linux/samples/bpf
Daniel Borkmann 3652c9a1b1 bpf, libbpf: Guard bpf inline asm from bpf_tail_call_static
Yaniv reported a compilation error after pulling latest libbpf:

  [...]
  ../libbpf/src/root/usr/include/bpf/bpf_helpers.h:99:10: error:
  unknown register name 'r0' in asm
                     : "r0", "r1", "r2", "r3", "r4", "r5");
  [...]

The issue got triggered given Yaniv was compiling tracing programs with native
target (e.g. x86) instead of BPF target, hence no BTF generated vmlinux.h nor
CO-RE used, and later llc with -march=bpf was invoked to compile from LLVM IR
to BPF object file. Given that clang was expecting x86 inline asm and not BPF
one the error complained that these regs don't exist on the former.

Guard bpf_tail_call_static() with defined(__bpf__) where BPF inline asm is valid
to use. BPF tracing programs on more modern kernels use BPF target anyway and
thus the bpf_tail_call_static() function will be available for them. BPF inline
asm is supported since clang 7 (clang <= 6 otherwise throws same above error),
and __bpf_unreachable() since clang 8, therefore include the latter condition
in order to prevent compilation errors for older clang versions. Given even an
old Ubuntu 18.04 LTS has official LLVM packages all the way up to llvm-10, I did
not bother to special case the __bpf_unreachable() inside bpf_tail_call_static()
further.

Also, undo the sockex3_kern's use of bpf_tail_call_static() sample given they
still have the old hacky way to even compile networking progs with native instead
of BPF target so bpf_tail_call_static() won't be defined there anymore.

