[PATCH 1/2] bootconfig: Support appending initrd config to embedded one

From: Petr Malat
Date: Tue Nov 21 2023 - 18:14:13 EST

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@xxxxxxxxx>
---
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