Convert a bulk of selftests that have maps with custom (not integer) key
and/or value.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

Switch tests that already rely on BTF to BTF-defined map definitions.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

Add file test for BTF-defined map definition.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

This patch adds support for a new way to define BPF maps. It relies on
BTF to describe mandatory and optional attributes of a map, as well as
captures type information of key and value naturally. This eliminates
the need for BPF_ANNOTATE_KV_PAIR hack and ensures key/value sizes are
always in sync with the key/value type.

Relying on BTF, this approach allows for both forward and backward
compatibility w.r.t. extending supported map definition features. By
default, any unrecognized attributes are treated as an error, but it's
possible relax this using MAPS_RELAX_COMPAT flag. New attributes, added
in the future will need to be optional.

The outline of the new map definition (short, BTF-defined maps) is as follows:
1. All the maps should be defined in .maps ELF section. It's possible to
   have both "legacy" map definitions in `maps` sections and BTF-defined
   maps in .maps sections. Everything will still work transparently.
2. The map declaration and initialization is done through
   a global/static variable of a struct type with few mandatory and
   extra optional fields:
   - type field is mandatory and specified type of BPF map;
   - key/value fields are mandatory and capture key/value type/size information;
   - max_entries attribute is optional; if max_entries is not specified or
     initialized, it has to be provided in runtime through libbpf API
     before loading bpf_object;
   - map_flags is optional and if not defined, will be assumed to be 0.
3. Key/value fields should be **a pointer** to a type describing
   key/value. The pointee type is assumed (and will be recorded as such
   and used for size determination) to be a type describing key/value of
   the map. This is done to save excessive amounts of space allocated in
   corresponding ELF sections for key/value of big size.
4. As some maps disallow having BTF type ID associated with key/value,
   it's possible to specify key/value size explicitly without
   associating BTF type ID with it. Use key_size and value_size fields
   to do that (see example below).

Here's an example of simple ARRAY map defintion:

struct my_value { int x, y, z; };

struct {
	int type;
	int max_entries;
	int *key;
	struct my_value *value;
} btf_map SEC(".maps") = {
	.type = BPF_MAP_TYPE_ARRAY,
	.max_entries = 16,
};

This will define BPF ARRAY map 'btf_map' with 16 elements. The key will
be of type int and thus key size will be 4 bytes. The value is struct
my_value of size 12 bytes. This map can be used from C code exactly the
same as with existing maps defined through struct bpf_map_def.

Here's an example of STACKMAP definition (which currently disallows BTF type
IDs for key/value):

struct {
	__u32 type;
	__u32 max_entries;
	__u32 map_flags;
	__u32 key_size;
	__u32 value_size;
} stackmap SEC(".maps") = {
	.type = BPF_MAP_TYPE_STACK_TRACE,
	.max_entries = 128,
	.map_flags = BPF_F_STACK_BUILD_ID,
	.key_size = sizeof(__u32),
	.value_size = PERF_MAX_STACK_DEPTH * sizeof(struct bpf_stack_build_id),
};

This approach is naturally extended to support map-in-map, by making a value
field to be another struct that describes inner map. This feature is not
implemented yet. It's also possible to incrementally add features like pinning
with full backwards and forward compatibility. Support for static
initialization of BPF_MAP_TYPE_PROG_ARRAY using pointers to BPF programs
is also on the roadmap.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

Libbpf does sanitization of BTF before loading it into kernel, if kernel
doesn't support some of newer BTF features. This removes some of the
important information from BTF (e.g., DATASEC and VAR description),
which will be used for map construction. This patch splits BTF
processing into initialization step, in which BTF is initialized from
ELF and all the original data is still preserved; and
sanitization/loading step, which ensures that BTF is safe to load into
kernel. This allows to use full BTF information to construct maps, while
still loading valid BTF into older kernels.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

To support maps to be defined in multiple sections, it's important to
identify map not just by offset within its section, but section index as
well. This patch adds tracking of section index.

