samples/bpf: Add note to README about the XDP utilities moved to xdp-tools

To help users find the XDP utilities, add a note to the README about the
new location and the conversion documentation in the commit messages.

Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/r/20230824102255.1561885-8-toke@redhat.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

samples/bpf: README: Update build dependencies required

Update samples/bpf/README.rst to add pahole to the build dependencies
list. Add the reference to "Documentation/process/changes.rst" for
minimum version required so that the version required will not be
outdated in the future.

Signed-off-by: Anh Tuan Phan <tuananhlfc@gmail.com>
Link: https://lore.kernel.org/r/aecaf7a2-9100-cd5b-5cf4-91e5dbb2c90d@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

samples/bpf: Fix typo in README

Fix 'cofiguration' typo in BPF samples README.

Signed-off-by: Kang Minchul <tegongkang@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20221030180254.34138-1-tegongkang@gmail.com

samples/bpf: Fix typos in README

This change fixes some typos found in the BPF samples README file.

Signed-off-by: Daniel Müller <deso@posteo.net>
Acked-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/r/20221018163231.1926462-1-deso@posteo.net
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>

bpf, docs: Update build procedure for manually compiling LLVM and Clang

The current LLVM and Clang build procedure in samples/bpf/README.rst is
out of date. See below that the links are not accessible any more.

$ git clone http://llvm.org/git/llvm.git
Cloning into 'llvm'...
fatal: unable to access 'http://llvm.org/git/llvm.git/': Maximum (20) redirects followed
$ git clone --depth 1 http://llvm.org/git/clang.git
Cloning into 'clang'...
fatal: unable to access 'http://llvm.org/git/clang.git/': Maximum (20) redirects followed

The LLVM community has adopted new ways to build the compiler. There are
different ways to build LLVM and Clang, the Clang Getting Started page [1]
has one way. As Yonghong said, it is better to copy the build procedure
in Documentation/bpf/bpf_devel_QA.rst to keep consistent.

I verified the procedure and it is proved to be feasible, so we should
update README.rst to reflect the reality. At the same time, update the
related comment in Makefile.

Additionally, as Fangrui said, the dir llvm-project/llvm/build/install is
not used, BUILD_SHARED_LIBS=OFF is the default option [2], so also change
Documentation/bpf/bpf_devel_QA.rst together.

At last, we recommend that developers who want the fastest incremental
builds use the Ninja build system [1], you can find it in your system's
package manager, usually the package is ninja or ninja-build [3], so add
ninja to build dependencies suggested by Nathan.

[1] https://clang.llvm.org/get_started.html
[2] https://www.llvm.org/docs/CMake.html
[3] https://github.com/ninja-build/ninja/wiki/Pre-built-Ninja-packages

Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Acked-by: Yonghong Song <yhs@fb.com>
Cc: Fangrui Song <maskray@google.com>
Link: https://lore.kernel.org/bpf/1611279584-26047-1-git-send-email-yangtiezhu@loongson.cn

samples/bpf: adjust Makefile and README.rst

Side effect of some kbuild changes resulted in breaking the
documented way to build samples/bpf/.

This patch change the samples/bpf/Makefile to work again, when
invoking make from the subdir samples/bpf/. Also update the
documentation in README.rst, to reflect the new way to build.

Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

samples/bpf: Add preparation steps and sysroot info to readme

Add couple preparation steps: clean and configuration. Also add newly
added sysroot support info to cross-compile section.

Signed-off-by: Ivan Khoronzhuk <ivan.khoronzhuk@linaro.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20191011002808.28206-16-ivan.khoronzhuk@linaro.org

samples/bpf: Add documentation on cross compilation

Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Joel Fernandes <joelaf@google.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

samples/bpf: Switch over to libbpf

Now that libbpf under tools/lib/bpf/* is synced with the version from
samples/bpf, we can get rid most of the libbpf library here.

