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Arnaldo Carvalho de Melo
811b4f0d78
Only one of the examples declare the bpf_insn bpf proggie as a const:
$ grep 'struct bpf_insn [a-z]' samples/bpf/*.c
samples/bpf/fds_example.c: static const struct bpf_insn insns[] = {
samples/bpf/sock_example.c: struct bpf_insn prog[] = {
samples/bpf/test_cgrp2_attach2.c: struct bpf_insn prog[] = {
samples/bpf/test_cgrp2_attach.c: struct bpf_insn prog[] = {
samples/bpf/test_cgrp2_sock.c: struct bpf_insn prog[] = {
$
Which causes this warning:
[root@f5065a7d6272 linux]# make -j4 O=/tmp/build/linux samples/bpf/
<SNIP>
HOSTCC samples/bpf/fds_example.o
/git/linux/samples/bpf/fds_example.c: In function 'bpf_prog_create':
/git/linux/samples/bpf/fds_example.c:63:6: warning: passing argument 2 of 'bpf_load_program' discards 'const' qualifier from pointer target type [-Wdiscarded-qualifiers]
insns, insns_cnt, "GPL", 0,
^~~~~
In file included from /git/linux/samples/bpf/libbpf.h:5:0,
from /git/linux/samples/bpf/bpf_load.h:4,
from /git/linux/samples/bpf/fds_example.c:15:
/git/linux/tools/lib/bpf/bpf.h:31:5: note: expected 'struct bpf_insn *' but argument is of type 'const struct bpf_insn *'
int bpf_load_program(enum bpf_prog_type type, struct bpf_insn *insns,
^~~~~~~~~~~~~~~~
HOSTCC samples/bpf/sockex1_user.o
So just ditch that 'const' to reduce build noise, leaving changing the
bpf_load_program() bpf_insn parameter to const to a later patch, if deemed
adequate.
Cc: Joe Stringer <joe@ovn.org>
Cc: Alexei Starovoitov <ast@fb.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-1z5xee8n3oa66jf62bpv16ed@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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`` 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 samples/bpf/ Do notice the "/" slash after the directory name. It is also possible to call make from this directory. This will just hide the the invocation of make as above with the appended "/". 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 samples/bpf/ LLC=~/git/llvm/build/bin/llc CLANG=~/git/llvm/build/bin/clang