Message-Id: <20231121231342.193646-2-oss@malat.biz>
Date:   Wed, 22 Nov 2023 00:13:41 +0100
From:   Petr Malat <oss@...at.biz>
To:     linux-kernel@...r.kernel.org
Cc:     mhiramat@...nel.org, paulmck@...nel.org, rostedt@...dmis.org,
        oss@...at.biz
Subject: [PATCH 1/2] bootconfig: Support appending initrd config to embedded one

When both embedded and initrd boot configs are present, initrd config is
preferred. Introduce CONFIG_BOOT_CONFIG_EMBED_APPEND_INITRD option, which
allows appending the initrd config to the embedded one.

We handle embedded boot config in-place to avoid allocations, which will
be handy for early parameters support.

Signed-off-by: Petr Malat <oss@...at.biz>
---
 include/linux/bootconfig.h |  10 ++-
 init/Kconfig               |   9 +++
 init/main.c                |  62 ++++++++++--------
 lib/bootconfig-data.S      |   3 +-
 lib/bootconfig.c           | 129 +++++++++++++++++++++++++++----------
 5 files changed, 146 insertions(+), 67 deletions(-)

diff --git a/include/linux/bootconfig.h b/include/linux/bootconfig.h
index ca73940e26df..88bbcffa82d5 100644
--- a/include/linux/bootconfig.h
+++ b/include/linux/bootconfig.h
@@ -281,7 +281,10 @@ static inline int __init xbc_node_compose_key(struct xbc_node *node,
 }
 
 /* XBC node initializer */
-int __init xbc_init(const char *buf, size_t size, const char **emsg, int *epos);
+int __init xbc_init(char *buf, size_t size, const char **emsg, int *epos);
+
+/* Append XBC data */
+int __init xbc_append(const char *data, size_t size, const char **emsg, int *epos);
 
 /* XBC node and size information */
 int __init xbc_get_info(int *node_size, size_t *data_size);
@@ -291,10 +294,11 @@ void __init xbc_exit(void);
 
 /* XBC embedded bootconfig data in kernel */
 #ifdef CONFIG_BOOT_CONFIG_EMBED
-const char * __init xbc_get_embedded_bootconfig(size_t *size);
+char * __init xbc_get_embedded_bootconfig(size_t *size);
 #else
-static inline const char *xbc_get_embedded_bootconfig(size_t *size)
+static inline char *xbc_get_embedded_bootconfig(size_t *size)
 {
+	*size = 0;
 	return NULL;
 }
 #endif
diff --git a/init/Kconfig b/init/Kconfig
index 6d35728b94b2..9161d2dbad0c 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1339,6 +1339,15 @@ config BOOT_CONFIG_EMBED
 
 	  If unsure, say N.
 
+config BOOT_CONFIG_EMBED_APPEND_INITRD
+	bool "Append initrd bootconfig to the embedded one"
+	depends on BOOT_CONFIG_EMBED && BLK_DEV_INITRD
+	default n
+	help
+	  By default if both embedded bootconfig and initrd bootconfig are
+	  found, initrd bootconfig is preferred. If this option is set, initrd
+	  bootconfig gets appended to the embedded one.
+
 config BOOT_CONFIG_EMBED_FILE
 	string "Embedded bootconfig file path"
 	depends on BOOT_CONFIG_EMBED
diff --git a/init/main.c b/init/main.c
index 436d73261810..0cd738f7f0cf 100644
--- a/init/main.c
+++ b/init/main.c
@@ -267,6 +267,9 @@ static void * __init get_boot_config_from_initrd(size_t *_size)
 	u32 *hdr;
 	int i;
 
+	if (_size)
+		*_size = 0;
+
 	if (!initrd_end)
 		return NULL;
 
