params: <level>_initcall-like kernel parameters

This patch adds a set of macros that can be used to declare
kernel parameters to be parsed _before_ initcalls at a chosen
level are executed.  We rename the now-unused "flags" field of
struct kernel_param as the level.  It's signed, for when we
use this for early params as well, in future.

Linker macro collating init calls had to be modified in order
to add additional symbols between levels that are later used
by the init code to split the calls into blocks.

Signed-off-by: Pawel Moll <pawel.moll@arm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

2 files changed, 57 insertions, 29 deletions

diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index 798603e8ec3..8aeadf6b553 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -616,30 +616,23 @@
 		*(.init.setup)						\
 		VMLINUX_SYMBOL(__setup_end) = .;
 
-#define INITCALLS							\
-	*(.initcallearly.init)						\
-	VMLINUX_SYMBOL(__early_initcall_end) = .;			\
-  	*(.initcall0.init)						\
-  	*(.initcall0s.init)						\
-  	*(.initcall1.init)						\
-  	*(.initcall1s.init)						\
-  	*(.initcall2.init)						\
-  	*(.initcall2s.init)						\
-  	*(.initcall3.init)						\
-  	*(.initcall3s.init)						\
-  	*(.initcall4.init)						\
-  	*(.initcall4s.init)						\
-  	*(.initcall5.init)						\
-  	*(.initcall5s.init)						\
-	*(.initcallrootfs.init)						\
-  	*(.initcall6.init)						\
-  	*(.initcall6s.init)						\
-  	*(.initcall7.init)						\
-  	*(.initcall7s.init)
+#define INIT_CALLS_LEVEL(level)						\
+		VMLINUX_SYMBOL(__initcall##level##_start) = .;		\
+		*(.initcall##level##.init)				\
+		*(.initcall##level##s.init)				\
 
 #define INIT_CALLS							\
 		VMLINUX_SYMBOL(__initcall_start) = .;			\
-		INITCALLS						\
+		*(.initcallearly.init)					\
+		INIT_CALLS_LEVEL(0)					\
+		INIT_CALLS_LEVEL(1)					\
+		INIT_CALLS_LEVEL(2)					\
+		INIT_CALLS_LEVEL(3)					\
+		INIT_CALLS_LEVEL(4)					\
+		INIT_CALLS_LEVEL(5)					\
+		INIT_CALLS_LEVEL(rootfs)				\
+		INIT_CALLS_LEVEL(6)					\
+		INIT_CALLS_LEVEL(7)					\
 		VMLINUX_SYMBOL(__initcall_end) = .;
 
 #define CON_INITCALL							\
diff --git a/include/linux/moduleparam.h b/include/linux/moduleparam.h
index 4daa895648d..ea36486378d 100644
--- a/include/linux/moduleparam.h
+++ b/include/linux/moduleparam.h
@@ -51,7 +51,7 @@ struct kernel_param {
 	const char *name;
 	const struct kernel_param_ops *ops;
 	u16 perm;
-	u16 flags;
+	s16 level;
 	union {
 		void *arg;
 		const struct kparam_string *str;
@@ -128,7 +128,40 @@ struct kparam_array
  * The ops can have NULL set or get functions.
  */
 #define module_param_cb(name, ops, arg, perm)				      \
-	__module_param_call(MODULE_PARAM_PREFIX, name, ops, arg, perm)
+	__module_param_call(MODULE_PARAM_PREFIX, name, ops, arg, perm, 0)
+
+/**
+ * <level>_param_cb - general callback for a module/cmdline parameter
+ *                    to be evaluated before certain initcall level
+ * @name: a valid C identifier which is the parameter name.
+ * @ops: the set & get operations for this parameter.
+ * @perm: visibility in sysfs.
+ *
+ * The ops can have NULL set or get functions.
+ */
+#define __level_param_cb(name, ops, arg, perm, level)			\
+	__module_param_call(MODULE_PARAM_PREFIX, name, ops, arg, perm, level)
+
+#define core_param_cb(name, ops, arg, perm)		\
+	__level_param_cb(name, ops, arg, perm, 1)
+
+#define postcore_param_cb(name, ops, arg, perm)		\
+	__level_param_cb(name, ops, arg, perm, 2)
+
+#define arch_param_cb(name, ops, arg, perm)		\
+	__level_param_cb(name, ops, arg, perm, 3)
+
+#define subsys_param_cb(name, ops, arg, perm)		\
+	__level_param_cb(name, ops, arg, perm, 4)
+
+#define fs_param_cb(name, ops, arg, perm)		\
+	__level_param_cb(name, ops, arg, perm, 5)
+
+#define device_param_cb(name, ops, arg, perm)		\
+	__level_param_cb(name, ops, arg, perm, 6)
+
+#define late_param_cb(name, ops, arg, perm)		\
+	__level_param_cb(name, ops, arg, perm, 7)
 
