Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
From:   Masami Hiramatsu <mhiramat@kernel.org>
To:     Steven Rostedt <rostedt@goodmis.org>
Cc:     Ingo Molnar <mingo@redhat.com>,
        Frank Rowand <frowand.list@gmail.com>,
        Randy Dunlap <rdunlap@infradead.org>,
        Namhyung Kim <namhyung@kernel.org>,
        Tim Bird <Tim.Bird@sony.com>, Jiri Olsa <jolsa@redhat.com>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        Tom Zanussi <tom.zanussi@linux.intel.com>,
        Rob Herring <robh+dt@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Alexey Dobriyan <adobriyan@gmail.com>,
        Jonathan Corbet <corbet@lwn.net>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        linux-doc@vger.kernel.org, linux-fsdevel@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: [PATCH v6 02/22] bootconfig: Load boot config from the tail of initrd
Date:   Sat, 11 Jan 2020 01:03:44 +0900
Message-Id: <157867222435.17873.9936667353335606867.stgit@devnote2>
In-Reply-To: <157867220019.17873.13377985653744804396.stgit@devnote2>
References: <157867220019.17873.13377985653744804396.stgit@devnote2>
User-Agent: StGit/0.17.1-dirty
MIME-Version: 1.0
Content-Type: text/plain; charset="utf-8"
Content-Transfer-Encoding: 8bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Load the extended boot config data from the tail of initrd
image. If there is an SKC data there, it has
[(u32)size][(u32)checksum] header (in really, this is a
footer) at the end of initrd. If the checksum (simple sum
of bytes) is match, this starts parsing it from there.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
---
 Changes in v4:
  - Rename skc to bootconfig.
---
 init/Kconfig |    1 +
 init/main.c  |   54 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 55 insertions(+)

diff --git a/init/Kconfig b/init/Kconfig
index 63450d3bbf12..ffd240fb88c3 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1217,6 +1217,7 @@ endif
 
 config BOOT_CONFIG
 	bool "Boot config support"
+	depends on BLK_DEV_INITRD
 	select LIBXBC
 	default y
 	help
diff --git a/init/main.c b/init/main.c
index 2cd736059416..59c418a57f92 100644
--- a/init/main.c
+++ b/init/main.c
@@ -28,6 +28,7 @@
 #include <linux/initrd.h>
 #include <linux/memblock.h>
 #include <linux/acpi.h>
+#include <linux/bootconfig.h>
 #include <linux/console.h>
 #include <linux/nmi.h>
 #include <linux/percpu.h>
@@ -245,6 +246,58 @@ static int __init loglevel(char *str)
 
 early_param("loglevel", loglevel);
 
+#ifdef CONFIG_BOOT_CONFIG
+u32 boot_config_checksum(unsigned char *p, u32 size)
+{
+	u32 ret = 0;
+
+	while (size--)
+		ret += *p++;
+
+	return ret;
+}
+
+static void __init setup_boot_config(void)
+{
+	u32 size, csum;
+	char *data, *copy;
+	u32 *hdr;
+
+	if (!initrd_end)
+		return;
+
+	hdr = (u32 *)(initrd_end - 8);
+	size = hdr[0];
+	csum = hdr[1];
+
+	if (size >= XBC_DATA_MAX)
+		return;
+
+	data = ((void *)hdr) - size;
+	if ((unsigned long)data < initrd_start)
+		return;
+
+	if (boot_config_checksum((unsigned char *)data, size) != csum)
+		return;
+
+	copy = memblock_alloc(size + 1, SMP_CACHE_BYTES);
+	if (!copy) {
+		pr_err("Failed to allocate memory for boot config\n");
+		return;
+	}
+
+	memcpy(copy, data, size);
+	copy[size] = '\0';
+
+	if (xbc_init(copy) < 0)
+		pr_err("Failed to parse boot config\n");
+	else
+		pr_info("Load boot config: %d bytes\n", size);
+}
+#else
+#define setup_boot_config()	do { } while (0)
+#endif
+
 /* Change NUL term back to "=", to make "param" the whole string. */
 static int __init repair_env_string(char *param, char *val,
 				    const char *unused, void *arg)
@@ -595,6 +648,7 @@ asmlinkage __visible void __init start_kernel(void)
 	pr_notice("%s", linux_banner);
 	early_security_init();
 	setup_arch(&command_line);
+	setup_boot_config();
 	setup_command_line(command_line);
 	setup_nr_cpu_ids();
 	setup_per_cpu_areas();