linux.git/tools/bpf/bpftool/map.c, branch v5.16

bpftool: Switch to libbpf's hashmap for PIDs/names references

2021-10-26T00:31:39+00:00

In order to show PIDs and names for processes holding references to BPF
programs, maps, links, or BTF objects, bpftool creates hash maps to
store all relevant information. This commit is part of a set that
transitions from the kernel's hash map implementation to the one coming
with libbpf.

The motivation is to make bpftool less dependent of kernel headers, to
ease the path to a potential out-of-tree mirror, like libbpf has.

This is the third and final step of the transition, in which we convert
the hash maps used for storing the information about the processes
holding references to BPF objects (programs, maps, links, BTF), and at
last we drop the inclusion of tools/include/linux/hashtable.h.

Note: Checkpatch complains about the use of __weak declarations, and the
missing empty lines after the bunch of empty function declarations when
compiling without the BPF skeletons (none of these were introduced in
this patch). We want to keep things as they are, and the reports should
be safe to ignore.

Signed-off-by: Quentin Monnet 
Signed-off-by: Andrii Nakryiko 
Link: https://lore.kernel.org/bpf/20211023205154.6710-6-quentin@isovalent.com

bpftool: Switch to libbpf's hashmap for pinned paths of BPF objects

2021-10-26T00:31:38+00:00

In order to show pinned paths for BPF programs, maps, or links when
listing them with the "-f" option, bpftool creates hash maps to store
all relevant paths under the bpffs. So far, it would rely on the
kernel implementation (from tools/include/linux/hashtable.h).

We can make bpftool rely on libbpf's implementation instead. The
motivation is to make bpftool less dependent of kernel headers, to ease
the path to a potential out-of-tree mirror, like libbpf has.

This commit is the first step of the conversion: the hash maps for
pinned paths for programs, maps, and links are converted to libbpf's
hashmap.{c,h}. Other hash maps used for the PIDs of process holding
references to BPF objects are left unchanged for now. On the build side,
this requires adding a dependency to a second header internal to libbpf,
and making it a dependency for the bootstrap bpftool version as well.
The rest of the changes are a rather straightforward conversion.

Signed-off-by: Quentin Monnet 
Signed-off-by: Andrii Nakryiko 
Link: https://lore.kernel.org/bpf/20211023205154.6710-4-quentin@isovalent.com

bpftool: Do not expose and init hash maps for pinned path in main.c

2021-10-26T00:31:38+00:00

BPF programs, maps, and links, can all be listed with their pinned paths
by bpftool, when the "-f" option is provided. To do so, bpftool builds
hash maps containing all pinned paths for each kind of objects.

These three hash maps are always initialised in main.c, and exposed
through main.h. There appear to be no particular reason to do so: we can
just as well make them static to the files that need them (prog.c,
map.c, and link.c respectively), and initialise them only when we want
to show objects and the "-f" switch is provided.

This may prevent unnecessary memory allocations if the implementation of
the hash maps was to change in the future.

Signed-off-by: Quentin Monnet 
Signed-off-by: Andrii Nakryiko 
Link: https://lore.kernel.org/bpf/20211023205154.6710-3-quentin@isovalent.com

tools: bpftool: Update and synchronise option list in doc and help msg

2021-07-30T22:40:27+00:00

All bpftool commands support the options for JSON output and debug from
libbpf. In addition, some commands support additional options
corresponding to specific use cases.

The list of options described in the man pages for the different
commands are not always accurate. The messages for interactive help are
mostly limited to HELP_SPEC_OPTIONS, and are even less representative of
the actual set of options supported for the commands.

Let's update the lists:

- HELP_SPEC_OPTIONS is modified to contain the "default" options (JSON
  and debug), and to be extensible (no ending curly bracket).
- All commands use HELP_SPEC_OPTIONS in their help message, and then
  complete the list with their specific options.
- The lists of options in the man pages are updated.
- The formatting of the list for bpftool.rst is adjusted to match
  formatting for the other man pages. This is for consistency, and also
  because it will be helpful in a future patch to automatically check
  that the files are synchronised.

Signed-off-by: Quentin Monnet 
Signed-off-by: Andrii Nakryiko 
Link: https://lore.kernel.org/bpf/20210730215435.7095-5-quentin@isovalent.com

tools: Replace btf__get_from_id() with btf__load_from_kernel_by_id()

2021-07-30T00:23:52+00:00

Replace the calls to function btf__get_from_id(), which we plan to
deprecate before the library reaches v1.0, with calls to
btf__load_from_kernel_by_id() in tools/ (bpftool, perf, selftests).
Update the surrounding code accordingly (instead of passing a pointer to
the btf struct, get it as a return value from the function).

