linux-toradex.git/tools/lib/bpf/Makefile, branch v5.10-rc2

libbpf: Compile in PIC mode only for shared library case

2020-09-30T00:05:31+00:00

Libbpf compiles .o's for static and shared library modes separately, so no
need to specify -fPIC for both. Keep it only for shared library mode.

Signed-off-by: Andrii Nakryiko 
Signed-off-by: Alexei Starovoitov 
Acked-by: Martin KaFai Lau 
Link: https://lore.kernel.org/bpf/20200929220604.833631-3-andriin@fb.com

libbpf: Compile libbpf under -O2 level by default and catch extra warnings

2020-09-30T00:05:31+00:00

For some reason compiler doesn't complain about uninitialized variable, fixed
in previous patch, if libbpf is compiled without -O2 optimization level. So do
compile it with -O2 and never let similar issue slip by again. -Wall is added
unconditionally, so no need to specify it again.

Signed-off-by: Andrii Nakryiko 
Signed-off-by: Alexei Starovoitov 
Acked-by: Martin KaFai Lau 
Link: https://lore.kernel.org/bpf/20200929220604.833631-2-andriin@fb.com

Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net

2020-09-22T23:45:34+00:00

Two minor conflicts:

1) net/ipv4/route.c, adding a new local variable while
   moving another local variable and removing it's
   initial assignment.

2) drivers/net/dsa/microchip/ksz9477.c, overlapping changes.
   One pretty prints the port mode differently, whilst another
   changes the driver to try and obtain the port mode from
   the port node rather than the switch node.

Signed-off-by: David S. Miller

tools/libbpf: Avoid counting local symbols in ABI check

2020-09-08T22:41:31+00:00

Encountered the following failure building libbpf from kernel 5.8.5 sources
with GCC 8.4.0 and binutils 2.34: (long paths shortened)

  Warning: Num of global symbols in sharedobjs/libbpf-in.o (234) does NOT
  match with num of versioned symbols in libbpf.so (236). Please make sure
  all LIBBPF_API symbols are versioned in libbpf.map.
  --- libbpf_global_syms.tmp    2020-09-02 07:30:58.920084380 +0000
  +++ libbpf_versioned_syms.tmp 2020-09-02 07:30:58.924084388 +0000
  @@ -1,3 +1,5 @@
  +_fini
  +_init
   bpf_btf_get_fd_by_id
   bpf_btf_get_next_id
   bpf_create_map
  make[4]: *** [Makefile:210: check_abi] Error 1

Investigation shows _fini and _init are actually local symbols counted
amongst global ones:

  $ readelf --dyn-syms --wide libbpf.so|head -10

  Symbol table '.dynsym' contains 343 entries:
     Num:    Value  Size Type    Bind   Vis      Ndx Name
       0: 00000000     0 NOTYPE  LOCAL  DEFAULT  UND
       1: 00004098     0 SECTION LOCAL  DEFAULT   11
       2: 00004098     8 FUNC    LOCAL  DEFAULT   11 _init@@LIBBPF_0.0.1
       3: 00023040     8 FUNC    LOCAL  DEFAULT   14 _fini@@LIBBPF_0.0.1
       4: 00000000     0 OBJECT  GLOBAL DEFAULT  ABS LIBBPF_0.0.4
       5: 00000000     0 OBJECT  GLOBAL DEFAULT  ABS LIBBPF_0.0.1
       6: 0000ffa4     8 FUNC    GLOBAL DEFAULT   12 bpf_object__find_map_by_offset@@LIBBPF_0.0.1

A previous commit filtered global symbols in sharedobjs/libbpf-in.o. Do the
same with the libbpf.so DSO for consistent comparison.

Fixes: 306b267cb3c4 ("libbpf: Verify versioned symbols")
Signed-off-by: Tony Ambardar 
Signed-off-by: Alexei Starovoitov 
Acked-by: Andrii Nakryiko 
Link: https://lore.kernel.org/bpf/20200905214831.1565465-1-Tony.Ambardar@gmail.com

libbpf: Remove arch-specific include path in Makefile

2020-09-03T13:45:00+00:00

Ubuntu mainline builds for ppc64le are failing with the below error (*):
    CALL    /home/kernel/COD/linux/scripts/atomic/check-atomics.sh
    DESCEND  bpf/resolve_btfids

  Auto-detecting system features:
  ...                        libelf: [ [32mon[m  ]
  ...                          zlib: [ [32mon[m  ]
  ...                           bpf: [ [31mOFF[m ]

  BPF API too old
  make[6]: *** [Makefile:295: bpfdep] Error 1
  make[5]: *** [Makefile:54: /home/kernel/COD/linux/debian/build/build-generic/tools/bpf/resolve_btfids//libbpf.a] Error 2
  make[4]: *** [Makefile:71: bpf/resolve_btfids] Error 2
  make[3]: *** [/home/kernel/COD/linux/Makefile:1890: tools/bpf/resolve_btfids] Error 2
  make[2]: *** [/home/kernel/COD/linux/Makefile:335: __build_one_by_one] Error 2
  make[2]: Leaving directory '/home/kernel/COD/linux/debian/build/build-generic'
  make[1]: *** [Makefile:185: __sub-make] Error 2
  make[1]: Leaving directory '/home/kernel/COD/linux'

resolve_btfids needs to be build as a host binary and it needs libbpf.
However, libbpf Makefile hardcodes an include path utilizing $(ARCH).
This results in mixing of cross-architecture headers resulting in a
build failure.

