Fix the following warnings triggered by 51570a5ab2 ("A Sample of
using socket cookie and uid for traffic monitoring"):
In file included from /home/foo/net-next/samples/bpf/cookie_uid_helper_example.c:54:0:
/home/foo/net-next/samples/bpf/cookie_uid_helper_example.c: In function 'prog_load':
/home/foo/net-next/samples/bpf/cookie_uid_helper_example.c:119:27: warning: overflow in implicit constant conversion [-Woverflow]
-32 + offsetof(struct stats, uid)),
^
/home/foo/net-next/samples/bpf/libbpf.h:135:12: note: in definition of macro 'BPF_STX_MEM'
.off = OFF, \
^
/home/foo/net-next/samples/bpf/cookie_uid_helper_example.c:121:27: warning: overflow in implicit constant conversion [-Woverflow]
-32 + offsetof(struct stats, packets), 1),
^
/home/foo/net-next/samples/bpf/libbpf.h:155:12: note: in definition of macro 'BPF_ST_MEM'
.off = OFF, \
^
/home/foo/net-next/samples/bpf/cookie_uid_helper_example.c:129:27: warning: overflow in implicit constant conversion [-Woverflow]
-32 + offsetof(struct stats, bytes)),
^
/home/foo/net-next/samples/bpf/libbpf.h:135:12: note: in definition of macro 'BPF_STX_MEM'
.off = OFF, \
^
HOSTLD /home/foo/net-next/samples/bpf/per_socket_stats_example
Fixes: 51570a5ab2 ("A Sample of using socket cookie and uid for traffic monitoring")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
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
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