module: show version information for built-in modules in sysfs

Currently only drivers that are built as modules have their versions
shown in /sys/module/<module_name>/version, but this information might
also be useful for built-in drivers as well. This especially important
for drivers that do not define any parameters - such drivers, if
built-in, are completely invisible from userspace.

This patch changes MODULE_VERSION() macro so that in case when we are
compiling built-in module, version information is stored in a separate
section. Kernel then uses this data to create 'version' sysfs attribute
in the same fashion it creates attributes for module parameters.

Signed-off-by: Dmitry Torokhov <dtor@vmware.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index 68649336c4adf98618ff4d4fd8d9f1d6b2867062..6ebb81030d2d109ce9f99069b130c29a39ccfa11 100644 (file)
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -364,6 +364,13 @@
                VMLINUX_SYMBOL(__start___param) = .;                    \
                *(__param)                                              \
                VMLINUX_SYMBOL(__stop___param) = .;                     \
+       }                                                               \
+                                                                       \
+       /* Built-in module versions. */                                 \
+       __modver : AT(ADDR(__modver) - LOAD_OFFSET) {                   \
+               VMLINUX_SYMBOL(__start___modver) = .;                   \
+               *(__modver)                                             \
+               VMLINUX_SYMBOL(__stop___modver) = .;                    \
                . = ALIGN((align));                                     \
                VMLINUX_SYMBOL(__end_rodata) = .;                       \
        }                                                               \

diff --git a/include/linux/module.h b/include/linux/module.h
index 8b17fd8c790d8601f8aff0a33c7b909984e30545..50efcd3ae8507fcbbbff6e361491f7f60c00a5ca 100644 (file)
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -58,6 +58,12 @@ struct module_attribute {
        void (*free)(struct module *);
 };
 
+struct module_version_attribute {
+       struct module_attribute mattr;
+       const char *module_name;
+       const char *version;
+};
+
 struct module_kobject
 {
        struct kobject kobj;
@@ -161,7 +167,28 @@ extern struct module __this_module;
   Using this automatically adds a checksum of the .c files and the
   local headers in "srcversion".
 */
+
+#ifdef MODULE
 #define MODULE_VERSION(_version) MODULE_INFO(version, _version)
+#else
+#define MODULE_VERSION(_version)                                       \
+       extern ssize_t __modver_version_show(struct module_attribute *, \
+                                            struct module *, char *);  \
+       static struct module_version_attribute __modver_version_attr    \
+       __used                                                          \
+    __attribute__ ((__section__ ("__modver"),aligned(sizeof(void *)))) \
+       = {                                                             \
+               .mattr  = {                                             \
+                       .attr   = {                                     \
+                               .name   = "version",                    \
+                               .mode   = S_IRUGO,                      \
+                       },                                              \
+                       .show   = __modver_version_show,                \
+               },                                                      \
+               .module_name    = KBUILD_MODNAME,                       \
+               .version        = _version,                             \
+       }
+#endif
 
 /* Optional firmware file (or files) needed by the module
  * format is simply firmware file name.  Multiple firmware

diff --git a/kernel/params.c b/kernel/params.c
index 08107d1817582000af8df78667db22e6d88e5f59..0da1411222b9a2e11c1de4ed228e4028e8aef2b1 100644 (file)
--- a/kernel/params.c
+++ b/kernel/params.c
@@ -719,9 +719,7 @@ void destroy_params(const struct kernel_param *params, unsigned num)
                        params[i].ops->free(params[i].arg);
 }
 
-static void __init kernel_add_sysfs_param(const char *name,
-                                         struct kernel_param *kparam,
-                                         unsigned int name_skip)
+static struct module_kobject * __init locate_module_kobject(const char *name)
 {
        struct module_kobject *mk;
        struct kobject *kobj;
@@ -729,10 +727,7 @@ static void __init kernel_add_sysfs_param(const char *name,
 
        kobj = kset_find_obj(module_kset, name);
        if (kobj) {
-               /* We already have one.  Remove params so we can add more. */
                mk = to_module_kobject(kobj);
-               /* We need to remove it before adding parameters. */
-               sysfs_remove_group(&mk->kobj, &mk->mp->grp);
        } else {
                mk = kzalloc(sizeof(struct module_kobject), GFP_KERNEL);
                BUG_ON(!mk);
@@ -743,15 +738,36 @@ static void __init kernel_add_sysfs_param(const char *name,
                                           "%s", name);
                if (err) {
                        kobject_put(&mk->kobj);
-                       printk(KERN_ERR "Module '%s' failed add to sysfs, "
-                              "error number %d\n", name, err);
-                       printk(KERN_ERR "The system will be unstable now.\n");
-                       return;
+                       printk(KERN_ERR
+                               "Module '%s' failed add to sysfs, error number %d\n",
+                               name, err);
+                       printk(KERN_ERR
+                               "The system will be unstable now.\n");
+                       return NULL;
                }
-               /* So that exit path is even. */
+
+               /* So that we hold reference in both cases. */
                kobject_get(&mk->kobj);
        }
 
+       return mk;
+}
+
+static void __init kernel_add_sysfs_param(const char *name,
+                                         struct kernel_param *kparam,
+                                         unsigned int name_skip)
+{
+       struct module_kobject *mk;
+       int err;
+
+       mk = locate_module_kobject(name);
+       if (!mk)
+               return;
+
+       /* We need to remove old parameters before adding more. */
+       if (mk->mp)
+               sysfs_remove_group(&mk->kobj, &mk->mp->grp);
+
        /* These should not fail at boot. */
        err = add_sysfs_param(mk, kparam, kparam->name + name_skip);
        BUG_ON(err);
@@ -796,6 +812,32 @@ static void __init param_sysfs_builtin(void)
        }
 }
 
+ssize_t __modver_version_show(struct module_attribute *mattr,
+                             struct module *mod, char *buf)
+{
+       struct module_version_attribute *vattr =
+               container_of(mattr, struct module_version_attribute, mattr);
+
+       return sprintf(buf, "%s\n", vattr->version);
+}
+
+extern struct module_version_attribute __start___modver[], __stop___modver[];
+
+static void __init version_sysfs_builtin(void)
+{
+       const struct module_version_attribute *vattr;
+       struct module_kobject *mk;
+       int err;
+
+       for (vattr = __start___modver; vattr < __stop___modver; vattr++) {
+               mk = locate_module_kobject(vattr->module_name);
+               if (mk) {
+                       err = sysfs_create_file(&mk->kobj, &vattr->mattr.attr);
+                       kobject_uevent(&mk->kobj, KOBJ_ADD);
+                       kobject_put(&mk->kobj);
+               }
+       }
+}
 
 /* module-related sysfs stuff */
 
@@ -875,6 +917,7 @@ static int __init param_sysfs_init(void)
        }
        module_sysfs_initialized = 1;
 
+       version_sysfs_builtin();
        param_sysfs_builtin();
 
        return 0;