Merge https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next

Daniel Borkmann says:

====================
bpf-next 2022-02-17

We've added 29 non-merge commits during the last 8 day(s) which contain
a total of 34 files changed, 1502 insertions(+), 524 deletions(-).

The main changes are:

1) Add BTFGen support to bpftool which allows to use CO-RE in kernels without
   BTF info, from Mauricio Vásquez, Rafael David Tinoco, Lorenzo Fontana and
   Leonardo Di Donato. (Details: https://lpc.events/event/11/contributions/948/)

2) Prepare light skeleton to be used in both kernel module and user space
   and convert bpf_preload.ko to use light skeleton, from Alexei Starovoitov.

3) Rework bpftool's versioning scheme and align with libbpf's version number;
   also add linked libbpf version info to "bpftool version", from Quentin Monnet.

4) Add minimal C++ specific additions to bpftool's skeleton codegen to
   facilitate use of C skeletons in C++ applications, from Andrii Nakryiko.

5) Add BPF verifier sanity check whether relative offset on kfunc calls overflows
   desc->imm and reject the BPF program if the case, from Hou Tao.

6) Fix libbpf to use a dynamically allocated buffer for netlink messages to
   avoid receiving truncated messages on some archs, from Toke Høiland-Jørgensen.

7) Various follow-up fixes to the JIT bpf_prog_pack allocator, from Song Liu.

8) Various BPF selftest and vmtest.sh fixes, from Yucong Sun.

9) Fix bpftool pretty print handling on dumping map keys/values when no BTF
   is available, from Jiri Olsa and Yinjun Zhang.

10) Extend XDP frags selftest to check for invalid length, from Lorenzo Bianconi.

* https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (29 commits)
  bpf: bpf_prog_pack: Set proper size before freeing ro_header
  selftests/bpf: Fix crash in core_reloc when bpftool btfgen fails
  selftests/bpf: Fix vmtest.sh to launch smp vm.
  libbpf: Fix memleak in libbpf_netlink_recv()
  bpftool: Fix C++ additions to skeleton
  bpftool: Fix pretty print dump for maps without BTF loaded
  selftests/bpf: Test "bpftool gen min_core_btf"
  bpftool: Gen min_core_btf explanation and examples
  bpftool: Implement btfgen_get_btf()
  bpftool: Implement "gen min_core_btf" logic
  bpftool: Add gen min_core_btf command
  libbpf: Expose bpf_core_{add,free}_cands() to bpftool
  libbpf: Split bpf_core_apply_relo()
  bpf: Reject kfunc calls that overflow insn->imm
  selftests/bpf: Add Skeleton templated wrapper as an example
  bpftool: Add C++-specific open/load/etc skeleton wrappers
  selftests/bpf: Fix GCC11 compiler warnings in -O2 mode
  bpftool: Fix the error when lookup in no-btf maps
  libbpf: Use dynamically allocated buffer when receiving netlink messages
  libbpf: Fix libbpf.map inheritance chain for LIBBPF_0.7.0
  ...
====================

Link: https://lore.kernel.org/r/20220217232027.29831-1-daniel@iogearbox.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 85 insertions, 2 deletions

diff --git a/tools/testing/selftests/bpf/test_cpp.cpp b/tools/testing/selftests/bpf/test_cpp.cpp
index e00201de2890..773f165c4898 100644
--- a/tools/testing/selftests/bpf/test_cpp.cpp
+++ b/tools/testing/selftests/bpf/test_cpp.cpp
@@ -5,18 +5,100 @@
 #include <bpf/btf.h>
 #include "test_core_extern.skel.h"
 
-/* do nothing, just make sure we can link successfully */
+template <typename T>
+class Skeleton {
+private:
+	T *skel;
+public:
+	Skeleton(): skel(nullptr) { }
+
+	~Skeleton() { if (skel) T::destroy(skel); }
+
+	int open(const struct bpf_object_open_opts *opts = nullptr)
+	{
+		int err;
+
+		if (skel)
+			return -EBUSY;
+
+		skel = T::open(opts);
+		err = libbpf_get_error(skel);
+		if (err) {
+			skel = nullptr;
+			return err;
+		}
+
+		return 0;
+	}
+
+	int load() { return T::load(skel); }
+
+	int attach() { return T::attach(skel); }
+
+	void detach() { return T::detach(skel); }
+
+	const T* operator->() const { return skel; }
+
+	T* operator->() { return skel; }
+
+	const T *get() const { return skel; }
+};
 
 static void dump_printf(void *ctx, const char *fmt, va_list args)
 {
 }
 
+static void try_skeleton_template()
+{
+	Skeleton<test_core_extern> skel;
+	std::string prog_name;
+	int err;
+	LIBBPF_OPTS(bpf_object_open_opts, opts);
+
+	err = skel.open(&opts);
+	if (err) {
+		fprintf(stderr, "Skeleton open failed: %d\n", err);
+		return;
+	}
+
+	skel->data->kern_ver = 123;
+	skel->data->int_val = skel->data->ushort_val;
+
+	err = skel.load();
+	if (err) {
+		fprintf(stderr, "Skeleton load failed: %d\n", err);
+		return;
+	}
+
+	if (!skel->kconfig->CONFIG_BPF_SYSCALL)
+		fprintf(stderr, "Seems like CONFIG_BPF_SYSCALL isn't set?!\n");
+
+	err = skel.attach();
+	if (err) {
+		fprintf(stderr, "Skeleton attach failed: %d\n", err);
+		return;
+	}
+
+	prog_name = bpf_program__name(skel->progs.handle_sys_enter);
+	if (prog_name != "handle_sys_enter")
+		fprintf(stderr, "Unexpected program name: %s\n", prog_name.c_str());
+
+	bpf_link__destroy(skel->links.handle_sys_enter);
+	skel->links.handle_sys_enter = bpf_program__attach(skel->progs.handle_sys_enter);
+
+	skel.detach();
+
+	/* destructor will destory underlying skeleton */
+}
+
 int main(int argc, char *argv[])
 {
 	struct btf_dump_opts opts = { };
 	struct test_core_extern *skel;
 	struct btf *btf;
 
+	try_skeleton_template();
+
 	/* libbpf.h */
 	libbpf_set_print(NULL);
 
@@ -25,7 +107,8 @@ int main(int argc, char *argv[])
 
 	/* btf.h */
 	btf = btf__new(NULL, 0);
-	btf_dump__new(btf, dump_printf, nullptr, &opts);
+	if (!libbpf_get_error(btf))
+		btf_dump__new(btf, dump_printf, nullptr, &opts);
 
 	/* BPF skeleton */
 	skel = test_core_extern__open_and_load();