 /* On alpha, ia64 and ppc64 relocations to global data cannot go into
    read-only sections (which is part of respective UNIX ABI on these
@@ -142,7 +175,7 @@ struct kparam_array
 
 /* This is the fundamental function for registering boot/module
    parameters. */
-#define __module_param_call(prefix, name, ops, arg, perm)		\
+#define __module_param_call(prefix, name, ops, arg, perm, level)	\
 	/* Default value instead of permissions? */			\
 	static int __param_perm_check_##name __attribute__((unused)) =	\
 	BUILD_BUG_ON_ZERO((perm) < 0 || (perm) > 0777 || ((perm) & 2))	\
@@ -151,7 +184,7 @@ struct kparam_array
 	static struct kernel_param __moduleparam_const __param_##name	\
 	__used								\
     __attribute__ ((unused,__section__ ("__param"),aligned(sizeof(void *)))) \
-	= { __param_str_##name, ops, perm, 0, { arg } }
+	= { __param_str_##name, ops, perm, level, { arg } }
 
 /* Obsolete - use module_param_cb() */
 #define module_param_call(name, set, get, arg, perm)			\
@@ -159,7 +192,7 @@ struct kparam_array
 		 { (void *)set, (void *)get };				\
 	__module_param_call(MODULE_PARAM_PREFIX,			\
 			    name, &__param_ops_##name, arg,		\
-			    (perm) + sizeof(__check_old_set_param(set))*0)
+			    (perm) + sizeof(__check_old_set_param(set))*0, 0)
 
 /* We don't get oldget: it's often a new-style param_get_uint, etc. */
 static inline int
@@ -239,7 +272,7 @@ static inline void __kernel_param_unlock(void)
  */
 #define core_param(name, var, type, perm)				\
 	param_check_##type(name, &(var));				\
-	__module_param_call("", name, &param_ops_##type, &var, perm)
+	__module_param_call("", name, &param_ops_##type, &var, perm, 0)
 #endif /* !MODULE */
 
 /**
@@ -257,7 +290,7 @@ static inline void __kernel_param_unlock(void)
 		= { len, string };					\
 	__module_param_call(MODULE_PARAM_PREFIX, name,			\
 			    &param_ops_string,				\
-			    .str = &__param_string_##name, perm);	\
+			    .str = &__param_string_##name, perm, 0);	\
 	__MODULE_PARM_TYPE(name, "string")
 
 /**
@@ -285,6 +318,8 @@ extern int parse_args(const char *name,
 		      char *args,
 		      const struct kernel_param *params,
 		      unsigned num,
+		      s16 level_min,
+		      s16 level_max,
 		      int (*unknown)(char *param, char *val));
 
 /* Called by module remove. */
@@ -396,7 +431,7 @@ extern int param_set_bint(const char *val, const struct kernel_param *kp);
 	__module_param_call(MODULE_PARAM_PREFIX, name,			\
 			    &param_array_ops,				\
 			    .arr = &__param_arr_##name,			\
-			    perm);					\
+			    perm, 0);					\
 	__MODULE_PARM_TYPE(name, "array of " #type)
 
 extern struct kernel_param_ops param_array_ops;