bpf: Replace deprecated -target with --target= for Clang

The -target option has been deprecated since clang 3.4 in 2013. Therefore, use
the preferred --target=bpf form instead. This also matches how we use --target=
in scripts/Makefile.clang.

Signed-off-by: Fangrui Song <maskray@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yhs@fb.com>
Acked-by: Quentin Monnet <quentin@isovalent.com>
Link: https://github.com/llvm/llvm-project/commit/274b6f0c87a6a1798de0a68135afc7f95def6277
Link: https://lore.kernel.org/bpf/20230624001856.1903733-1-maskray@google.com

bpftool: Always disable stack protection for BPF objects

When the clang toolchain has stack protection enabled in order to be
consistent with gcc - which just happens to be the case on Gentoo -
the bpftool build fails:

[...]
clang \
-I. \
-I/tmp/portage/dev-util/bpftool-6.0.12/work/linux-6.0/tools/include/uapi/ \
-I/tmp/portage/dev-util/bpftool-6.0.12/work/linux-6.0/tools/bpf/bpftool/bootstrap/libbpf/include \
-g -O2 -Wall -target bpf -c skeleton/pid_iter.bpf.c -o pid_iter.bpf.o
clang \
-I. \
-I/tmp/portage/dev-util/bpftool-6.0.12/work/linux-6.0/tools/include/uapi/ \
-I/tmp/portage/dev-util/bpftool-6.0.12/work/linux-6.0/tools/bpf/bpftool/bootstrap/libbpf/include \
-g -O2 -Wall -target bpf -c skeleton/profiler.bpf.c -o profiler.bpf.o
skeleton/profiler.bpf.c:40:14: error: A call to built-in function '__stack_chk_fail' is not supported.
int BPF_PROG(fentry_XXX)
^
skeleton/profiler.bpf.c:94:14: error: A call to built-in function '__stack_chk_fail' is not supported.
int BPF_PROG(fexit_XXX)
^
2 errors generated.
[...]

Since stack-protector makes no sense for the BPF bits just unconditionally
disable it.

Bug: https://bugs.gentoo.org/890638
Signed-off-by: Holger Hoffstätte <holger@applied-asynchrony.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Quentin Monnet <quentin@isovalent.com>
Link: https://lore.kernel.org/bpf/74cd9d2e-6052-312a-241e-2b514a75c92c@applied-asynchrony.com

bpftool: Add missing quotes to libbpf bootstrap submake vars

When passing compiler variables like CC=$(HOSTCC) to a submake
we must ensure the variable is quoted in order to handle cases
where $(HOSTCC) may be multiple binaries.

For example when using ccache $HOSTCC may be:
"/usr/bin/ccache /usr/bin/gcc"

If we pass CC without quotes like CC=$(HOSTCC) only the first
"/usr/bin/ccache" part will be assigned to the CC variable which
will cause an error due to dropping the "/usr/bin/gcc" part of
the variable in the submake invocation.

This fixes errors such as:
/usr/bin/ccache: invalid option -- 'd'

Signed-off-by: James Hilliard <james.hilliard1@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Quentin Monnet <quentin@isovalent.com>
Link: https://lore.kernel.org/bpf/20230110014504.3120711-1-james.hilliard1@gmail.com

bpf: makefiles: Do not generate empty vmlinux.h

Remove the empty vmlinux.h if bpftool failed to dump btf info.
The empty vmlinux.h can hide real error when reading output
of make.

This is done by adding .DELETE_ON_ERROR special target in related
makefiles.

Signed-off-by: Changbin Du <changbin.du@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Quentin Monnet <quentin@isovalent.com>
Link: https://lore.kernel.org/bpf/20221217223509.88254-3-changbin.du@gmail.com

bpftool: Fix linkage with statically built libllvm

Since the commit eb9d1acf634b ("bpftool: Add LLVM as default library for
disassembling JIT-ed programs") we might link the bpftool program with the
libllvm library. This works fine when a shared libllvm library is available,
but fails if we want to link bpftool with a statically built LLVM:

[...]
/usr/bin/ld: /usr/local/lib/libLLVMSupport.a(CrashRecoveryContext.cpp.o): in function `llvm::CrashRecoveryContextCleanup::~CrashRecoveryContextCleanup()':
CrashRecoveryContext.cpp:(.text._ZN4llvm27CrashRecoveryContextCleanupD0Ev+0x17): undefined reference to `operator delete(void*, unsigned long)'
/usr/bin/ld: /usr/local/lib/libLLVMSupport.a(CrashRecoveryContext.cpp.o): in function `llvm::CrashRecoveryContext::~CrashRecoveryContext()':
CrashRecoveryContext.cpp:(.text._ZN4llvm20CrashRecoveryContextD2Ev+0xc8): undefined reference to `operator delete(void*, unsigned long)'
[...]

So in the case of static libllvm we need to explicitly link bpftool with
required libraries, namely, libstdc++ and those provided by the `llvm-config
--system-libs` command. We can distinguish between the shared and static cases
by using the `llvm-config --shared-mode` command.

Fixes: eb9d1acf634b ("bpftool: Add LLVM as default library for disassembling JIT-ed programs")
Signed-off-by: Anton Protopopov <aspsk@isovalent.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/bpf/20221222102627.1643709-1-aspsk@isovalent.com

bpftool: Add LLVM as default library for disassembling JIT-ed programs

To disassemble instructions for JIT-ed programs, bpftool has relied on
the libbfd library. This has been problematic in the past: libbfd's
interface is not meant to be stable and has changed several times. For
building bpftool, we have to detect how the libbfd version on the system
behaves, which is why we have to handle features disassembler-four-args
and disassembler-init-styled in the Makefile. When it comes to shipping
bpftool, this has also caused issues with several distribution
maintainers unwilling to support the feature (see for example Debian's
page for binutils-dev, which ships libbfd: "Note that building Debian
packages which depend on the shared libbfd is Not Allowed." [0]).

For these reasons, we add support for LLVM as an alternative to libbfd
for disassembling instructions of JIT-ed programs. Thanks to the
preparation work in the previous commits, it's easy to add the library
by passing the relevant compilation options in the Makefile, and by
adding the functions for setting up the LLVM disassembler in file
jit_disasm.c.

The LLVM disassembler requires the LLVM development package (usually
llvm-dev or llvm-devel).

The expectation is that the interface for this disassembler will be more
stable. There is a note in LLVM's Developer Policy [1] stating that the
stability for the C API is "best effort" and not guaranteed, but at
least there is some effort to keep compatibility when possible (which
hasn't really been the case for libbfd so far). Furthermore, the Debian
page for the related LLVM package does not caution against linking to
the lib, as binutils-dev page does.

Naturally, the display of disassembled instructions comes with a few
minor differences. Here is a sample output with libbfd (already
supported before this patch):

# bpftool prog dump jited id 56
bpf_prog_6deef7357e7b4530:
0: nopl 0x0(%rax,%rax,1)
5: xchg %ax,%ax
7: push %rbp
8: mov %rsp,%rbp
b: push %rbx
c: push %r13
e: push %r14
10: mov %rdi,%rbx
13: movzwq 0xb4(%rbx),%r13
1b: xor %r14d,%r14d
1e: or $0x2,%r14d
22: mov $0x1,%eax
27: cmp $0x2,%r14
2b: jne 0x000000000000002f
2d: xor %eax,%eax
2f: pop %r14
31: pop %r13
33: pop %rbx
34: leave
35: ret

LLVM supports several variants that we could set when initialising the
disassembler, for example with:

LLVMSetDisasmOptions(*ctx,
LLVMDisassembler_Option_AsmPrinterVariant);

but the default printer is used for now. Here is the output with LLVM:

# bpftool prog dump jited id 56
bpf_prog_6deef7357e7b4530:
0: nopl (%rax,%rax)
5: nop
7: pushq %rbp
8: movq %rsp, %rbp
b: pushq %rbx
c: pushq %r13
e: pushq %r14
10: movq %rdi, %rbx
13: movzwq 180(%rbx), %r13
1b: xorl %r14d, %r14d
1e: orl $2, %r14d
22: movl $1, %eax
27: cmpq $2, %r14
2b: jne 0x2f
2d: xorl %eax, %eax
2f: popq %r14
31: popq %r13
33: popq %rbx
34: leave
35: retq

The LLVM disassembler comes as the default choice, with libbfd as a
fall-back.

Of course, we could replace libbfd entirely and avoid supporting two
different libraries. One reason for keeping libbfd is that, right now,
it works well, we have all we need in terms of features detection in the
Makefile, so it provides a fallback for disassembling JIT-ed programs if
libbfd is installed but LLVM is not. The other motivation is that libbfd
supports nfp instruction for Netronome's SmartNICs and can be used to
disassemble offloaded programs, something that LLVM cannot do. If
libbfd's interface breaks again in the future, we might reconsider
keeping support for it.

[0] https://packages.debian.org/buster/binutils-dev
[1] https://llvm.org/docs/DeveloperPolicy.html#c-api-changes

Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Tested-by: Niklas Söderlund <niklas.soderlund@corigine.com>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/r/20221025150329.97371-7-quentin@isovalent.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

bpftool: Group libbfd defs in Makefile, only pass them if we use libbfd

Bpftool uses libbfd for disassembling JIT-ed programs. But the feature
is optional, and the tool can be compiled without libbfd support. The
Makefile sets the relevant variables accordingly. It also sets variables
related to libbfd's interface, given that it has changed over time.

