68de80a4 ("bpf: Add resolve_btfids tool to resolve BTF IDs in ELF object")
Signed-off-by: Toke Høiland-Jørgensen 
Signed-off-by: Daniel Borkmann 
Acked-by: Jiri Olsa 
Link: https://lore.kernel.org/bpf/20200901144343.179552-1-toke@redhat.com

tools/resolve_btfids: Fix sections with wrong alignment

2020-08-20T21:17:20+00:00

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: fbbb68de80a4 ("bpf: Add resolve_btfids tool to resolve BTF IDs in ELF object")
Reported-by: Jesper Dangaard Brouer 
Signed-off-by: Jiri Olsa 
Signed-off-by: Alexei Starovoitov 
Acked-by: Jesper Dangaard Brouer 
Acked-by: Yonghong Song 
Cc: Mark Wielaard 
Cc: Nick Clifton 
Link: https://lore.kernel.org/bpf/20200819092342.259004-1-jolsa@kernel.org

bpf: Add missing return to resolve_btfids

2020-08-06T23:51:11+00:00

int sets_patch(struct object *obj) doesn't have a 'return 0' at the end.

Fixes: fbbb68de80a4 ("bpf: Add resolve_btfids tool to resolve BTF IDs in ELF object")
Signed-off-by: Stanislav Fomichev 
Signed-off-by: Alexei Starovoitov 
Link: https://lore.kernel.org/bpf/20200806155225.637202-1-sdf@google.com

tools/resolve_btfids: Use libbpf's btf__parse() API

2020-08-03T14:39:48+00:00

Instead of re-implementing generic BTF parsing logic, use libbpf's API.
Also add .gitignore for resolve_btfids's build artifacts.

Signed-off-by: Andrii Nakryiko 
Signed-off-by: Daniel Borkmann 
Link: https://lore.kernel.org/bpf/20200802013219.864880-4-andriin@fb.com

bpf: Fix cross build for CONFIG_DEBUG_INFO_BTF option

2020-07-14T17:20:31+00:00

Stephen and 0-DAY CI Kernel Test Service reported broken cross build
for arm (arm-linux-gnueabi-gcc (GCC) 9.3.0), with following output:

   /tmp/ccMS5uth.s: Assembler messages:
   /tmp/ccMS5uth.s:69: Error: unrecognized symbol type ""
   /tmp/ccMS5uth.s:82: Error: unrecognized symbol type ""

Having '@object' for .type  diretive is  wrong because '@' is comment
character for some architectures. Using STT_OBJECT instead that should
work everywhere.

Also using HOST* variables to build resolve_btfids so it's properly
build in crossbuilds (stolen from objtool's Makefile).

Reported-by: kernel test robot 
Reported-by: Stephen Rothwell 
Signed-off-by: Jiri Olsa 
Signed-off-by: Alexei Starovoitov 
Tested-by: Geert Uytterhoeven 
Link: https://lore.kernel.org/bpf/20200714102534.299280-2-jolsa@kernel.org

bpf: Add resolve_btfids tool to resolve BTF IDs in ELF object

2020-07-13T17:42:02+00:00

The resolve_btfids tool scans elf object for .BTF_ids section
and resolves its symbols with BTF ID values.

It will be used to during linking time to resolve arrays of BTF
ID values used in verifier, so these IDs do not need to be
resolved in runtime.

The expected layout of .BTF_ids section is described in main.c
header. Related kernel changes are coming in following changes.

Build issue reported by 0-DAY CI Kernel Test Service.

Signed-off-by: Jiri Olsa 
Signed-off-by: Alexei Starovoitov 
Link: https://lore.kernel.org/bpf/20200711215329.41165-2-jolsa@kernel.org