proc: bootconfig: Add /proc/bootconfig to show boot config list

Add /proc/bootconfig which shows the list of key-value pairs
in boot config. Since after boot, all boot configs and tree
are removed, this interface just keep a copy of key-value
pairs in text.

Link: http://lkml.kernel.org/r/157867225967.17873.12155805787236073787.stgit@devnote2
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

diff --git a/MAINTAINERS b/MAINTAINERS
index 0600500..903e8a7 100644 (file)
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -15774,6 +15774,7 @@ EXTRA BOOT CONFIG
 M:     Masami Hiramatsu <mhiramat@kernel.org>
 S:     Maintained
 F:     lib/bootconfig.c
+F:     fs/proc/bootconfig.c
 F:     include/linux/bootconfig.h
 F:     tools/bootconfig/*
 

diff --git a/fs/proc/Makefile b/fs/proc/Makefile
index ead487e..bd08616 100644 (file)
--- a/fs/proc/Makefile
+++ b/fs/proc/Makefile
@@ -33,3 +33,4 @@ proc-$(CONFIG_PROC_KCORE)     += kcore.o
 proc-$(CONFIG_PROC_VMCORE)     += vmcore.o
 proc-$(CONFIG_PRINTK)  += kmsg.o
 proc-$(CONFIG_PROC_PAGE_MONITOR)       += page.o
+proc-$(CONFIG_BOOT_CONFIG)     += bootconfig.o

diff --git a/fs/proc/bootconfig.c b/fs/proc/bootconfig.c
new file mode 100644 (file)
index 0000000..9955d75
--- /dev/null
+++ b/fs/proc/bootconfig.c
@@ -0,0 +1,89 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * /proc/bootconfig - Extra boot configuration
+ */
+#include <linux/fs.h>
+#include <linux/init.h>
+#include <linux/printk.h>
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
+#include <linux/bootconfig.h>
+#include <linux/slab.h>
+
+static char *saved_boot_config;
+
+static int boot_config_proc_show(struct seq_file *m, void *v)
+{
+       if (saved_boot_config)
+               seq_puts(m, saved_boot_config);
+       return 0;
+}
+
+/* Rest size of buffer */
+#define rest(dst, end) ((end) > (dst) ? (end) - (dst) : 0)
+
+/* Return the needed total length if @size is 0 */
+static int __init copy_xbc_key_value_list(char *dst, size_t size)
+{
+       struct xbc_node *leaf, *vnode;
+       const char *val;
+       char *key, *end = dst + size;
+       int ret = 0;
+
+       key = kzalloc(XBC_KEYLEN_MAX, GFP_KERNEL);
+
+       xbc_for_each_key_value(leaf, val) {
+               ret = xbc_node_compose_key(leaf, key, XBC_KEYLEN_MAX);
+               if (ret < 0)
+                       break;
+               ret = snprintf(dst, rest(dst, end), "%s = ", key);
+               if (ret < 0)
+                       break;
+               dst += ret;
+               vnode = xbc_node_get_child(leaf);
+               if (vnode && xbc_node_is_array(vnode)) {
+                       xbc_array_for_each_value(vnode, val) {
+                               ret = snprintf(dst, rest(dst, end), "\"%s\"%s",
+                                       val, vnode->next ? ", " : "\n");
+                               if (ret < 0)
+                                       goto out;
+                               dst += ret;
+                       }
+               } else {
+                       ret = snprintf(dst, rest(dst, end), "\"%s\"\n", val);
+                       if (ret < 0)
+                               break;
+                       dst += ret;
+               }
+       }
+out:
+       kfree(key);
+
+       return ret < 0 ? ret : dst - (end - size);
+}
+
+static int __init proc_boot_config_init(void)
+{
+       int len;
+
+       len = copy_xbc_key_value_list(NULL, 0);
+       if (len < 0)
+               return len;
+
+       if (len > 0) {
+               saved_boot_config = kzalloc(len + 1, GFP_KERNEL);
+               if (!saved_boot_config)
+                       return -ENOMEM;
+
+               len = copy_xbc_key_value_list(saved_boot_config, len + 1);
+               if (len < 0) {
+                       kfree(saved_boot_config);
+                       return len;
+               }
+       }
+
+       proc_create_single("bootconfig", 0, NULL, boot_config_proc_show);
+
+       return 0;
+}
+fs_initcall(proc_boot_config_init);