答复: [PATCH] symbol : Make the size of the compile-related array fixed

From: "韩大鹏(Han Dapeng)" <handapeng@oppo.com>
To: Daniel Axtens <dja@axtens.net>,
	Michael Ellerman <mpe@ellerman.id.au>,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Paul Mackerras <paulus@samba.org>,
	Heiko Carstens <hca@linux.ibm.com>,
	Vasily Gorbik <gor@linux.ibm.com>,
	Christian Borntraeger <borntraeger@de.ibm.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	"x86@kernel.org" <x86@kernel.org>,
	"H. Peter Anvin" <hpa@zytor.com>,
	Masahiro Yamada <masahiroy@kernel.org>,
	Michal Marek <michal.lkml@markovi.net>,
	Mike Rapoport <rppt@kernel.org>,
	Pekka Enberg <penberg@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Arseny Solokha <asolokha@kb.kras.ru>,
	Arvind Sankar <nivedita@alum.mit.edu>,
	Kees Cook <keescook@chromium.org>, Joerg Roedel <jroedel@suse.de>,
	Christian Brauner <christian.brauner@ubuntu.com>,
	Kirill Tkhai <ktkhai@virtuozzo.com>,
	"linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-s390@vger.kernel.org" <linux-s390@vger.kernel.org>,
	"linux-kbuild@vger.kernel.org" <linux-kbuild@vger.kernel.org>
Cc: "陈安庆(Anqing)" <chenanqing@oppo.com>
Subject: 答复: [PATCH] symbol : Make the size of the compile-related array fixed
Date: Fri, 16 Apr 2021 06:34:46 +0000	[thread overview]
Message-ID: <TY2PR02MB3709540DD6A9BA8382EE275FCB4C9@TY2PR02MB3709.apcprd02.prod.outlook.com> (raw)
In-Reply-To: <87h7k6g39v.fsf@linkitivity.dja.id.au>

Thank you!Got it.
I tried to use Git, but it didn't work.
I'll do it next time.

-----邮件原件-----
发件人: Daniel Axtens <dja@axtens.net>
发送时间: 2021年4月16日 14:19
收件人: 韩大鹏(Han Dapeng) <handapeng@oppo.com>; Michael Ellerman <mpe@ellerman.id.au>; Benjamin Herrenschmidt <benh@kernel.crashing.org>; Paul Mackerras <paulus@samba.org>; Heiko Carstens <hca@linux.ibm.com>; Vasily Gorbik <gor@linux.ibm.com>; Christian Borntraeger <borntraeger@de.ibm.com>; Thomas Gleixner <tglx@linutronix.de>; Ingo Molnar <mingo@redhat.com>; Borislav Petkov <bp@alien8.de>; x86@kernel.org; H. Peter Anvin <hpa@zytor.com>; Masahiro Yamada <masahiroy@kernel.org>; Michal Marek <michal.lkml@markovi.net>; Mike Rapoport <rppt@kernel.org>; Pekka Enberg <penberg@kernel.org>; Andrew Morton <akpm@linux-foundation.org>; Arseny Solokha <asolokha@kb.kras.ru>; 韩大鹏(Han Dapeng) <handapeng@oppo.com>; Arvind Sankar <nivedita@alum.mit.edu>; Kees Cook <keescook@chromium.org>; Joerg Roedel <jroedel@suse.de>; Christian Brauner <christian.brauner@ubuntu.com>; Kirill Tkhai <ktkhai@virtuozzo.com>; linuxppc-dev@lists.ozlabs.org; linux-kernel@vger.kernel.org; linux-s390@vger.kernel.org; linux-kbuild@vger.kernel.org
抄送: 陈安庆(Anqing) <chenanqing@oppo.com>
主题: Re: [PATCH] symbol : Make the size of the compile-related array fixed

Hi,

Thanks for your contribution to the kernel!

I notice that your patch is sumbitted as an attachment. In future, please could you submit your patch inline, rather than as an attachment?
See https://apc01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.kernel.org%2Fdoc%2Fhtml%2Fv4.15%2Fprocess%2F5.Posting.html&amp;data=04%7C01%7Chandapeng%40oppo.com%7Cd00adeb268d34207f5bb08d9009f98b2%7Cf1905eb1c35341c5951662b4a54b5ee6%7C0%7C0%7C637541508341234090%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&amp;sdata=8Sncu0Yyqvv3AtEZiL73vexVEpwmxmwrUjJ124ez%2BPs%3D&amp;reserved=0
I'd recommend you use git send-email if possible: see e.g.
https://apc01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.kernel.org%2Fdoc%2Fhtml%2Fv4.15%2Fprocess%2Femail-clients.html&amp;data=04%7C01%7Chandapeng%40oppo.com%7Cd00adeb268d34207f5bb08d9009f98b2%7Cf1905eb1c35341c5951662b4a54b5ee6%7C0%7C0%7C637541508341234090%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&amp;sdata=Ny2BFB4AE05nHHqITJkixtOwfPrB8s1KboWVLTFVXF8%3D&amp;reserved=0

> Subject: [PATCH] symbol : Make the size of the compile-related array
> fixed
>
> For the same code, the machine's user name, hostname, or compilation
> time may cause the kernel symbol address to be inconsistent, which is
> not friendly to some symbol-dependent software, such as Crash.

If I understand correctly, this patch makes it easier to recompile the kernel from the same source but at a different time or on a different machine or with a different user, but still get the same symbols.
Is that right?

