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>

2 files changed, 30 insertions, 0 deletions

diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index 7440a0dceddb..7881406c03ec 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/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) = .;          \
diff --git a/include/linux/init.h b/include/linux/init.h
index 93538b696e3d..cf9fa7f174af 100644
--- a/include/linux/init.h
+++ b/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__ */
 
 /**