For global data, we record section index of corresponding
.data/.bss/.rodata ELF section for uniformity, and thus don't need
a special value of offset for those maps.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

User and global data maps initialization has gotten pretty complicated
and unnecessarily convoluted. This patch splits out the logic for global
data map and user-defined map initialization. It also removes the
restriction of pre-calculating how many maps will be initialized,
instead allowing to keep adding new maps as they are discovered, which
will be used later for BTF-defined map definitions.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

Simplify ELF parsing logic by exiting early, as there is no common clean
up path to execute. That makes it unnecessary to track when err was set
and when it was cleared. It also reduces nesting in some places.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

As a preparation for adding BTF-based BPF map loading, extract .BTF and
.BTF.ext loading logic.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

Multiple files in libbpf redefine their own definitions for min/max.
Let's define them in libbpf_internal.h and use those everywhere.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

If CONFIG_INET is not set, building fails:

kernel/bpf/verifier.o: In function `check_mem_access':
verifier.c: undefined reference to `bpf_xdp_sock_is_valid_access'
kernel/bpf/verifier.o: In function `convert_ctx_accesses':
verifier.c: undefined reference to `bpf_xdp_sock_convert_ctx_access'
Reported-by: Hulk Robot <hulkci@huawei.com>
Fixes: fada7fdc ("bpf: Allow bpf_map_lookup_elem() on an xskmap")
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Acked-by: Jonathan Lemon <jonathan.lemon@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

This lets us test that both BPF_PROG_TYPE_CGROUP_SOCK_ADDR and
BPF_PROG_TYPE_SOCK_OPS can access underlying bpf_sock.

Cc: Martin Lau <kafai@fb.com>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

Add sk to struct bpf_sock_addr and struct bpf_sock_ops.

Cc: Martin Lau <kafai@fb.com>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

And let it use bpf_sk_storage_{get,delete} helpers to access socket
storage. Kernel context (struct bpf_sock_ops_kern) already has sk
member, so I just expose it to the BPF hooks. I use
PTR_TO_SOCKET_OR_NULL and return NULL in !is_fullsock case.

I also export bpf_tcp_sock to make it possible to access tcp socket stats.

Cc: Martin Lau <kafai@fb.com>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

And let it use bpf_sk_storage_{get,delete} helpers to access socket
storage. Kernel context (struct bpf_sock_addr_kern) already has sk
member, so I just expose it to the BPF hooks. Using PTR_TO_SOCKET
instead of PTR_TO_SOCK_COMMON should be safe because the hook is
called on bind/connect.

Cc: Martin Lau <kafai@fb.com>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

This patch adds a test for the new sockopt SO_REUSEPORT_DETACH_BPF.
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Reviewed-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

SO_DETACH_REUSEPORT_BPF is needed for the test in the next patch.
It is defined in the socket.h.
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Reviewed-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

There is SO_ATTACH_REUSEPORT_[CE]BPF but there is no DETACH.
This patch adds SO_DETACH_REUSEPORT_BPF sockopt.  The same
sockopt can be used to undo both SO_ATTACH_REUSEPORT_[CE]BPF.

reseport_detach_prog() is added and it is mostly a mirror
of the existing reuseport_attach_prog().  The differences are,
it does not call reuseport_alloc() and returns -ENOENT when
there is no old prog.

Cc: Craig Gallek <kraig@google.com>
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Reviewed-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

Kernel internally checks that either key or value type ID is specified,
before using btf_fd. Do the same in libbpf's map creation code for
determining when to retry map creation w/o BTF.
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Fixes: fba01a06 ("libbpf: use negative fd to specify missing BTF")
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

The "len" variable needs to be signed for the error handling to work
properly.

