[Blackfin] arch: move the init sections to the end of memory

Move the init sections to the end of memory so that after they
are free, run time memory is all continugous - this should help decrease
memory fragementation.

When doing this, we also pack some of the other sections a little closer
together, to make sure we don't waste memory. To make this happen,
we need to rename the .data.init_task section to .init_task.data, so
it doesn't get picked up by the linker script glob.

Signed-off-by: Mike Frysinger <vapier.adi@gmail.com>
Signed-off-by: Bryan Wu <bryan.wu@analog.com>

3 files changed, 36 insertions, 27 deletions

diff --git a/arch/blackfin/kernel/init_task.c b/arch/blackfin/kernel/init_task.c
index 673c860ffc23..c640154030e2 100644
--- a/arch/blackfin/kernel/init_task.c
+++ b/arch/blackfin/kernel/init_task.c
@@ -57,5 +57,5 @@ EXPORT_SYMBOL(init_task);
  * "init_task" linker map entry.
  */
 union thread_union init_thread_union
-    __attribute__ ((__section__(".data.init_task"))) = {
+    __attribute__ ((__section__(".init_task.data"))) = {
 INIT_THREAD_INFO(init_task)};
diff --git a/arch/blackfin/kernel/setup.c b/arch/blackfin/kernel/setup.c
index aca5e6e5bbdd..060080789495 100644
--- a/arch/blackfin/kernel/setup.c
+++ b/arch/blackfin/kernel/setup.c
@@ -427,7 +427,7 @@ static __init void parse_cmdline_early(char *cmdline_p)
 static __init void  memory_setup(void)
 {
         _rambase = (unsigned long)_stext;
-        _ramstart = (unsigned long)__bss_stop;
+        _ramstart = (unsigned long)_end;
 
         if (DMA_UNCACHED_REGION > (_ramend - _ramstart)) {
                 console_init();
@@ -489,7 +489,7 @@ static __init void  memory_setup(void)
         }
 
         /* Relocate MTD image to the top of memory after the uncached memory area */
-        dma_memcpy((char *)memory_end, __bss_stop, mtd_size);
+        dma_memcpy((char *)memory_end, _end, mtd_size);
 
         memory_mtd_start = memory_end;
         _ebss = memory_mtd_start;       /* define _ebss for compatible */
@@ -528,13 +528,13 @@ static __init void  memory_setup(void)
         printk(KERN_INFO "Board Memory: %ldMB\n", physical_mem_end >> 20);
         printk(KERN_INFO "Kernel Managed Memory: %ldMB\n", _ramend >> 20);
 
-        printk( KERN_INFO "Memory map:\n"
+        printk(KERN_INFO "Memory map:\n"
                 KERN_INFO "  text      = 0x%p-0x%p\n"
                 KERN_INFO "  rodata    = 0x%p-0x%p\n"
+                KERN_INFO "  bss       = 0x%p-0x%p\n"
                 KERN_INFO "  data      = 0x%p-0x%p\n"
                 KERN_INFO "    stack   = 0x%p-0x%p\n"
                 KERN_INFO "  init      = 0x%p-0x%p\n"
-                KERN_INFO "  bss       = 0x%p-0x%p\n"
                 KERN_INFO "  available = 0x%p-0x%p\n"
 #ifdef CONFIG_MTD_UCLINUX
                 KERN_INFO "  rootfs    = 0x%p-0x%p\n"
@@ -544,12 +544,12 @@ static __init void  memory_setup(void)
 #endif
                 , _stext, _etext,
                 __start_rodata, __end_rodata,
+                __bss_start, __bss_stop,
                 _sdata, _edata,
                 (void *)&init_thread_union,
                 (void *)((int)(&init_thread_union) + 0x2000),
-               __init_begin, __init_end,
-               __bss_start, __bss_stop,
-               (void *)_ramstart, (void *)memory_end
+                __init_begin, __init_end,
+                (void *)_ramstart, (void *)memory_end
 #ifdef CONFIG_MTD_UCLINUX
                 , (void *)memory_mtd_start, (void *)(memory_mtd_start + mtd_size)
 #endif
diff --git a/arch/blackfin/kernel/vmlinux.lds.S b/arch/blackfin/kernel/vmlinux.lds.S
index 858722421b40..aed832540b3b 100644
--- a/arch/blackfin/kernel/vmlinux.lds.S
+++ b/arch/blackfin/kernel/vmlinux.lds.S
@@ -41,6 +41,9 @@ _jiffies = _jiffies_64;
 SECTIONS
 {
         . = CONFIG_BOOT_LOAD;
+        /* Neither the text, ro_data or bss section need to be aligned
+         * So pack them back to back
+         */
         .text :
         {
                 __text = .;
@@ -58,22 +61,25 @@ SECTIONS
                 *(__ex_table)
                 ___stop___ex_table = .;
 
-                . = ALIGN(4);
                 __etext = .;
         }
 
-        RO_DATA(PAGE_SIZE)
+        /* Just in case the first read only is a 32-bit access */
+        RO_DATA(4)
+
+        .bss :
+        {
+                . = ALIGN(4);
+                ___bss_start = .;
+                *(.bss .bss.*)
+                *(COMMON)
+                ___bss_stop = .;
+        }
 
         .data :
         {
-                /* make sure the init_task is aligned to the
-                 * kernel thread size so we can locate the kernel
-                 * stack properly and quickly.
-                 */
                 __sdata = .;
-                . = ALIGN(THREAD_SIZE);
-                *(.data.init_task)
-
+                /* This gets done first, so the glob doesn't suck it in */
                 . = ALIGN(32);
                 *(.data.cacheline_aligned)
 
@@ -81,10 +87,22 @@ SECTIONS
                 *(.data.*)
                 CONSTRUCTORS
 
+                /* make sure the init_task is aligned to the
+                 * kernel thread size so we can locate the kernel
+                 * stack properly and quickly.
+                 */
                 . = ALIGN(THREAD_SIZE);
+                *(.init_task.data)
+
                 __edata = .;
         }
 
+        /* The init section should be last, so when we free it, it goes into
+         * the general memory pool, and (hopefully) will decrease fragmentation
+         * a tiny bit. The init section has a _requirement_ that it be
+         * PAGE_SIZE aligned
+         */
+        . = ALIGN(PAGE_SIZE);
         ___init_begin = .;
 
         .init.text :
@@ -179,16 +197,7 @@ SECTIONS
         . = ALIGN(PAGE_SIZE);
         ___init_end = .;
 
-        .bss :
-        {
-                . = ALIGN(4);
-                ___bss_start = .;
-                *(.bss .bss.*)
-                *(COMMON)
-                . = ALIGN(4);
-                ___bss_stop = .;
-                __end = .;
-        }
+        __end =.;
 
         STABS_DEBUG