Fixes: 0e9f6841f6 ("bpf, libbpf: Add bpf_tail_call_static helper for bpf programs")
Reported-by: Yaniv Agman <yanivagman@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Tested-by: Yaniv Agman <yanivagman@gmail.com>
Link: https://lore.kernel.org/bpf/CAMy7=ZUk08w5Gc2Z-EKi4JFtuUCaZYmE4yzhJjrExXpYKR4L8w@mail.gmail.com
Link: https://lore.kernel.org/bpf/20201021203257.26223-1-daniel@iogearbox.net
2020-10-22 01:46:52 +02:00
..
.gitignore samples, bpf: Add xsk_fwd test file to .gitignore 2020-09-04 16:37:53 +02:00
Makefile samples: bpf: Replace attach_tracepoint() to attach() in xdp_redirect_cpu 2020-10-11 12:14:36 -07:00
Makefile.target samples/bpf: Add makefile.target for separate CC target build 2019-10-12 16:08:59 -07:00
README.rst samples/bpf: adjust Makefile and README.rst 2019-11-11 21:42:09 -08:00
asm_goto_workaround.h samples/bpf: Add a workaround for asm_inline 2019-10-03 17:37:11 +02:00
bpf_insn.h selftests: bpf: functional and min/max reasoning unit tests for JMP32 2019-01-26 13:33:02 -08:00
bpf_load.c samples, bpf: Move read_trace_pipe to trace_helpers 2020-03-23 22:27:51 +01:00
bpf_load.h samples, bpf: Move read_trace_pipe to trace_helpers 2020-03-23 22:27:51 +01:00
cookie_uid_helper_example.c samples: bpf: rename libbpf.h to bpf_insn.h 2018-05-14 22:52:10 -07:00
cpustat_kern.c samples: bpf: Refactor tracepoint tracing programs with libbpf 2020-08-24 20:59:35 -07:00
cpustat_user.c samples: bpf: Refactor tracepoint tracing programs with libbpf 2020-08-24 20:59:35 -07:00
do_hbm_test.sh bpf: Add support for fq's EDT to HBM 2019-07-03 15:03:00 +02:00
fds_example.c bpf: Fix fds_example SIGSEGV error 2020-07-10 23:25:25 +02:00
hash_func01.h samples/bpf: add Paul Hsieh's (LGPL 2.1) hash function SuperFastHash 2018-08-10 16:07:49 +02:00
hbm.c samples/bpf: Fix a compilation error with fallthrough marking 2020-10-06 11:45:03 -07:00
hbm.h bpf: Add more stats to HBM 2019-05-31 16:41:29 -07:00
hbm_edt_kern.c bpf: Add support for fq's EDT to HBM 2019-07-03 15:03:00 +02:00
hbm_kern.h samples/bpf: Use consistent include paths for libbpf 2020-01-20 16:37:45 -08:00
hbm_out_kern.c bpf: Add more stats to HBM 2019-05-31 16:41:29 -07:00
ibumad_kern.c samples/bpf: Use consistent include paths for libbpf 2020-01-20 16:37:45 -08:00
ibumad_user.c samples/bpf: Use consistent include paths for libbpf 2020-01-20 16:37:45 -08:00
lathist_kern.c samples: bpf: Refactor kprobe tracing programs with libbpf 2020-08-24 20:59:35 -07:00
lathist_user.c samples: bpf: Refactor kprobe tracing programs with libbpf 2020-08-24 20:59:35 -07:00
lwt_len_hist.sh License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
lwt_len_hist_kern.c samples/bpf: Use consistent include paths for libbpf 2020-01-20 16:37:45 -08:00
lwt_len_hist_user.c samples: bpf: Fix build error 2020-05-14 12:37:39 -07:00
map_perf_test_kern.c samples: bpf: Refactor BPF map performance test with libbpf 2020-07-08 01:33:14 +02:00
map_perf_test_user.c samples: bpf: Refactor BPF map performance test with libbpf 2020-07-08 01:33:14 +02:00
offwaketime_kern.c samples: bpf: Refactor tracepoint tracing programs with libbpf 2020-08-24 20:59:35 -07:00
offwaketime_user.c samples: bpf: Refactor tracepoint tracing programs with libbpf 2020-08-24 20:59:35 -07:00
parse_ldabs.c samples/bpf: Use consistent include paths for libbpf 2020-01-20 16:37:45 -08:00
parse_simple.c samples/bpf: Use consistent include paths for libbpf 2020-01-20 16:37:45 -08:00
parse_varlen.c samples/bpf: Use consistent include paths for libbpf 2020-01-20 16:37:45 -08:00
run_cookie_uid_helper_example.sh License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
sampleip_kern.c samples, bpf: Refactor kprobe, tail call kern progs map definition 2020-05-19 17:13:03 +02:00
sampleip_user.c samples, bpf: Refactor pointer error check with libbpf 2020-05-19 17:12:49 +02:00
sock_example.c samples: bpf: force IPv4 in ping 2019-03-01 00:53:45 +01:00
sock_example.h samples: bpf: include bpf/bpf.h instead of local libbpf.h 2018-05-14 22:52:10 -07:00
sock_flags_kern.c samples/bpf: Use consistent include paths for libbpf 2020-01-20 16:37:45 -08:00
sockex1_kern.c samples/bpf: Use consistent include paths for libbpf 2020-01-20 16:37:45 -08:00
sockex1_user.c samples/bpf: Use consistent include paths for libbpf 2020-01-20 16:37:45 -08:00
sockex2_kern.c samples/bpf: Remove compiler warnings 2020-05-13 12:30:50 -07:00
sockex2_user.c samples/bpf: Use consistent include paths for libbpf 2020-01-20 16:37:45 -08:00
sockex3_kern.c bpf, libbpf: Guard bpf inline asm from bpf_tail_call_static 2020-10-22 01:46:52 +02:00
sockex3_user.c samples, bpf: Replace bpf_program__title() with bpf_program__section_name() 2020-09-04 16:37:48 +02:00
