* Re: [PATCH v6 bpf-next 1/3] libbpf: BTF dumper support for typed data
[not found] ` <1626362126-27775-2-git-send-email-alan.maguire@oracle.com>
@ 2021-07-19 12:11 ` Naresh Kamboju
2021-07-19 14:15 ` Alan Maguire
0 siblings, 1 reply; 2+ messages in thread
From: Naresh Kamboju @ 2021-07-19 12:11 UTC (permalink / raw)
To: Alan Maguire, Linux-Next Mailing List
Cc: Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko,
Martin KaFai Lau, Song Liu, Yonghong Song, john.fastabend,
kpsingh, morbo, Shuah Khan, bpf, Netdev,
open list:KERNEL SELFTEST FRAMEWORK, open list, Stephen Rothwell,
lkft-triage
On Thu, 15 Jul 2021 at 20:46, Alan Maguire <alan.maguire@oracle.com> wrote:
>
> Add a BTF dumper for typed data, so that the user can dump a typed
> version of the data provided.
>
> The API is
>
> int btf_dump__dump_type_data(struct btf_dump *d, __u32 id,
> void *data, size_t data_sz,
> const struct btf_dump_type_data_opts *opts);
>
> ...where the id is the BTF id of the data pointed to by the "void *"
> argument; for example the BTF id of "struct sk_buff" for a
> "struct skb *" data pointer. Options supported are
>
> - a starting indent level (indent_lvl)
> - a user-specified indent string which will be printed once per
> indent level; if NULL, tab is chosen but any string <= 32 chars
> can be provided.
> - a set of boolean options to control dump display, similar to those
> used for BPF helper bpf_snprintf_btf(). Options are
> - compact : omit newlines and other indentation
> - skip_names: omit member names
> - emit_zeroes: show zero-value members
>
> Default output format is identical to that dumped by bpf_snprintf_btf(),
> for example a "struct sk_buff" representation would look like this:
>
> struct sk_buff){
> (union){
> (struct){
> .next = (struct sk_buff *)0xffffffffffffffff,
> .prev = (struct sk_buff *)0xffffffffffffffff,
> (union){
> .dev = (struct net_device *)0xffffffffffffffff,
> .dev_scratch = (long unsigned int)18446744073709551615,
> },
> },
> ...
>
> If the data structure is larger than the *data_sz*
> number of bytes that are available in *data*, as much
> of the data as possible will be dumped and -E2BIG will
> be returned. This is useful as tracers will sometimes
> not be able to capture all of the data associated with
> a type; for example a "struct task_struct" is ~16k.
> Being able to specify that only a subset is available is
> important for such cases. On success, the amount of data
> dumped is returned.
>
> Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
> ---
> tools/lib/bpf/btf.h | 19 ++
> tools/lib/bpf/btf_dump.c | 819 ++++++++++++++++++++++++++++++++++++++++++++++-
> tools/lib/bpf/libbpf.map | 1 +
> 3 files changed, 834 insertions(+), 5 deletions(-)
<trim>
> diff --git a/tools/lib/bpf/btf_dump.c b/tools/lib/bpf/btf_dump.c
> index 5dc6b517..929cf93 100644
> --- a/tools/lib/bpf/btf_dump.c
> +++ b/tools/lib/bpf/btf_dump.c
Following perf build errors noticed on i386 and arm 32-bit architectures on
linux next 20210719 tag with gcc-11.
metadata:
--------------
git_repo: https://gitlab.com/Linaro/lkft/mirrors/next/linux-next
git_short_log: 08076eab6fef ( Add linux-next specific files for 20210719 )
toolchain: gcc-11
target_arch: arm and i386
> +static void btf_dump_int128(struct btf_dump *d,
> + const struct btf_type *t,
> + const void *data)
> +{
> + __int128 num = *(__int128 *)data;
btf_dump.c: In function 'btf_dump_int128':
btf_dump.c:1559:9: error: expected expression before '__int128'
1559 | __int128 num = *(__int128 *)data;
| ^~~~~~~~
btf_dump.c:1561:14: error: 'num' undeclared (first use in this function)
1561 | if ((num >> 64) == 0)
| ^~~
btf_dump.c:1561:14: note: each undeclared identifier is reported only
once for each function it appears in
btf_dump.c: At top level:
btf_dump.c:1568:17: error: '__int128' is not supported on this target
1568 | static unsigned __int128 btf_dump_bitfield_get_data(struct btf_dump *d,
| ^~~~~~~~
btf_dump.c: In function 'btf_dump_bitfield_get_data':
btf_dump.c:1576:18: error: '__int128' is not supported on this target
1576 | unsigned __int128 num = 0, ret;
| ^~~~~~~~
btf_dump.c: In function 'btf_dump_bitfield_check_zero':
btf_dump.c:1608:9: error: expected expression before '__int128'
1608 | __int128 check_num;
| ^~~~~~~~
btf_dump.c:1610:9: error: 'check_num' undeclared (first use in this function)
1610 | check_num = btf_dump_bitfield_get_data(d, t, data,
bits_offset, bit_sz);
| ^~~~~~~~~
btf_dump.c: In function 'btf_dump_bitfield_data':
btf_dump.c:1622:18: error: '__int128' is not supported on this target
1622 | unsigned __int128 print_num;
| ^~~~~~~~
btf_dump.c: In function 'btf_dump_dump_type_data':
btf_dump.c:2212:34: error: '__int128' is not supported on this target
2212 | unsigned __int128 print_num;
| ^~~~~~~~
Reported-by: Linux Kernel Functional Testing <lkft@linaro.org>
reference build link,
build: https://builds.tuxbuild.com/1vWeCpIox9EoV35c80bwOvU9nbb/
config: https://builds.tuxbuild.com/1vWeCpIox9EoV35c80bwOvU9nbb/config
steps to reproduce:
---------------------
# TuxMake is a command line tool and Python library that provides
# portable and repeatable Linux kernel builds across a variety of
# architectures, toolchains, kernel configurations, and make targets.
#
# TuxMake supports the concept of runtimes.
# See https://docs.tuxmake.org/runtimes/, for that to work it requires
# that you install podman or docker on your system.
#
# To install tuxmake on your system globally:
# sudo pip3 install -U tuxmake
#
# See https://docs.tuxmake.org/ for complete documentation.
tuxmake --runtime podman --target-arch arm --toolchain gcc-11
--kconfig defconfig --kconfig-add
https://builds.tuxbuild.com/1vWeCpIox9EoV35c80bwOvU9nbb/config
--
Linaro LKFT
https://lkft.linaro.org
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