Signed-off-by: Quentin Monnet 
Signed-off-by: Andrii Nakryiko 
Acked-by: John Fastabend 
Link: https://lore.kernel.org/bpf/20210729162028.29512-6-quentin@isovalent.com

bpftool: Fix maybe-uninitialized warnings

2021-03-16T19:26:49+00:00

Somehow when bpftool is compiled in -Og mode, compiler produces new warnings
about possibly uninitialized variables. Fix all the reported problems.

Fixes: 2119f2189df1 ("bpftool: add C output format option to btf dump subcommand")
Signed-off-by: Andrii Nakryiko 
Signed-off-by: Alexei Starovoitov 
Link: https://lore.kernel.org/bpf/20210313210920.1959628-3-andrii@kernel.org

bpftool: Add support for task local storage

2020-11-06T16:08:37+00:00

Updates the binary to handle the BPF_MAP_TYPE_TASK_STORAGE as
"task_storage" for printing and parsing. Also updates the documentation
and bash completion

Signed-off-by: KP Singh 
Signed-off-by: Alexei Starovoitov 
Acked-by: Song Liu 
Acked-by: Martin KaFai Lau 
Link: https://lore.kernel.org/bpf/20201106103747.2780972-5-kpsingh@chromium.org

tools: bpftool: Add "inner_map" to "bpftool map create" outer maps

2020-09-11T00:29:21+00:00

There is no support for creating maps of types array-of-map or
hash-of-map in bpftool. This is because the kernel needs an inner_map_fd
to collect metadata on the inner maps to be supported by the new map,
but bpftool does not provide a way to pass this file descriptor.

Add a new optional "inner_map" keyword that can be used to pass a
reference to a map, retrieve a fd to that map, and pass it as the
inner_map_fd.

Add related documentation and bash completion. Note that we can
reference the inner map by its name, meaning we can have several times
the keyword "name" with different meanings (mandatory outer map name,
and possibly a name to use to find the inner_map_fd). The bash
completion will offer it just once, and will not suggest "name" on the
following command:

    # bpftool map create /sys/fs/bpf/my_outer_map type hash_of_maps \
        inner_map name my_inner_map [TAB]

Fixing that specific case seems too convoluted. Completion will work as
expected, however, if the outer map name comes first and the "inner_map
name ..." is passed second.

Signed-off-by: Quentin Monnet 
Signed-off-by: Alexei Starovoitov 
Acked-by: Andrii Nakryiko 
Link: https://lore.kernel.org/bpf/20200910102652.10509-4-quentin@isovalent.com

tools: bpftool: Keep errors for map-of-map dumps if distinct from ENOENT

2020-09-11T00:29:20+00:00

When dumping outer maps or prog_array maps, and on lookup failure,
bpftool simply skips the entry with no error message. This is because
the kernel returns non-zero when no value is found for the provided key,
which frequently happen for those maps if they have not been filled.

When such a case occurs, errno is set to ENOENT. It seems unlikely we
could receive other error codes at this stage (we successfully retrieved
map info just before), but to be on the safe side, let's skip the entry
only if errno was ENOENT, and not for the other errors.

v3: New patch

Signed-off-by: Quentin Monnet 
Signed-off-by: Alexei Starovoitov 
Acked-by: Andrii Nakryiko 
Link: https://lore.kernel.org/bpf/20200910102652.10509-3-quentin@isovalent.com

tools: bpftool: Clean up function to dump map entry

2020-09-11T00:29:20+00:00

The function used to dump a map entry in bpftool is a bit difficult to
follow, as a consequence to earlier refactorings. There is a variable
("num_elems") which does not appear to be necessary, and the error
handling would look cleaner if moved to its own function. Let's clean it
up. No functional change.

v2:
- v1 was erroneously removing the check on fd maps in an attempt to get
  support for outer map dumps. This is already working. Instead, v2
  focuses on cleaning up the dump_map_elem() function, to avoid
  similar confusion in the future.

Signed-off-by: Quentin Monnet 
Signed-off-by: Alexei Starovoitov 
Acked-by: Andrii Nakryiko 
Link: https://lore.kernel.org/bpf/20200910102652.10509-2-quentin@isovalent.com