From: Arvind Sankar <nivedita@alum.mit.edu>
To: Nick Terrell <nickrterrell@gmail.com>
Cc: 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>,
Kees Cook <keescook@chromium.org>,
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>,
Alex Xu <alex_y_xu@yahoo.ca>, Nick Terrell <terrelln@fb.com>
Subject: Re: [PATCH v7 2/7] lib: add zstd support to decompress
Date: Tue, 14 Jul 2020 17:42:42 -0400 [thread overview]
Message-ID: <20200714214242.GA1000731@rani.riverdale.lan> (raw)
In-Reply-To: <20200708185024.2767937-3-nickrterrell@gmail.com>
On Wed, Jul 08, 2020 at 11:50:19AM -0700, Nick Terrell wrote:
> From: Nick Terrell <terrelln@fb.com>
>
> * Add unzstd() and the zstd decompress interface.
> * Add zstd support to decompress_method().
>
> The decompress_method() and unzstd() functions are used to decompress
> the initramfs and the initrd. The __decompress() function is used in
> the preboot environment to decompress a zstd compressed kernel.
>
> The zstd decompression function allows the input and output buffers to
> overlap because that is used by x86 kernel decompression.
>
> Reviewed-by: Kees Cook <keescook@chromium.org>
> Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
> Signed-off-by: Nick Terrell <terrelln@fb.com>
> + *
> + * __DISABLE_EXPORTS stops zstd and xxhash from declaring themselves
> + * as modules by disabling the EXPORT_SYMBOL macro.
> + */
Hi Nick, this doesn't actually work, because misc.c includes export.h
via
"misc.h" -> <linux/linkage.h> -> <linux/export.h>
and EXPORT_SYMBOL is already defined before __DISABLE_EXPORTS is defined
here.
Adding -D__EXPORT_SYMBOLS to KBUILD_CFLAGS in arch/x86/boot/compressed/Makefile
fixes that, and then you don't have to define it here.
Also, __DISABLE_EXPORTS does not currently inhibit MODULE_INFO, so a
.modinfo section gets emitted into misc.o. I *think* this is harmless
and it will get discarded when building compressed/vmlinux, but thought
I'd point it out.
next prev parent reply other threads:[~2020-07-14 21:42 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-08 18:50 [GIT PULL][PATCH v7 0/7] Add support for ZSTD-compressed kernel and initramfs Nick Terrell
2020-07-08 18:50 ` [PATCH v7 1/7] lib: prepare zstd for preboot environment Nick Terrell
2020-07-08 18:50 ` [PATCH v7 2/7] lib: add zstd support to decompress Nick Terrell
2020-07-14 21:42 ` Arvind Sankar [this message]
2020-07-17 16:29 ` Nick Terrell
2020-07-08 18:50 ` [PATCH v7 3/7] init: add support for zstd compressed kernel Nick Terrell
2020-07-08 18:50 ` [PATCH v7 4/7] usr: add support for zstd compressed initramfs Nick Terrell
2020-07-08 18:50 ` [PATCH v7 5/7] x86: bump ZO_z_extra_bytes margin for zstd Nick Terrell
2020-07-08 18:50 ` [PATCH v7 6/7] x86: Add support for ZSTD compressed kernel Nick Terrell
2020-07-08 18:50 ` [PATCH v7 7/7] .gitignore: add ZSTD-compressed files Nick Terrell
2020-07-09 8:54 ` [GIT PULL][PATCH v7 0/7] Add support for ZSTD-compressed kernel and initramfs Sedat Dilek
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