[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>

1 files changed, 28 insertions, 19 deletions

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