spintest_kern.c samples: bpf: Refactor kprobe tracing programs with libbpf 2020-08-24 20:59:35 -07:00
spintest_user.c samples, bpf: Replace bpf_program__title() with bpf_program__section_name() 2020-09-04 16:37:48 +02:00
syscall_nrs.c samples: bpf: syscall_nrs: use mmap2 if defined 2019-08-21 14:31:38 +02:00
syscall_tp_kern.c samples: bpf: Refactor tracepoint tracing programs with libbpf 2020-08-24 20:59:35 -07:00
syscall_tp_user.c samples: bpf: Refactor tracepoint tracing programs with libbpf 2020-08-24 20:59:35 -07:00
task_fd_query_kern.c samples: bpf: Fix broken bpf programs due to removed symbol 2020-08-18 17:10:03 -07:00
task_fd_query_user.c samples: bpf: Fix broken bpf programs due to removed symbol 2020-08-18 17:10:03 -07:00
tc_l2_redirect.sh License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
tc_l2_redirect_kern.c samples/bpf: Use consistent include paths for libbpf 2020-01-20 16:37:45 -08:00
tc_l2_redirect_user.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 206 2019-05-30 11:29:53 -07:00
tcbpf1_kern.c samples/bpf: Use consistent include paths for libbpf 2020-01-20 16:37:45 -08:00
tcp_basertt_kern.c samples/bpf: Use consistent include paths for libbpf 2020-01-20 16:37:45 -08:00
tcp_bpf.readme samples/bpf: fix tcp_bpf.readme detach command 2019-07-03 16:52:02 +02:00
tcp_bufs_kern.c samples/bpf: Use consistent include paths for libbpf 2020-01-20 16:37:45 -08:00
tcp_clamp_kern.c samples/bpf: Use consistent include paths for libbpf 2020-01-20 16:37:45 -08:00
tcp_cong_kern.c samples/bpf: Use consistent include paths for libbpf 2020-01-20 16:37:45 -08:00
tcp_dumpstats_kern.c samples/bpf: Use consistent include paths for libbpf 2020-01-20 16:37:45 -08:00
tcp_iw_kern.c samples/bpf: Use consistent include paths for libbpf 2020-01-20 16:37:45 -08:00
tcp_rwnd_kern.c samples/bpf: Use consistent include paths for libbpf 2020-01-20 16:37:45 -08:00
tcp_synrto_kern.c samples/bpf: Use consistent include paths for libbpf 2020-01-20 16:37:45 -08:00
tcp_tos_reflect_kern.c samples/bpf: Use consistent include paths for libbpf 2020-01-20 16:37:45 -08:00
test_cgrp2_array_pin.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 206 2019-05-30 11:29:53 -07:00
test_cgrp2_attach.c samples: bpf: rename libbpf.h to bpf_insn.h 2018-05-14 22:52:10 -07:00
test_cgrp2_sock.c samples: bpf: rename libbpf.h to bpf_insn.h 2018-05-14 22:52:10 -07:00
test_cgrp2_sock.sh samples/bpf: detach prog from cgroup 2018-03-02 00:16:36 +01:00
test_cgrp2_sock2.c samples/bpf: test_cgrp2_sock2: fix an off by one 2018-07-16 15:01:09 -07:00
test_cgrp2_sock2.sh samples/bpf: detach prog from cgroup 2018-03-02 00:16:36 +01:00
test_cgrp2_tc.sh License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
test_cgrp2_tc_kern.c samples/bpf: Use consistent include paths for libbpf 2020-01-20 16:37:45 -08:00
test_cls_bpf.sh License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
test_current_task_under_cgroup_kern.c samples: bpf: Refactor kprobe tracing programs with libbpf 2020-08-24 20:59:35 -07:00
test_current_task_under_cgroup_user.c samples: bpf: Refactor kprobe tracing programs with libbpf 2020-08-24 20:59:35 -07:00
test_ipip.sh License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
test_lru_dist.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 206 2019-05-30 11:29:53 -07:00
test_lwt_bpf.c samples/bpf: Use consistent include paths for libbpf 2020-01-20 16:37:45 -08:00
test_lwt_bpf.sh License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
test_map_in_map_kern.c samples/bpf: Fix test_map_in_map on s390 2020-09-19 01:02:55 +02:00
test_map_in_map_user.c samples: bpf: Refactor BPF map in map test with libbpf 2020-07-08 01:33:10 +02:00
test_overhead_kprobe_kern.c samples/bpf, selftests/bpf: Use bpf_probe_read_kernel 2020-07-21 13:26:26 -07:00
test_overhead_raw_tp_kern.c samples/bpf: Use consistent include paths for libbpf 2020-01-20 16:37:45 -08:00
test_overhead_tp_kern.c samples/bpf: Use consistent include paths for libbpf 2020-01-20 16:37:45 -08:00
test_overhead_user.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 206 2019-05-30 11:29:53 -07:00
test_override_return.sh samples/bpf: add a test for bpf_override_return 2017-12-12 09:02:40 -08:00
test_probe_write_user_kern.c samples: bpf: Refactor kprobe tracing programs with libbpf 2020-08-24 20:59:35 -07:00
test_probe_write_user_user.c samples: bpf: Refactor kprobe tracing programs with libbpf 2020-08-24 20:59:35 -07:00
trace_common.h samples, bpf: Refactor kprobe tracing user progs with libbpf 2020-05-19 17:12:53 +02:00
trace_event_kern.c samples, bpf: Refactor kprobe, tail call kern progs map definition 2020-05-19 17:13:03 +02:00
trace_event_user.c samples, bpf: Refactor pointer error check with libbpf 2020-05-19 17:12:49 +02:00
