linux-kernel - [PATCH 24/27] modpost: generate linker script to collect symbol versions

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Date:   Mon, 25 Apr 2022 04:08:08 +0900
From:   Masahiro Yamada <masahiroy@...nel.org>
To:     linux-kbuild@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org,
        Masahiro Yamada <masahiroy@...nel.org>,
        Michal Marek <michal.lkml@...kovi.net>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Nicolas Schier <nicolas@...sle.eu>,
        Rasmus Villemoes <linux@...musvillemoes.dk>
Subject: [PATCH 24/27] modpost: generate linker script to collect symbol versions

Merge version CRCs per vmlinux or per module.

These linker scripts will be fed to the final link stage.

Signed-off-by: Masahiro Yamada <masahiroy@...nel.org>
---

 .gitignore            |  1 +
 Makefile              |  1 +
 scripts/mod/modpost.c | 27 +++++++++++++++++++++++++++
 3 files changed, 29 insertions(+)

diff --git a/.gitignore b/.gitignore
index 265959544978..f9dad6b917e6 100644
--- a/.gitignore
+++ b/.gitignore
@@ -42,6 +42,7 @@
 *.so.dbg
 *.su
 *.symtypes
+*.symver.lds
 *.symversions
 *.tab.[ch]
 *.tar
diff --git a/Makefile b/Makefile
index 235d68fa1470..0779db3d1c0c 100644
--- a/Makefile
+++ b/Makefile
@@ -1859,6 +1859,7 @@ clean: $(clean-dirs)
 		-o -name '*.c.[012]*.*' \
 		-o -name '*.ll' \
 		-o -name '*.gcno' \
+		-o -name '*.symver.lds' \
 		-o -name '*.*.symversions' \) -type f -print | xargs rm -f
 
 # Generate tags for editors
diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index 43ab4f000ae3..ef779ada04c6 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -2577,6 +2577,30 @@ static void write_dump(const char *fname)
 	free(buf.p);
 }
 
+static void write_symversions_lds(struct module *mod)
+{
+	struct buffer buf = { };
+	struct symbol *sym;
+	char lds_file[PATH_MAX];
+	int ret;
+
+	ret = snprintf(lds_file, sizeof(lds_file), "%s.symver.lds", mod->name);
+	if (ret >= sizeof(lds_file)) {
+		error("%s: too long path was truncated\n", lds_file);
+		return;
+	}
+
+	list_for_each_entry(sym, &mod->exported_symbols, list) {
+		if (!sym->crc_valid)
+			continue;
+
+		buf_printf(&buf, "__crc_%s = 0x%08x;\n", sym->name, sym->crc);
+	}
+
+	write_if_changed(&buf, lds_file);
+	free(buf.p);
+}
+
 static void write_namespace_deps_files(const char *fname)
 {
 	struct module *mod;
@@ -2673,6 +2697,9 @@ int main(int argc, char **argv)
 		char fname[PATH_MAX];
 		int ret;
 
+		if (modversions && !mod->from_dump)
+			write_symversions_lds(mod);
+
 		if (mod->is_vmlinux || mod->from_dump)
 			continue;
 
-- 
2.32.0