Fixes: 596092ef ("selftests/bpf: enable all available cgroup v2 controllers")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

Recent commit included libbpf.h in selftests/bpf/bpf_util.h.
Since some samples use bpf_util.h and samples/bpf/Makefile doesn't
have libbpf.h path included, build was failing. Let's add the path
in samples/bpf/Makefile.
Signed-off-by: Prashant Bhole <prashantbhole.linux@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

Compiling kernel/bpf/core.c with W=1 causes a flood of warnings:

kernel/bpf/core.c:1198:65: warning: initialized field overwritten [-Woverride-init]
 1198 | #define BPF_INSN_3_TBL(x, y, z) [BPF_##x | BPF_##y | BPF_##z] = true
      |                                                                 ^~~~
kernel/bpf/core.c:1087:2: note: in expansion of macro 'BPF_INSN_3_TBL'
 1087 |  INSN_3(ALU, ADD,  X),   \
      |  ^~~~~~
kernel/bpf/core.c:1202:3: note: in expansion of macro 'BPF_INSN_MAP'
 1202 |   BPF_INSN_MAP(BPF_INSN_2_TBL, BPF_INSN_3_TBL),
      |   ^~~~~~~~~~~~
kernel/bpf/core.c:1198:65: note: (near initialization for 'public_insntable[12]')
 1198 | #define BPF_INSN_3_TBL(x, y, z) [BPF_##x | BPF_##y | BPF_##z] = true
      |                                                                 ^~~~
kernel/bpf/core.c:1087:2: note: in expansion of macro 'BPF_INSN_3_TBL'
 1087 |  INSN_3(ALU, ADD,  X),   \
      |  ^~~~~~
kernel/bpf/core.c:1202:3: note: in expansion of macro 'BPF_INSN_MAP'
 1202 |   BPF_INSN_MAP(BPF_INSN_2_TBL, BPF_INSN_3_TBL),
      |   ^~~~~~~~~~~~

98 copies of the above.

The attached patch silences the warnings, because we *know* we're overwriting
the default initializer. That leaves bpf/core.c with only 6 other warnings,
which become more visible in comparison.
Signed-off-by: Valdis Kletnieks <valdis.kletnieks@vt.edu>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

Hechao Li says:

====================
Getting number of possible CPUs is commonly used for per-CPU BPF maps
and perf_event_maps. Add a new API libbpf_num_possible_cpus() that
helps user with per-CPU related operations and remove duplicate
implementations in bpftool and selftests.

v2: Save errno before calling pr_warning in case it is changed.
v3: Make sure libbpf_num_possible_cpus never returns 0 so that user only
    has to check if ret value < 0.
v4: Fix error code when reading 0 bytes from possible CPU file.
v5: Fix selftests compliation issue.
v6: Split commit to reuse libbpf_num_possible_cpus() into two commits:
    One commit to remove bpf_util.h from test BPF C programs.
    One commit to reuse libbpf_num_possible_cpus() in bpftools
    and bpf_util.h.
====================
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

Use the newly added bpf_num_possible_cpus() in bpftool and selftests
and remove duplicate implementations.
Signed-off-by: Hechao Li <hechaol@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

Though currently there is no problem including bpf_util.h in kernel
space BPF C programs, in next patch in this stack, I will reuse
libbpf_num_possible_cpus() in bpf_util.h thus include libbpf.h in it,
which will cause BPF C programs compile error. Therefore I will first
remove bpf_util.h from all test BPF programs.

This can also make it clear that bpf_util.h is a user-space utility
while bpf_helpers.h is a kernel space utility.
Signed-off-by: Hechao Li <hechaol@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

Adding a new API libbpf_num_possible_cpus() that helps user with
per-CPU map operations.
Signed-off-by: Hechao Li <hechaol@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

An error "implicit declaration of function 'reallocarray'" can be thrown
with the following steps:

$ cd tools/testing/selftests/bpf
$ make clean && make CC=<Path to GCC 4.8.5>
$ make clean && make CC=<Path to GCC 7.x>

The cause is that the feature folder generated by GCC 4.8.5 is not
removed, leaving feature-reallocarray being 1, which causes reallocarray
not defined when re-compliing with GCC 7.x. This diff adds feature
folder to EXTRA_CLEAN to avoid this problem.

v2: Rephrase the commit message.
Signed-off-by: Hechao Li <hechaol@fb.com>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

Fix signature of bpf_probe_read and bpf_probe_write_user to mark source
pointer as const. This causes warnings during compilation for
applications relying on those helpers.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

Quentin reports that commit 07c3bbdb ("samples: bpf: print
a warning about headers_install") is producing the false
positive when make is invoked locally, from the samples/bpf/
directory.