trace_output_kern.c samples: bpf: Refactor kprobe tracing programs with libbpf 2020-08-24 20:59:35 -07:00
trace_output_user.c samples: bpf: Refactor kprobe tracing programs with libbpf 2020-08-24 20:59:35 -07:00
tracex1_kern.c samples/bpf, selftests/bpf: Use bpf_probe_read_kernel 2020-07-21 13:26:26 -07:00
tracex1_user.c samples, bpf: Refactor kprobe tracing user progs with libbpf 2020-05-19 17:12:53 +02:00
tracex2_kern.c samples, bpf: Refactor kprobe, tail call kern progs map definition 2020-05-19 17:13:03 +02:00
tracex2_user.c samples, bpf: Refactor kprobe tracing user progs with libbpf 2020-05-19 17:12:53 +02:00
tracex3_kern.c samples: bpf: Fix broken bpf programs due to removed symbol 2020-08-18 17:10:03 -07:00
tracex3_user.c samples, bpf: Refactor kprobe tracing user progs with libbpf 2020-05-19 17:12:53 +02:00
tracex4_kern.c samples, bpf: Refactor kprobe, tail call kern progs map definition 2020-05-19 17:13:03 +02:00
tracex4_user.c samples, bpf: Refactor kprobe tracing user progs with libbpf 2020-05-19 17:12:53 +02:00
tracex5_kern.c samples/bpf, selftests/bpf: Use bpf_probe_read_kernel 2020-07-21 13:26:26 -07:00
tracex5_user.c samples, bpf: Replace bpf_program__title() with bpf_program__section_name() 2020-09-04 16:37:48 +02:00
tracex6_kern.c samples, bpf: Refactor kprobe, tail call kern progs map definition 2020-05-19 17:13:03 +02:00
tracex6_user.c samples, bpf: Refactor kprobe tracing user progs with libbpf 2020-05-19 17:12:53 +02:00
tracex7_kern.c samples/bpf: Use consistent include paths for libbpf 2020-01-20 16:37:45 -08:00
tracex7_user.c samples, bpf: Refactor kprobe tracing user progs with libbpf 2020-05-19 17:12:53 +02:00
xdp1_kern.c samples/bpf: Use consistent include paths for libbpf 2020-01-20 16:37:45 -08:00
xdp1_user.c samples/bpf: Use consistent include paths for libbpf 2020-01-20 16:37:45 -08:00
xdp2_kern.c samples/bpf: Use consistent include paths for libbpf 2020-01-20 16:37:45 -08:00
xdp2skb_meta.sh samples/bpf: Fix tc and ip paths in xdp2skb_meta.sh 2018-07-10 09:19:01 +02:00
xdp2skb_meta_kern.c samples/bpf: Use consistent include paths for libbpf 2020-01-20 16:37:45 -08:00
xdp_adjust_tail_kern.c samples/bpf: Use consistent include paths for libbpf 2020-01-20 16:37:45 -08:00
xdp_adjust_tail_user.c samples/bpf: Use consistent include paths for libbpf 2020-01-20 16:37:45 -08:00
xdp_fwd_kern.c samples/bpf: Use consistent include paths for libbpf 2020-01-20 16:37:45 -08:00
xdp_fwd_user.c samples/bpf: Use consistent include paths for libbpf 2020-01-20 16:37:45 -08:00
xdp_monitor_kern.c samples: bpf: Refactor XDP kern program maps with BTF-defined map 2020-10-11 12:14:36 -07:00
xdp_monitor_user.c samples: bpf: Refactor xdp_monitor with libbpf 2020-10-11 12:14:36 -07:00
xdp_redirect_cpu_kern.c samples/bpf: xdp_redirect_cpu: Load a eBPF program on cpumap 2020-07-16 17:00:32 +02:00
xdp_redirect_cpu_user.c samples: bpf: Replace attach_tracepoint() to attach() in xdp_redirect_cpu 2020-10-11 12:14:36 -07:00
xdp_redirect_kern.c samples/bpf: Use consistent include paths for libbpf 2020-01-20 16:37:45 -08:00
xdp_redirect_map_kern.c samples/bpf: Use consistent include paths for libbpf 2020-01-20 16:37:45 -08:00
xdp_redirect_map_user.c samples/bpf: Use consistent include paths for libbpf 2020-01-20 16:37:45 -08:00
xdp_redirect_user.c samples/bpf: Use consistent include paths for libbpf 2020-01-20 16:37:45 -08:00
xdp_router_ipv4_kern.c samples/bpf: Use consistent include paths for libbpf 2020-01-20 16:37:45 -08:00
xdp_router_ipv4_user.c samples/bpf: Use consistent include paths for libbpf 2020-01-20 16:37:45 -08:00
xdp_rxq_info_kern.c samples/bpf: Use consistent include paths for libbpf 2020-01-20 16:37:45 -08:00
xdp_rxq_info_user.c bpf, xdp, samples: Fix null pointer dereference in *_user code 2020-06-16 14:55:35 +02:00
xdp_sample_pkts_kern.c samples: bpf: Refactor XDP kern program maps with BTF-defined map 2020-10-11 12:14:36 -07:00
xdp_sample_pkts_user.c samples: bpf: Refactor XDP kern program maps with BTF-defined map 2020-10-11 12:14:36 -07:00
xdp_tx_iptunnel_common.h treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 206 2019-05-30 11:29:53 -07:00
xdp_tx_iptunnel_kern.c samples/bpf: Use consistent include paths for libbpf 2020-01-20 16:37:45 -08:00
xdp_tx_iptunnel_user.c samples/bpf: Use consistent include paths for libbpf 2020-01-20 16:37:45 -08:00
xdpsock.h samples/bpf: Add XDP_SHARED_UMEM support to xdpsock 2019-11-10 19:30:45 -08:00
xdpsock_kern.c samples/bpf: Use consistent include paths for libbpf 2020-01-20 16:37:45 -08:00
xdpsock_user.c samples: bpf: Driver interrupt statistics in xdpsock 2020-10-06 11:46:50 -07:00
xsk_fwd.c samples/bpf: Add new sample xsk_fwd.c 2020-08-31 21:17:55 +02:00

