On Fri, Aug 30, 2024 at 10:54 AM Alan Maguire <alan.maguire@xxxxxxxxxx> wrote:
>
> On 30/08/2024 18:34, Eduard Zingerman wrote:
> > Create a BTF with endianness different from host, make a distilled
> > base/split BTF pair from it, dump as raw bytes, import again and
> > verify that endianness is preserved.
> >
> > Signed-off-by: Eduard Zingerman <eddyz87@xxxxxxxxx>
>
> One small thing below, but
>
> Reviewed-by: Alan Maguire <alan.maguire@xxxxxxxxxx>
> Tested-by: Alan Maguire <alan.maguire@xxxxxxxxxx>
will add and force-push, thanks
>
> Thanks!
>
> > ---
> > .../selftests/bpf/prog_tests/btf_distill.c | 73 +++++++++++++++++++
> > 1 file changed, 73 insertions(+)
> >
> > diff --git a/tools/testing/selftests/bpf/prog_tests/btf_distill.c b/tools/testing/selftests/bpf/prog_tests/btf_distill.c
> > index bfbe795823a2..810b2e434562 100644
> > --- a/tools/testing/selftests/bpf/prog_tests/btf_distill.c
> > +++ b/tools/testing/selftests/bpf/prog_tests/btf_distill.c
> > @@ -535,6 +535,77 @@ static void test_distilled_base_vmlinux(void)
> > btf__free(vmlinux_btf);
> > }
> >
> > +static bool is_host_big_endian(void)
> > +{
> > + return htons(0x1234) == 0x1234;
> > +}
> > +
> > +/* Split and new base BTFs should inherit endianness from source BTF. */
> > +static void test_distilled_endianness(void)
> > +{
> > + struct btf *base = NULL, *split = NULL, *new_base = NULL, *new_split = NULL;
> > + struct btf *new_base1 = NULL, *new_split1 = NULL;
> > + enum btf_endianness inverse_endianness;
> > + const void *raw_data;
> > + __u32 size;
> > +
> > + printf("is_host_big_endian? %d\n", is_host_big_endian());
> > + inverse_endianness = is_host_big_endian() ? BTF_LITTLE_ENDIAN : BTF_BIG_ENDIAN;
> > + base = btf__new_empty();
>
>
> nit: I think you could avoid the need for is_host_big_endian() by doing
> this:
>
> inverse_endianness = btf__endianness(base) == BTF_LITTLE_ENDIAN ?
> BTF_BIG_ENDIAN : BTF_LITTLE_ENDIAN;
good point, I'll fix it up
>
>
> > + btf__set_endianness(base, inverse_endianness);
> > + if (!ASSERT_OK_PTR(base, "empty_main_btf"))
> > + return;
> > + btf__add_int(base, "int", 4, BTF_INT_SIGNED); /* [1] int */
> > + VALIDATE_RAW_BTF(
> > + base,
> > + "[1] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED");
> > + split = btf__new_empty_split(base);
> > + if (!ASSERT_OK_PTR(split, "empty_split_btf"))
> > + goto cleanup;
> > + btf__add_ptr(split, 1);
> > + VALIDATE_RAW_BTF(
> > + split,
> > + "[1] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED",
> > + "[2] PTR '(anon)' type_id=1");
> > + if (!ASSERT_EQ(0, btf__distill_base(split, &new_base, &new_split),
> > + "distilled_base") ||
> > + !ASSERT_OK_PTR(new_base, "distilled_base") ||
> > + !ASSERT_OK_PTR(new_split, "distilled_split") ||
> > + !ASSERT_EQ(2, btf__type_cnt(new_base), "distilled_base_type_cnt"))
> > + goto cleanup;
> > + VALIDATE_RAW_BTF(
> > + new_split,
> > + "[1] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED",
> > + "[2] PTR '(anon)' type_id=1");
> > +
> > + raw_data = btf__raw_data(new_base, &size);
> > + if (!ASSERT_OK_PTR(raw_data, "btf__raw_data #1"))
> > + goto cleanup;
> > + new_base1 = btf__new(raw_data, size);
> > + if (!ASSERT_OK_PTR(new_base1, "new_base1 = btf__new()"))
> > + goto cleanup;
> > + raw_data = btf__raw_data(new_split, &size);
> > + if (!ASSERT_OK_PTR(raw_data, "btf__raw_data #2"))
> > + goto cleanup;
> > + new_split1 = btf__new_split(raw_data, size, new_base1);
> > + if (!ASSERT_OK_PTR(new_split1, "new_split1 = btf__new()"))
> > + goto cleanup;
> > +
> > + ASSERT_EQ(btf__endianness(new_base1), inverse_endianness, "new_base1 endianness");
> > + ASSERT_EQ(btf__endianness(new_split1), inverse_endianness, "new_split1 endianness");
> > + VALIDATE_RAW_BTF(
> > + new_split1,
> > + "[1] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED",
> > + "[2] PTR '(anon)' type_id=1");
> > +cleanup:
> > + btf__free(new_split1);
> > + btf__free(new_base1);
> > + btf__free(new_split);
> > + btf__free(new_base);
> > + btf__free(split);
> > + btf__free(base);
> > +}
> > +
> > void test_btf_distill(void)
> > {
> > if (test__start_subtest("distilled_base"))
> > @@ -549,4 +620,6 @@ void test_btf_distill(void)
> > test_distilled_base_multi_err2();
> > if (test__start_subtest("distilled_base_vmlinux"))
> > test_distilled_base_vmlinux();
> > + if (test__start_subtest("distilled_endianness"))
> > + test_distilled_endianness();
> > }
