Re: [RFC PATCH bpf-next 03/14] selftests/bpf: add selftests for new insn_set map

[Anton Protopopov <aspsk@isovalent.com>]

On 25/03/18 01:56PM, Yonghong Song wrote:
> 
> 
> On 3/18/25 7:33 AM, Anton Protopopov wrote:
> > Tests are split in two parts.
> > 
> > The `bpf_insn_set_ops` test checks that the map is managed properly:
> > 
> >    * Incorrect instruction indexes are rejected
> >    * Non-sorted and non-unique indexes are rejected
> >    * Unfrozen maps are not accepted
> >    * Two programs can't use the same map
> >    * BPF progs can't operate the map
> > 
> > The `bpf_insn_set_reloc` part validates, as best as it can do it from user
> > space, that instructions are relocated properly:
> > 
> >    * no relocations => map is the same
> >    * expected relocations when instructions are added
> >    * expected relocations when instructions are deleted
> >    * expected relocations when multiple functions are present
> > 
> > Signed-off-by: Anton Protopopov <aspsk@isovalent.com>
> > ---
> >   .../selftests/bpf/prog_tests/bpf_insn_set.c   | 639 ++++++++++++++++++
> >   1 file changed, 639 insertions(+)
> >   create mode 100644 tools/testing/selftests/bpf/prog_tests/bpf_insn_set.c
> > 
> > diff --git a/tools/testing/selftests/bpf/prog_tests/bpf_insn_set.c b/tools/testing/selftests/bpf/prog_tests/bpf_insn_set.c
> > new file mode 100644
> > index 000000000000..796980bd4fcb
> > --- /dev/null
> > +++ b/tools/testing/selftests/bpf/prog_tests/bpf_insn_set.c
> > @@ -0,0 +1,639 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +
> > +#include <bpf/bpf.h>
> > +#include <test_progs.h>
> > +
> > +static inline int map_create(__u32 map_type, __u32 max_entries)
> > +{
> > +	const char *map_name = "insn_set";
> > +	__u32 key_size = 4;
> > +	__u32 value_size = 4;
> > +
> > +	return bpf_map_create(map_type, map_name, key_size, value_size, max_entries, NULL);
> > +}
> > +
> > +/*
> > + * Load a program, which will not be anyhow mangled by the verifier.  Add an
> > + * insn_set map pointing to every instruction. Check that it hasn't changed
> > + * after the program load.
> > + */
> > +static void check_one_to_one_mapping(void)
> > +{
> > +	struct bpf_insn insns[] = {
> > +		BPF_MOV64_IMM(BPF_REG_0, 4),
> > +		BPF_MOV64_IMM(BPF_REG_0, 3),
> > +		BPF_MOV64_IMM(BPF_REG_0, 2),
> > +		BPF_MOV64_IMM(BPF_REG_0, 1),
> > +		BPF_MOV64_IMM(BPF_REG_0, 0),
> > +		BPF_EXIT_INSN(),
> > +	};
> > +	int prog_fd, map_fd;
> 
> prog_fd needs to be initialized to something like -1.

Thanks! I've fixed this and similar occurrences.

Also replaced syscall(BPF_PROG_LOAD) with libbpf wrappers, so the code
is a bit shorter now.  Will resend the patch to this thread shortly.

> > +	union bpf_attr attr = {
> > +		.prog_type = BPF_PROG_TYPE_XDP, /* we don't care */
> > +		.insns     = ptr_to_u64(insns),
> > +		.insn_cnt  = ARRAY_SIZE(insns),
> > +		.license   = ptr_to_u64("GPL"),
> > +		.fd_array = ptr_to_u64(&map_fd),
> > +		.fd_array_cnt = 1,
> > +	};
> > +	int i;
> > +
> > +	map_fd = map_create(BPF_MAP_TYPE_INSN_SET, ARRAY_SIZE(insns));
> > +	if (!ASSERT_GE(map_fd, 0, "map_create"))
> > +		return;
> > +
> > +	for (i = 0; i < ARRAY_SIZE(insns); i++)
> > +		if (!ASSERT_EQ(bpf_map_update_elem(map_fd, &i, &i, 0), 0, "bpf_map_update_elem"))
> > +			goto cleanup;
> 
> Otherwise, goto cleanup here will goto cleanup and close(prog_fd) will close
> a random prog_fd. Please check the rest of prog_fd usage.
> 
> > +
> > +	if (!ASSERT_EQ(bpf_map_freeze(map_fd), 0, "bpf_map_freeze"))
> > +		return;
> > +
> > +	prog_fd = syscall(__NR_bpf, BPF_PROG_LOAD, &attr, sizeof(attr));
> > +	if (!ASSERT_GE(prog_fd, 0, "bpf(BPF_PROG_LOAD)"))
> > +		goto cleanup;
> > +
> > +	for (i = 0; i < ARRAY_SIZE(insns); i++) {
> > +		__u32 val;
> > +
> > +		if (!ASSERT_EQ(bpf_map_lookup_elem(map_fd, &i, &val), 0, "bpf_map_lookup_elem"))
> > +			goto cleanup;
> > +
> > +		ASSERT_EQ(val, i, "val should be equal i");
> > +	}
> > +
> > +cleanup:
> > +	close(prog_fd);
> > +	close(map_fd);
> > +}
> > +
> 
> [...]
>