@@ -309,6 +312,8 @@ static void * __init get_boot_config_from_initrd(size_t *_size)
 #else
 static void * __init get_boot_config_from_initrd(size_t *_size)
 {
+	if (_size)
+		*_size = 0;
 	return NULL;
 }
 #endif
@@ -404,16 +409,16 @@ static int __init warn_bootconfig(char *str)
 static void __init setup_boot_config(void)
 {
 	static char tmp_cmdline[COMMAND_LINE_SIZE] __initdata;
-	const char *msg, *data;
+	const char *msg, *initrd_data;
 	int pos, ret;
-	size_t size;
-	char *err;
+	size_t initrd_size, embeded_size = 0;
+	char *err, *embeded_data = NULL;
 
 	/* Cut out the bootconfig data even if we have no bootconfig option */
-	data = get_boot_config_from_initrd(&size);
+	initrd_data = get_boot_config_from_initrd(&initrd_size);
 	/* If there is no bootconfig in initrd, try embedded one. */
-	if (!data)
-		data = xbc_get_embedded_bootconfig(&size);
+	if (!initrd_data || IS_ENABLED(CONFIG_BOOT_CONFIG_EMBED_APPEND_INITRD))
+		embeded_data = xbc_get_embedded_bootconfig(&embeded_size);
 
 	strscpy(tmp_cmdline, boot_command_line, COMMAND_LINE_SIZE);
 	err = parse_args("bootconfig", tmp_cmdline, NULL, 0, 0, 0, NULL,
@@ -426,7 +431,7 @@ static void __init setup_boot_config(void)
 	if (err)
 		initargs_offs = err - tmp_cmdline;
 
-	if (!data) {
+	if (!initrd_data && !embeded_data) {
 		/* If user intended to use bootconfig, show an error level message */
 		if (bootconfig_found)
 			pr_err("'bootconfig' found on command line, but no bootconfig found\n");
@@ -435,28 +440,29 @@ static void __init setup_boot_config(void)
 		return;
 	}
 
-	if (size >= XBC_DATA_MAX) {
-		pr_err("bootconfig size %ld greater than max size %d\n",
-			(long)size, XBC_DATA_MAX);
-		return;
-	}
-
-	ret = xbc_init(data, size, &msg, &pos);
-	if (ret < 0) {
-		if (pos < 0)
-			pr_err("Failed to init bootconfig: %s.\n", msg);
-		else
-			pr_err("Failed to parse bootconfig: %s at %d.\n",
-				msg, pos);
-	} else {
-		xbc_get_info(&ret, NULL);
-		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 */
-		extra_init_args = xbc_make_cmdline("init");
-	}
+	ret = xbc_init(embeded_data, embeded_size, &msg, &pos);
+	if (ret < 0)
+		goto err0;
+
+	/* Call append even if no data are there as embedded bootconfig is in .init */
+	ret = xbc_append(initrd_data, initrd_size, &msg, &pos);
+	if (ret < 0)
+		goto err0;
+
+	xbc_get_info(&ret, NULL);
+	pr_info("Load bootconfig: %ld bytes %d nodes\n", (long)(embeded_size + initrd_size), ret);
+	/* keys starting with "kernel." are passed via cmdline */
+	extra_command_line = xbc_make_cmdline("kernel");
+	/* Also, "init." keys are init arguments */
+	extra_init_args = xbc_make_cmdline("init");
 	return;
+
+err0:	if (pos < 0)
+		pr_err("Failed to init bootconfig: %s.\n", msg);
+	else
+		pr_err("Failed to parse %s bootconfig: %s at %zu.\n",
+				pos < embeded_size ? "embedded" : "initrd",
+				msg, pos < embeded_size ? pos : pos - embeded_size);
 }
 
 static void __init exit_boot_config(void)
diff --git a/lib/bootconfig-data.S b/lib/bootconfig-data.S
index ef85ba1a82f4..f447e24eb8fa 100644
--- a/lib/bootconfig-data.S
+++ b/lib/bootconfig-data.S
@@ -2,9 +2,10 @@
 /*
  * Embed default bootconfig in the kernel.
  */
-	.section .init.rodata, "aw"
+	.section .init.data, "aw"
 	.global embedded_bootconfig_data
 embedded_bootconfig_data:
 	.incbin "lib/default.bconf"
+	.byte 0
 	.global embedded_bootconfig_data_end
 embedded_bootconfig_data_end:
diff --git a/lib/bootconfig.c b/lib/bootconfig.c
index c59d26068a64..841163ce5313 100644
--- a/lib/bootconfig.c
+++ b/lib/bootconfig.c
@@ -15,13 +15,13 @@
 
