arm: Put assembly functions into separate sections

This patch changes the ENTRY() macro in asm.h to create a new section
for every assembler function, thus providing dcache_clean/invalidate_all
and friends with the same --gc-sections goodness that our C functions
have. This requires a few minor changes of moving around data (to make
sure it ends up in the right section) and changing some libgcc functions
(which apparently need to have two names?), but nothing serious.

(You may note that some of our assembly functions have data, sometimes
even writable, within the same .text section. This has been this way
before and I'm not looking to change it for now, although it's not
totally clean. Since we don't enforce read-only sections through paging,
it doesn't really hurt.)

BUG=None
TEST=Nyan and Snow still boot. Confirm dcache_invalidate_all is not
output into any binary anymore since no one actually uses it.

Original-Change-Id: I247b29d6173ba516c8dff59126c93b66f7dc4b8d
Original-Signed-off-by: Julius Werner <jwerner@chromium.org>
Original-Reviewed-on: https://chromium-review.googlesource.com/183891
(cherry picked from commit 4a3f2e45e06cc8592d56c3577f41ff879f10e9cc)
Signed-off-by: Marc Jones <marc.jones@se-eng.com>

Change-Id: Ieaa4f2ea9d81c5b9e2b36a772ff9610bdf6446f9
Reviewed-on: http://review.coreboot.org/7451
Tested-by: build bot (Jenkins)
Reviewed-by: David Hendricks <dhendrix@chromium.org>

payloads/libpayload/arch/arm/exception_asm.S

@@ -27,13 +27,7 @@
  * SUCH DAMAGE.
  */
 
-	.global exception_stack_end
-exception_stack_end:
-	.word	0
-
-exception_handler:
-	.word 0
-
+	.text
 
 	.align 6
 	.arm
@@ -88,6 +82,7 @@ exception_common:
 	ldmfd	sp!, { pc }^
 
 
+	.align 2
 _undefined_instruction:	.word exception_undefined_instruction
 _software_interrupt:	.word exception_software_interrupt
 _prefetch_abort:	.word exception_prefetch_abort
@@ -96,6 +91,13 @@ _not_used:		.word exception_not_used
 _irq:			.word exception_irq
 _fiq:			.word exception_fiq
 
+	.global exception_stack_end
+exception_stack_end:
+	.word 0
+
+exception_handler:
+	.word 0
+
 	.thumb
 	.global set_vbar
 	.thumb_func

payloads/libpayload/arch/arm/head.S

@@ -29,10 +29,6 @@
 
 #include <arch/asm.h>
 
-1:
-.align 4
-.word	_stack
-
 /*
  * Our entry point
  */
@@ -43,7 +39,7 @@ ENTRY(_entry)
 	/* TODO: Clear BSS */
 
 	/* Setup new stack */
-	ldr sp, 1b
+	ldr sp, 1f
 
 	/* TODO: Save old stack pointer and link register */
 
@@ -57,3 +53,7 @@ ENTRY(_entry)
 	/* Return to the original context. */
 	bx lr
 ENDPROC(_entry)
+
+.align 4
+1:
+.word	_stack

payloads/libpayload/arch/arm/memcpy.S

@@ -52,8 +52,6 @@
 	ldmfd sp!, {r0, \reg1, \reg2}
 	.endm
 
-	.text
-
 /* Prototype: void *memcpy(void *dest, const void *src, size_t n); */
 
 ENTRY(memcpy)

payloads/libpayload/arch/arm/memmove.S

@@ -13,8 +13,6 @@
 #include <arch/asm.h>
 #include "asmlib.h"
 
-		.text
-
 /*
  * Prototype: void *memmove(void *dest, const void *src, size_t n);
  *

payloads/libpayload/arch/arm/memset.S

@@ -13,9 +13,6 @@
 #include <arch/asm.h>
 #include "asmlib.h"
 
-	.text
-	.align	5
-
 ENTRY(memset)
 	ands	r3, r0, #3		@ 1 unaligned?
 	mov	ip, r0			@ preserve r0 as return value

payloads/libpayload/include/arm/arch/asm.h

@@ -40,16 +40,14 @@
 	END(name)
 
 #define ENTRY(name) \
-	.globl name; \
+	.section .text.name, "ax", %progbits; \
+	.global name; \
 	ALIGN; \
 	name:
 
 #define END(name) \
 	.size name, .-name
 
-/* Everything should go into the text section by default. */
-	.text
-
 /* Thumb code uses the (new) unified assembly syntax. */
 THUMB(	.syntax unified )