Group all those libbfd-related definitions so that it's easier to
understand what we are testing for, and only use variables related to
libbfd's interface if we need libbfd in the first place.

In addition to make the Makefile clearer, grouping the definitions
related to disassembling JIT-ed programs will help support alternatives
to libbfd.

Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Tested-by: Niklas Söderlund <niklas.soderlund@corigine.com>
Acked-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20221025150329.97371-5-quentin@isovalent.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

bpftool: Split FEATURE_TESTS/FEATURE_DISPLAY definitions in Makefile

Make FEATURE_TESTS and FEATURE_DISPLAY easier to read and less likely to
be subject to conflicts on updates by having one feature per line.

Suggested-by: Andres Freund <andres@anarazel.de>
Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Tested-by: Niklas Söderlund <niklas.soderlund@corigine.com>
Acked-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20221025150329.97371-4-quentin@isovalent.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

bpftool: Complete libbfd feature detection

Commit 6e8ccb4f624a7 ("tools/bpf: properly account for libbfd variations")
sets the linking flags depending on which flavor of the libbfd feature was
detected.

However, the flavors except libbfd cannot be detected, as they are not in
the feature list.

Complete the list of features to detect by adding libbfd-liberty and
libbfd-liberty-z.

Committer notes:

Adjust conflict with with:

1e1613f64cc8a09d ("tools bpftool: Don't display disassembler-four-args feature test")
600b7b26c07a070d ("tools bpftool: Fix compilation error with new binutils")

Fixes: 6e8ccb4f624a73c5 ("tools/bpf: properly account for libbfd variations")
Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andres Freund <andres@anarazel.de>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: bpf@vger.kernel.org
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: KP Singh <kpsingh@kernel.org>
Cc: llvm@lists.linux.dev
Cc: Martin KaFai Lau <martin.lau@linux.dev>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Nick Terrell <terrelln@fb.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Monnet <quentin@isovalent.com>
Cc: Song Liu <song@kernel.org>
Cc: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/r/20220719170555.2576993-2-roberto.sassu@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools bpftool: Don't display disassembler-four-args feature test

The feature check does not seem important enough to display.

Requested-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Andres Freund <andres@anarazel.de>
Acked-by: Quentin Monnet <quentin@isovalent.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Ben Hutchings <benh@debian.org>
Cc: Quentin Monnet <quentin@isovalent.com>
Cc: Sedat Dilek <sedat.dilek@gmail.com>
Cc: bpf@vger.kernel.org
Link: http://lore.kernel.org/lkml/20220622181918.ykrs5rsnmx3og4sv@alap3.anarazel.de
Link: https://lore.kernel.org/r/20220801013834.156015-9-andres@anarazel.de
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools bpftool: Fix compilation error with new binutils

binutils changed the signature of init_disassemble_info(), which now causes
compilation to fail for tools/bpf/bpftool/jit_disasm.c, e.g. on debian
unstable.

Relevant binutils commit:

https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=60a3da00bd5407f07

Wire up the feature test and switch to init_disassemble_info_compat(),
which were introduced in prior commits, fixing the compilation failure.

I verified that bpftool can still disassemble bpf programs, both with an
old and new dis-asm.h API. There are no output changes for plain and json
formats. When comparing the output from old binutils (2.35)
to new bintuils with the patch (upstream snapshot) there are a few output
differences, but they are unrelated to this patch. An example hunk is:

2f: pop %r14
31: pop %r13
33: pop %rbx
- 34: leaveq
- 35: retq
+ 34: leave
+ 35: ret

Signed-off-by: Andres Freund <andres@anarazel.de>
Acked-by: Quentin Monnet <quentin@isovalent.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Ben Hutchings <benh@debian.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Quentin Monnet <quentin@isovalent.com>
Cc: Sedat Dilek <sedat.dilek@gmail.com>
Cc: bpf@vger.kernel.org
Link: http://lore.kernel.org/lkml/20220622181918.ykrs5rsnmx3og4sv@alap3.anarazel.de
Link: https://lore.kernel.org/r/20220801013834.156015-8-andres@anarazel.de
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

bpftool: Remove zlib feature test from Makefile

The feature test to detect the availability of zlib in bpftool's
Makefile does not bring much. The library is not optional: it may or may
not be required along libbfd for disassembling instructions, but in any
case it is necessary to build feature.o or even libbpf, on which bpftool
depends.

If we remove the feature test, we lose the nicely formatted error
message, but we get a compiler error about "zlib.h: No such file or
directory", which is equally informative. Let's get rid of the test.

Suggested-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220705200456.285943-1-quentin@isovalent.com

bpftool: Fix bootstrapping during a cross compilation

This change adjusts the Makefile to use "HOSTAR" as the archive tool
to keep the sanity of the build process for the bootstrap part in
check. For the rationale, please continue reading.

When cross compiling bpftool with buildroot, it leads to an invocation
like:

$ AR="/path/to/buildroot/host/bin/arc-linux-gcc-ar" \
CC="/path/to/buildroot/host/bin/arc-linux-gcc" \
...
make

Which in return fails while building the bootstrap section:

----------------------------------8<----------------------------------

make: Entering directory '/src/bpftool-v6.7.0/src'
... libbfd: [ on ]
... disassembler-four-args: [ on ]
... zlib: [ on ]
... libcap: [ OFF ]
... clang-bpf-co-re: [ on ] <-- triggers bootstrap

.
.
.

LINK /src/bpftool-v6.7.0/src/bootstrap/bpftool
/usr/bin/ld: /src/bpftool-v6.7.0/src/bootstrap/libbpf/libbpf.a:
error adding symbols: archive has no index; run ranlib
to add one
collect2: error: ld returned 1 exit status
make: *** [Makefile:211: /src/bpftool-v6.7.0/src/bootstrap/bpftool]
Error 1
make: *** Waiting for unfinished jobs....
AR /src/bpftool-v6.7.0/src/libbpf/libbpf.a
make[1]: Leaving directory '/src/bpftool-v6.7.0/libbpf/src'
make: Leaving directory '/src/bpftool-v6.7.0/src'

---------------------------------->8----------------------------------

This occurs because setting "AR" confuses the build process for the
bootstrap section and it calls "arc-linux-gcc-ar" to create and index
"libbpf.a" instead of the host "ar".

Signed-off-by: Shahab Vahedi <shahab@synopsys.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Cc: Jean-Philippe Brucker <jean-philippe@linaro.org>
Link: https://lore.kernel.org/bpf/8d297f0c-cfd0-ef6f-3970-6dddb3d9a87a@synopsys.com

kbuild: replace $(if A,A,B) with $(or A,B)

$(or ...) is available since GNU Make 3.81, and useful to shorten the
code in some places.

Covert as follows:

$(if A,A,B) --> $(or A,B)

This patch also converts:

$(if A, A, B) --> $(or A, B)

Strictly speaking, the latter is not an equivalent conversion because
GNU Make keeps spaces after commas; if A is not empty, $(if A, A, B)
expands to " A", while $(or A, B) expands to "A".

Anyway, preceding spaces are not significant in the code hunks I touched.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>

bpftool: Remove redundant slashes

Because the OUTPUT variable ends with a slash but CURDIR doesn't, to keep
the _OUTPUT value consistent, we add a trailing slash to CURDIR when
defining _OUTPUT variable.

Since the _OUTPUT variable holds a value ending with a trailing slash,
there is no need to add another one when defining BOOTSTRAP_OUTPUT and
LIBBPF_OUTPUT variables. Likewise, when defining LIBBPF_INCLUDE and
LIBBPF_BOOTSTRAP_INCLUDE, we shouldn't add an extra slash either for the
same reason.

When building libbpf, the value of the DESTDIR argument should also not
end with a trailing slash.

Signed-off-by: Yuntao Wang <ytcoode@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Link: https://lore.kernel.org/bpf/20220226163815.520133-1-ytcoode@gmail.com

bpftool: Remove usage of reallocarray()

This commit fixes a compilation error on systems with glibc < 2.26 [0]:

```
In file included from main.h:14:0,
from gen.c:24:
linux/tools/include/tools/libc_compat.h:11:21: error: attempt to use poisoned "reallocarray"
static inline void *reallocarray(void *ptr, size_t nmemb, size_t size)
```

This happens because gen.c pulls <bpf/libbpf_internal.h>, and then
<tools/libc_compat.h> (through main.h). When
COMPAT_NEED_REALLOCARRAY is set, libc_compat.h defines reallocarray()
which libbpf_internal.h poisons with a GCC pragma.

This commit reuses libbpf_reallocarray() implemented in commit
029258d7b228 ("libbpf: Remove any use of reallocarray() in libbpf").

v1 -> v2:
- reuse libbpf_reallocarray() instead of reimplementing it

Fixes: a9caaba399f9 ("bpftool: Implement "gen min_core_btf" logic")
Reported-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Mauricio Vásquez <mauricio@kinvolk.io>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20220221125617.39610-1-mauricio@kinvolk.io

[0]: https://lore.kernel.org/bpf/3bf2bd49-9f2d-a2df-5536-bc0dde70a83b@isovalent.com/

bpftool: Implement "gen min_core_btf" logic

This commit implements the logic for the gen min_core_btf command.
Specifically, it implements the following functions:

- minimize_btf(): receives the path of a source and destination BTF
files and a list of BPF objects. This function records the relocations
for all objects and then generates the BTF file by calling
btfgen_get_btf() (implemented in the following commit).

- btfgen_record_obj(): loads the BTF and BTF.ext sections of the BPF
objects and loops through all CO-RE relocations. It uses
bpf_core_calc_relo_insn() from libbpf and passes the target spec to
btfgen_record_reloc(), that calls one of the following functions
depending on the relocation kind.

