generic: add dyn_array support

Allow crazy big arrays via bootmem at init stage.
Architectures use CONFIG_HAVE_DYN_ARRAY to enable it.

usage:

| static struct irq_desc irq_desc_init __initdata = {
|        .status = IRQ_DISABLED,
|        .chip = &no_irq_chip,
|        .handle_irq = handle_bad_irq,
|        .depth = 1,
|        .lock = __SPIN_LOCK_UNLOCKED(irq_desc->lock),
| #ifdef CONFIG_SMP
|        .affinity = CPU_MASK_ALL
| #endif
| };
|
| static void __init init_work(void *data)
| {
|        struct dyn_array *da = data;
|        struct  irq_desc *desc;
|        int i;
|
|        desc = *da->name;
|
|        for (i = 0; i < *da->nr; i++)
|                memcpy(&desc[i], &irq_desc_init, sizeof(struct irq_desc));
| }
|
| struct irq_desc *irq_desc;
| DEFINE_DYN_ARRAY(irq_desc, sizeof(struct irq_desc), nr_irqs, PAGE_SIZE, init_work);

after pre_alloc_dyn_array() after setup_arch(), the array is ready to be
used.

Via this facility we can replace irq_desc[NR_IRQS] array with dyn_array
irq_desc[nr_irqs].

v2: remove _nopanic in pre_alloc_dyn_array()

Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

include/asm-generic/vmlinux.lds.h

@@ -210,6 +210,13 @@
  * All archs are supposed to use RO_DATA() */
 #define RODATA RO_DATA(4096)
 
+#define DYN_ARRAY_INIT(align)							\
+	. = ALIGN((align));						\
+	.dyn_array.init : AT(ADDR(.dyn_array.init) - LOAD_OFFSET) {	\
+		VMLINUX_SYMBOL(__dyn_array_start) = .;			\
+		*(.dyn_array.init)					\
+		VMLINUX_SYMBOL(__dyn_array_end) = .;			\
+	}
 #define SECURITY_INIT							\
 	.security_initcall.init : AT(ADDR(.security_initcall.init) - LOAD_OFFSET) { \
 		VMLINUX_SYMBOL(__security_initcall_start) = .;		\

include/linux/init.h

@@ -246,6 +246,29 @@ struct obs_kernel_param {
 
 /* Relies on boot_command_line being set */
 void __init parse_early_param(void);
+
+struct dyn_array {
+	void **name;
+	unsigned long size;
+	unsigned int *nr;
+	unsigned long align;
+	void (*init_work)(void *);
+};
+extern struct dyn_array *__dyn_array_start[], *__dyn_array_end[];
+
+#define DEFINE_DYN_ARRAY(nameX, sizeX, nrX, alignX, init_workX) \
+		static struct dyn_array __dyn_array_##nameX __initdata = \
+		{	.name = (void **)&nameX,\
+			.size = sizeX,\
+			.nr   = &nrX,\
+			.align = alignX,\
+			.init_work = init_workX,\
+		}; \
+		static struct dyn_array *__dyn_array_ptr_##nameX __used \
+		__attribute__((__section__(".dyn_array.init"))) = \
+			&__dyn_array_##nameX
+
+extern void pre_alloc_dyn_array(void);
 #endif /* __ASSEMBLY__ */
 
 /**

init/main.c

@@ -536,6 +536,29 @@ void __init __weak thread_info_cache_init(void)
 {
 }
 
+void pre_alloc_dyn_array(void)
+{
+#ifdef CONFIG_HAVE_DYN_ARRAY
+	unsigned long size, phys = 0;
+	struct dyn_array **daa;
+
+	for (daa = __dyn_array_start ; daa < __dyn_array_end; daa++) {
+		struct dyn_array *da = *daa;
+
+		size = da->size * (*da->nr);
+		print_fn_descriptor_symbol("dyna_array %s ", da->name);
+		printk(KERN_CONT "size:%#lx nr:%d align:%#lx",
+			da->size, *da->nr, da->align);
+		*da->name = __alloc_bootmem(size, da->align, phys);
+		phys = virt_to_phys(*da->name);
+		printk(KERN_CONT " ==> [%#lx - %#lx]\n", phys, phys + size);
+
+		if (da->init_work)
+			da->init_work(da);
+	}
+#endif
+}
+
 asmlinkage void __init start_kernel(void)
 {
 	char * command_line;
@@ -567,6 +590,7 @@ asmlinkage void __init start_kernel(void)
 	printk(KERN_NOTICE);
 	printk(linux_banner);
 	setup_arch(&command_line);
+	pre_alloc_dyn_array();
 	mm_init_owner(&init_mm, &init_task);
 	setup_command_line(command_line);
 	unwind_setup();