Reduce space lost to object alignment

Currently, sections within .text/.rodata/.data/.bss are emitted in the
order they are seen by the linker. This leads to wasted space, when a
section with a larger alignment follows one with a smaller alignment.
We can avoid this wasted space by sorting the sections.

To take full advantage of this, we must disable generation of common
symbols, so "common" data can be sorted along with the rest of .bss.

An example of the improvement, from `make DEBUG=1 PLAT=sun50i_a64 bl31`:
  .text   => no change
  .rodata => 16 bytes saved
  .data   => 11 bytes saved
  .bss    => 576 bytes saved

As a side effect, the addition of `-fno-common` in TF_CFLAGS makes it
easier to spot bugs in header files.

Signed-off-by: Samuel Holland <samuel@sholland.org>
Change-Id: I073630a9b0b84e7302a7a500d4bb4b547be01d51

6 files changed, 34 insertions, 33 deletions

diff --git a/Makefile b/Makefile
index d634b336b..e10004b70 100644
--- a/Makefile
+++ b/Makefile
@@ -285,8 +285,9 @@ CPPFLAGS		=	${DEFINES} ${INCLUDES} ${MBEDTLS_INC} -nostdinc	\
 ASFLAGS			+=	$(CPPFLAGS) $(ASFLAGS_$(ARCH))			\
 				-ffreestanding -Wa,--fatal-warnings
 TF_CFLAGS		+=	$(CPPFLAGS) $(TF_CFLAGS_$(ARCH))		\
-				-ffreestanding -fno-builtin -std=gnu99		\
-				-Os -ffunction-sections -fdata-sections
+				-ffunction-sections -fdata-sections		\
+				-ffreestanding -fno-builtin -fno-common		\
+				-Os -std=gnu99
 
 ifeq (${SANITIZE_UB},on)
 TF_CFLAGS		+=	-fsanitize=undefined -fno-sanitize-recover
diff --git a/bl1/bl1.ld.S b/bl1/bl1.ld.S
index c4f6b99fc..877af8e01 100644
--- a/bl1/bl1.ld.S
+++ b/bl1/bl1.ld.S
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2013-2018, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2013-2019, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -27,7 +27,7 @@ SECTIONS
     .text . : {
         __TEXT_START__ = .;
         *bl1_entrypoint.o(.text*)
-        *(.text*)
+        *(SORT_BY_ALIGNMENT(.text*))
         *(.vectors)
         . = ALIGN(PAGE_SIZE);
         __TEXT_END__ = .;
@@ -44,7 +44,7 @@ SECTIONS
 
     .rodata . : {
         __RODATA_START__ = .;
-        *(.rodata*)
+        *(SORT_BY_ALIGNMENT(.rodata*))
 
         /* Ensure 8-byte alignment for descriptors and ensure inclusion */
         . = ALIGN(8);
@@ -72,8 +72,8 @@ SECTIONS
     ro . : {
         __RO_START__ = .;
         *bl1_entrypoint.o(.text*)
-        *(.text*)
-        *(.rodata*)
+        *(SORT_BY_ALIGNMENT(.text*))
+        *(SORT_BY_ALIGNMENT(.rodata*))
 
         /* Ensure 8-byte alignment for descriptors and ensure inclusion */
         . = ALIGN(8);
@@ -114,7 +114,7 @@ SECTIONS
      */
     .data . : ALIGN(16) {
         __DATA_RAM_START__ = .;
-        *(.data*)
+        *(SORT_BY_ALIGNMENT(.data*))
         __DATA_RAM_END__ = .;
     } >RAM AT>ROM
 
@@ -131,7 +131,7 @@ SECTIONS
      */
     .bss : ALIGN(16) {
         __BSS_START__ = .;
-        *(.bss*)
+        *(SORT_BY_ALIGNMENT(.bss*))
         *(COMMON)
         __BSS_END__ = .;
     } >RAM
diff --git a/bl2/bl2.ld.S b/bl2/bl2.ld.S
index 30cdf7d78..6230562ed 100644
--- a/bl2/bl2.ld.S
+++ b/bl2/bl2.ld.S
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2013-2018, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2013-2019, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -27,7 +27,7 @@ SECTIONS
     .text . : {
         __TEXT_START__ = .;
         *bl2_entrypoint.o(.text*)
-        *(.text*)
+        *(SORT_BY_ALIGNMENT(.text*))
         *(.vectors)
         . = ALIGN(PAGE_SIZE);
         __TEXT_END__ = .;
@@ -44,7 +44,7 @@ SECTIONS
 
     .rodata . : {
         __RODATA_START__ = .;
-        *(.rodata*)
+        *(SORT_BY_ALIGNMENT(.rodata*))
 
         /* Ensure 8-byte alignment for descriptors and ensure inclusion */
         . = ALIGN(8);
@@ -59,8 +59,8 @@ SECTIONS
     ro . : {
         __RO_START__ = .;
         *bl2_entrypoint.o(.text*)
-        *(.text*)
-        *(.rodata*)
+        *(SORT_BY_ALIGNMENT(.text*))
+        *(SORT_BY_ALIGNMENT(.rodata*))
 