- btfgen_record_field_relo(): uses the target specification to mark all
the types that are involved in a field-based CO-RE relocation. In this
case types resolved and marked recursively using btfgen_mark_type().
Only the struct and union members (and their types) involved in the
relocation are marked to optimize the size of the generated BTF file.

- btfgen_record_type_relo(): marks the types involved in a type-based
CO-RE relocation. In this case no members for the struct and union types
are marked as libbpf doesn't use them while performing this kind of
relocation. Pointed types are marked as they are used by libbpf in this
case.

- btfgen_record_enumval_relo(): marks the whole enum type for enum-based
relocations.

Signed-off-by: Mauricio Vásquez <mauricio@kinvolk.io>
Signed-off-by: Rafael David Tinoco <rafael.tinoco@aquasec.com>
Signed-off-by: Lorenzo Fontana <lorenzo.fontana@elastic.co>
Signed-off-by: Leonardo Di Donato <leonardo.didonato@elastic.co>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220215225856.671072-5-mauricio@kinvolk.io

bpftool: Update versioning scheme, align on libbpf's version number

Since the notion of versions was introduced for bpftool, it has been
following the version number of the kernel (using the version number
corresponding to the tree in which bpftool's sources are located). The
rationale was that bpftool's features are loosely tied to BPF features
in the kernel, and that we could defer versioning to the kernel
repository itself.

But this versioning scheme is confusing today, because a bpftool binary
should be able to work with both older and newer kernels, even if some
of its recent features won't be available on older systems. Furthermore,
if bpftool is ported to other systems in the future, keeping a
Linux-based version number is not a good option.

Looking at other options, we could either have a totally independent
scheme for bpftool, or we could align it on libbpf's version number
(with an offset on the major version number, to avoid going backwards).
The latter comes with a few drawbacks:

- We may want bpftool releases in-between two libbpf versions. We can
always append pre-release numbers to distinguish versions, although
those won't look as "official" as something with a proper release
number. But at the same time, having bpftool with version numbers that
look "official" hasn't really been an issue so far.

- If no new feature lands in bpftool for some time, we may move from
e.g. 6.7.0 to 6.8.0 when libbpf levels up and have two different
versions which are in fact the same.

- Following libbpf's versioning scheme sounds better than kernel's, but
ultimately it doesn't make too much sense either, because even though
bpftool uses the lib a lot, its behaviour is not that much conditioned
by the internal evolution of the library (or by new APIs that it may
not use).

Having an independent versioning scheme solves the above, but at the
cost of heavier maintenance. Developers will likely forget to increase
the numbers when adding features or bug fixes, and we would take the
risk of having to send occasional "catch-up" patches just to update the
version number.

Based on these considerations, this patch aligns bpftool's version
number on libbpf's. This is not a perfect solution, but 1) it's
certainly an improvement over the current scheme, 2) the issues raised
above are all minor at the moment, and 3) we can still move to an
independent scheme in the future if we realise we need it.

Given that libbpf is currently at version 0.7.0, and bpftool, before
this patch, was at 5.16, we use an offset of 6 for the major version,
bumping bpftool to 6.7.0. Libbpf does not export its patch number;
leave bpftool's patch number at 0 for now.

It remains possible to manually override the version number by setting
BPFTOOL_VERSION when calling make.

Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220210104237.11649-3-quentin@isovalent.com

bpftool: Enable cross-building with clang

Cross-building using clang requires passing the "-target" flag rather
than using the CROSS_COMPILE prefix. Makefile.include transforms
CROSS_COMPILE into CLANG_CROSS_FLAGS, and adds that to CFLAGS. Remove
the cross flags for the bootstrap bpftool, and erase the CROSS_COMPILE
flag for the bootstrap libbpf.

Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Quentin Monnet <quentin@isovalent.com>
Link: https://lore.kernel.org/bpf/20211216163842.829836-5-jean-philippe@linaro.org

bpftool: Remove inclusion of utilities.mak from Makefiles

Bpftool's Makefile, and the Makefile for its documentation, both include
scripts/utilities.mak, but they use none of the items defined in this
file. Remove the includes.

Fixes: 71bb428fe2c1 ("tools: bpf: add bpftool")
Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211110114632.24537-3-quentin@isovalent.com

bpftool: Normalize compile rules to specify output file last

When dealing with verbose Makefile output, it's extremely confusing when
compiler invocation commands don't specify -o <output.o> as the last
argument. Normalize bpftool's Makefile to do just that, as most other
BPF-related Makefiles are already doing that.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211111053624.190580-2-andrii@kernel.org

bpftool: Fix SPDX tag for Makefiles and .gitignore

Bpftool is dual-licensed under GPLv2 and BSD-2-Clause. In commit
907b22365115 ("tools: bpftool: dual license all files") we made sure
that all its source files were indeed covered by the two licenses, and
that they had the correct SPDX tags.

However, bpftool's Makefile, the Makefile for its documentation, and the
.gitignore file were skipped at the time (their GPL-2.0-only tag was
added later). Let's update the tags.

Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Tobias Klauser <tklauser@distanz.ch>
Acked-by: Joe Stringer <joe@cilium.io>
Acked-by: Song Liu <songliubraving@fb.com>
Acked-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Link: https://lore.kernel.org/bpf/20211105221904.3536-1-quentin@isovalent.com

bpftool: Install libbpf headers for the bootstrap version, too

We recently changed bpftool's Makefile to make it install libbpf's
headers locally instead of pulling them from the source directory of the
library. Although bpftool needs two versions of libbpf, a "regular" one
and a "bootstrap" version, we would only install headers for the regular
libbpf build. Given that this build always occurs before the bootstrap
build when building bpftool, this is enough to ensure that the bootstrap
bpftool will have access to the headers exported through the regular
libbpf build.

However, this did not account for the case when we only want the
bootstrap version of bpftool, through the "bootstrap" target. For
example, perf needs the bootstrap version only, to generate BPF
skeletons. In that case, when are the headers installed? For some time,
the issue has been masked, because we had a step (the installation of
headers internal to libbpf) which would depend on the regular build of
libbpf and hence trigger the export of the headers, just for the sake of
creating a directory. But this changed with commit 8b6c46241c77
("bpftool: Remove Makefile dep. on $(LIBBPF) for
$(LIBBPF_INTERNAL_HDRS)"), where we cleaned up that stage and removed
the dependency on the regular libbpf build. As a result, when we only
want the bootstrap bpftool version, the regular libbpf is no longer
built. The bootstrap libbpf version is built, but headers are not
exported, and the bootstrap bpftool build fails because of the missing
headers.

To fix this, we also install the library headers for the bootstrap
version of libbpf, to use them for the bootstrap bpftool and for
generating the skeletons.

Fixes: f012ade10b34 ("bpftool: Install libbpf headers instead of including the dir")
Reported-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Link: https://lore.kernel.org/bpf/20211105015813.6171-1-quentin@isovalent.com

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

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

bpftool: Remove Makefile dep. on $(LIBBPF) for $(LIBBPF_INTERNAL_HDRS)

The dependency is only useful to make sure that the $(LIBBPF_HDRS_DIR)
directory is created before we try to install locally the required
libbpf internal header. Let's create this directory properly instead.

This is in preparation of making $(LIBBPF_INTERNAL_HDRS) a dependency to
the bootstrap bpftool version, in which case we want no dependency on
$(LIBBPF).

Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211023205154.6710-2-quentin@isovalent.com

bpftool: Remove useless #include to <perf-sys.h> from map_perf_ring.c

The header is no longer needed since the event_pipe implementation
was updated to rely on libbpf's perf_buffer. This makes bpftool free of
dependencies to perf files, and we can update the Makefile accordingly.

Fixes: 9b190f185d2f ("tools/bpftool: switch map event_pipe to libbpf's perf_buffer")
Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211020094826.16046-1-quentin@isovalent.com

bpftool: Turn check on zlib from a phony target into a conditional error

One of bpftool's object files depends on zlib. To make sure we do not
attempt to build that object when the library is not available, commit
d66fa3c70e59 ("tools: bpftool: add feature check for zlib") introduced a
feature check to detect whether zlib is present.

This check comes as a rule for which the target ("zdep") is a
nonexistent file (phony target), which means that the Makefile always
attempts to rebuild it. It is mostly harmless. However, one side effect
is that, on running again once bpftool is already built, make considers
that "something" (the recipe for zdep) was executed, and does not print
the usual message "make: Nothing to be done for 'all'", which is a
user-friendly indicator that the build went fine.

Before, with some level of debugging information:

$ make --debug=m
[...]
Reading makefiles...

Auto-detecting system features:
... libbfd: [ on ]
... disassembler-four-args: [ on ]
... zlib: [ on ]
... libcap: [ on ]
... clang-bpf-co-re: [ on ]

Updating makefiles....
Updating goal targets....
File 'all' does not exist.
File 'zdep' does not exist.
Must remake target 'zdep'.
File 'all' does not exist.
Must remake target 'all'.
Successfully remade target file 'all'.

After the patch:

$ make --debug=m
[...]

Auto-detecting system features:
... libbfd: [ on ]
... disassembler-four-args: [ on ]
... zlib: [ on ]
... libcap: [ on ]
... clang-bpf-co-re: [ on ]

Updating makefiles....
Updating goal targets....
File 'all' does not exist.
Must remake target 'all'.
Successfully remade target file 'all'.
make: Nothing to be done for 'all'.

