Add /proc/sup_cmdline which shows the list of key-value pairs
in SKC data. Since after boot, all SKC data and tree are
removed, this interface just keep a copy of key-value
pairs in text.
Signed-off-by: Masami Hiramatsu <mhira...@kernel.org>
---
MAINTAINERS | 1
fs/proc/Makefile | 1
fs/proc/sup_cmdline.c | 106 +++++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 108 insertions(+)
create mode 100644 fs/proc/sup_cmdline.c
diff --git a/MAINTAINERS b/MAINTAINERS
index 67590c0e37c5..10dd38311d96 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -15366,6 +15366,7 @@ SUPPLEMENTAL KERNEL CMDLINE
M: Masami Hiramatsu <mhira...@kernel.org>
S: Maintained
F: lib/skc.c
+F: fs/proc/sup_cmdline.c
F: include/linux/skc.h
SUN3/3X
diff --git a/fs/proc/Makefile b/fs/proc/Makefile
index ead487e80510..a5d018f9422c 100644
--- 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_SKC) += sup_cmdline.o
diff --git a/fs/proc/sup_cmdline.c b/fs/proc/sup_cmdline.c
new file mode 100644
index 000000000000..97bc40f0c9dd
--- /dev/null
+++ b/fs/proc/sup_cmdline.c
@@ -0,0 +1,106 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * /proc/sup_cmdline - Supplemental kernel command line
+ */
+#include <linux/fs.h>
+#include <linux/init.h>
+#include <linux/printk.h>
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
+#include <linux/skc.h>
+#include <linux/slab.h>
+
+static char *saved_sup_cmdline;
+
+static int skc_proc_show(struct seq_file *m, void *v)
+{
+ if (saved_sup_cmdline)
+ seq_puts(m, saved_sup_cmdline);
+ else
+ seq_putc(m, '\n');
+ return 0;
+}
+
+static int __init update_snprintf(char **dstp, size_t *sizep,
+ const char *fmt, ...)
+{
+ va_list args;
+ int ret;
+
+ va_start(args, fmt);
+ ret = vsnprintf(*dstp, *sizep, fmt, args);
+ va_end(args);
+
+ if (*sizep && ret > 0) {
+ *sizep -= ret;
+ *dstp += ret;
+ }
+
+ return ret;
+}
+
+/* Return the needed total length if @size is 0 */
+static int __init copy_skc_key_value_list(char *dst, size_t size)
+{
+ struct skc_node *leaf, *vnode;
+ const char *val;
+ int len = 0, ret = 0;
+ char *key;
+
+ key = kzalloc(SKC_KEYLEN_MAX, GFP_KERNEL);
+
+ skc_for_each_key_value(leaf, val) {
+ ret = skc_node_compose_key(leaf, key, SKC_KEYLEN_MAX);
+ if (ret < 0)
+ break;
+ ret = update_snprintf(&dst, &size, "%s = ", key);
+ if (ret < 0)
+ break;
+ len += ret;
+ vnode = skc_node_get_child(leaf);
+ if (vnode && skc_node_is_array(vnode)) {
+ skc_array_for_each_value(vnode, val) {
+ ret = update_snprintf(&dst, &size, "\"%s\"%s",
+ val, vnode->next ? ", " : ";\n");
+ if (ret < 0)
+ goto out;
+ len += ret;
+ }
+ } else {
+ ret = update_snprintf(&dst, &size, "\"%s\";\n", val);
+ if (ret < 0)
+ break;
+ len += ret;
+ }
+ }
+out:
+ kfree(key);
+
+ return ret < 0 ? ret : len;
+}
+
+static int __init proc_skc_init(void)
+{
+ int len;
+
+ len = copy_skc_key_value_list(NULL, 0);
+ if (len < 0)
+ return len;
+
+ if (len > 0) {
+ saved_sup_cmdline = kzalloc(len + 1, GFP_KERNEL);
+ if (!saved_sup_cmdline)
+ return -ENOMEM;
+
+ len = copy_skc_key_value_list(saved_sup_cmdline, len + 1);
+ if (len < 0) {
+ kfree(saved_sup_cmdline);
+ return len;
+ }
+ }
+
+ proc_create_single("sup_cmdline", 0, NULL, skc_proc_show);
+
+ return 0;
+}
+fs_initcall(proc_skc_init);
