diff mbox series

[v4,7/7] modpost: Create modalias for builtin modules

Message ID 321947106ec997b5a2a9c93ec2229cb2f9eb377c.1750511018.git.legion@kernel.org
State New
Headers show
Series Add generated modalias to modules.builtin.modinfo | expand

Commit Message

Alexey Gladkov June 21, 2025, 1:57 p.m. UTC 
For some modules, modalias is generated using the modpost utility and
the section is added to the module file.

When a module is added inside vmlinux, modpost does not generate
modalias for such modules and the information is lost.

As a result kmod (which uses modules.builtin.modinfo in userspace)
cannot determine that modalias is handled by a builtin kernel module.

$ cat /sys/devices/pci0000:00/0000:00:14.0/modalias
pci:v00008086d0000A36Dsv00001043sd00008694bc0Csc03i30

$ modinfo xhci_pci
name:           xhci_pci
filename:       (builtin)
license:        GPL
file:           drivers/usb/host/xhci-pci
description:    xHCI PCI Host Controller Driver

Missing modalias "pci:v*d*sv*sd*bc0Csc03i30*" which will be generated by
modpost if the module is built separately.

To fix this it is necessary to generate the same modalias for vmlinux as
for the individual modules. Fortunately '.vmlinux.export.o' is already
generated from which '.modinfo' can be extracted in the same way as for
vmlinux.o.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Alexey Gladkov <legion@kernel.org>
---
 include/linux/module.h   |  4 ----
 scripts/Makefile.vmlinux |  5 ++++-
 scripts/mksysmap         |  3 +++
 scripts/mod/file2alias.c | 16 ++++++++++++++++
 scripts/mod/modpost.c    | 17 ++++++++++++++++-
 scripts/mod/modpost.h    |  2 ++
 6 files changed, 41 insertions(+), 6 deletions(-)
diff mbox series

Patch

diff --git a/include/linux/module.h b/include/linux/module.h
index e0f826fab2ac..3aeee5d0a77c 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -251,14 +251,10 @@  struct module_kobject *lookup_or_create_module_kobject(const char *name);
 	__PASTE(type,			\
 	__PASTE(__, name)))))
 
-#ifdef MODULE
 /* Creates an alias so file2alias.c can find device table. */
 #define MODULE_DEVICE_TABLE(type, name)			\
 static typeof(name) __mod_device_table(type, name)	\
   __attribute__ ((used, alias(__stringify(name))))
-#else  /* !MODULE */
-#define MODULE_DEVICE_TABLE(type, name)
-#endif
 
 /* Version of form [<epoch>:]<version>[-<extra-version>].
  * Or for CVS/RCS ID version, everything but the number is stripped.
diff --git a/scripts/Makefile.vmlinux b/scripts/Makefile.vmlinux
index fdab5aa90215..fcc188d26ead 100644
--- a/scripts/Makefile.vmlinux
+++ b/scripts/Makefile.vmlinux
@@ -89,8 +89,11 @@  endif
 remove-section-y                                   := .modinfo
 remove-section-$(CONFIG_ARCH_VMLINUX_NEEDS_RELOCS) += '.rel*'
 
+remove-symbols := -w --strip-symbol='__mod_device_table__*'
+
 quiet_cmd_strip_relocs = OBJCOPY $@
-      cmd_strip_relocs = $(OBJCOPY) $(addprefix --remove-section=,$(remove-section-y)) $< $@
+      cmd_strip_relocs = $(OBJCOPY) $(addprefix --remove-section=,$(remove-section-y)) \
+                         $(remove-symbols) $< $@
 
 targets += vmlinux
 vmlinux: vmlinux.unstripped FORCE
diff --git a/scripts/mksysmap b/scripts/mksysmap
index a607a0059d11..c4531eacde20 100755
--- a/scripts/mksysmap
+++ b/scripts/mksysmap
@@ -59,6 +59,9 @@ 
 # EXPORT_SYMBOL (namespace)
 / __kstrtabns_/d
 
+# MODULE_DEVICE_TABLE (symbol name)
+/ __mod_device_table__/d
+
 # ---------------------------------------------------------------------------
 # Ignored suffixes
 #  (do not forget '$' after each pattern)
diff --git a/scripts/mod/file2alias.c b/scripts/mod/file2alias.c
index 13021266a18f..7da9735e7ab3 100644
--- a/scripts/mod/file2alias.c
+++ b/scripts/mod/file2alias.c
@@ -1527,5 +1527,21 @@  void handle_moddevtable(struct module *mod, struct elf_info *info,
 		}
 	}
 
+	if (mod->is_vmlinux) {
+		struct module_alias *alias;
+
+		/*
+		 * If this is vmlinux, record the name of the builtin module.
+		 * Traverse the linked list in the reverse order, and set the
+		 * builtin_modname unless it has already been set in the
+		 * previous call.
+		 */
+		list_for_each_entry_reverse(alias, &mod->aliases, node) {
+			if (alias->builtin_modname)
+				break;
+			alias->builtin_modname = xstrndup(modname, modnamelen);
+		}
+	}
+
 	free(zeros);
 }
diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index be89921d60b6..67668b159444 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -2021,11 +2021,26 @@  static void write_if_changed(struct buffer *b, const char *fname)
 static void write_vmlinux_export_c_file(struct module *mod)
 {
 	struct buffer buf = { };
+	struct module_alias *alias, *next;
 
 	buf_printf(&buf,
-		   "#include <linux/export-internal.h>\n");
+		   "#include <linux/export-internal.h>\n"
+		   "#include <linux/module.h>\n");
 
 	add_exported_symbols(&buf, mod);
+
+	buf_printf(&buf,
+		   "#undef __MODULE_INFO_PREFIX\n"
+		   "#define __MODULE_INFO_PREFIX\n");
+
+	list_for_each_entry_safe(alias, next, &mod->aliases, node) {
+		buf_printf(&buf, "MODULE_INFO(%s.alias, \"%s\");\n",
+			   alias->builtin_modname, alias->str);
+		list_del(&alias->node);
+		free(alias->builtin_modname);
+		free(alias);
+	}
+
 	write_if_changed(&buf, ".vmlinux.export.c");
 	free(buf.p);
 }
diff --git a/scripts/mod/modpost.h b/scripts/mod/modpost.h
index 9133e4c3803f..2aecb8f25c87 100644
--- a/scripts/mod/modpost.h
+++ b/scripts/mod/modpost.h
@@ -99,10 +99,12 @@  buf_write(struct buffer *buf, const char *s, int len);
  * struct module_alias - auto-generated MODULE_ALIAS()
  *
  * @node: linked to module::aliases
+ * @modname: name of the builtin module (only for vmlinux)
  * @str: a string for MODULE_ALIAS()
  */
 struct module_alias {
 	struct list_head node;
+	char *builtin_modname;
 	char str[];
 };