 #ifdef CONFIG_BOOT_CONFIG_EMBED
 /* embedded_bootconfig_data is defined in bootconfig-data.S */
-extern __visible const char embedded_bootconfig_data[];
-extern __visible const char embedded_bootconfig_data_end[];
+extern __visible char embedded_bootconfig_data[];
+extern __visible char embedded_bootconfig_data_end[];
 
-const char * __init xbc_get_embedded_bootconfig(size_t *size)
+char * __init xbc_get_embedded_bootconfig(size_t *size)
 {
 	*size = embedded_bootconfig_data_end - embedded_bootconfig_data;
-	return (*size) ? embedded_bootconfig_data : NULL;
+	return *size ? embedded_bootconfig_data : NULL;
 }
 #endif
 
@@ -48,6 +48,7 @@ const char * __init xbc_get_embedded_bootconfig(size_t *size)
 static struct xbc_node *xbc_nodes __initdata;
 static int xbc_node_num __initdata;
 static char *xbc_data __initdata;
+static bool xbc_data_allocated __initdata;
 static size_t xbc_data_size __initdata;
 static struct xbc_node *last_parent __initdata;
 static const char *xbc_err_msg __initdata;
@@ -846,13 +847,14 @@ static int __init xbc_verify_tree(void)
 }
 
 /* Need to setup xbc_data and xbc_nodes before call this. */
-static int __init xbc_parse_tree(void)
+static int __init xbc_parse_tree(int offset)
 {
 	char *p, *q;
 	int ret = 0, c;
 
-	last_parent = NULL;
-	p = xbc_data;
+	if (!offset)
+		last_parent = NULL;
+	p = xbc_data + offset;
 	do {
 		q = strpbrk(p, "{}=+;:\n#");
 		if (!q) {
@@ -906,18 +908,42 @@ static int __init xbc_parse_tree(void)
  */
 void __init xbc_exit(void)
 {
-	xbc_free_mem(xbc_data, xbc_data_size);
+	if (xbc_data_allocated)
+		xbc_free_mem(xbc_data, xbc_data_size);
 	xbc_data = NULL;
 	xbc_data_size = 0;
+	xbc_data_allocated = 0;
 	xbc_node_num = 0;
 	xbc_free_mem(xbc_nodes, sizeof(struct xbc_node) * XBC_NODE_MAX);
 	xbc_nodes = NULL;
 	brace_index = 0;
 }
 
+static int xbc_parse_and_verify_tree(int offset, int *epos, const char **emsg)
+{
+	int ret;
+
+	ret = xbc_parse_tree(offset);
+	if (!ret) {
+		ret = xbc_verify_tree();
+		if (!ret)
+			return xbc_node_num;
+	}
+
+	if (epos)
+		*epos = xbc_err_pos;
+	if (emsg)
+		*emsg = xbc_err_msg;
+
+	xbc_exit();
+	return ret;
+}
+
 /**
  * xbc_init() - Parse given XBC file and build XBC internal tree
- * @data: The boot config text original data
+ * @data: Null terminated boot config data, that can be directly
+ *        modified by the parser and will exist till xbc_exit()
+ *        or xbc_append() is called.
  * @size: The size of @data
  * @emsg: A pointer of const char * to store the error message
  * @epos: A pointer of int to store the error position
@@ -930,10 +956,8 @@ void __init xbc_exit(void)
  * @epos will be updated with the error position which is the byte offset
  * of @buf. If the error is not a parser error, @epos will be -1.
  */
-int __init xbc_init(const char *data, size_t size, const char **emsg, int *epos)
+int __init xbc_init(char *data, size_t size, const char **emsg, int *epos)
 {
-	int ret;
-
 	if (epos)
 		*epos = -1;
 
