[PATCH v10 06/11] modpost: Add -b option for emitting built-in aliases

[Allen Webb <allenwebb@google.com>]

This adds a command line option for writing the match-id based built-in
aliases to a file. A future patch extends file2alias.c to support this
command.

The -b option accepts the output path as a parameter and requires
vmlinuz.o to be one of the input files for the aliases to be found.

Signed-off-by: Allen Webb <allenwebb@google.com>
---
 scripts/mod/modpost.c | 30 ++++++++++++++++++++++++++++--
 scripts/mod/modpost.h |  1 +
 2 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index efff8078e395..2e452aec0fc6 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -2173,6 +2173,19 @@ static void write_if_changed(struct buffer *b, const char *fname)
 	write_buf(b, fname);
 }
 
+/* Write the builtin aliases to the specified file. */
+static void write_builtin(const char *fname)
+{
+	struct buffer buf = { };
+	struct module *mod;
+
+	list_for_each_entry(mod, &modules, list)
+		buf_write(&buf, mod->modalias_buf.p, mod->modalias_buf.pos);
+
+	write_if_changed(&buf, fname);
+	free(buf.p);
+}
+
 static void write_vmlinux_export_c_file(struct module *mod)
 {
 	struct buffer buf = { };
@@ -2329,13 +2342,23 @@ int main(int argc, char **argv)
 {
 	struct module *mod;
 	char *missing_namespace_deps = NULL;
-	char *dump_write = NULL, *files_source = NULL;
+	char *builtin_write = NULL, *dump_write = NULL, *files_source = NULL;
 	int opt;
 	LIST_HEAD(dump_lists);
 	struct dump_list *dl, *dl2;
 
-	while ((opt = getopt(argc, argv, "ei:mnT:o:awENd:")) != -1) {
+	while ((opt = getopt(argc, argv, "b:ei:mnT:o:awENd:")) != -1) {
 		switch (opt) {
+		case 'b':
+			/*
+			 * Writes the match-id based built-in module aliases to
+			 * the specified path.
+			 *
+			 * vmlinuz.o needs to be one of the input files for the
+			 * aliases to be found.
+			 */
+			builtin_write = optarg;
+			break;
 		case 'e':
 			external_module = true;
 			break;
@@ -2398,6 +2421,9 @@ int main(int argc, char **argv)
 			write_mod_c_file(mod);
 	}
 
+	if (builtin_write)
+		write_builtin(builtin_write);
+
 	if (missing_namespace_deps)
 		write_namespace_deps_files(missing_namespace_deps);
 
diff --git a/scripts/mod/modpost.h b/scripts/mod/modpost.h
index 34fe5fc0b02c..c55a6aeb46bf 100644
--- a/scripts/mod/modpost.h
+++ b/scripts/mod/modpost.h
@@ -123,6 +123,7 @@ struct module {
 	bool has_init;
 	bool has_cleanup;
 	struct buffer dev_table_buf;
+	struct buffer modalias_buf;
 	char	     srcversion[25];
 	// Missing namespace dependencies
 	struct list_head missing_namespaces;
-- 
2.39.2