ARM: Define custom ELF headers for ARM.

At least when building with the gnu toolchain, the headers the linker
automatically generate save space for the actual ELF headers in one of the
loadable segments. This creates two problems. First, the data you intended to
be at the start of the image doesn't actually show up there, it's actually the
ELF headers. Second, the ELF headers are essentially useless for firmware
since there's currently nothing to tell you where they are, and even if there
was, there isn't much of a reason to look at them. They're useful in userspace
for, for instance, the dynamic linker, but not really in firmware.

This change adds a PHDRS construct to each of the linker scripts used on ARM
which define a single segment called to_load which does not have the flag set
which would tell the linker to put headers in it. The first section defined in
the script has ": to_load" to tell the linker which segment to put it in, and
from that point on the other sections go in there by default.

Change-Id: I24b721eb436d17afd234002ae82f9166d2fcf65d
Signed-off-by: Gabe Black <gabeblack@chromium.org>
Reviewed-on: http://review.coreboot.org/3580
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>

src/arch/armv7/bootblock.lds

@@ -22,6 +22,11 @@
 OUTPUT_FORMAT("elf32-littlearm", "elf32-littlearm", "elf32-littlearm")
 OUTPUT_ARCH(arm)
 
+PHDRS
+{
+	to_load PT_LOAD;
+}
+
 TARGET(binary)
 SECTIONS
 {
@@ -39,7 +44,7 @@ SECTIONS
 		*(.rom.data.*);
 		*(.rodata.*);
 		_erom = .;
-	} = 0xff
+	} : to_load = 0xff
 
 	/DISCARD/ : {
 		*(.comment)

src/arch/armv7/coreboot_ram.ld

@@ -24,6 +24,11 @@ INCLUDE ldoptions
 
 ENTRY(stage_entry)
 
+PHDRS
+{
+	to_load PT_LOAD;
+}
+
 SECTIONS
 {
 	. = CONFIG_SYS_SDRAM_BASE;
@@ -38,7 +43,7 @@ SECTIONS
 		*(.text.*);
 		. = ALIGN(16);
 		_etext = .;
-	}
+	} : to_load
 
 	.ctors : {
 		. = ALIGN(0x100);

src/arch/armv7/romstage.ld

@@ -30,6 +30,11 @@ OUTPUT_ARCH(arm)
 
 ENTRY(stage_entry)
 
+PHDRS
+{
+	to_load PT_LOAD;
+}
+
 SECTIONS
 {
 	/* TODO make this a configurable option (per chipset). */
@@ -41,7 +46,7 @@ SECTIONS
 		*(.text.stage_entry.armv7);
 		*(.text.startup);
 		*(.text);
-	}
+	} : to_load
 
 	.romdata . : {
 		*(.rodata);