linux-kernel - Re: [PATCH v8 6/7] x86: Add support for ZSTD compressed kernel

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]

Message-ID: <AC589A09-D0F0-4E24-A431-C3601370B2E7@fb.com>
Date:   Mon, 27 Jul 2020 22:43:54 +0000
From:   Nick Terrell <terrelln@...com>
To:     Ingo Molnar <mingo@...nel.org>
CC:     Nick Terrell <nickrterrell@...il.com>,
        Borislav Petkov <bp@...en8.de>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Chris Mason <clm@...com>,
        "linux-kbuild@...r.kernel.org" <linux-kbuild@...r.kernel.org>,
        "x86@...nel.org" <x86@...nel.org>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        Petr Malat <oss@...at.biz>, Kees Cook <keescook@...omium.org>,
        Kernel Team <Kernel-team@...com>,
        Adam Borowski <kilobyte@...band.pl>,
        Patrick Williams <patrickw3@...com>,
        "Michael van der Westhuizen" <rmikey@...com>,
        Patrick Williams <patrick@...cx.xyz>,
        Sedat Dilek <sedat.dilek@...il.com>,
        Norbert Lange <nolange79@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Alex Xu <alex_y_xu@...oo.ca>,
        Arvind Sankar <nivedita@...m.mit.edu>
Subject: Re: [PATCH v8 6/7] x86: Add support for ZSTD compressed kernel



> On Jul 24, 2020, at 5:26 AM, Ingo Molnar <mingo@...nel.org> wrote:
> 
> 
> * Nick Terrell <nickrterrell@...il.com> wrote:
> 
>> --- a/arch/x86/boot/compressed/misc.c
>> +++ b/arch/x86/boot/compressed/misc.c
>> @@ -12,6 +12,11 @@
>>  * High loaded stuff by Hans Lermen & Werner Almesberger, Feb. 1996
>>  */
>> 
>> +/* decompressors bring in EXPORT_SYMBOL which is meaningless and will
>> + * cause compiler errors in some cases.
>> + */
>> +#define __DISABLE_EXPORTS
>> +
>> #include "misc.h"
>> #include "error.h"
>> #include "pgtable.h"
>> @@ -77,6 +82,10 @@ static int lines, cols;
>> #ifdef CONFIG_KERNEL_LZ4
>> #include "../../../../lib/decompress_unlz4.c"
>> #endif
>> +
>> +#ifdef CONFIG_KERNEL_ZSTD
>> +#include "../../../../lib/decompress_unzstd.c"
>> +#endif
>> /*
>>  * NOTE: When adding a new decompressor, please update the analysis in
>>  * ../header.S.
>> diff --git a/arch/x86/include/asm/boot.h b/arch/x86/include/asm/boot.h
>> index 680c320363db..d6dd43d25d9f 100644
>> --- a/arch/x86/include/asm/boot.h
>> +++ b/arch/x86/include/asm/boot.h
>> @@ -24,9 +24,11 @@
>> # error "Invalid value for CONFIG_PHYSICAL_ALIGN"
>> #endif
>> 
>> -#ifdef CONFIG_KERNEL_BZIP2
>> +#if defined(CONFIG_KERNEL_BZIP2)
>> # define BOOT_HEAP_SIZE		0x400000
>> -#else /* !CONFIG_KERNEL_BZIP2 */
>> +#elif defined(CONFIG_KERNEL_ZSTD)
>> +# define BOOT_HEAP_SIZE		 0x30000
>> +#else
>> # define BOOT_HEAP_SIZE		 0x10000
>> #endif
> 
> So the other patches explain why the decompression buffer extra space 
> was increased from 64k to 128k, but is there a similar 
> calculation/estimate for bumping BOOT_HEAD_SIZE from 64k to 192k?
> 
> Admittedly the BZ2 exception doesn't set a good example, but maybe we 
> can do this for ZSTD?

Yup, the next version will include an explanation. Thanks for the review!