Re: [PATCH v10 bpf-next 02/11] selftests/bpf: add selftests for new insn_array map

[Anton Protopopov <a.s.protopopov@gmail.com>]

On 25/11/03 06:10PM, Alexei Starovoitov wrote:
> On Sun, Nov 2, 2025 at 12:52 PM Anton Protopopov
> <a.s.protopopov@gmail.com> wrote:
> >
> > Add the following selftests for new insn_array map:
> >
> >   * Incorrect instruction indexes are rejected
> >   * Two programs can't use the same map
> >   * BPF progs can't operate the map
> >   * no changes to code => map is the same
> >   * expected changes when instructions are added
> >   * expected changes when instructions are deleted
> >   * expected changes when multiple functions are present
> >
> > Signed-off-by: Anton Protopopov <a.s.protopopov@gmail.com>
> > Acked-by: Eduard Zingerman <eddyz87@gmail.com>
> > ---
> >  .../selftests/bpf/prog_tests/bpf_insn_array.c | 409 ++++++++++++++++++
> >  1 file changed, 409 insertions(+)
> >  create mode 100644 tools/testing/selftests/bpf/prog_tests/bpf_insn_array.c
> >
> > diff --git a/tools/testing/selftests/bpf/prog_tests/bpf_insn_array.c b/tools/testing/selftests/bpf/prog_tests/bpf_insn_array.c
> > new file mode 100644
> > index 000000000000..96ee9c9984f1
> > --- /dev/null
> > +++ b/tools/testing/selftests/bpf/prog_tests/bpf_insn_array.c
> > @@ -0,0 +1,409 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +
> > +#include <bpf/bpf.h>
> > +#include <test_progs.h>
> > +
> > +#ifdef __x86_64__
> > +static int map_create(__u32 map_type, __u32 max_entries)
> > +{
> > +       const char *map_name = "insn_array";
> > +       __u32 key_size = 4;
> > +       __u32 value_size = sizeof(struct bpf_insn_array_value);
> > +
> > +       return bpf_map_create(map_type, map_name, key_size, value_size, max_entries, NULL);
> > +}
> > +
> > +static int prog_load(struct bpf_insn *insns, __u32 insn_cnt, int *fd_array, __u32 fd_array_cnt)
> > +{
> > +       LIBBPF_OPTS(bpf_prog_load_opts, opts);
> > +
> > +       opts.fd_array = fd_array;
> > +       opts.fd_array_cnt = fd_array_cnt;
> > +
> > +       return bpf_prog_load(BPF_PROG_TYPE_XDP, NULL, "GPL", insns, insn_cnt, &opts);
> > +}
> > +
> > +static void __check_success(struct bpf_insn *insns, __u32 insn_cnt, __u32 *map_in, __u32 *map_out)
> > +{
> > +       struct bpf_insn_array_value val = {};
> > +       int prog_fd = -1, map_fd, i;
> > +
> > +       map_fd = map_create(BPF_MAP_TYPE_INSN_ARRAY, insn_cnt);
> > +       if (!ASSERT_GE(map_fd, 0, "map_create"))
> > +               return;
> > +
> > +       for (i = 0; i < insn_cnt; i++) {
> > +               val.orig_off = map_in[i];
> > +               if (!ASSERT_EQ(bpf_map_update_elem(map_fd, &i, &val, 0), 0, "bpf_map_update_elem"))
> > +                       goto cleanup;
> > +       }
> > +
> > +       if (!ASSERT_EQ(bpf_map_freeze(map_fd), 0, "bpf_map_freeze"))
> > +               goto cleanup;
> > +
> > +       prog_fd = prog_load(insns, insn_cnt, &map_fd, 1);
> > +       if (!ASSERT_GE(prog_fd, 0, "bpf(BPF_PROG_LOAD)"))
> > +               goto cleanup;
> > +
> > +       for (i = 0; i < insn_cnt; i++) {
> > +               char buf[64];
> > +
> > +               if (!ASSERT_EQ(bpf_map_lookup_elem(map_fd, &i, &val), 0, "bpf_map_lookup_elem"))
> > +                       goto cleanup;
> > +
> > +               snprintf(buf, sizeof(buf), "val.xlated_off should be equal map_out[%d]", i);
> > +               ASSERT_EQ(val.xlated_off, map_out[i], buf);
> > +       }
> > +
> > +cleanup:
> > +       close(prog_fd);
> > +       close(map_fd);
> > +}
> > +
> > +/*
> > + * Load a program, which will not be anyhow mangled by the verifier.  Add an
> > + * insn_array 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(),
> > +       };
> > +       __u32 map_in[] = {0, 1, 2, 3, 4, 5};
> > +       __u32 map_out[] = {0, 1, 2, 3, 4, 5};
> > +
> > +       __check_success(insns, ARRAY_SIZE(insns), map_in, map_out);
> > +}
> > +
> > +/*
> > + * Load a program with two patches (get jiffies, for simplicity). Add an
> > + * insn_array map pointing to every instruction. Check how it was changed
> > + * after the program load.