Committer notes:

Built it in a docker fedora rawhide container and ran it in the f25 host, seems
to work just like it did before this patch, i.e. the switch to tools/lib/bpf/
doesn't seem to have introduced problems and Joe said he tested it with
all the entries in samples/bpf/ and other code he found:

[root@f5065a7d6272 linux]# make -j4 O=/tmp/build/linux headers_install
<SNIP>
[root@f5065a7d6272 linux]# rm -rf /tmp/build/linux/samples/bpf/
[root@f5065a7d6272 linux]# make -j4 O=/tmp/build/linux samples/bpf/
make[1]: Entering directory '/tmp/build/linux'
CHK include/config/kernel.release
HOSTCC scripts/basic/fixdep
GEN ./Makefile
CHK include/generated/uapi/linux/version.h
Using /git/linux as source for kernel
CHK include/generated/utsrelease.h
HOSTCC scripts/basic/bin2c
HOSTCC arch/x86/tools/relocs_32.o
HOSTCC arch/x86/tools/relocs_64.o
LD samples/bpf/built-in.o
<SNIP>
HOSTCC samples/bpf/fds_example.o
HOSTCC samples/bpf/sockex1_user.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/sockex2_user.o
<SNIP>
HOSTCC samples/bpf/xdp_tx_iptunnel_user.o
clang -nostdinc -isystem /usr/lib/gcc/x86_64-redhat-linux/6.2.1/include -I/git/linux/arch/x86/include -I./arch/x86/include/generated/uapi -I./arch/x86/include/generated -I/git/linux/include -I./include -I/git/linux/arch/x86/include/uapi -I/git/linux/include/uapi -I./include/generated/uapi -include /git/linux/include/linux/kconfig.h \
-D__KERNEL__ -D__ASM_SYSREG_H -Wno-unused-value -Wno-pointer-sign \
-Wno-compare-distinct-pointer-types \
-Wno-gnu-variable-sized-type-not-at-end \
-Wno-address-of-packed-member -Wno-tautological-compare \
-O2 -emit-llvm -c /git/linux/samples/bpf/sockex1_kern.c -o -| llc -march=bpf -filetype=obj -o samples/bpf/sockex1_kern.o
HOSTLD samples/bpf/tc_l2_redirect
<SNIP>
HOSTLD samples/bpf/lwt_len_hist
HOSTLD samples/bpf/xdp_tx_iptunnel
make[1]: Leaving directory '/tmp/build/linux'
[root@f5065a7d6272 linux]#

And then, in the host:

[root@jouet bpf]# mount | grep "docker.*devicemapper\/"
/dev/mapper/docker-253:0-1705076-9bd8aa1e0af33adce89ff42090847868ca676932878942be53941a06ec5923f9 on /var/lib/docker/devicemapper/mnt/9bd8aa1e0af33adce89ff42090847868ca676932878942be53941a06ec5923f9 type xfs (rw,relatime,context="system_u:object_r:container_file_t:s0:c73,c276",nouuid,attr2,inode64,sunit=1024,swidth=1024,noquota)
[root@jouet bpf]# cd /var/lib/docker/devicemapper/mnt/9bd8aa1e0af33adce89ff42090847868ca676932878942be53941a06ec5923f9/rootfs/tmp/build/linux/samples/bpf/
[root@jouet bpf]# file offwaketime
offwaketime: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically linked, interpreter /lib64/ld-linux-x86-64.so.2, for GNU/Linux 2.6.32, BuildID[sha1]=f423d171e0487b2f802b6a792657f0f3c8f6d155, not stripped
[root@jouet bpf]# readelf -SW offwaketime
offwaketime offwaketime_kern.o offwaketime_user.o
[root@jouet bpf]# readelf -SW offwaketime_kern.o
There are 11 section headers, starting at offset 0x700:

