From: "Arnd Bergmann" <arnd@arndb.de>
To: "Ard Biesheuvel" <ardb+git@google.com>, linux-kernel@vger.kernel.org
Cc: "Ard Biesheuvel" <ardb@kernel.org>,
"Masahiro Yamada" <masahiroy@kernel.org>,
"Martin KaFai Lau" <martin.lau@linux.dev>,
Linux-Arch <linux-arch@vger.kernel.org>,
linux-kbuild@vger.kernel.org, bpf@vger.kernel.org,
"Andrii Nakryiko" <andrii@kernel.org>
Subject: Re: [PATCH v2 3/3] btf: Avoid weak external references
Date: Tue, 09 Apr 2024 17:05:08 +0200 [thread overview]
Message-ID: <fe75de1c-f500-42f3-bef0-8830d9f45ea1@app.fastmail.com> (raw)
In-Reply-To: <20240409150132.4097042-8-ardb+git@google.com>
On Tue, Apr 9, 2024, at 17:01, Ard Biesheuvel wrote:
> From: Ard Biesheuvel <ardb@kernel.org>
>
> If the BTF code is enabled in the build configuration, the start/stop
> BTF markers are guaranteed to exist in the final link but not during the
> first linker pass.
>
> Avoid GOT based relocations to these markers in the final executable by
> providing preliminary definitions that will be used by the first linker
> pass, and superseded by the actual definitions in the subsequent ones.
>
> Make the preliminary definitions dependent on CONFIG_DEBUG_INFO_BTF so
> that inadvertent references to this section will trigger a link failure
> if they occur in code that does not honour CONFIG_DEBUG_INFO_BTF.
>
> Note that Clang will notice that taking the address of__start_BTF cannot
> yield NULL any longer, so testing for that condition is no longer
> needed.
>
> Acked-by: Andrii Nakryiko <andrii@kernel.org>
> Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
next prev parent reply other threads:[~2024-04-09 15:05 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-09 15:01 [PATCH v2 0/3] kbuild: Avoid weak external linkage where possible Ard Biesheuvel
2024-04-09 15:01 ` [PATCH v2 1/3] kallsyms: Avoid weak references for kallsyms symbols Ard Biesheuvel
2024-04-09 15:04 ` Arnd Bergmann
2024-04-09 15:01 ` [PATCH v2 2/3] vmlinux: Avoid weak reference to notes section Ard Biesheuvel
2024-04-09 15:04 ` Arnd Bergmann
2024-04-09 15:01 ` [PATCH v2 3/3] btf: Avoid weak external references Ard Biesheuvel
2024-04-09 15:05 ` Arnd Bergmann [this message]
2024-04-10 8:21 ` Jiri Olsa
2024-04-10 8:37 ` Ard Biesheuvel
2024-04-10 9:30 ` Jiri Olsa
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