The specific header include path doesn't seem necessary for a libbpf
build. Hence, remove the same.

(*) https://kernel.ubuntu.com/~kernel-ppa/mainline/v5.9-rc3/ppc64el/log

Reported-by: Vaidyanathan Srinivasan 
Signed-off-by: Naveen N. Rao 
Signed-off-by: Daniel Borkmann 
Acked-by: Andrii Nakryiko 
Link: https://lore.kernel.org/bpf/20200902084246.1513055-1-naveen.n.rao@linux.vnet.ibm.com

tools, bpf/build: Cleanup feature files on make clean

2020-08-28T12:04:27+00:00

The system for "Auto-detecting system features" located under
tools/build/ are (currently) used by perf, libbpf and bpftool. It can
contain stalled feature detection files, which are not cleaned up by
libbpf and bpftool on make clean (side-note: perf tool is correct).

Fix this by making the users invoke the make clean target.

Some details about the changes. The libbpf Makefile already had a
clean-config target (which seems to be copy-pasted from perf), but this
target was not "connected" (a make dependency) to clean target. Choose
not to rename target as someone might be using it. Did change the output
from "CLEAN config" to "CLEAN feature-detect", to make it more clear
what happens.

This is related to the complaint and troubleshooting in the following
link: https://lore.kernel.org/lkml/20200818122007.2d1cfe2d@carbon/

Signed-off-by: Jesper Dangaard Brouer 
Signed-off-by: Daniel Borkmann 
Acked-by: Jiri Olsa 
Link: https://lore.kernel.org/lkml/20200818122007.2d1cfe2d@carbon/
Link: https://lore.kernel.org/bpf/159851841661.1072907.13770213104521805592.stgit@firesoul

bpf: Add kernel module with user mode driver that populates bpffs.

2020-08-20T14:02:36+00:00

Add kernel module with user mode driver that populates bpffs with
BPF iterators.

$ mount bpffs /my/bpffs/ -t bpf
$ ls -la /my/bpffs/
total 4
drwxrwxrwt  2 root root    0 Jul  2 00:27 .
drwxr-xr-x 19 root root 4096 Jul  2 00:09 ..
-rw-------  1 root root    0 Jul  2 00:27 maps.debug
-rw-------  1 root root    0 Jul  2 00:27 progs.debug

The user mode driver will load BPF Type Formats, create BPF maps, populate BPF
maps, load two BPF programs, attach them to BPF iterators, and finally send two
bpf_link IDs back to the kernel.
The kernel will pin two bpf_links into newly mounted bpffs instance under
names "progs.debug" and "maps.debug". These two files become human readable.

$ cat /my/bpffs/progs.debug
  id name            attached
  11 dump_bpf_map    bpf_iter_bpf_map
  12 dump_bpf_prog   bpf_iter_bpf_prog
  27 test_pkt_access
  32 test_main       test_pkt_access test_pkt_access
  33 test_subprog1   test_pkt_access_subprog1 test_pkt_access
  34 test_subprog2   test_pkt_access_subprog2 test_pkt_access
  35 test_subprog3   test_pkt_access_subprog3 test_pkt_access
  36 new_get_skb_len get_skb_len test_pkt_access
  37 new_get_skb_ifindex get_skb_ifindex test_pkt_access
  38 new_get_constant get_constant test_pkt_access

The BPF program dump_bpf_prog() in iterators.bpf.c is printing this data about
all BPF programs currently loaded in the system. This information is unstable
and will change from kernel to kernel as ".debug" suffix conveys.

Signed-off-by: Alexei Starovoitov 
Signed-off-by: Daniel Borkmann 
Link: https://lore.kernel.org/bpf/20200819042759.51280-4-alexei.starovoitov@gmail.com

tools: Remove feature-libelf-mmap feature detection

2020-08-19T01:38:25+00:00

It's trivial to handle missing ELF_C_MMAP_READ support in libelf the way that
objtool has solved it in
("774bec3fddcc objtool: Add fallback from ELF_C_READ_MMAP to ELF_C_READ").

So instead of having an entire feature detector for that, just do what objtool
does for perf and libbpf. And keep their Makefiles a bit simpler.

Signed-off-by: Andrii Nakryiko 
Signed-off-by: Alexei Starovoitov 
Link: https://lore.kernel.org/bpf/20200819013607.3607269-5-andriin@fb.com

libbpf: Remove any use of reallocarray() in libbpf

2020-08-19T01:38:25+00:00

Re-implement glibc's reallocarray() for libbpf internal-only use.
reallocarray(), unfortunately, is not available in all versions of glibc, so
requires extra feature detection and using reallocarray() stub from
 and COMPAT_NEED_REALLOCARRAY. All this complicates build
of libbpf unnecessarily and is just a maintenance burden. Instead, it's
trivial to implement libbpf-specific internal version and use it throughout
libbpf.

Which is what this patch does, along with converting some realloc() uses that
should really have been reallocarray() in the first place.

Signed-off-by: Andrii Nakryiko 
Signed-off-by: Alexei Starovoitov 
Link: https://lore.kernel.org/bpf/20200819013607.3607269-2-andriin@fb.com

libbpf: Disable -Wswitch-enum compiler warning

2020-08-19T00:16:15+00:00

That compilation warning is more annoying, than helpful.

Signed-off-by: Andrii Nakryiko 
Signed-off-by: Alexei Starovoitov 
Link: https://lore.kernel.org/bpf/20200818213356.2629020-2-andriin@fb.com