linux-kernel - Re: [PATCH 1/2] tools/bootconfig: Align the bootconfig applied initrd image size to 4

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Message-ID: <ebdf162b-88f8-8b05-1fd9-454daaf4d941@gmail.com>
Date:   Mon, 16 Nov 2020 18:34:29 -0500
From:   Woody Suwalski <terraluna977@...il.com>
To:     Masami Hiramatsu <mhiramat@...nel.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     Chen Yu <yu.c.chen@...el.com>, Chen Yu <yu.chen.surf@...il.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...nel.org>
Subject: Re: [PATCH 1/2] tools/bootconfig: Align the bootconfig applied initrd
 image size to 4

Masami Hiramatsu wrote:
> Align the bootconfig applied initrd image size to 4. To pad the data,
> bootconfig will use space (0x20) in front of the bootconfig data,
> and expands its size and update checksum.
>
> Signed-off-by: Masami Hiramatsu <mhiramat@...nel.org>
> ---
>   include/linux/bootconfig.h          |    1 +
>   tools/bootconfig/main.c             |   33 ++++++++++++++++++++++++++++-----
>   tools/bootconfig/test-bootconfig.sh |    6 +++++-
>   3 files changed, 34 insertions(+), 6 deletions(-)
>
> diff --git a/include/linux/bootconfig.h b/include/linux/bootconfig.h
> index 9903088891fa..461f621047f3 100644
> --- a/include/linux/bootconfig.h
> +++ b/include/linux/bootconfig.h
> @@ -12,6 +12,7 @@
>   
>   #define BOOTCONFIG_MAGIC	"#BOOTCONFIG\n"
>   #define BOOTCONFIG_MAGIC_LEN	12
> +#define BOOTCONFIG_ALIGN	4
>   
>   /* XBC tree node */
>   struct xbc_node {
> diff --git a/tools/bootconfig/main.c b/tools/bootconfig/main.c
> index eb92027817a7..4b48e6a5ad1b 100644
> --- a/tools/bootconfig/main.c
> +++ b/tools/bootconfig/main.c
> @@ -332,11 +332,13 @@ static int delete_xbc(const char *path)
>   
>   static int apply_xbc(const char *path, const char *xbc_path)
>   {
> +	const char padbuf[BOOTCONFIG_ALIGN] = { 0 };
>   	u32 size, csum;
>   	char *buf, *data;
>   	int ret, fd;
>   	const char *msg;
> -	int pos;
> +	struct stat st;
> +	int pos, pad;
>   
>   	ret = load_xbc_file(xbc_path, &buf);
>   	if (ret < 0) {
> @@ -347,12 +349,10 @@ static int apply_xbc(const char *path, const char *xbc_path)
>   	csum = checksum((unsigned char *)buf, size);
>   
>   	/* Prepare xbc_path data */
> -	data = malloc(size + 8);
> +	data = malloc(size);
>   	if (!data)
>   		return -ENOMEM;
>   	strcpy(data, buf);
> -	*(u32 *)(data + size) = size;
> -	*(u32 *)(data + size + 4) = csum;
>   
>   	/* Check the data format */
>   	ret = xbc_init(buf, &msg, &pos);
> @@ -387,12 +387,35 @@ static int apply_xbc(const char *path, const char *xbc_path)
>   		free(data);
>   		return fd;
>   	}
> +
> +	/* To algin up the total size to BOOTCONFIG_ALIGN, get padding size */
> +	ret = fstat(fd, &st);
> +	if (ret < 0) {
> +		pr_err("Failed to get the stat of %s\n", path);
> +		free(data);
> +		return ret;
> +	}
> +	pad = BOOTCONFIG_ALIGN - (st.st_size + size) % BOOTCONFIG_ALIGN;
> +
>   	/* TODO: Ensure the @path is initramfs/initrd image */
> -	ret = write(fd, data, size + 8);
> +	ret = write(fd, data, size);
>   	if (ret < 0) {
>   		pr_err("Failed to apply a boot config: %d\n", ret);
>   		goto out;
>   	}
> +
> +	if (pad != BOOTCONFIG_ALIGN) {
> +		/* Write padding null characters */
> +		ret = write(fd, padbuf, pad);
> +		if (ret < 0) {
> +			pr_err("Failed to write padding: %d\n", ret);
> +			goto out;
> +		}
> +		size += pad;
> +	}
> +	ret = write(fd, &size, sizeof(u32));
> +	ret = write(fd, &csum, sizeof(u32));
> +
>   	/* Write a magic word of the bootconfig */
>   	ret = write(fd, BOOTCONFIG_MAGIC, BOOTCONFIG_MAGIC_LEN);
>   	if (ret < 0) {
> diff --git a/tools/bootconfig/test-bootconfig.sh b/tools/bootconfig/test-bootconfig.sh
> index d295e406a756..baed891d0ba4 100755
> --- a/tools/bootconfig/test-bootconfig.sh
> +++ b/tools/bootconfig/test-bootconfig.sh
> @@ -9,6 +9,7 @@ else
>     TESTDIR=.
>   fi
>   BOOTCONF=${TESTDIR}/bootconfig
> +ALIGN=4
>   
>   INITRD=`mktemp ${TESTDIR}/initrd-XXXX`
>   TEMPCONF=`mktemp ${TESTDIR}/temp-XXXX.bconf`
> @@ -59,7 +60,10 @@ echo "Show command test"
>   xpass $BOOTCONF $INITRD
>   
>   echo "File size check"
> -xpass test $new_size -eq $(expr $bconf_size + $initrd_size + 9 + 12)
> +total_size=$(expr $bconf_size + $initrd_size + 9 + 12 + $ALIGN - 1 )
> +total_size=$(expr $total_size / $ALIGN)
> +total_size=$(expr $total_size \* $ALIGN)
> +xpass test $new_size -eq $total_size
>   
>   echo "Apply command repeat test"
>   xpass $BOOTCONF -a $TEMPCONF $INITRD
>
Typo in the comment line 391: algin

Woody