linux-kernel - Re: [PATCH] bpftool, selftests/hid/bpf: fix 29 clang warnings

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date: Sun, 5 May 2024 23:36:14 +0100
From: Quentin Monnet <qmo@...nel.org>
To: John Hubbard <jhubbard@...dia.com>, Shuah Khan <shuah@...nel.org>
Cc: Jiri Kosina <jikos@...nel.org>, Benjamin Tissoires <bentiss@...nel.org>,
 Justin Stitt <justinstitt@...gle.com>,
 Peter Hutterer <peter.hutterer@...-t.net>,
 Jason Gerecke <jason.gerecke@...om.com>,
 Joshua Dickens <joshua@...hua-dickens.com>,
 Alexei Starovoitov <ast@...nel.org>, Daniel Borkmann <daniel@...earbox.net>,
 Andrii Nakryiko <andrii@...nel.org>, Martin KaFai Lau
 <martin.lau@...ux.dev>, Eduard Zingerman <eddyz87@...il.com>,
 Song Liu <song@...nel.org>, Yonghong Song <yonghong.song@...ux.dev>,
 John Fastabend <john.fastabend@...il.com>, KP Singh <kpsingh@...nel.org>,
 Stanislav Fomichev <sdf@...gle.com>, Hao Luo <haoluo@...gle.com>,
 Jiri Olsa <jolsa@...nel.org>, bpf@...r.kernel.org,
 linux-input@...r.kernel.org, Valentin Obst <kernel@...entinobst.de>,
 linux-kselftest@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>,
 llvm@...ts.linux.dev
Subject: Re: [PATCH] bpftool, selftests/hid/bpf: fix 29 clang warnings

On 05/05/2024 22:56, John Hubbard wrote:
> When building either tools/bpf/bpftool, or tools/testing/selftests/hid,
> (the same Makefile is used for these), clang generates many instances of
> a warning that is useless here:
> 
>     "clang: warning: -lLLVM-17: 'linker' input unused"
> 
> Silence this in both locations, by disabling that warning when building
> with clang.
> 
> Signed-off-by: John Hubbard <jhubbard@...dia.com>
> ---
>  tools/bpf/bpftool/Makefile | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/tools/bpf/bpftool/Makefile b/tools/bpf/bpftool/Makefile
> index e9154ace80ff..c7457921d136 100644
> --- a/tools/bpf/bpftool/Makefile
> +++ b/tools/bpf/bpftool/Makefile
> @@ -133,6 +133,10 @@ CFLAGS += -DUSE_LIBCAP
>  LIBS += -lcap
>  endif
>  
> +ifneq ($(LLVM),)
> +    CFLAGS += -Wno-unused-command-line-argument
> +endif
Thanks! If possible, I'd rather keep the warning enabled, and fix the
command line instead. Looking at the error and the Makefile, we may not 
need the -lLLVM<version> in the CFLAGS at all, but only in $(LIBS). On
my setup, I can build successfully, without the warnings, with the
following patch:

------
diff --git a/tools/bpf/bpftool/Makefile b/tools/bpf/bpftool/Makefile
index b67454b45a49..dfa4f1bebbb3 100644
--- a/tools/bpf/bpftool/Makefile
+++ b/tools/bpf/bpftool/Makefile
@@ -147,7 +147,7 @@ ifeq ($(feature-llvm),1)
   # If LLVM is available, use it for JIT disassembly
   CFLAGS  += -DHAVE_LLVM_SUPPORT
   LLVM_CONFIG_LIB_COMPONENTS := mcdisassembler all-targets
-  CFLAGS  += $(shell $(LLVM_CONFIG) --cflags --libs $(LLVM_CONFIG_LIB_COMPONENTS))
+  CFLAGS  += $(shell $(LLVM_CONFIG) --cflags)
   LIBS    += $(shell $(LLVM_CONFIG) --libs $(LLVM_CONFIG_LIB_COMPONENTS))
   ifeq ($(shell $(LLVM_CONFIG) --shared-mode),static)
     LIBS += $(shell $(LLVM_CONFIG) --system-libs $(LLVM_CONFIG_LIB_COMPONENTS))
------

Could you please check whether that works on your side, too?

Quentin