(Note the last line, which is not part of make's debug information.)

Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20211009210341.6291-4-quentin@isovalent.com

bpftool: Do not FORCE-build libbpf

In bpftool's Makefile, libbpf has a FORCE dependency, to make sure we
rebuild it in case its source files changed. Let's instead make the
rebuild depend on the source files directly, through a call to the
"$(wildcard ...)" function. This avoids descending into libbpf's
directory if there is nothing to update.

Do the same for the bootstrap libbpf version.

This results in a slightly faster operation and less verbose output when
running make a second time in bpftool's directory.

Before:

Auto-detecting system features:
... libbfd: [ on ]
... disassembler-four-args: [ on ]
... zlib: [ on ]
... libcap: [ on ]
... clang-bpf-co-re: [ on ]

make[1]: Entering directory '/root/dev/linux/tools/lib/bpf'
make[1]: Entering directory '/root/dev/linux/tools/lib/bpf'
make[1]: Nothing to be done for 'install_headers'.
make[1]: Leaving directory '/root/dev/linux/tools/lib/bpf'
make[1]: Leaving directory '/root/dev/linux/tools/lib/bpf'

After:

Auto-detecting system features:
... libbfd: [ on ]
... disassembler-four-args: [ on ]
... zlib: [ on ]
... libcap: [ on ]
... clang-bpf-co-re: [ on ]

Other ways to clean up the output could be to pass the "-s" option, or
to redirect the output to >/dev/null, when calling make recursively to
descend into libbpf's directory. However, this would suppress some
useful output if something goes wrong during the build. A better
alternative would be to pass "--no-print-directory" to the recursive
make, but that would still leave us with some noise for
"install_headers". Skipping the descent into libbpf's directory if no
source file has changed works best, and seems the most logical option
overall.

Reported-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20211009210341.6291-3-quentin@isovalent.com

bpftool: Fix install for libbpf's internal header(s)

We recently updated bpftool's Makefile to make it install the headers
from libbpf, instead of pulling them directly from libbpf's directory.
There is also an additional header, internal to libbpf, that needs be
installed. The way that bpftool's Makefile installs that particular
header is currently correct, but would break if we were to modify
$(LIBBPF_INTERNAL_HDRS) to make it point to more than one header.

Use a static pattern rule instead, so that the Makefile can withstand
the addition of other headers to install.

The objective is simply to make the Makefile more robust. It should
_not_ be read as an invitation to import more internal headers from
libbpf into bpftool.

Fixes: f012ade10b34 ("bpftool: Install libbpf headers instead of including the dir")
Reported-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20211009210341.6291-2-quentin@isovalent.com

bpftool: Add install-bin target to install binary only

With "make install", bpftool installs its binary and its bash completion
file. Usually, this is what we want. But a few components in the kernel
repository (namely, BPF iterators and selftests) also install bpftool
locally before using it. In such a case, bash completion is not
necessary and is just a useless build artifact.

Let's add an "install-bin" target to bpftool, to offer a way to install
the binary only.

Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211007194438.34443-13-quentin@isovalent.com

bpftool: Install libbpf headers instead of including the dir

Bpftool relies on libbpf, therefore it relies on a number of headers
from the library and must be linked against the library. The Makefile
for bpftool exposes these objects by adding tools/lib as an include
directory ("-I$(srctree)/tools/lib"). This is a working solution, but
this is not the cleanest one. The risk is to involuntarily include
objects that are not intended to be exposed by the libbpf.

The headers needed to compile bpftool should in fact be "installed" from
libbpf, with its "install_headers" Makefile target. In addition, there
is one header which is internal to the library and not supposed to be
used by external applications, but that bpftool uses anyway.

Adjust the Makefile in order to install the header files properly before
compiling bpftool. Also copy the additional internal header file
(nlattr.h), but call it out explicitly. Build (and install headers) in a
subdirectory under bpftool/ instead of tools/lib/bpf/. When descending
from a parent Makefile, this is configurable by setting the OUTPUT,
LIBBPF_OUTPUT and LIBBPF_DESTDIR variables.

Also adjust the Makefile for BPF selftests, so as to reuse the (host)
libbpf compiled earlier and to avoid compiling a separate version of the
library just for bpftool.

Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211007194438.34443-4-quentin@isovalent.com

libbpf: Make libbpf_version.h non-auto-generated

Turn previously auto-generated libbpf_version.h header into a normal
header file. This prevents various tricky Makefile integration issues,
simplifies the overall build process, but also allows to further extend
it with some more versioning-related APIs in the future.

To prevent accidental out-of-sync versions as defined by libbpf.map and
libbpf_version.h, Makefile checks their consistency at build time.

Simultaneously with this change bump libbpf.map to v0.6.

Also undo adding libbpf's output directory into include path for
kernel/bpf/preload, bpftool, and resolve_btfids, which is not necessary
because libbpf_version.h is just a normal header like any other.

Fixes: 0b46b7550560 ("libbpf: Add LIBBPF_DEPRECATED_SINCE macro for scheduling API deprecations")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210913222309.3220849-1-andrii@kernel.org

libbpf: Add LIBBPF_DEPRECATED_SINCE macro for scheduling API deprecations

Introduce a macro LIBBPF_DEPRECATED_SINCE(major, minor, message) to prepare
the deprecation of two API functions. This macro marks functions as deprecated
when libbpf's version reaches the values passed as an argument.

As part of this change libbpf_version.h header is added with recorded major
(LIBBPF_MAJOR_VERSION) and minor (LIBBPF_MINOR_VERSION) libbpf version macros.
They are now part of libbpf public API and can be relied upon by user code.
libbpf_version.h is installed system-wide along other libbpf public headers.

Due to this new build-time auto-generated header, in-kernel applications
relying on libbpf (resolve_btfids, bpftool, bpf_preload) are updated to
include libbpf's output directory as part of a list of include search paths.
Better fix would be to use libbpf's make_install target to install public API
headers, but that clean up is left out as a future improvement. The build
changes were tested by building kernel (with KBUILD_OUTPUT and O= specified
explicitly), bpftool, libbpf, selftests/bpf, and resolve_btfids builds. No
problems were detected.

Note that because of the constraints of the C preprocessor we have to write
a few lines of macro magic for each version used to prepare deprecation (0.6
for now).

Also, use LIBBPF_DEPRECATED_SINCE() to schedule deprecation of
btf__get_from_id() and btf__load(), which are replaced by
btf__load_from_kernel_by_id() and btf__load_into_kernel(), respectively,
starting from future libbpf v0.6. This is part of libbpf 1.0 effort ([0]).

[0] Closes: https://github.com/libbpf/libbpf/issues/278

Co-developed-by: Quentin Monnet <quentin@isovalent.com>
Co-developed-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210908213226.1871016-1-andrii@kernel.org

tools/bpftool: Fix cross-build

When the bootstrap and final bpftool have different architectures, we
need to build two distinct disasm.o objects. Add a recipe for the
bootstrap disasm.o.

After commit d510296d331a ("bpftool: Use syscall/loader program in
"prog load" and "gen skeleton" command.") cross-building bpftool didn't
work anymore, because the bootstrap bpftool was linked using objects
from different architectures:

$ make O=/tmp/bpftool ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- -C tools/bpf/bpftool/ V=1
[...]
aarch64-linux-gnu-gcc ... -c -MMD -o /tmp/bpftool/disasm.o /home/z/src/linux/kernel/bpf/disasm.c
gcc ... -c -MMD -o /tmp/bpftool//bootstrap/main.o main.c
gcc ... -o /tmp/bpftool//bootstrap/bpftool /tmp/bpftool//bootstrap/main.o ... /tmp/bpftool/disasm.o
/usr/bin/ld: /tmp/bpftool/disasm.o: Relocations in generic ELF (EM: 183)
/usr/bin/ld: /tmp/bpftool/disasm.o: Relocations in generic ELF (EM: 183)
/usr/bin/ld: /tmp/bpftool/disasm.o: Relocations in generic ELF (EM: 183)
/usr/bin/ld: /tmp/bpftool/disasm.o: error adding symbols: file in wrong format
collect2: error: ld returned 1 exit status
[...]

The final bpftool was built for e.g. arm64, while the bootstrap bpftool,
executed on the host, was built for x86. The problem here was that disasm.o
linked into the bootstrap bpftool was arm64 rather than x86. With the fix
we build two disasm.o, one for the target bpftool in arm64, and one for
the bootstrap bpftool in x86.

Fixes: d510296d331a ("bpftool: Use syscall/loader program in "prog load" and "gen skeleton" command.")
Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210603170515.1854642-1-jean-philippe@linaro.org

bpftool: Use syscall/loader program in "prog load" and "gen skeleton" command.

Add -L flag to bpftool to use libbpf gen_trace facility and syscall/loader program
for skeleton generation and program loading.

"bpftool gen skeleton -L" command will generate a "light skeleton" or "loader skeleton"
that is similar to existing skeleton, but has one major difference:
$ bpftool gen skeleton lsm.o > lsm.skel.h
$ bpftool gen skeleton -L lsm.o > lsm.lskel.h
$ diff lsm.skel.h lsm.lskel.h
@@ -5,34 +4,34 @@
#define __LSM_SKEL_H__

#include <stdlib.h>
-#include <bpf/libbpf.h>
+#include <bpf/bpf.h>

The light skeleton does not use majority of libbpf infrastructure.
It doesn't need libelf. It doesn't parse .o file.
It only needs few sys_bpf wrappers. All of them are in bpf/bpf.h file.
In future libbpf/bpf.c can be inlined into bpf.h, so not even libbpf.a would be
needed to work with light skeleton.