When make is run locally it hits the "all" target, which
will recursively invoke make through the full build system.

Speed up the "local" run which doesn't actually build anything,
and avoid false positives by skipping all the probes if not in
kbuild environment (cover both the new warning and the BTF
probes).
Reported-by: Quentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

Jonathan Lemon says:

====================
Currently, the AF_XDP code uses a separate map in order to
determine if an xsk is bound to a queue.  Have the xskmap
lookup return a XDP_SOCK pointer on the kernel side, which
the verifier uses to extract relevant values.

Patches:
 1 - adds XSK_SOCK type
 2 - sync bpf.h with tools
 3 - add tools selftest
 4 - update lib/bpf, removing qidconf

v4->v5:
 - xskmap lookup now returns XDP_SOCK type instead of pointer to element.
 - no changes lib/bpf/xsk.c

v3->v4:
 - Clarify error handling path.

v2->v3:
 - Use correct map type.
====================
Acked-by: Björn Töpel <bjorn.topel@intel.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

Use the recent change to XSKMAP bpf_map_lookup_elem() to test if
there is a xsk present in the map instead of duplicating the work
with qidconf.

Fix things so callers using XSK_LIBBPF_FLAGS__INHIBIT_PROG_LOAD
bypass any internal bpf maps, so xsk_socket__{create|delete} works
properly.

Clean up error handling path.
Signed-off-by: Jonathan Lemon <jonathan.lemon@gmail.com>
Acked-by: Song Liu <songliubraving@fb.com>
Tested-by: Björn Töpel <bjorn.topel@intel.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

Check that bpf_map_lookup_elem lookup and structure
access operats correctly.
Signed-off-by: Jonathan Lemon <jonathan.lemon@gmail.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

Sync uapi/linux/bpf.h
Signed-off-by: Jonathan Lemon <jonathan.lemon@gmail.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

Currently, the AF_XDP code uses a separate map in order to
determine if an xsk is bound to a queue.  Instead of doing this,
have bpf_map_lookup_elem() return a xdp_sock.

Rearrange some xdp_sock members to eliminate structure holes.

Remove selftest - will be added back in later patch.
Signed-off-by: Jonathan Lemon <jonathan.lemon@gmail.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

Currently bpf_skb_cgroup_id() is not supported for CGROUP_SKB
programs. An attempt to load such a program generates an error
like this:

    libbpf:
    0: (b7) r6 = 0
    ...
    9: (85) call bpf_skb_cgroup_id#79
    unknown func bpf_skb_cgroup_id#79

There are no particular reasons for denying it, and we have some
use cases where it might be useful.

So let's add it to the list of allowed helpers.
Signed-off-by: Roman Gushchin <guro@fb.com>
Cc: Yonghong Song <yhs@fb.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

It seems like periodically someone posts patches to "fix"
header includes.  The issue is that samples expect the
include path to have the uAPI headers (from usr/) first,
and then tools/ headers, so that locally installed uAPI
headers take precedence.  This means that if users didn't
run headers_install they will see all sort of strange
compilation errors, e.g.:

  HOSTCC  samples/bpf/test_lru_dist
  samples/bpf/test_lru_dist.c:39:8: error: redefinition of ‘struct list_head’
   struct list_head {
          ^~~~~~~~~
   In file included from samples/bpf/test_lru_dist.c:9:0:
   ../tools/include/linux/types.h:69:8: note: originally defined here
    struct list_head {
           ^~~~~~~~~

Try to detect this situation, and print a helpful warning.

v2: just use HOSTCC (Jiong).
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

The variable err is assigned with the value -EINVAL that is never
read and it is re-assigned a new value later on.  The assignment is
redundant and can be removed.

Addresses-Coverity: ("Unused value")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

There is a spelling mistake in the help information, fix this.
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

Alexei Starovoitov says:

====================
pull-request: bpf-next 2019-05-31

The following pull-request contains BPF updates for your *net-next* tree.

Lots of exciting new features in the first PR of this developement cycle!
The main changes are:

1) misc verifier improvements, from Alexei.

