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![]() Macro PAGE_OFFSET(0xffff880000000000) in sampleip_user.c is inaccurate, for example, in aarch64 architecture, this value depends on the CONFIG_ARM64_VA_BITS compilation configuration, this value defaults to 48, the corresponding PAGE_OFFSET is 0xffff800000000000, if we use the value defined in sampleip_user.c, then all KSYMs obtained by sampleip are (user) Symbol error due to PAGE_OFFSET error: $ sudo ./sampleip 1 Sampling at 99 Hertz for 1 seconds. Ctrl-C also ends. ADDR KSYM COUNT 0xffff80000810ceb8 (user) 1 0xffffb28ec880 (user) 1 0xffff8000080c82b8 (user) 1 0xffffb23fed24 (user) 1 0xffffb28944fc (user) 1 0xffff8000084628bc (user) 1 0xffffb2a935c0 (user) 1 0xffff80000844677c (user) 1 0xffff80000857a3a4 (user) 1 ... A few examples of addresses in the CONFIG_ARM64_VA_BITS=48 environment in the aarch64 environment: $ sudo head /proc/kallsyms ffff8000080a0000 T _text ffff8000080b0000 t gic_handle_irq ffff8000080b0000 T _stext ffff8000080b0000 T __irqentry_text_start ffff8000080b00b0 t gic_handle_irq ffff8000080b0230 t gic_handle_irq ffff8000080b03b4 T __irqentry_text_end ffff8000080b03b8 T __softirqentry_text_start ffff8000080b03c0 T __do_softirq ffff8000080b0718 T __entry_text_start We just need to replace the PAGE_OFFSET with the address _text in /proc/kallsyms to solve this problem: $ sudo ./sampleip 1 Sampling at 99 Hertz for 1 seconds. Ctrl-C also ends. ADDR KSYM COUNT 0xffffb2892ab0 (user) 1 0xffffb2b1edfc (user) 1 0xffff800008462834 __arm64_sys_ppoll 1 0xffff8000084b87f4 eventfd_read 1 0xffffb28e6788 (user) 1 0xffff8000081e96d8 rcu_all_qs 1 0xffffb2ada878 (user) 1 ... Signed-off-by: Rong Tao <rongtao@cestc.cn> Link: https://lore.kernel.org/r/tencent_A0E82E0BEE925285F8156D540731DF805F05@qq.com Signed-off-by: Alexei Starovoitov <ast@kernel.org> |
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.. | ||
gnu | ||
.gitignore | ||
asm_goto_workaround.h | ||
bpf_insn.h | ||
cookie_uid_helper_example.c | ||
cpustat_kern.c | ||
cpustat_user.c | ||
do_hbm_test.sh | ||
fds_example.c | ||
hash_func01.h | ||
hbm.c | ||
hbm.h | ||
hbm_edt_kern.c | ||
hbm_kern.h | ||
hbm_out_kern.c | ||
ibumad_kern.c | ||
ibumad_user.c | ||
lathist_kern.c | ||
lathist_user.c | ||
lwt_len_hist.bpf.c | ||
lwt_len_hist.sh | ||
lwt_len_hist_user.c | ||
Makefile | ||
Makefile.target | ||
map_perf_test.bpf.c | ||
map_perf_test_user.c | ||
net_shared.h | ||
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.bpf.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.sh | ||
tc_l2_redirect_kern.c | ||
tc_l2_redirect_user.c | ||
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_sock.c | ||
test_cgrp2_sock.sh | ||
test_cgrp2_sock2.c | ||
test_cgrp2_sock2.sh | ||
test_cgrp2_tc.bpf.c | ||
test_cgrp2_tc.sh | ||
test_cls_bpf.sh | ||
test_current_task_under_cgroup.bpf.c | ||
test_current_task_under_cgroup_user.c | ||
test_lru_dist.c | ||
test_lwt_bpf.c | ||
test_lwt_bpf.sh | ||
test_map_in_map.bpf.c | ||
test_map_in_map_user.c | ||
test_overhead_kprobe.bpf.c | ||
test_overhead_raw_tp.bpf.c | ||
test_overhead_tp.bpf.c | ||
test_overhead_user.c | ||
test_override_return.sh | ||
test_probe_write_user.bpf.c | ||
test_probe_write_user_user.c | ||
trace_event_kern.c | ||
trace_event_user.c | ||
trace_output.bpf.c | ||
trace_output_user.c | ||
tracex1_kern.c | ||
tracex1_user.c | ||
tracex2.bpf.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.sh | ||
xdp2skb_meta_kern.c | ||
xdp_adjust_tail_kern.c | ||
xdp_adjust_tail_user.c | ||
xdp_fwd_kern.c | ||
xdp_fwd_user.c | ||
xdp_monitor.bpf.c | ||
xdp_monitor_user.c | ||
xdp_redirect.bpf.c | ||
xdp_redirect_cpu.bpf.c | ||
xdp_redirect_cpu_user.c | ||
xdp_redirect_map.bpf.c | ||
xdp_redirect_map_multi.bpf.c | ||
xdp_redirect_map_multi_user.c | ||
xdp_redirect_map_user.c | ||
xdp_redirect_user.c | ||
xdp_router_ipv4.bpf.c | ||
xdp_router_ipv4_user.c | ||
xdp_rxq_info_kern.c | ||
xdp_rxq_info_user.c | ||
xdp_sample.bpf.c | ||
xdp_sample.bpf.h | ||
xdp_sample_pkts_kern.c | ||
xdp_sample_pkts_user.c | ||
xdp_sample_shared.h | ||
xdp_sample_user.c | ||
xdp_sample_user.h | ||
xdp_tx_iptunnel_common.h | ||
xdp_tx_iptunnel_kern.c | ||
xdp_tx_iptunnel_user.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 create a local "usr/include" directory in the git/build top level directory, that the make system will automatically pick up 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" We recommend that developers who want the fastest incremental builds use the Ninja build system, you can find it in your system's package manager, usually the package is ninja or ninja-build. Quick sniplet for manually compiling LLVM and clang (build dependencies are ninja, cmake and gcc-c++):: $ git clone https://github.com/llvm/llvm-project.git $ mkdir -p llvm-project/llvm/build $ cd llvm-project/llvm/build $ cmake .. -G "Ninja" -DLLVM_TARGETS_TO_BUILD="BPF;X86" \ -DLLVM_ENABLE_PROJECTS="clang" \ -DCMAKE_BUILD_TYPE=Release \ -DLLVM_BUILD_RUNTIME=OFF $ ninja 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-project/llvm/build/bin/llc CLANG=~/git/llvm-project/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, configuration 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