> > + */
> > +static void check_simple(void)
> > +{
> > +       struct bpf_insn insns[] = {
> > +               BPF_MOV64_IMM(BPF_REG_0, 2),
> > +               BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_jiffies64),
> > +               BPF_MOV64_IMM(BPF_REG_0, 1),
> > +               BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_jiffies64),
> > +               BPF_MOV64_IMM(BPF_REG_0, 0),
> > +               BPF_EXIT_INSN(),
> > +       };
> > +       __u32 map_in[] = {0, 1, 2, 3, 4, 5};
> > +       __u32 map_out[] = {0, 1, 4, 5, 8, 9};
> > +
> > +       __check_success(insns, ARRAY_SIZE(insns), map_in, map_out);
> > +}
> > +
> > +/*
> > + * Verifier can delete code in two cases: nops & dead code. From insn
> > + * array's point of view, the two cases are the same, so test using
> > + * the simplest method: by loading some nops
> > + */
> > +static void check_deletions(void)
> > +{
> > +       struct bpf_insn insns[] = {
> > +               BPF_MOV64_IMM(BPF_REG_0, 2),
> > +               BPF_JMP_IMM(BPF_JA, 0, 0, 0), /* nop */
> > +               BPF_MOV64_IMM(BPF_REG_0, 1),
> > +               BPF_JMP_IMM(BPF_JA, 0, 0, 0), /* nop */
> > +               BPF_MOV64_IMM(BPF_REG_0, 0),
> > +               BPF_EXIT_INSN(),
> > +       };
> > +       __u32 map_in[] = {0, 1, 2, 3, 4, 5};
> > +       __u32 map_out[] = {0, -1, 1, -1, 2, 3};
> > +
> > +       __check_success(insns, ARRAY_SIZE(insns), map_in, map_out);
> > +}
> > +
> > +/*
> > + * Same test as check_deletions, but also add code which adds instructions
> > + */
> > +static void check_deletions_with_functions(void)
> > +{
> > +       struct bpf_insn insns[] = {
> > +               BPF_JMP_IMM(BPF_JA, 0, 0, 0), /* nop */
> > +               BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_jiffies64),
> > +               BPF_JMP_IMM(BPF_JA, 0, 0, 0), /* nop */
> > +               BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 1, 0, 2),
> > +               BPF_MOV64_IMM(BPF_REG_0, 1),
> > +               BPF_EXIT_INSN(),
> > +               BPF_JMP_IMM(BPF_JA, 0, 0, 0), /* nop */
> > +               BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_jiffies64),
> > +               BPF_JMP_IMM(BPF_JA, 0, 0, 0), /* nop */
> > +               BPF_MOV64_IMM(BPF_REG_0, 2),
> > +               BPF_EXIT_INSN(),
> > +       };
> > +       __u32 map_in[] =  { 0, 1,  2, 3, 4, 5, /* func */  6, 7,  8, 9, 10};
> > +       __u32 map_out[] = {-1, 0, -1, 3, 4, 5, /* func */ -1, 6, -1, 9, 10};
> > +
> > +       __check_success(insns, ARRAY_SIZE(insns), map_in, map_out);
> > +}
> 
> I was thinking of taking the first 5 patches, but this one fails:
> ./test_progs -t bpf_insn_array
> ...
> #19/4    bpf_insn_array/deletions-with-functions:FAIL
> #19/5    bpf_insn_array/blindness:OK
> #19/6    bpf_insn_array/incorrect-index:OK
> #19/7    bpf_insn_array/load-unfrozen-map:OK
> #19/8    bpf_insn_array/no-map-reuse:OK
> #19/9    bpf_insn_array/bpf-side-ops:OK
> #19      bpf_insn_array:FAIL
> 
> I don't see what you're changing later in the patches
> to make it pass, but the failure highlights the issue with
> bisectability. Pls take a look.

Thanks! I've found the chunk, it was

@@ -21664,2 +21705,4 @@ static int jit_subprogs(struct bpf_verifier_env *env)
                func[i]->aux->arena = prog->aux->arena;
+               func[i]->aux->used_maps = env->used_maps;
+               func[i]->aux->used_map_cnt = env->used_map_cnt;
                num_exentries = 0;

> This one also fails:
> #170/3   libbpf_str/bpf_map_type_str:FAIL
> #170     libbpf_str:FAIL
> 
> I was thinking of hacking it as an extra patch
> (without full support in patch 8), but gave up when I saw
> deletions-with-functions failing.
> 
> Maybe also split the main libbpf patch into prep patch
> with basic introduction of insn_array ?

I've split a commit that teaches libbpf about insn_array + moved
the bpftool commit lower. All the tests pass now.

> Or keep it as-is, if respin comes soon.

I can send the first chunk separately today,
or the whole thing a few days later.

> [...]