"bpftool prog load -L file.o" command is introduced for debugging of syscall/loader
program generation. Just like the same command without -L it will try to load
the programs from file.o into the kernel. It won't even try to pin them.

"bpftool prog load -L -d file.o" command will provide additional debug messages
on how syscall/loader program was generated.
Also the execution of syscall/loader program will use bpf_trace_printk() for
each step of loading BTF, creating maps, and loading programs.
The user can do "cat /.../trace_pipe" for further debug.

An example of fexit_sleep.lskel.h generated from progs/fexit_sleep.c:
struct fexit_sleep {
struct bpf_loader_ctx ctx;
struct {
struct bpf_map_desc bss;
} maps;
struct {
struct bpf_prog_desc nanosleep_fentry;
struct bpf_prog_desc nanosleep_fexit;
} progs;
struct {
int nanosleep_fentry_fd;
int nanosleep_fexit_fd;
} links;
struct fexit_sleep__bss {
int pid;
int fentry_cnt;
int fexit_cnt;
} *bss;
};

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210514003623.28033-18-alexei.starovoitov@gmail.com

bpftool: Add Makefile target bootstrap

This target is used to only build the bootstrap bpftool, which will be
used to generate bpf skeletons for other tools, like perf.

Signed-off-by: Song Liu <songliubraving@fb.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: kernel-team@fb.com
Link: http://lore.kernel.org/lkml/20201228174054.907740-2-songliubraving@fb.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools: Factor Clang, LLC and LLVM utils definitions

When dealing with BPF/BTF/pahole and DWARF v5 I wanted to build bpftool.

While looking into the source code I found duplicate assignments in misc tools
for the LLVM eco system, e.g. clang and llvm-objcopy.

Move the Clang, LLC and/or LLVM utils definitions to tools/scripts/Makefile.include
file and add missing includes where needed. Honestly, I was inspired by the commit
c8a950d0d3b9 ("tools: Factor HOSTCC, HOSTLD, HOSTAR definitions").

I tested with bpftool and perf on Debian/testing AMD64 and LLVM/Clang v11.1.0-rc1.

Build instructions:

[ make and make-options ]
MAKE="make V=1"
MAKE_OPTS="HOSTCC=clang HOSTCXX=clang++ HOSTLD=ld.lld CC=clang LD=ld.lld LLVM=1 LLVM_IAS=1"
MAKE_OPTS="$MAKE_OPTS PAHOLE=/opt/pahole/bin/pahole"

[ clean-up ]
$MAKE $MAKE_OPTS -C tools/ clean

[ bpftool ]
$MAKE $MAKE_OPTS -C tools/bpf/bpftool/

[ perf ]
PYTHON=python3 $MAKE $MAKE_OPTS -C tools/perf/

I was careful with respecting the user's wish to override custom compiler, linker,
GNU/binutils and/or LLVM utils settings.

Signed-off-by: Sedat Dilek <sedat.dilek@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Jiri Olsa <jolsa@redhat.com> # tools/build and tools/perf
Link: https://lore.kernel.org/bpf/20210128015117.20515-1-sedat.dilek@gmail.com

tools/bpftool: Add -Wall when building BPF programs

No additional warnings are generated by enabling this, but having it
enabled will help avoid regressions.

Signed-off-by: Ian Rogers <irogers@google.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210113223609.3358812-2-irogers@google.com

tools/bpf: Always run the *-clean recipes

Make $(LIBBPF)-clean and $(LIBBPF_BOOTSTRAP)-clean .PHONY targets, in
case those files exist. And keep consistency within the Makefile by
making the directory dependencies order-only.

Suggested-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20201112091049.3159055-2-jean-philippe@linaro.org

tools/bpftool: Fix build slowdown

Commit ba2fd563b740 ("tools/bpftool: Support passing BPFTOOL_VERSION to
make") changed BPFTOOL_VERSION to a recursively expanded variable,
forcing it to be recomputed on every expansion of CFLAGS and
dramatically slowing down the bpftool build. Restore BPFTOOL_VERSION as
a simply expanded variable, guarded by an ifeq().

Fixes: ba2fd563b740 ("tools/bpftool: Support passing BPFTOOL_VERSION to make")
Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20201110164310.2600671-8-jean-philippe@linaro.org

tools/bpftool: Fix cross-build

The bpftool build first creates an intermediate binary, executed on the
host, to generate skeletons required by the final build. When
cross-building bpftool for an architecture different from the host, the
intermediate binary should be built using the host compiler (gcc) and
the final bpftool using the cross compiler (e.g. aarch64-linux-gnu-gcc).

Generate the intermediate objects into the bootstrap/ directory using
the host toolchain.

Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20201110164310.2600671-4-jean-philippe@linaro.org

tools/bpftool: Force clean of out-of-tree build

Cleaning a partial build can fail if the output directory for libbpf
wasn't created:

$ make -C tools/bpf/bpftool O=/tmp/bpf clean
/bin/sh: line 0: cd: /tmp/bpf/libbpf/: No such file or directory
tools/scripts/Makefile.include:17: *** output directory "/tmp/bpf/libbpf/" does not exist. Stop.
make: *** [Makefile:36: /tmp/bpf/libbpf/libbpf.a-clean] Error 2

As a result make never gets around to clearing the leftover objects. Add
the libbpf output directory as clean dependency to ensure clean always
succeeds (similarly to the "descend" macro). The directory is later
removed by the clean recipe.

Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20201110164310.2600671-3-jean-philippe@linaro.org

tools/bpftool: Support passing BPFTOOL_VERSION to make

This change facilitates out-of-tree builds, packaging, and versioning for
test and debug purposes. Defining BPFTOOL_VERSION allows self-contained
builds within the tools tree, since it avoids use of the 'kernelversion'
target in the top-level makefile, which would otherwise pull in several
other includes from outside the tools tree.

Signed-off-by: Tony Ambardar <Tony.Ambardar@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Quentin Monnet <quentin@isovalent.com>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20200917115833.1235518-1-Tony.Ambardar@gmail.com

tools, bpf/build: Cleanup feature files on make clean

The system for "Auto-detecting system features" located under
tools/build/ are (currently) used by perf, libbpf and bpftool. It can
contain stalled feature detection files, which are not cleaned up by
libbpf and bpftool on make clean (side-note: perf tool is correct).

Fix this by making the users invoke the make clean target.

Some details about the changes. The libbpf Makefile already had a
clean-config target (which seems to be copy-pasted from perf), but this
target was not "connected" (a make dependency) to clean target. Choose
not to rename target as someone might be using it. Did change the output
from "CLEAN config" to "CLEAN feature-detect", to make it more clear
what happens.

This is related to the complaint and troubleshooting in the following
link: https://lore.kernel.org/lkml/20200818122007.2d1cfe2d@carbon/

Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Link: https://lore.kernel.org/lkml/20200818122007.2d1cfe2d@carbon/
Link: https://lore.kernel.org/bpf/159851841661.1072907.13770213104521805592.stgit@firesoul

tools/bpftool: Strip BPF .o files before skeleton generation

Strip away DWARF info from .bpf.o files, before generating BPF skeletons.
This reduces bpftool binary size from 3.43MB to 2.58MB.

Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Quentin Monnet <quentin@isovalent.com>
Link: https://lore.kernel.org/bpf/20200722043804.2373298-1-andriin@fb.com

tools/bpftool: Turn off -Wnested-externs warning

Turn off -Wnested-externs to avoid annoying warnings in BUILD_BUG_ON macro when
compiling bpftool:

In file included from /data/users/andriin/linux/tools/include/linux/build_bug.h:5,
from /data/users/andriin/linux/tools/include/linux/kernel.h:8,
from /data/users/andriin/linux/kernel/bpf/disasm.h:10,
from /data/users/andriin/linux/kernel/bpf/disasm.c:8:
/data/users/andriin/linux/kernel/bpf/disasm.c: In function ‘__func_get_name’:
/data/users/andriin/linux/tools/include/linux/compiler.h:37:38: warning: nested extern declaration of ‘__compiletime_assert_0’ [-Wnested-externs]
_compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
^~~~~~~~~~~~~~~~~~~~~
/data/users/andriin/linux/tools/include/linux/compiler.h:16:15: note: in definition of macro ‘__compiletime_assert’
extern void prefix ## suffix(void) __compiletime_error(msg); \
^~~~~~
/data/users/andriin/linux/tools/include/linux/compiler.h:37:2: note: in expansion of macro ‘_compiletime_assert’
_compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
^~~~~~~~~~~~~~~~~~~
/data/users/andriin/linux/tools/include/linux/build_bug.h:39:37: note: in expansion of macro ‘compiletime_assert’
#define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg)
^~~~~~~~~~~~~~~~~~
/data/users/andriin/linux/tools/include/linux/build_bug.h:50:2: note: in expansion of macro ‘BUILD_BUG_ON_MSG’
BUILD_BUG_ON_MSG(condition, "BUILD_BUG_ON failed: " #condition)
^~~~~~~~~~~~~~~~
/data/users/andriin/linux/kernel/bpf/disasm.c:20:2: note: in expansion of macro ‘BUILD_BUG_ON’
BUILD_BUG_ON(ARRAY_SIZE(func_id_str) != __BPF_FUNC_MAX_ID);
^~~~~~~~~~~~

Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20200701212816.2072340-1-andriin@fb.com

tools/bpftool: Allow substituting custom vmlinux.h for the build

In some build contexts (e.g., Travis CI build for outdated kernel), vmlinux.h,
generated from available kernel, doesn't contain all the types necessary for
BPF program compilation. For such set up, the most maintainable way to deal
with this problem is to keep pre-generated (almost up-to-date) vmlinux.h
checked in and use it for compilation purposes. bpftool after that can deal
with kernel missing some of the features in runtime with no problems.