         /* Ensure 8-byte alignment for descriptors and ensure inclusion */
         . = ALIGN(8);
@@ -93,7 +93,7 @@ SECTIONS
      */
     .data . : {
         __DATA_START__ = .;
-        *(.data*)
+        *(SORT_BY_ALIGNMENT(.data*))
         __DATA_END__ = .;
     } >RAM
 
diff --git a/bl2/bl2_el3.ld.S b/bl2/bl2_el3.ld.S
index 82b51a862..dc398eb02 100644
--- a/bl2/bl2_el3.ld.S
+++ b/bl2/bl2_el3.ld.S
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2017-2018, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2017-2019, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -44,7 +44,7 @@ SECTIONS
 	*bl2_el3_entrypoint.o(.text*)
 	*(.text.asm.*)
 	__TEXT_RESIDENT_END__ = .;
-        *(.text*)
+        *(SORT_BY_ALIGNMENT(.text*))
         *(.vectors)
         . = ALIGN(PAGE_SIZE);
         __TEXT_END__ = .;
@@ -52,7 +52,7 @@ SECTIONS
 
     .rodata . : {
         __RODATA_START__ = .;
-        *(.rodata*)
+        *(SORT_BY_ALIGNMENT(.rodata*))
 
         /* Ensure 8-byte alignment for descriptors and ensure inclusion */
         . = ALIGN(8);
@@ -82,8 +82,8 @@ SECTIONS
 	*bl2_el3_entrypoint.o(.text*)
 	*(.text.asm.*)
 	__TEXT_RESIDENT_END__ = .;
-        *(.text*)
-        *(.rodata*)
+        *(SORT_BY_ALIGNMENT(.text*))
+        *(SORT_BY_ALIGNMENT(.rodata*))
 
         /*
          * Ensure 8-byte alignment for cpu_ops so that its fields are also
@@ -135,7 +135,7 @@ SECTIONS
      */
     .data . : {
         __DATA_RAM_START__ = .;
-        *(.data*)
+        *(SORT_BY_ALIGNMENT(.data*))
         __DATA_RAM_END__ = .;
     } >RAM AT>ROM
 
diff --git a/bl2u/bl2u.ld.S b/bl2u/bl2u.ld.S
index 8d4984fbf..8d257cee9 100644
--- a/bl2u/bl2u.ld.S
+++ b/bl2u/bl2u.ld.S
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015-2018, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2015-2019, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -27,7 +27,7 @@ SECTIONS
     .text . : {
         __TEXT_START__ = .;
         *bl2u_entrypoint.o(.text*)
-        *(.text*)
+        *(SORT_BY_ALIGNMENT(.text*))
         *(.vectors)
         . = ALIGN(PAGE_SIZE);
         __TEXT_END__ = .;
@@ -44,7 +44,7 @@ SECTIONS
 
     .rodata . : {
         __RODATA_START__ = .;
-        *(.rodata*)
+        *(SORT_BY_ALIGNMENT(.rodata*))
         . = ALIGN(PAGE_SIZE);
         __RODATA_END__ = .;
     } >RAM
@@ -52,8 +52,8 @@ SECTIONS
     ro . : {
         __RO_START__ = .;
         *bl2u_entrypoint.o(.text*)
-        *(.text*)
-        *(.rodata*)
+        *(SORT_BY_ALIGNMENT(.text*))
+        *(SORT_BY_ALIGNMENT(.rodata*))
 
         *(.vectors)
         __RO_END_UNALIGNED__ = .;
@@ -80,7 +80,7 @@ SECTIONS
      */
     .data . : {
         __DATA_START__ = .;
-        *(.data*)
+        *(SORT_BY_ALIGNMENT(.data*))
         __DATA_END__ = .;
     } >RAM
 
diff --git a/bl31/bl31.ld.S b/bl31/bl31.ld.S
index c7d587cb0..708ee329f 100644
--- a/bl31/bl31.ld.S
+++ b/bl31/bl31.ld.S
@@ -33,7 +33,7 @@ SECTIONS
     .text . : {
         __TEXT_START__ = .;
         *bl31_entrypoint.o(.text*)
-        *(.text*)
+        *(SORT_BY_ALIGNMENT(.text*))
         *(.vectors)
         . = ALIGN(PAGE_SIZE);
         __TEXT_END__ = .;
@@ -41,7 +41,7 @@ SECTIONS
 
     .rodata . : {
         __RODATA_START__ = .;
-        *(.rodata*)
+        *(SORT_BY_ALIGNMENT(.rodata*))
 
         /* Ensure 8-byte alignment for descriptors and ensure inclusion */
         . = ALIGN(8);
@@ -87,8 +87,8 @@ SECTIONS
     ro . : {
         __RO_START__ = .;
         *bl31_entrypoint.o(.text*)
-        *(.text*)
-        *(.rodata*)
+        *(SORT_BY_ALIGNMENT(.text*))
+        *(SORT_BY_ALIGNMENT(.rodata*))
 
         /* Ensure 8-byte alignment for descriptors and ensure inclusion */
         . = ALIGN(8);
@@ -179,7 +179,7 @@ SECTIONS
      */
    .data . : {
         __DATA_START__ = .;
-        *(.data*)
+        *(SORT_BY_ALIGNMENT(.data*))
         __DATA_END__ = .;
     } >RAM
 
@@ -211,7 +211,7 @@ SECTIONS
      */
     .bss (NOLOAD) : ALIGN(16) {
         __BSS_START__ = .;
-        *(.bss*)
+        *(SORT_BY_ALIGNMENT(.bss*))
         *(COMMON)
 #if !USE_COHERENT_MEM
         /*