Section Headers:
[Nr] Name Type Address Off Size ES Flg Lk Inf Al
[ 0] NULL 0000000000000000 000000 000000 00 0 0 0
[ 1] .strtab STRTAB 0000000000000000 000658 0000a8 00 0 0 1
[ 2] .text PROGBITS 0000000000000000 000040 000000 00 AX 0 0 4
[ 3] kprobe/try_to_wake_up PROGBITS 0000000000000000 000040 0000d8 00 AX 0 0 8
[ 4] .relkprobe/try_to_wake_up REL 0000000000000000 0005a8 000020 10 10 3 8
[ 5] tracepoint/sched/sched_switch PROGBITS 0000000000000000 000118 000318 00 AX 0 0 8
[ 6] .reltracepoint/sched/sched_switch REL 0000000000000000 0005c8 000090 10 10 5 8
[ 7] maps PROGBITS 0000000000000000 000430 000050 00 WA 0 0 4
[ 8] license PROGBITS 0000000000000000 000480 000004 00 WA 0 0 1
[ 9] version PROGBITS 0000000000000000 000484 000004 00 WA 0 0 4
[10] .symtab SYMTAB 0000000000000000 000488 000120 18 1 4 8
Key to Flags:
W (write), A (alloc), X (execute), M (merge), S (strings)
I (info), L (link order), G (group), T (TLS), E (exclude), x (unknown)
O (extra OS processing required) o (OS specific), p (processor specific)
[root@jouet bpf]# ./offwaketime | head -3
qemu-system-x86;entry_SYSCALL_64_fastpath;sys_ppoll;do_sys_poll;poll_schedule_timeout;schedule_hrtimeout_range;schedule_hrtimeout_range_clock;schedule;__schedule;-;try_to_wake_up;hrtimer_wakeup;__hrtimer_run_queues;hrtimer_interrupt;local_apic_timer_interrupt;smp_apic_timer_interrupt;__irqentry_text_start;cpuidle_enter_state;cpuidle_enter;call_cpuidle;cpu_startup_entry;rest_init;start_kernel;x86_64_start_reservations;x86_64_start_kernel;start_cpu;;swapper/0 4
firefox;entry_SYSCALL_64_fastpath;sys_poll;do_sys_poll;poll_schedule_timeout;schedule_hrtimeout_range;schedule_hrtimeout_range_clock;schedule;__schedule;-;try_to_wake_up;pollwake;__wake_up_common;__wake_up_sync_key;pipe_write;__vfs_write;vfs_write;sys_write;entry_SYSCALL_64_fastpath;;Timer 1
swapper/2;start_cpu;start_secondary;cpu_startup_entry;schedule_preempt_disabled;schedule;__schedule;-;---;; 61
[root@jouet bpf]#

Signed-off-by: Joe Stringer <joe@ovn.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexei Starovoitov <ast@fb.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Wang Nan <wangnan0@huawei.com>
Cc: netdev@vger.kernel.org
Link: https://github.com/joestringer/linux/commit/5c40f54a52b1f437123c81e21873f4b4b1f9bd55.patch
Link: http://lkml.kernel.org/n/tip-xr8twtx7sjh5821g8qw47yxk@git.kernel.org
[ Use -I$(srctree)/tools/lib/ to support out of source code tree builds, as noticed by Wang Nan ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

samples/bpf: like LLC also verify and allow redefining CLANG command

Users are likely to manually compile both LLVM 'llc' and 'clang'
tools. Thus, also allow redefining CLANG and verify command exist.

Makefile implementation wise, the target that verify the command have
been generalized.

Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

samples/bpf: allow make to be run from samples/bpf/ directory

It is not intuitive that 'make' must be run from the top level
directory with argument "samples/bpf/" to compile these eBPF samples.

Introduce a kbuild make file trick that allow make to be run from the
"samples/bpf/" directory itself. It basically change to the top level
directory and call "make samples/bpf/" with the "/" slash after the
directory name.

Also add a clean target that only cleans this directory, by taking
advantage of the kbuild external module setting M=$PWD.

Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

samples/bpf: add a README file to get users started

Getting started with using examples in samples/bpf/ is not
straightforward. There are several dependencies, and specific
versions of these dependencies.

Just compiling the example tool is also slightly obscure, e.g. one
need to call make like:

make samples/bpf/

Do notice the "/" slash after the directory name.

Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Acked-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>