From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id CB40D7B for ; Thu, 31 Mar 2022 07:21:01 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 15669C340F2; Thu, 31 Mar 2022 07:20:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1648711261; bh=qjNjEbUBrdLs50AHIuc+pd6M1krGCKQ6Ip1cy6iwHWM=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=cLxzl+StS0GApIA6tVj8R/amrIY1/eqVHyDcFyTx1qZDTekUha1tlKUyt377hKxml LRXOqNf92I/iBmZXDOW1emtp0qOMueBXJa1vgpPNcO1OX+rApl2oLTlUYXIawQ7Jl9 MORHzeg+ykN3SL+xfIxPWQ4ezyfuUVP3XSk73jpbytd7JX/UokapAzraI+7Vpj/bFf idem8sKH1EsrIjkMJSrbPEffKaW4j3CWLt5a5f5Zha4bb+sCMSteGzTxQoezmYqTiK +cwOuU7ZsBQ5zcOF/8Ps1fF/Ub92v/Yxax9GRSl27GT3v3zDh2U1UinqaqLJGwqID9 Qm9VgESYj+ldA== Date: Thu, 31 Mar 2022 16:20:56 +0900 From: Masami Hiramatsu To: Masahiro Yamada Cc: Steven Rostedt , Padmanabha Srinivasaiah , LKML , Jonathan Corbet , "open list:DOCUMENTATION" , Randy Dunlap , Nick Desaulniers , Sami Tolvanen , Nathan Chancellor , llvm@lists.linux.dev, Linux Kbuild mailing list Subject: Re: [PATCH v6 3/4] bootconfig: Support embedding a bootconfig file in kernel Message-Id: <20220331162056.43b06415962bc116daa260db@kernel.org> In-Reply-To: References: <164870615889.127053.9055569952366814752.stgit@devnote2> <164870619150.127053.3677457860116913262.stgit@devnote2> <20220331154918.67fdd2b2c18262631588e07c@kernel.org> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.32; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: llvm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Thu, 31 Mar 2022 15:54:40 +0900 Masahiro Yamada wrote: > On Thu, Mar 31, 2022 at 3:49 PM Masami Hiramatsu wrote: > > > > On Thu, 31 Mar 2022 15:27:56 +0900 > > Masahiro Yamada wrote: > > > > > On Thu, Mar 31, 2022 at 2:56 PM Masami Hiramatsu wrote: > > > > > > > > This allows kernel developer to embed a default bootconfig file in > > > > the kernel instead of embedding it in the initrd. This will be good > > > > for who are using the kernel without initrd, or who needs a default > > > > bootconfigs. > > > > This needs to set two kconfigs: CONFIG_EMBED_BOOT_CONFIG=y and set > > > > the file path to CONFIG_EMBED_BOOT_CONFIG_FILE. > > > > > > > > Note that you still need 'bootconfig' command line option to load the > > > > embedded bootconfig. Also if you boot using an initrd with a different > > > > bootconfig, the kernel will use the bootconfig in the initrd, instead > > > > of the default bootconfig. > > > > > > > > Signed-off-by: Masami Hiramatsu > > > > --- > > > > Changes in v6: > > > > - Split out the .incbin asm part as bootconfig-data.S according to > > > > Masahiro's comment. > > > > Changes in v5: > > > > - Fix .gitignore to be sorted alphabetically. > > > > - Make default.bconf is cleaned up correctly. > > > > - Allow user to specify relative path to CONFIG_EMBED_BOOT_CONFIG_FILE. > > > > (Thanks Masahiro!) > > > > Changes in v4: > > > > - Avoid updating the default.bconf if the file is not changed. > > > > --- > > > > MAINTAINERS | 1 + > > > > include/linux/bootconfig.h | 10 ++++++++++ > > > > init/Kconfig | 21 +++++++++++++++++++++ > > > > init/main.c | 13 ++++++++----- > > > > lib/.gitignore | 1 + > > > > lib/Makefile | 8 ++++++++ > > > > lib/bootconfig-data.S | 11 +++++++++++ > > > > lib/bootconfig.c | 13 +++++++++++++ > > > > 8 files changed, 73 insertions(+), 5 deletions(-) > > > > create mode 100644 lib/bootconfig-data.S > > > > > > > > diff --git a/MAINTAINERS b/MAINTAINERS > > > > index b555a5e8704f..9b4910685412 100644 > > > > --- a/MAINTAINERS > > > > +++ b/MAINTAINERS > > > > @@ -7350,6 +7350,7 @@ S: Maintained > > > > F: Documentation/admin-guide/bootconfig.rst > > > > F: fs/proc/bootconfig.c > > > > F: include/linux/bootconfig.h > > > > +F: lib/bootconfig-data.S > > > > F: lib/bootconfig.c > > > > F: tools/bootconfig/* > > > > F: tools/bootconfig/scripts/* > > > > diff --git a/include/linux/bootconfig.h b/include/linux/bootconfig.h > > > > index a4665c7ab07c..5dbda5e3e9bb 100644 > > > > --- a/include/linux/bootconfig.h > > > > +++ b/include/linux/bootconfig.h > > > > @@ -289,4 +289,14 @@ int __init xbc_get_info(int *node_size, size_t *data_size); > > > > /* XBC cleanup data structures */ > > > > void __init xbc_exit(void); > > > > > > > > +/* XBC embedded bootconfig data in kernel */ > > > > +#ifdef CONFIG_EMBED_BOOT_CONFIG > > > > +char * __init xbc_get_embedded_bootconfig(size_t *size); > > > > +#else > > > > +static inline char *xbc_get_embedded_bootconfig(size_t *size) > > > > +{ > > > > + return NULL; > > > > +} > > > > +#endif > > > > + > > > > #endif > > > > diff --git a/init/Kconfig b/init/Kconfig > > > > index 97463a33baa7..f5d14a78cfce 100644 > > > > --- a/init/Kconfig > > > > +++ b/init/Kconfig > > > > @@ -1361,6 +1361,27 @@ config BOOT_CONFIG > > > > > > > > If unsure, say Y. > > > > > > > > +config EMBED_BOOT_CONFIG > > > > + bool "Embed bootconfig file in the kernel" > > > > + depends on BOOT_CONFIG > > > > + default n > > > > + help > > > > + Embed a bootconfig file given by EMBED_BOOT_CONFIG_FILE in the > > > > + kernel. Usually, the bootconfig file is loaded with the initrd > > > > + image. But if the system doesn't support initrd, this option will > > > > + help you by embedding a bootconfig file while building the kernel. > > > > + > > > > + If unsure, say N. > > > > + > > > > +config EMBED_BOOT_CONFIG_FILE > > > > + string "Embedded bootconfig file path" > > > > + default "" > > > > + depends on EMBED_BOOT_CONFIG > > > > + help > > > > + Specify a bootconfig file which will be embedded to the kernel. > > > > + This bootconfig will be used if there is no initrd or no other > > > > + bootconfig in the initrd. > > > > + > > > > choice > > > > prompt "Compiler optimization level" > > > > default CC_OPTIMIZE_FOR_PERFORMANCE > > > > diff --git a/init/main.c b/init/main.c > > > > index 266d61bc67b0..a5db3e36b809 100644 > > > > --- a/init/main.c > > > > +++ b/init/main.c > > > > @@ -266,7 +266,7 @@ static int __init loglevel(char *str) > > > > early_param("loglevel", loglevel); > > > > > > > > #ifdef CONFIG_BLK_DEV_INITRD > > > > -static void * __init get_boot_config_from_initrd(u32 *_size) > > > > +static void * __init get_boot_config_from_initrd(size_t *_size) > > > > { > > > > u32 size, csum; > > > > char *data; > > > > @@ -412,12 +412,15 @@ static void __init setup_boot_config(void) > > > > static char tmp_cmdline[COMMAND_LINE_SIZE] __initdata; > > > > const char *msg; > > > > int pos; > > > > - u32 size; > > > > + size_t size; > > > > char *data, *err; > > > > int ret; > > > > > > > > /* Cut out the bootconfig data even if we have no bootconfig option */ > > > > data = get_boot_config_from_initrd(&size); > > > > + /* If there is no bootconfig in initrd, try embedded one. */ > > > > + if (!data) > > > > + data = xbc_get_embedded_bootconfig(&size); > > > > > > > > strlcpy(tmp_cmdline, boot_command_line, COMMAND_LINE_SIZE); > > > > err = parse_args("bootconfig", tmp_cmdline, NULL, 0, 0, 0, NULL, > > > > @@ -436,8 +439,8 @@ static void __init setup_boot_config(void) > > > > } > > > > > > > > if (size >= XBC_DATA_MAX) { > > > > - pr_err("bootconfig size %d greater than max size %d\n", > > > > - size, XBC_DATA_MAX); > > > > + pr_err("bootconfig size %ld greater than max size %d\n", > > > > + (long)size, XBC_DATA_MAX); > > > > return; > > > > } > > > > > > > > @@ -450,7 +453,7 @@ static void __init setup_boot_config(void) > > > > msg, pos); > > > > } else { > > > > xbc_get_info(&ret, NULL); > > > > - pr_info("Load bootconfig: %d bytes %d nodes\n", size, ret); > > > > + pr_info("Load bootconfig: %ld bytes %d nodes\n", (long)size, ret); > > > > /* keys starting with "kernel." are passed via cmdline */ > > > > extra_command_line = xbc_make_cmdline("kernel"); > > > > /* Also, "init." keys are init arguments */ > > > > diff --git a/lib/.gitignore b/lib/.gitignore > > > > index e5e217b8307b..54596b634ecb 100644 > > > > --- a/lib/.gitignore > > > > +++ b/lib/.gitignore > > > > @@ -1,6 +1,7 @@ > > > > # SPDX-License-Identifier: GPL-2.0-only > > > > /crc32table.h > > > > /crc64table.h > > > > +/default.bconf > > > > /gen_crc32table > > > > /gen_crc64table > > > > /oid_registry_data.c > > > > diff --git a/lib/Makefile b/lib/Makefile > > > > index 08053df16c7c..2a82cc324f91 100644 > > > > --- a/lib/Makefile > > > > +++ b/lib/Makefile > > > > @@ -280,6 +280,14 @@ $(foreach file, $(libfdt_files), \ > > > > lib-$(CONFIG_LIBFDT) += $(libfdt_files) > > > > > > > > obj-$(CONFIG_BOOT_CONFIG) += bootconfig.o > > > > +obj-$(CONFIG_EMBED_BOOT_CONFIG) += bootconfig-data.o > > > > + > > > > +$(obj)/bootconfig-data.o: $(obj)/default.bconf > > > > + > > > > +targets += default.bconf > > > > +filechk_defbconf = cat $(or $(real-prereqs), /dev/null) > > > > +$(obj)/default.bconf: $(CONFIG_EMBED_BOOT_CONFIG_FILE) FORCE > > > > + $(call filechk,defbconf) > > > > > > > > obj-$(CONFIG_RBTREE_TEST) += rbtree_test.o > > > > obj-$(CONFIG_INTERVAL_TREE_TEST) += interval_tree_test.o > > > > diff --git a/lib/bootconfig-data.S b/lib/bootconfig-data.S > > > > new file mode 100644 > > > > index 000000000000..df674ea7d8be > > > > --- /dev/null > > > > +++ b/lib/bootconfig-data.S > > > > @@ -0,0 +1,11 @@ > > > > +/* SPDX-License-Identifier: GPL-2.0 */ > > > > +/* > > > > + * Embed default bootconfig in the kernel. > > > > + */ > > > > + .pushsection .init.data, "aw" > > > > + .global embedded_bootconfig_data > > > > +embedded_bootconfig_data: > > > > + .incbin "lib/default.bconf" > > > > + .global embedded_bootconfig_data_end > > > > +embedded_bootconfig_data_end: > > > > + .popsection > > > > > > > > > > > > You used .pushsection / .popsection because it was > > > previously located in bootconfig.c, where there are > > > functions, which should go to the ".text" section. > > > > Oops, yes. I have made a dumb copy from the inline asm... > > > > > Now that you split this into a separate compilation unit, > > > there is only one ".init.data" section in the file. > > > > > > > > > .section .init.data, "aw" > > > > > > should be enough. > > > > OK. > > > > > BTW, is it reasonable/possible to make it explicitly read-only? > > > > > > I have not tested this patch at all. Nor do I have enough insight. > > > > > > .section .init.rodata, "a" > > > > > > I am not sure whether this is possible or not. > > > > Yes, it can be. The data is passed via 'const char *'. > > But, you didn't add "const" in the C code: > > extern __visible char embedded_bootconfig_data[]; > extern __visible char embedded_bootconfig_data_end[]; > > > Is it possible to use "const char" ? Yes, I need to update C part too, and that is not a problem. :) Thank you! > > > > -- > Best Regards > Masahiro Yamada -- Masami Hiramatsu