To that effect, allow to specify path to custom vmlinux.h to bpftool's
Makefile with VMLINUX_H variable.

Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20200630004759.521530-1-andriin@fb.com

tools, bpftool: Correctly evaluate $(BUILD_BPF_SKELS) in Makefile

Currently, if the clang-bpf-co-re feature is not available, the build
fails with e.g.

CC prog.o
prog.c:1462:10: fatal error: profiler.skel.h: No such file or directory
1462 | #include "profiler.skel.h"
| ^~~~~~~~~~~~~~~~~

This is due to the fact that the BPFTOOL_WITHOUT_SKELETONS macro is not
defined, despite BUILD_BPF_SKELS not being set. Fix this by correctly
evaluating $(BUILD_BPF_SKELS) when deciding on whether to add
-DBPFTOOL_WITHOUT_SKELETONS to CFLAGS.

Fixes: 05aca6da3b5a ("tools/bpftool: Generalize BPF skeleton support and generate vmlinux.h")
Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200623103710.10370-1-tklauser@distanz.ch

tools/bpftool: Show info for processes holding BPF map/prog/link/btf FDs

Add bpf_iter-based way to find all the processes that hold open FDs against
BPF object (map, prog, link, btf). bpftool always attempts to discover this,
but will silently give up if kernel doesn't yet support bpf_iter BPF programs.
Process name and PID are emitted for each process (task group).

Sample output for each of 4 BPF objects:

$ sudo ./bpftool prog show
2694: cgroup_device tag 8c42dee26e8cd4c2 gpl
loaded_at 2020-06-16T15:34:32-0700 uid 0
xlated 648B jited 409B memlock 4096B
pids systemd(1)
2907: cgroup_skb name egress tag 9ad187367cf2b9e8 gpl
loaded_at 2020-06-16T18:06:54-0700 uid 0
xlated 48B jited 59B memlock 4096B map_ids 2436
btf_id 1202
pids test_progs(2238417), test_progs(2238445)

$ sudo ./bpftool map show
2436: array name test_cgr.bss flags 0x400
key 4B value 8B max_entries 1 memlock 8192B
btf_id 1202
pids test_progs(2238417), test_progs(2238445)
2445: array name pid_iter.rodata flags 0x480
key 4B value 4B max_entries 1 memlock 8192B
btf_id 1214 frozen
pids bpftool(2239612)

$ sudo ./bpftool link show
61: cgroup prog 2908
cgroup_id 375301 attach_type egress
pids test_progs(2238417), test_progs(2238445)
62: cgroup prog 2908
cgroup_id 375344 attach_type egress
pids test_progs(2238417), test_progs(2238445)

$ sudo ./bpftool btf show
1202: size 1527B prog_ids 2908,2907 map_ids 2436
pids test_progs(2238417), test_progs(2238445)
1242: size 34684B
pids bpftool(2258892)

Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Link: https://lore.kernel.org/bpf/20200619231703.738941-9-andriin@fb.com

tools/bpftool: Generalize BPF skeleton support and generate vmlinux.h

Adapt Makefile to support BPF skeleton generation beyond single profiler.bpf.c
case. Also add vmlinux.h generation and switch profiler.bpf.c to use it.

clang-bpf-global-var feature is extended and renamed to clang-bpf-co-re to
check for support of preserve_access_index attribute, which, together with BTF
for global variables, is the minimum requirement for modern BPF programs.

Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Link: https://lore.kernel.org/bpf/20200619231703.738941-7-andriin@fb.com

tools/bpftool: Minimize bootstrap bpftool

Build minimal "bootstrap mode" bpftool to enable skeleton (and, later,
vmlinux.h generation), instead of building almost complete, but slightly
different (w/o skeletons, etc) bpftool to bootstrap complete bpftool build.

Current approach doesn't scale well (engineering-wise) when adding more BPF
programs to bpftool and other complicated functionality, as it requires
constant adjusting of the code to work in both bootstrapped mode and normal
mode.

So it's better to build only minimal bpftool version that supports only BPF
skeleton code generation and BTF-to-C conversion. Thankfully, this is quite
easy to accomplish due to internal modularity of bpftool commands. This will
also allow to keep adding new functionality to bpftool in general, without the
need to care about bootstrap mode for those new parts of bpftool.

Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Link: https://lore.kernel.org/bpf/20200619231703.738941-6-andriin@fb.com

tools/bpf: Don't use $(COMPILE.c)

When using make kselftest TARGETS=bpf, tools/bpf is built with
MAKEFLAGS=rR, which causes $(COMPILE.c) to be undefined, which in turn
causes the build to fail with

CC kselftest/bpf/tools/build/bpftool/map_perf_ring.o
/bin/sh: 1: -MMD: not found

Fix by using $(CC) $(CFLAGS) -c instead of $(COMPILE.c).

Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20200602175649.2501580-2-iii@linux.ibm.com

tools: bpftool: Make libcap dependency optional

The new libcap dependency is not used for an essential feature of
bpftool, and we could imagine building the tool without checks on
CAP_SYS_ADMIN by disabling probing features as an unprivileged users.

Make it so, in order to avoid a hard dependency on libcap, and to ease
packaging/embedding of bpftool.

Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20200429144506.8999-4-quentin@isovalent.com

tools: bpftool: Allow unprivileged users to probe features

There is demand for a way to identify what BPF helper functions are
available to unprivileged users. To do so, allow unprivileged users to
run "bpftool feature probe" to list BPF-related features. This will only
show features accessible to those users, and may not reflect the full
list of features available (to administrators) on the system.

To avoid the case where bpftool is inadvertently run as non-root and
would list only a subset of the features supported by the system when it
would be expected to list all of them, running as unprivileged is gated
behind the "unprivileged" keyword passed to the command line. When used
by a privileged user, this keyword allows to drop the CAP_SYS_ADMIN and
to list the features available to unprivileged users. Note that this
addsd a dependency on libpcap for compiling bpftool.

Note that there is no particular reason why the probes were restricted
to root, other than the fact I did not need them for unprivileged and
did not bother with the additional checks at the time probes were added.

Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20200429144506.8999-3-quentin@isovalent.com

tools/bpf: Move linux/types.h for selftests and bpftool

Commit fe4eb069edb7 ("bpftool: Use linux/types.h from source tree for
profiler build") added a build dependency on tools/testing/selftests/bpf
to tools/bpf/bpftool. This is suboptimal with respect to a possible
stand-alone build of bpftool.

Fix this by moving tools/testing/selftests/bpf/include/uapi/linux/types.h
to tools/include/uapi/linux/types.h.

This requires an adjustment in the include search path order for the
tests in tools/testing/selftests/bpf so that tools/include/linux/types.h
is selected when building host binaries and
tools/include/uapi/linux/types.h is selected when building bpf binaries.

Verified by compiling bpftool and the bpf selftests on x86_64 with this
change.

Fixes: fe4eb069edb7 ("bpftool: Use linux/types.h from source tree for profiler build")
Suggested-by: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Link: https://lore.kernel.org/bpf/20200313113105.6918-1-tklauser@distanz.ch

bpftool: Skeleton should depend on libbpf

Add the dependency to libbpf, to fix build errors like:

In file included from skeleton/profiler.bpf.c:5:
.../bpf_helpers.h:5:10: fatal error: 'bpf_helper_defs.h' file not found
#include "bpf_helper_defs.h"
^~~~~~~~~~~~~~~~~~~
1 error generated.
make: *** [skeleton/profiler.bpf.o] Error 1
make: *** Waiting for unfinished jobs....

Fixes: 47c09d6a9f67 ("bpftool: Introduce "prog profile" command")
Suggested-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20200312182332.3953408-3-songliubraving@fb.com

bpftool: Only build bpftool-prog-profile if supported by clang

bpftool-prog-profile requires clang to generate BTF for global variables.
When compared with older clang, skip this command. This is achieved by
adding a new feature, clang-bpf-global-var, to tools/build/feature.

Signed-off-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Link: https://lore.kernel.org/bpf/20200312182332.3953408-2-songliubraving@fb.com

bpftool: Use linux/types.h from source tree for profiler build

When compiling bpftool on a system where the /usr/include/asm symlink
doesn't exist (e.g. on an Ubuntu system without gcc-multilib installed),
the build fails with:

CLANG skeleton/profiler.bpf.o
In file included from skeleton/profiler.bpf.c:4:
In file included from /usr/include/linux/bpf.h:11:
/usr/include/linux/types.h:5:10: fatal error: 'asm/types.h' file not found
#include <asm/types.h>
^~~~~~~~~~~~~
1 error generated.
make: *** [Makefile:123: skeleton/profiler.bpf.o] Error 1

This indicates that the build is using linux/types.h from system headers
instead of source tree headers.

To fix this, adjust the clang search path to include the necessary
headers from tools/testing/selftests/bpf/include/uapi and
tools/include/uapi. Also use __bitwise__ instead of __bitwise in
skeleton/profiler.h to avoid clashing with the definition in
tools/testing/selftests/bpf/include/uapi/linux/types.h.

Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Link: https://lore.kernel.org/bpf/20200312130330.32239-1-tklauser@distanz.ch

bpftool: Introduce "prog profile" command

With fentry/fexit programs, it is possible to profile BPF program with
hardware counters. Introduce bpftool "prog profile", which measures key
metrics of a BPF program.

bpftool prog profile command creates per-cpu perf events. Then it attaches
fentry/fexit programs to the target BPF program. The fentry program saves
perf event value to a map. The fexit program reads the perf event again,
and calculates the difference, which is the instructions/cycles used by
the target program.

Example input and output:

./bpftool prog profile id 337 duration 3 cycles instructions llc_misses

4228 run_cnt
3403698 cycles (84.08%)
3525294 instructions # 1.04 insn per cycle (84.05%)
13 llc_misses # 3.69 LLC misses per million isns (83.50%)

This command measures cycles and instructions for BPF program with id
337 for 3 seconds. The program has triggered 4228 times. The rest of the
output is similar to perf-stat. In this example, the counters were only
counting ~84% of the time because of time multiplexing of perf counters.

Note that, this approach measures cycles and instructions in very small
increments. So the fentry/fexit programs introduce noticeable errors to
the measurement results.

The fentry/fexit programs are generated with BPF skeletons. Therefore, we
build bpftool twice. The first time _bpftool is built without skeletons.
Then, _bpftool is used to generate the skeletons. The second time, bpftool
is built with skeletons.

Signed-off-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20200309173218.2739965-2-songliubraving@fb.com

bpftool: Use consistent include paths for libbpf

Fix bpftool to include libbpf header files with the bpf/ prefix, to be
consistent with external users of the library. Also ensure that all
includes of exported libbpf header files (those that are exported on 'make
install' of the library) use bracketed includes instead of quoted.

To make sure no new files are introduced that doesn't include the bpf/
prefix in its include, remove tools/lib/bpf from the include path entirely,
and use tools/lib instead.

Fixes: 6910d7d3867a ("selftests/bpf: Ensure bpf_helper_defs.h are taken from selftests dir")
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/157952560684.1683545.4765181397974997027.stgit@toke.dk

tools: bpftool: do not link twice against libbpf.a in Makefile

In bpftool's Makefile, $(LIBS) includes $(LIBBPF), therefore the library
is used twice in the linking command. No need to have $(LIBBPF) (from
$^) on that command, let's do with "$(OBJS) $(LIBS)" (but move $(LIBBPF)
_before_ the -l flags in $(LIBS)).

Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

tools: bpf: account for generated feature/ and libbpf/ directories

When building "tools/bpf" from the top of the Linux repository, the
build system passes a value for the $(OUTPUT) Makefile variable to
tools/bpf/Makefile and tools/bpf/bpftool/Makefile, which results in
generating "libbpf/" (for bpftool) and "feature/" (bpf and bpftool)
directories inside the tree.

This commit adds such directories to the relevant .gitignore files, and
edits the Makefiles to ensure they are removed on "make clean". The use
of "rm" is also made consistent throughout those Makefiles (relies on
the $(RM) variable, use "--" to prevent interpreting
$(OUTPUT)/$(DESTDIR) as options.

v2:
- New patch.

Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

tools: bpftool: improve and check builds for different make invocations

There are a number of alternative "make" invocations that can be used to
compile bpftool. The following invocations are expected to work:

- through the kbuild system, from the top of the repository
(make tools/bpf)
- by telling make to change to the bpftool directory
(make -C tools/bpf/bpftool)
- by building the BPF tools from tools/
(cd tools && make bpf)
- by running make from bpftool directory
(cd tools/bpf/bpftool && make)

Additionally, setting the O or OUTPUT variables should tell the build
system to use a custom output path, for each of these alternatives.

The following patch fixes the following invocations:

$ make tools/bpf
$ make tools/bpf O=<dir>
$ make -C tools/bpf/bpftool OUTPUT=<dir>
$ make -C tools/bpf/bpftool O=<dir>
$ cd tools/ && make bpf O=<dir>
$ cd tools/bpf/bpftool && make OUTPUT=<dir>
$ cd tools/bpf/bpftool && make O=<dir>

After this commit, the build still fails for two variants when passing
the OUTPUT variable:

$ make tools/bpf OUTPUT=<dir>
$ cd tools/ && make bpf OUTPUT=<dir>

In order to remember and check what make invocations are supposed to
work, and to document the ones which do not, a new script is added to
the BPF selftests. Note that some invocations require the kernel to be
configured, so the script skips them if no .config file is found.

v2:
- In make_and_clean(), set $ERROR to 1 when "make" returns non-zero,
even if the binary was produced.
- Run "make clean" from the correct directory (bpf/ instead of bpftool/,
when relevant).

Reported-by: Lorenz Bauer <lmb@cloudflare.com>
Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

tools: bpftool: ignore make built-in rules for getting kernel version

Bpftool calls the toplevel Makefile to get the kernel version for the
sources it is built from. But when the utility is built from the top of
the kernel repository, it may dump the following error message for
certain architectures (including x86):

$ make tools/bpf
[...]
make[3]: *** [checkbin] Error 1
[...]

This does not prevent bpftool compilation, but may feel disconcerting.
The "checkbin" arch-dependent target is not supposed to be called for
target "kernelversion", which is a simple "echo" of the version number.

It turns out this is caused by the make invocation in tools/bpf/bpftool,
which attempts to find implicit rules to apply. Extract from debug
output:

Reading makefiles...
Reading makefile 'Makefile'...
Reading makefile 'scripts/Kbuild.include' (search path) (no ~ expansion)...
Reading makefile 'scripts/subarch.include' (search path) (no ~ expansion)...
Reading makefile 'arch/x86/Makefile' (search path) (no ~ expansion)...
Reading makefile 'scripts/Makefile.kcov' (search path) (no ~ expansion)...
Reading makefile 'scripts/Makefile.gcc-plugins' (search path) (no ~ expansion)...
Reading makefile 'scripts/Makefile.kasan' (search path) (no ~ expansion)...
Reading makefile 'scripts/Makefile.extrawarn' (search path) (no ~ expansion)...
Reading makefile 'scripts/Makefile.ubsan' (search path) (no ~ expansion)...
Updating makefiles....
Considering target file 'scripts/Makefile.ubsan'.
Looking for an implicit rule for 'scripts/Makefile.ubsan'.
Trying pattern rule with stem 'Makefile.ubsan'.
[...]
Trying pattern rule with stem 'Makefile.ubsan'.
Trying implicit prerequisite 'scripts/Makefile.ubsan.o'.
Looking for a rule with intermediate file 'scripts/Makefile.ubsan.o'.
Avoiding implicit rule recursion.
Trying pattern rule with stem 'Makefile.ubsan'.
Trying rule prerequisite 'prepare'.
Trying rule prerequisite 'FORCE'.
Found an implicit rule for 'scripts/Makefile.ubsan'.
Considering target file 'prepare'.
File 'prepare' does not exist.
Considering target file 'prepare0'.
File 'prepare0' does not exist.
Considering target file 'archprepare'.
File 'archprepare' does not exist.
Considering target file 'archheaders'.
File 'archheaders' does not exist.
Finished prerequisites of target file 'archheaders'.
Must remake target 'archheaders'.
Putting child 0x55976f4f6980 (archheaders) PID 31743 on the chain.

To avoid that, pass the -r and -R flags to eliminate the use of make
built-in rules (and while at it, built-in variables) when running
command "make kernelversion" from bpftool's Makefile.

Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

tools: bpftool: compile with $(EXTRA_WARNINGS)

Compile bpftool with $(EXTRA_WARNINGS), as defined in
scripts/Makefile.include, and fix the new warnings produced.

Simply leave -Wswitch-enum out of the warning list, as we have several
switch-case structures where it is not desirable to process all values
of an enum.

Remove -Wshadow from the warnings we manually add to CFLAGS, as it is
handled in $(EXTRA_WARNINGS).

Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

tools: bpftool: add feature check for zlib

bpftool requires libelf, and zlib for decompressing /proc/config.gz.
zlib is a transitive dependency via libelf, and became mandatory since
elfutils 0.165 (Jan 2016). The feature check of libelf is already done
in the elfdep target of tools/lib/bpf/Makefile, pulled in by bpftool via
a dependency on libbpf.a. Add a similar feature check for zlib.

Suggested-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Peter Wu <peter@lekensteyn.nl>
Acked-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

tools: bpftool: fix reading from /proc/config.gz

/proc/config has never existed as far as I can see, but /proc/config.gz
is present on Arch Linux. Add support for decompressing config.gz using
zlib which is a mandatory dependency of libelf anyway. Replace existing
stdio functions with gzFile operations since the latter transparently
handles uncompressed and gzip-compressed files.

Cc: Quentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: Peter Wu <peter@lekensteyn.nl>
Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

treewide: Add SPDX license identifier - Makefile/Kconfig

Add SPDX license identifiers to all Make/Kconfig files which:

- Have no license information of any form

These files fall under the project license, GPL v2 only. The resulting SPDX
license identifier is:

GPL-2.0-only

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

tools/bpf: properly account for libbfd variations

On some platforms, in order to link against libbfd, we need to
link against liberty and even possibly libz. Account for that
in the bpftool Makefile. We now have proper feature detection
for each case, so handle each one separately.

See recent commit 14541b1e7e72 ("perf build: Don't unconditionally link the
libbfd feature test to -liberty and -lz") where I fixed feature
detection.

v2 (addressed Jakub's nits):
* better syntax for 'else ifeq'
* no space between ifeq args
v3:
* use LIBS, not EXTLIBS for -DHAVE_LIBBFD_SUPPORT

Fixes: 29a9c10e4110 ("bpftool: make libbfd optional")
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Acked-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

tools: bpftool: do not force gcc as CC

This allows transparent cross-compilation with CROSS_COMPILE by
relying on 7ed1c1901fe5 ("tools: fix cross-compile var clobbering").

