From: Kees Cook <keescook@chromium.org>
To: Arvind Sankar <nivedita@alum.mit.edu>
Cc: Nick Terrell <nickrterrell@gmail.com>,
Borislav Petkov <bp@alien8.de>,
Thomas Gleixner <tglx@linutronix.de>,
linux-kernel@vger.kernel.org, Chris Mason <clm@fb.com>,
linux-kbuild@vger.kernel.org, x86@kernel.org,
gregkh@linuxfoundation.org, Petr Malat <oss@malat.biz>,
Kernel Team <Kernel-team@fb.com>,
Adam Borowski <kilobyte@angband.pl>,
Patrick Williams <patrickw3@fb.com>,
rmikey@fb.com, mingo@kernel.org,
Patrick Williams <patrick@stwcx.xyz>,
Sedat Dilek <sedat.dilek@gmail.com>,
Norbert Lange <nolange79@gmail.com>,
Andrew Morton <akpm@linux-foundation.org>,
Nick Terrell <terrelln@fb.com>
Subject: Re: [PATCH v6 2/8] lib: prepare xxhash for preboot environment
Date: Tue, 7 Jul 2020 19:49:25 -0700 [thread overview]
Message-ID: <202007071947.5E9723AF48@keescook> (raw)
In-Reply-To: <20200707215925.GA1591079@rani.riverdale.lan>
On Tue, Jul 07, 2020 at 05:59:25PM -0400, Arvind Sankar wrote:
> On Mon, Jul 06, 2020 at 08:45:58PM -0700, Nick Terrell wrote:
> > From: Nick Terrell <terrelln@fb.com>
> >
> > Don't export symbols if XXH_PREBOOT is defined.
> >
> > This change is necessary to get xxhash to work in a preboot environment,
> > which is needed to support zstd-compressed kernels.
>
> The usual way to do it is by adding -D__DISABLE_EXPORTS to the CFLAGS, which will
> cause EXPORT_SYMBOL to be stubbed out. Doesn't that work here?
This is quite rare, actually:
$ git grep DISABLE_EXPORTS
arch/s390/purgatory/Makefile:CFLAGS_sha256.o := -D__DISABLE_EXPORTS
arch/x86/boot/compressed/kaslr.c:#define __DISABLE_EXPORTS
arch/x86/purgatory/Makefile:CFLAGS_sha256.o := -D__DISABLE_EXPORTS
drivers/firmware/efi/libstub/Makefile: -D__DISABLE_EXPORTS
include/linux/export.h:#if !defined(CONFIG_MODULES) || defined(__DISABLE_EXPORTS)
But yes, it seems that would be the better approach.
--
Kees Cook
next prev parent reply other threads:[~2020-07-08 2:49 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-07 3:45 [GIT PULL][PATCH v6 0/8] Add support for ZSTD-compressed kernel and initramfs Nick Terrell
2020-07-07 3:45 ` [PATCH v6 1/8] lib: prepare zstd for preboot environment Nick Terrell
2020-07-07 3:45 ` [PATCH v6 2/8] lib: prepare xxhash " Nick Terrell
2020-07-07 21:59 ` Arvind Sankar
2020-07-08 2:03 ` Nick Terrell
2020-07-08 2:49 ` Kees Cook [this message]
2020-07-08 3:23 ` Arvind Sankar
2020-07-07 3:45 ` [PATCH v6 3/8] lib: add zstd support to decompress Nick Terrell
2020-07-07 3:46 ` [PATCH v6 4/8] init: add support for zstd compressed kernel Nick Terrell
2020-07-07 7:19 ` Norbert Lange
2020-07-07 15:31 ` Nick Terrell
2020-07-07 16:40 ` Norbert Lange
2020-07-07 22:11 ` Arvind Sankar
2020-07-08 2:01 ` Nick Terrell
2020-07-08 3:09 ` Arvind Sankar
2020-07-08 3:25 ` Arvind Sankar
2020-07-07 3:46 ` [PATCH v6 5/8] usr: add support for zstd compressed initramfs Nick Terrell
2020-07-07 3:46 ` [PATCH v6 6/8] x86: bump ZO_z_extra_bytes margin for zstd Nick Terrell
2020-07-07 3:46 ` [PATCH v6 7/8] x86: Add support for ZSTD compressed kernel Nick Terrell
2020-07-07 3:46 ` [PATCH v6 8/8] .gitignore: add ZSTD-compressed files Nick Terrell
2020-07-07 4:03 ` [GIT PULL][PATCH v6 0/8] Add support for ZSTD-compressed kernel and initramfs Sedat Dilek
2020-07-07 9:01 ` Sedat Dilek
2020-07-07 21:32 ` Kees Cook
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