@@ -942,44 +966,79 @@ int __init xbc_init(const char *data, size_t size, const char **emsg, int *epos)
 			*emsg = "Bootconfig is already initialized";
 		return -EBUSY;
 	}
-	if (size > XBC_DATA_MAX || size == 0) {
+	if (size > XBC_DATA_MAX || (size == 0 && data != NULL)) {
 		if (emsg)
 			*emsg = size ? "Config data is too big" :
 				"Config data is empty";
 		return -ERANGE;
 	}
 
-	xbc_data = xbc_alloc_mem(size + 1);
-	if (!xbc_data) {
-		if (emsg)
-			*emsg = "Failed to allocate bootconfig data";
-		return -ENOMEM;
-	}
-	memcpy(xbc_data, data, size);
-	xbc_data[size] = '\0';
-	xbc_data_size = size + 1;
-
 	xbc_nodes = xbc_alloc_mem(sizeof(struct xbc_node) * XBC_NODE_MAX);
 	if (!xbc_nodes) {
 		if (emsg)
 			*emsg = "Failed to allocate bootconfig nodes";
-		xbc_exit();
 		return -ENOMEM;
 	}
 	memset(xbc_nodes, 0, sizeof(struct xbc_node) * XBC_NODE_MAX);
 
-	ret = xbc_parse_tree();
-	if (!ret)
-		ret = xbc_verify_tree();
+	if (!data)
+		return 0;
+	xbc_data = data;
+	xbc_data_size = size;
+	return xbc_parse_and_verify_tree(0, epos, emsg);
+}
 
-	if (ret < 0) {
-		if (epos)
-			*epos = xbc_err_pos;
+/**
+ * xbc_append() - Append data to already existing XBC tree
+ * @data: Boot config data, which are copied by the function.
+ * @size: The size of @data
+ * @emsg: A pointer of const char * to store the error message
+ * @epos: A pointer of int to store the error position
+ */
+int __init xbc_append(const char *data, size_t size, const char **emsg, int *epos)
+{
+	size_t new_size, parse_start;
+	char *new_data;
+
+	new_size = xbc_data_size + size;
+	if (new_size > XBC_DATA_MAX) {
 		if (emsg)
-			*emsg = xbc_err_msg;
-		xbc_exit();
-	} else
-		ret = xbc_node_num;
+			*emsg = "Merged config data is too big";
+		return -ERANGE;
+	}
+	if (new_size == 0) {
+		if (data) {
+			if (emsg)
+				*emsg = "Appended data is empty";
+			return -ERANGE;
+		}
+		return 0;
+	}
 
-	return ret;
+	new_data = xbc_alloc_mem(new_size);
+	if (!new_data) {
+		if (emsg)
+			*emsg = "Failed to allocate bootconfig data";
+		return -ENOMEM;
+	}
+
+	if (xbc_data_size) {
+		memcpy(new_data, xbc_data, xbc_data_size - 1);
+		new_data[xbc_data_size - 1] = '\n';
+		parse_start = xbc_data_size - 1;
+	} else {
+		parse_start = 0;
+	}
+	memcpy(new_data + xbc_data_size, data, size);
+	new_data[new_size - 1] = 0;
+	if (xbc_data_allocated)
+		xbc_free_mem(xbc_data, xbc_data_size);
+	xbc_data_allocated = 1;
+	xbc_data = new_data;
+	xbc_data_size = new_size;
+
+	if (!data)
+		return 0;
+
+	return xbc_parse_and_verify_tree(parse_start, epos, emsg);
 }
-- 
2.30.2

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