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Date: Wed, 15 Dec 2010 14:00:19 -0800
From: Dmitry Torokhov <dtor@...are.com>
To: LKML <linux-kernel@...r.kernel.org>
Cc: Rusty Russell <rusty@...tcorp.com.au>
Subject: [PATCH] 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@...are.com>
---
This change is driven by our desire to detect whether vmw_balloon driver
is built-in into the kernel when we installing our tool package in the
guest and avoid installing our own version of the driver.
Since vmw_balloon does not have any module parameter nor registers any
driver core devices, without this patch it is completely invisible from
userspace when built into the kernel.
Thanks,
Dmitry
include/asm-generic/vmlinux.lds.h | 7 ++++
include/linux/module.h | 27 +++++++++++++++
kernel/params.c | 65 ++++++++++++++++++++++++++++++------
3 files changed, 88 insertions(+), 11 deletions(-)
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index bd69d79..0d83dd1 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -355,6 +355,13 @@
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 7575bbb..f74ddda 100644
--- 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__ ((unused,__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 08107d1..0da1411 100644
--- 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;
--
1.7.3.2
--
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