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Date:   Wed, 1 Apr 2020 08:49:22 -0700
From:   Kees Cook <keescook@chromium.org>
To:     Slava Bacherikov <slava@bacher09.org>
Cc:     andriin@fb.com, bpf@vger.kernel.org, linux-kernel@vger.kernel.org,
        jannh@google.com, alexei.starovoitov@gmail.com,
        daniel@iogearbox.net, kernel-hardening@lists.openwall.com,
        liuyd.fnst@cn.fujitsu.com, KP Singh <kpsingh@google.com>
Subject: Re: [PATCH v3 bpf] kbuild: fix dependencies for DEBUG_INFO_BTF
Message-ID: <202004010849.CC7E9412@keescook>
References: <202004010033.A1523890@keescook>
 <20200401142057.453892-1-slava@bacher09.org>
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On Wed, Apr 01, 2020 at 05:20:58PM +0300, Slava Bacherikov wrote:
> Currently turning on DEBUG_INFO_SPLIT when DEBUG_INFO_BTF is also
> enabled will produce invalid btf file, since gen_btf function in
> link-vmlinux.sh script doesn't handle *.dwo files.
> 
> Enabling DEBUG_INFO_REDUCED will also produce invalid btf file, and
> using GCC_PLUGIN_RANDSTRUCT with BTF makes no sense.
> 
> Signed-off-by: Slava Bacherikov <slava@bacher09.org>

Very cool; thanks! :)

Reviewed-by: Kees Cook <keescook@chromium.org>

-Kees

> Reported-by: Jann Horn <jannh@google.com>
> Reported-by: Liu Yiding <liuyd.fnst@cn.fujitsu.com>
> Acked-by: KP Singh <kpsingh@google.com>
> Acked-by: Andrii Nakryiko <andriin@fb.com>
> Fixes: e83b9f55448a ("kbuild: add ability to generate BTF type info for vmlinux")
> ---
>  lib/Kconfig.debug | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
> index f61d834e02fe..b94227be2d62 100644
> --- a/lib/Kconfig.debug
> +++ b/lib/Kconfig.debug
> @@ -222,7 +222,9 @@ config DEBUG_INFO_DWARF4
>  
>  config DEBUG_INFO_BTF
>  	bool "Generate BTF typeinfo"
> -	depends on DEBUG_INFO
> +	depends on DEBUG_INFO || COMPILE_TEST
> +	depends on !DEBUG_INFO_SPLIT && !DEBUG_INFO_REDUCED
> +	depends on !GCC_PLUGIN_RANDSTRUCT || COMPILE_TEST
>  	help
>  	  Generate deduplicated BTF type information from DWARF debug info.
>  	  Turning this on expects presence of pahole tool, which will convert

-- 
Kees Cook