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3652c9a1b1
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:
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.. | ||
.gitignore | ||
asm_goto_workaround.h | ||
bpf_insn.h | ||
bpf_load.c | ||
bpf_load.h | ||
cookie_uid_helper_example.c | ||
cpustat_kern.c | ||
cpustat_user.c | ||
do_hbm_test.sh | ||
fds_example.c | ||
hash_func01.h | ||
hbm_edt_kern.c | ||
hbm_kern.h | ||
hbm_out_kern.c | ||
hbm.c | ||
hbm.h | ||
ibumad_kern.c | ||
ibumad_user.c | ||
lathist_kern.c | ||
lathist_user.c | ||
lwt_len_hist_kern.c | ||
lwt_len_hist_user.c | ||
lwt_len_hist.sh | ||
Makefile | ||
Makefile.target | ||
map_perf_test_kern.c | ||
map_perf_test_user.c | ||
offwaketime_kern.c | ||
offwaketime_user.c | ||
parse_ldabs.c | ||
parse_simple.c | ||
parse_varlen.c | ||
README.rst | ||
run_cookie_uid_helper_example.sh | ||
sampleip_kern.c | ||
sampleip_user.c | ||
sock_example.c | ||
sock_example.h | ||
sock_flags_kern.c | ||
sockex1_kern.c | ||
sockex1_user.c | ||
sockex2_kern.c | ||
sockex2_user.c | ||
sockex3_kern.c | ||
sockex3_user.c | ||
spintest_kern.c | ||
spintest_user.c | ||
syscall_nrs.c | ||
syscall_tp_kern.c | ||
syscall_tp_user.c | ||
task_fd_query_kern.c | ||
task_fd_query_user.c | ||
tc_l2_redirect_kern.c | ||
tc_l2_redirect_user.c | ||
tc_l2_redirect.sh | ||
tcbpf1_kern.c | ||
tcp_basertt_kern.c | ||
tcp_bpf.readme | ||
tcp_bufs_kern.c | ||
tcp_clamp_kern.c | ||
tcp_cong_kern.c | ||
tcp_dumpstats_kern.c | ||
tcp_iw_kern.c | ||
tcp_rwnd_kern.c | ||
tcp_synrto_kern.c | ||
tcp_tos_reflect_kern.c | ||
test_cgrp2_array_pin.c | ||
test_cgrp2_attach.c | ||
test_cgrp2_sock2.c | ||
test_cgrp2_sock2.sh | ||
test_cgrp2_sock.c | ||
test_cgrp2_sock.sh | ||
test_cgrp2_tc_kern.c | ||
test_cgrp2_tc.sh | ||
test_cls_bpf.sh | ||
test_current_task_under_cgroup_kern.c | ||
test_current_task_under_cgroup_user.c | ||
test_ipip.sh | ||
test_lru_dist.c | ||
test_lwt_bpf.c | ||
test_lwt_bpf.sh | ||
test_map_in_map_kern.c | ||
test_map_in_map_user.c | ||
test_overhead_kprobe_kern.c | ||
test_overhead_raw_tp_kern.c | ||
test_overhead_tp_kern.c | ||
test_overhead_user.c | ||
test_override_return.sh | ||
test_probe_write_user_kern.c | ||
test_probe_write_user_user.c | ||
trace_common.h | ||
trace_event_kern.c | ||
trace_event_user.c | ||
trace_output_kern.c | ||
trace_output_user.c | ||
tracex1_kern.c | ||
tracex1_user.c | ||
tracex2_kern.c | ||
tracex2_user.c | ||
tracex3_kern.c | ||
tracex3_user.c | ||
tracex4_kern.c | ||
tracex4_user.c | ||
tracex5_kern.c | ||
tracex5_user.c | ||
tracex6_kern.c | ||
tracex6_user.c | ||
tracex7_kern.c | ||
tracex7_user.c | ||
xdp1_kern.c | ||
xdp1_user.c | ||
xdp2_kern.c | ||
xdp2skb_meta_kern.c | ||
xdp2skb_meta.sh | ||
xdp_adjust_tail_kern.c | ||
xdp_adjust_tail_user.c | ||
xdp_fwd_kern.c | ||
xdp_fwd_user.c | ||
xdp_monitor_kern.c | ||
xdp_monitor_user.c | ||
xdp_redirect_cpu_kern.c | ||
xdp_redirect_cpu_user.c | ||
xdp_redirect_kern.c | ||
xdp_redirect_map_kern.c | ||
xdp_redirect_map_user.c | ||
xdp_redirect_user.c | ||
xdp_router_ipv4_kern.c | ||
xdp_router_ipv4_user.c | ||
xdp_rxq_info_kern.c | ||
xdp_rxq_info_user.c | ||
xdp_sample_pkts_kern.c | ||
xdp_sample_pkts_user.c | ||
xdp_tx_iptunnel_common.h | ||
xdp_tx_iptunnel_kern.c | ||
xdp_tx_iptunnel_user.c | ||
xdpsock_kern.c | ||
xdpsock_user.c | ||
xdpsock.h | ||
xsk_fwd.c |
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