Signed-off-by: Ivan Babrou <ivan@cloudflare.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

bpftool: make libbfd optional

Make it possible to build bpftool without libbfd. libbfd and libopcodes are
typically provided in dev/dbg packages (binutils-dev in debian) which we
usually don't have installed on the fleet machines and we'd like a way to have
bpftool version that works without installing any additional packages.
This excludes support for disassembling jit-ted code and prints an error if
the user tries to use these features.

Tested by:
cat > FEATURES_DUMP.bpftool <<EOF
feature-libbfd=0
feature-disassembler-four-args=1
feature-reallocarray=0
feature-libelf=1
feature-libelf-mmap=1
feature-bpf=1
EOF
FEATURES_DUMP=$PWD/FEATURES_DUMP.bpftool make
ldd bpftool | grep libbfd

Signed-off-by: Stanislav Fomichev <sdf@google.com>
Acked-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

bpftool: Allow add linker flags via EXTRA_LDFLAGS variable

Adding EXTRA_LDFLAGS allowing user to specify extra flags
for LD_FLAGS variable. Also adding LDFLAGS to build command
line.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

bpftool: Allow to add compiler flags via EXTRA_CFLAGS variable

Adding EXTRA_CFLAGS allowing user to specify extra flags
for CFLAGS variable.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

tools: bpftool: don't pass FEATURES_DUMP to libbpf

bpftool does not export features it probed for, i.e.
FEATURE_DUMP_EXPORT is always empty, so don't try to communicate
the features to libbpf. It has no effect.

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

tools: bpf: make use of reallocarray

reallocarray() is a safer variant of realloc which checks for
multiplication overflow in case of array allocation. Since it's
not available in Glibc < 2.26 import kernel's overflow.h and
add a static inline implementation when needed. Use feature
detection to probe for existence of reallocarray.

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com>
Reviewed-by: Jiong Wang <jiong.wang@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

tools: bpftool: use correct make variable type to improve compilation time

Commit 4bfe3bd3cc35 ("tools/bpftool: use version from the kernel
source tree") added version to bpftool. The version used is
equal to the kernel version and obtained by running make kernelversion
against kernel source tree. Version is then communicated
to the sources with a command line define set in CFLAGS.

Use a simply expanded variable for the version, otherwise the
recursive make will run every time CFLAGS are used.

This brings the single-job compilation time for me from almost
16 sec down to less than 4 sec.

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

tools: bpftool: add simple perf event output reader

Users of BPF sooner or later discover perf_event_output() helpers
and BPF_MAP_TYPE_PERF_EVENT_ARRAY. Dumping this array type is
not possible, however, we can add simple reading of perf events.
Create a new event_pipe subcommand for maps, this sub command
will only work with BPF_MAP_TYPE_PERF_EVENT_ARRAY maps.

Parts of the code from samples/bpf/trace_output_user.c.

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

tools: bpf: remove feature detection output

bpf tools use feature detection for libbfd dependency, clean up
the output files on make clean.

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

tools: bpftool: fix dependency file path

Auto-generated dependency files are in the OUTPUT directory,
we need to include them from there. This fixes object files
not being rebuilt after header changes.

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

tools: bpftool: silence 'missing initializer' warnings

When building bpf tool, gcc emits piles of warnings:

prog.c: In function ‘prog_fd_by_tag’:
prog.c:101:9: warning: missing initializer for field ‘type’ of ‘struct bpf_prog_info’ [-Wmissing-field-initializers]
struct bpf_prog_info info = {};
^
In file included from /home/storage/jbenc/git/net-next/tools/lib/bpf/bpf.h:26:0,
from prog.c:47:
/home/storage/jbenc/git/net-next/tools/include/uapi/linux/bpf.h:925:8: note: ‘type’ declared here
__u32 type;
^

As these warnings are not useful, switch them off.

Signed-off-by: Jiri Benc <jbenc@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

tools: bpftool: add -DPACKAGE when including bfd.h

bfd.h is requiring including of config.h except when PACKAGE or
PACKAGE_VERSION are defined.

/* PR 14072: Ensure that config.h is included first. */
#if !defined PACKAGE && !defined PACKAGE_VERSION
#error config.h must be included before this header
#endif

This check has been introduced since May-2012. It doesn't show up in bfd.h
on some Linux distribution, probably because distributions have remove it
when building the package.

However, sometimes the user might just build libfd from source code then
link bpftool against it. For this case, bfd.h will be original that we need
to define PACKAGE or PACKAGE_VERSION.

Acked-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Jiong Wang <jiong.wang@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

tools/bpftool: fix bpftool build with bintutils >= 2.9

Bpftool build is broken with binutils version 2.29 and later.
The cause is commit 003ca0fd2286 ("Refactor disassembler selection")
in the binutils repo, which changed the disassembler() function
signature.

Fix this by adding a new "feature" to the tools/build/features
infrastructure and make it responsible for decision which
disassembler() function signature to use.

Signed-off-by: Roman Gushchin <guro@fb.com>
Cc: Jakub Kicinski <jakub.kicinski@netronome.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

tools/bpftool: use version from the kernel source tree

Bpftool determines it's own version based on the kernel
version, which is picked from the linux/version.h header.

It's strange to use the version of the installed kernel
headers, and makes much more sense to use the version
of the actual source tree, where bpftool sources are.

Fix this by building kernelversion target and use
the resulting string as bpftool version.

Example:
before:

$ bpftool version
bpftool v4.14.6

after:
$ bpftool version
bpftool v4.15.0-rc3

$bpftool version --json
{"version":"4.15.0-rc3"}

Signed-off-by: Roman Gushchin <guro@fb.com>
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

tools: bpftool: create "uninstall", "doc-uninstall" make targets

Create two targets to remove executable and documentation that would
have been previously installed with `make install` and `make
doc-install`.

Also create a "QUIET_UNINST" helper in tools/scripts/Makefile.include.

Do not attempt to remove directories /usr/local/sbin and
/usr/share/bash-completions/completions, even if they are empty, as
those specific directories probably already existed on the system before
we installed the program, and we do not wish to break other makefiles
that might assume their existence. Do remvoe /usr/local/share/man/man8
if empty however, as this directory does not seem to exist by default.

Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

tools: bpftool: harmonise Makefile and Documentation/Makefile

Several minor fixes and harmonisation items for Makefiles:

* Use the same mechanism for verbose/non-verbose output in two files
("$(Q)"), for all commands.
* Use calls to "QUIET_INSTALL" and equivalent in Makefile. In
particular, use "call(descend, ...)" instead of "make -C" to run
documentation targets.
* Add a "doc-clean" target, aligned on "doc" and "doc-install".
* Make "install" target in Makefile depend on "bpftool".
* Remove condition on DESTDIR to initialise prefix in doc Makefile.
* Remove modification of VPATH based on OUTPUT, it is unused.
* Formatting: harmonise spaces around equal signs.
* Make install path for man pages /usr/local/man instead of
/usr/local/share/man (respects the Makefile conventions, and the
latter is usually a symbolic link to the former anyway).
* Do not erase prefix if set by user in bpftool Makefile.
* Fix install target for bpftool: append DESTDIR to install path.

Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

tools: bpftool: declare phony targets as such

In the Makefile, targets install, doc and doc-install should be added to
.PHONY. Let's fix this.

Fixes: 71bb428fe2c1 ("tools: bpf: add bpftool")
Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Acked-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

tools: bpftool: unify installation directories

Programs and documentation not managed by package manager are generally
installed under /usr/local/, instead of the user's home directory. In
particular, `man` is generally able to find manual pages under
`/usr/local/share/man`.

bpftool generally follows perf's example, and perf installs to home
directory. However bpftool requires root credentials, so it seems
sensible to follow the more common convention of installing files under
/usr/local instead. So, make /usr/local the default prefix for
installing the binary with `make install`, and the documentation with
`make doc-install`. Also, create /usr/local/sbin if it does not exist.

Note that the bash-completion file, however, is still installed under
/usr/share/bash-completion/completions, as the default setup for bash
does not attempt to load completion files under /usr/local/.

Reported-by: David Beckett <david.beckett@netronome.com>
Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Acked-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

tools: bpftool: add bash completion for bpftool

Add a completion file for bash. The completion function runs bpftool
when needed, making it smart enough to help users complete ids or tags
for eBPF programs and maps currently on the system.

Update Makefile to install completion file to
/usr/share/bash-completion/completions when running `make install`.

Emacs file mode and (at the end) Vim modeline have been added, to keep
the style in use for most existing bash completion files. In this, it
differs from tools/perf/perf-completion.sh, which seems to be the only
other completion file among the kernel sources repository. This is also
valid for indent style: 4-space indents, as in other completion files.

Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tools: bpftool: use the kernel's instruction printer

Compile the instruction printer from kernel/bpf and use it
for disassembling "translated" eBPF code.

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Simon Horman <simon.horman@netronome.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

tools: bpftool: add documentation

Add documentation for bpftool. Separate files for each subcommand.
Use rst format. Documentation is compiled into man pages using
rst2man.

Signed-off-by: David Beckett <david.beckett@netronome.com>
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

tools: bpf: add bpftool

Add a simple tool for querying and updating BPF objects on the system.

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Simon Horman <simon.horman@netronome.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>