2) bpftool can now convert btf to valid C, from Andrii.

3) verifier can insert explicit ZEXT insn when requested by 32-bit JITs.
   This feature greatly improves BPF speed on 32-bit architectures. From Jiong.

4) cgroups will now auto-detach bpf programs. This fixes issue of thousands
   bpf programs got stuck in dying cgroups. From Roman.

5) new bpf_send_signal() helper, from Yonghong.

6) cgroup inet skb programs can signal CN to the stack, from Lawrence.

7) miscellaneous cleanups, from many developers.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

xdping allows us to get latency estimates from XDP.  Output looks
like this:

./xdping -I eth4 192.168.55.8
Setting up XDP for eth4, please wait...
XDP setup disrupts network connectivity, hit Ctrl+C to quit

Normal ping RTT data
[Ignore final RTT; it is distorted by XDP using the reply]
PING 192.168.55.8 (192.168.55.8) from 192.168.55.7 eth4: 56(84) bytes of data.
64 bytes from 192.168.55.8: icmp_seq=1 ttl=64 time=0.302 ms
64 bytes from 192.168.55.8: icmp_seq=2 ttl=64 time=0.208 ms
64 bytes from 192.168.55.8: icmp_seq=3 ttl=64 time=0.163 ms
64 bytes from 192.168.55.8: icmp_seq=8 ttl=64 time=0.275 ms

4 packets transmitted, 4 received, 0% packet loss, time 3079ms
rtt min/avg/max/mdev = 0.163/0.237/0.302/0.054 ms

XDP RTT data:
64 bytes from 192.168.55.8: icmp_seq=5 ttl=64 time=0.02808 ms
64 bytes from 192.168.55.8: icmp_seq=6 ttl=64 time=0.02804 ms
64 bytes from 192.168.55.8: icmp_seq=7 ttl=64 time=0.02815 ms
64 bytes from 192.168.55.8: icmp_seq=8 ttl=64 time=0.02805 ms

The xdping program loads the associated xdping_kern.o BPF program
and attaches it to the specified interface.  If run in client
mode (the default), it will add a map entry keyed by the
target IP address; this map will store RTT measurements, current
sequence number etc.  Finally in client mode the ping command
is executed, and the xdping BPF program will use the last ICMP
reply, reformulate it as an ICMP request with the next sequence
number and XDP_TX it.  After the reply to that request is received
we can measure RTT and repeat until the desired number of
measurements is made.  This is why the sequence numbers in the
normal ping are 1, 2, 3 and 8.  We XDP_TX a modified version
of ICMP reply 4 and keep doing this until we get the 4 replies
we need; hence the networking stack only sees reply 8, where
we have XDP_PASSed it upstream since we are done.

In server mode (-s), xdping simply takes ICMP requests and replies
to them in XDP rather than passing the request up to the networking
stack.  No map entry is required.

xdping can be run in native XDP mode (the default, or specified
via -N) or in skb mode (-S).

A test program test_xdping.sh exercises some of these options.

Note that native XDP does not seem to XDP_TX for veths, hence -N
is not tested.  Looking at the code, it looks like XDP_TX is
supported so I'm not sure if that's expected.  Running xdping in
native mode for ixgbe as both client and server works fine.

Changes since v4

- close fds on cleanup (Song Liu)

Changes since v3

- fixed seq to be __be16 (Song Liu)
- fixed fd checks in xdping.c (Song Liu)

Changes since v2

- updated commit message to explain why seq number of last
  ICMP reply is 8 not 4 (Song Liu)
- updated types of seq number, raddr and eliminated csum variable
  in xdpclient/xdpserver functions as it was not needed (Song Liu)
- added XDPING_DEFAULT_COUNT definition and usage specification of
  default/max counts (Song Liu)

Changes since v1
 - moved from RFC to PATCH
 - removed unused variable in ipv4_csum() (Song Liu)
 - refactored ICMP checks into icmp_check() function called by client
   and server programs and reworked client and server programs due
   to lack of shared code (Song Liu)
 - added checks to ensure that SKB and native mode are not requested
   together (Song Liu)
Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>