selftests/bpf: Enable inline bpf_kptr_xchg() test for RV64

Enable inline bpf_kptr_xchg() test for RV64, and the test have passed as
show below:

Summary: 1/0 PASSED, 0 SKIPPED, 0 FAILED

Signed-off-by: Pu Lehui <pulehui@huawei.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Björn Töpel <bjorn@kernel.org>
Link: https://lore.kernel.org/bpf/20240130124659.670321-3-pulehui@huaweicloud.com

selftests/bpf: Enable kptr_xchg_inline test for arm64

Now arm64 bpf jit has enable bpf_jit_supports_ptr_xchg(), so enable
the test for arm64 as well.

Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20240119102529.99581-3-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

selftests/bpf: Test the inlining of bpf_kptr_xchg()

The test uses bpf_prog_get_info_by_fd() to obtain the xlated
instructions of the program first. Since these instructions have
already been rewritten by the verifier, the tests then checks whether
the rewritten instructions are as expected. And to ensure LLVM generates
code exactly as expected, use inline assembly and a naked function.

Suggested-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Hou Tao <houtao1@huawei.com>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20240105104819.3916743-4-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>