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