I wonder if there are other reproducible build techniques that might be simpler to apply? There is a kernel documentation page at
https://apc01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.kernel.org%2Fdoc%2Fhtml%2Flatest%2Fkbuild%2Freproducible-builds.html&amp;data=04%7C01%7Chandapeng%40oppo.com%7Cd00adeb268d34207f5bb08d9009f98b2%7Cf1905eb1c35341c5951662b4a54b5ee6%7C0%7C0%7C637541508341234090%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&amp;sdata=s54GLV2Pue3ArPgX4OcEyhAGsanJyBy1LRESkVMOGts%3D&amp;reserved=0
which gives exisiting techniques to override the date, user and host.
Would they be sufficient to address your use case?

Kind regards,
Daniel

>
> Signed-off-by: Han Dapeng <handapeng@oppo.com>
> ---
>  arch/powerpc/mm/nohash/kaslr_booke.c | 2 +-
>  arch/s390/boot/version.c             | 2 +-
>  arch/x86/boot/compressed/kaslr.c     | 2 +-
>  arch/x86/boot/version.c              | 2 +-
>  init/version.c                       | 4 ++--
>  scripts/mkcompile_h                  | 2 ++
>  6 files changed, 8 insertions(+), 6 deletions(-)
>
> diff --git a/arch/powerpc/mm/nohash/kaslr_booke.c
> b/arch/powerpc/mm/nohash/kaslr_booke.c
> index 4c74e8a5482b..494ef408e60c 100644
> --- a/arch/powerpc/mm/nohash/kaslr_booke.c
> +++ b/arch/powerpc/mm/nohash/kaslr_booke.c
> @@ -37,7 +37,7 @@ struct regions {
>  };
>
>  /* Simplified build-specific string for starting entropy. */ -static
> const char build_str[] = UTS_RELEASE " (" LINUX_COMPILE_BY "@"
> +static const char build_str[COMPILE_STR_MAX] = UTS_RELEASE " (" LINUX_COMPILE_BY "@"
>  LINUX_COMPILE_HOST ") (" LINUX_COMPILER ") " UTS_VERSION;
>
>  struct regions __initdata regions;
> diff --git a/arch/s390/boot/version.c b/arch/s390/boot/version.c index
> d32e58bdda6a..627416a27d74 100644
> --- a/arch/s390/boot/version.c
> +++ b/arch/s390/boot/version.c
> @@ -3,5 +3,5 @@
>  #include <generated/compile.h>
>  #include "boot.h"
>
> -const char kernel_version[] = UTS_RELEASE
> +const char kernel_version[COMPILE_STR_MAX] = UTS_RELEASE
>  " (" LINUX_COMPILE_BY "@" LINUX_COMPILE_HOST ") " UTS_VERSION; diff
> --git a/arch/x86/boot/compressed/kaslr.c
> b/arch/x86/boot/compressed/kaslr.c
> index b92fffbe761f..7b72b518a4c8 100644
> --- a/arch/x86/boot/compressed/kaslr.c
> +++ b/arch/x86/boot/compressed/kaslr.c
> @@ -43,7 +43,7 @@
>  extern unsigned long get_cmd_line_ptr(void);
>
>  /* Simplified build-specific string for starting entropy. */ -static
> const char build_str[] = UTS_RELEASE " (" LINUX_COMPILE_BY "@"
> +static const char build_str[COMPILE_STR_MAX] = UTS_RELEASE " (" LINUX_COMPILE_BY "@"
>  LINUX_COMPILE_HOST ") (" LINUX_COMPILER ") " UTS_VERSION;
>
>  static unsigned long rotate_xor(unsigned long hash, const void *area,
> diff --git a/arch/x86/boot/version.c b/arch/x86/boot/version.c index
> a1aaaf6c06a6..08feaa2d7a10 100644
> --- a/arch/x86/boot/version.c
> +++ b/arch/x86/boot/version.c
> @@ -14,6 +14,6 @@
>  #include <generated/utsrelease.h>
>  #include <generated/compile.h>
>
> -const char kernel_version[] =
> +const char kernel_version[COMPILE_STR_MAX] =
>  UTS_RELEASE " (" LINUX_COMPILE_BY "@" LINUX_COMPILE_HOST ") "
>  UTS_VERSION;
> diff --git a/init/version.c b/init/version.c index
> 92afc782b043..adfc9e91b56b 100644
> --- a/init/version.c
> +++ b/init/version.c
> @@ -35,11 +35,11 @@ struct uts_namespace init_uts_ns = {
> EXPORT_SYMBOL_GPL(init_uts_ns);
>
>  /* FIXED STRINGS! Don't touch! */
> -const char linux_banner[] =
> +const char linux_banner[COMPILE_STR_MAX] =
>  "Linux version " UTS_RELEASE " (" LINUX_COMPILE_BY "@"
>  LINUX_COMPILE_HOST ") (" LINUX_COMPILER ") " UTS_VERSION "\n";
>
> -const char linux_proc_banner[] =
> +const char linux_proc_banner[COMPILE_STR_MAX] =
>  "%s version %s"
>  " (" LINUX_COMPILE_BY "@" LINUX_COMPILE_HOST ")"
>  " (" LINUX_COMPILER ") %s\n";
> diff --git a/scripts/mkcompile_h b/scripts/mkcompile_h index
> 4ae735039daf..02b9d9d54da9 100755
> --- a/scripts/mkcompile_h
> +++ b/scripts/mkcompile_h
> @@ -65,6 +65,8 @@ UTS_VERSION="$(echo $UTS_VERSION $CONFIG_FLAGS $TIMESTAMP | cut -b -$UTS_LEN)"
>    LD_VERSION=$($LD -v | head -n1 | sed 's/(compatible with [^)]*)//' \
>        | sed 's/[[:space:]]*$//')
>    printf '#define LINUX_COMPILER "%s"\n' "$CC_VERSION, $LD_VERSION"
> +
> +  echo \#define COMPILE_STR_MAX 512
>  } > .tmpcompile
>
>  # Only replace the real compile.h if the new one is different,
> --
> 2.27.0
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