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 <[e-mail]>
Signed-off-by: Rusty Russell <[e-mail]>

arch/powerpc/mm/hugetlbpage.c

···
 	int i;
 
 	strlcpy(cmdline, boot_command_line, COMMAND_LINE_SIZE);
-	parse_args("hugetlb gpages", cmdline, NULL, 0, &do_gpage_early_setup);
+	parse_args("hugetlb gpages", cmdline, NULL, 0, 0, 0,
+			&do_gpage_early_setup);
 
 	/*
 	 * Walk gpage list in reverse, allocating larger page sizes first.

include/asm-generic/vmlinux.lds.h

···
 		*(.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							\

include/linux/moduleparam.h

···
 	const char *name;
 	const struct kernel_param_ops *ops;
 	u16 perm;
-	u16 flags;
+	s16 level;
 	union {
 		void *arg;
 		const struct kparam_string *str;
···
  * 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
···
 
 /* 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))	\
···
 	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)			\
···
 		 { (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
···
  */
 #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 */
 
 /**
···
 		= { 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")
 
 /**
···
 		      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. */
···
 	__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;

init/main.c

···
 
 void __init parse_early_options(char *cmdline)
 {
-	parse_args("early options", cmdline, NULL, 0, do_early_param);
+	parse_args("early options", cmdline, NULL, 0, 0, 0, do_early_param);
 }
 
 /* Arch code calls this early on, or if not, just before other parsing. */
···
 	parse_early_param();
 	parse_args("Booting kernel", static_command_line, __start___param,
 		   __stop___param - __start___param,
-		   &unknown_bootoption);
+		   0, 0, &unknown_bootoption);
 
 	jump_label_init();
 
···
 }
 
 
-extern initcall_t __initcall_start[], __initcall_end[], __early_initcall_end[];
+extern initcall_t __initcall_start[];
+extern initcall_t __initcall0_start[];
+extern initcall_t __initcall1_start[];
+extern initcall_t __initcall2_start[];
+extern initcall_t __initcall3_start[];
+extern initcall_t __initcall4_start[];
+extern initcall_t __initcall5_start[];
+extern initcall_t __initcall6_start[];
+extern initcall_t __initcall7_start[];
+extern initcall_t __initcall_end[];
+
+static initcall_t *initcall_levels[] __initdata = {
+	__initcall0_start,
+	__initcall1_start,
+	__initcall2_start,
+	__initcall3_start,
+	__initcall4_start,
+	__initcall5_start,
+	__initcall6_start,
+	__initcall7_start,
+	__initcall_end,
+};
+
+static char *initcall_level_names[] __initdata = {
+	"early parameters",
+	"core parameters",
+	"postcore parameters",
+	"arch parameters",
+	"subsys parameters",
+	"fs parameters",
+	"device parameters",
+	"late parameters",
+};
+
+static int __init ignore_unknown_bootoption(char *param, char *val)
+{
+	return 0;
+}
+
+static void __init do_initcall_level(int level)
+{
+	extern const struct kernel_param __start___param[], __stop___param[];
+	initcall_t *fn;
+
+	strcpy(static_command_line, saved_command_line);
+	parse_args(initcall_level_names[level],
+		   static_command_line, __start___param,
+		   __stop___param - __start___param,
+		   level, level,
+		   ignore_unknown_bootoption);
+
+	for (fn = initcall_levels[level]; fn < initcall_levels[level+1]; fn++)
+		do_one_initcall(*fn);
+}
 
 static void __init do_initcalls(void)
 {
-	initcall_t *fn;
+	int level;
 
-	for (fn = __early_initcall_end; fn < __initcall_end; fn++)
-		do_one_initcall(*fn);
+	for (level = 0; level < ARRAY_SIZE(initcall_levels) - 1; level++)
+		do_initcall_level(level);
 }
 
 /*
···
 {
 	initcall_t *fn;
 
-	for (fn = __initcall_start; fn < __early_initcall_end; fn++)
+	for (fn = __initcall_start; fn < __initcall0_start; fn++)
 		do_one_initcall(*fn);
 }
 

kernel/module.c

···
 	mutex_unlock(&module_mutex);
 
 	/* Module is ready to execute: parsing args may do that. */
-	err = parse_args(mod->name, mod->args, mod->kp, mod->num_kp, NULL);
+	err = parse_args(mod->name, mod->args, mod->kp, mod->num_kp,
+			 -32768, 32767, NULL);
 	if (err < 0)
 		goto unlink;
 

kernel/params.c

···
 		     char *val,
 		     const struct kernel_param *params,
 		     unsigned num_params,
+		     s16 min_level,
+		     s16 max_level,
 		     int (*handle_unknown)(char *param, char *val))
 {
 	unsigned int i;
···
 	/* Find parameter */
 	for (i = 0; i < num_params; i++) {
 		if (parameq(param, params[i].name)) {
+			if (params[i].level < min_level
+			    || params[i].level > max_level)
+				return 0;
 			/* No one handled NULL, so do it here. */
 			if (!val && params[i].ops->set != param_set_bool
 			    && params[i].ops->set != param_set_bint)
···
 	       char *args,
 	       const struct kernel_param *params,
 	       unsigned num,
+	       s16 min_level,
+	       s16 max_level,
 	       int (*unknown)(char *param, char *val))
 {
 	char *param, *val;
···
 
 		args = next_arg(args, &param, &val);
 		irq_was_disabled = irqs_disabled();
-		ret = parse_one(param, val, params, num, unknown);
+		ret = parse_one(param, val, params, num,
+				min_level, max_level, unknown);
 		if (irq_was_disabled && !irqs_disabled()) {
 			printk(KERN_WARNING "parse_args(): option '%s' enabled "
 					"irq's!\n", param);
···
 		       unsigned int min, unsigned int max,
 		       void *elem, int elemsize,
 		       int (*set)(const char *, const struct kernel_param *kp),
-		       u16 flags,
+		       s16 level,
 		       unsigned int *num)
 {
 	int ret;
···
 	/* Get the name right for errors. */
 	kp.name = name;
 	kp.arg = elem;
-	kp.flags = flags;
+	kp.level = level;
 
 	*num = 0;
 	/* We expect a comma-separated list of values. */
···
 	unsigned int temp_num;
 
 	return param_array(kp->name, val, 1, arr->max, arr->elem,
-			   arr->elemsize, arr->ops->set, kp->flags,
+			   arr->elemsize, arr->ops->set, kp->level,
 			   arr->num ?: &temp_num);
 }