README.rst

eBPF sample programs
====================

This directory contains a test stubs, verifier test-suite and examples
for using eBPF. The examples use libbpf from tools/lib/bpf.

Build dependencies
==================

Compiling requires having installed:
 * clang >= version 3.4.0
 * llvm >= version 3.7.1

Note that LLVM's tool 'llc' must support target 'bpf', list version
and supported targets with command: ``llc --version``

Clean and configuration
-----------------------

It can be needed to clean tools, samples or kernel before trying new arch or
after some changes (on demand)::

 make -C tools clean
 make -C samples/bpf clean
 make clean

Configure kernel, defconfig for instance::

 make defconfig

Kernel headers
--------------

There are usually dependencies to header files of the current kernel.
To avoid installing devel kernel headers system wide, as a normal
user, simply call::

 make headers_install

This will creates a local "usr/include" directory in the git/build top
level directory, that the make system automatically pickup first.

Compiling
=========

For building the BPF samples, issue the below command from the kernel
top level directory::

 make M=samples/bpf

It is also possible to call make from this directory.  This will just
hide the invocation of make as above.

Manually compiling LLVM with 'bpf' support
------------------------------------------

Since version 3.7.0, LLVM adds a proper LLVM backend target for the
BPF bytecode architecture.

By default llvm will build all non-experimental backends including bpf.
To generate a smaller llc binary one can use::

 -DLLVM_TARGETS_TO_BUILD="BPF"

Quick sniplet for manually compiling LLVM and clang
(build dependencies are cmake and gcc-c++)::

 $ git clone http://llvm.org/git/llvm.git
 $ cd llvm/tools
 $ git clone --depth 1 http://llvm.org/git/clang.git
 $ cd ..; mkdir build; cd build
 $ cmake .. -DLLVM_TARGETS_TO_BUILD="BPF;X86"
 $ make -j $(getconf _NPROCESSORS_ONLN)

It is also possible to point make to the newly compiled 'llc' or
'clang' command via redefining LLC or CLANG on the make command line::

 make M=samples/bpf LLC=~/git/llvm/build/bin/llc CLANG=~/git/llvm/build/bin/clang

Cross compiling samples
-----------------------
In order to cross-compile, say for arm64 targets, export CROSS_COMPILE and ARCH
environment variables before calling make. But do this before clean,
cofiguration and header install steps described above. This will direct make to
build samples for the cross target::

 export ARCH=arm64
 export CROSS_COMPILE="aarch64-linux-gnu-"

Headers can be also installed on RFS of target board if need to keep them in
sync (not necessarily and it creates a local "usr/include" directory also)::

 make INSTALL_HDR_PATH=~/some_sysroot/usr headers_install

Pointing LLC and CLANG is not necessarily if it's installed on HOST and have
in its targets appropriate arm64 arch (usually it has several arches).
Build samples::

 make M=samples/bpf

Or build samples with SYSROOT if some header or library is absent in toolchain,
say libelf, providing address to file system containing headers and libs,
can be RFS of target board::

 make M=samples/bpf SYSROOT=~/some_sysroot